def __init__(self, hosts='127.0.0.1:2181',
timeout=10.0, client_id=None, handler=None,
default_acl=None, auth_data=None, read_only=None,
randomize_hosts=True, connection_retry=None,
command_retry=None, logger=None, **kwargs):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
:param connection_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
retrying the connection to Zookeeper. Also can be a dict of
options which will be used for creating one.
:param command_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
the :meth:`KazooClient.retry` method. Also can be a dict of
options which will be used for creating one.
:param logger: A custom logger to use instead of the module
global `log` instance.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
.. versionadded:: 1.2
The connection_retry, command_retry and logger options.
"""
self.logger = logger or log
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts = None
self.chroot = None
self.set_hosts(hosts)
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = self._conn_retry = None
if type(connection_retry) is dict:
self._conn_retry = KazooRetry(**connection_retry)
elif type(connection_retry) is KazooRetry:
self._conn_retry = connection_retry
if type(command_retry) is dict:
self.retry = KazooRetry(**command_retry)
elif type(command_retry) is KazooRetry:
self.retry = command_retry
if type(self._conn_retry) is KazooRetry:
if self.handler.sleep_func != self._conn_retry.sleep_func:
raise ConfigurationError("Retry handler and event handler "
" must use the same sleep func")
if type(self.retry) is KazooRetry:
if self.handler.sleep_func != self.retry.sleep_func:
raise ConfigurationError("Command retry handler and event "
"handler must use the same sleep func")
if self.retry is None or self._conn_retry is None:
old_retry_keys = dict(_RETRY_COMPAT_DEFAULTS)
for key in old_retry_keys:
try:
old_retry_keys[key] = kwargs.pop(key)
warnings.warn('Passing retry configuration param %s to the'
' client directly is deprecated, please pass a'
' configured retry object (using param %s)' % (
key, _RETRY_COMPAT_MAPPING[key]),
DeprecationWarning, stacklevel=2)
except KeyError:
pass
retry_keys = {}
for oldname, value in old_retry_keys.items():
retry_keys[_RETRY_COMPAT_MAPPING[oldname]] = value
if self._conn_retry is None:
self._conn_retry = KazooRetry(
sleep_func=self.handler.sleep_func,
**retry_keys)
if self.retry is None:
self.retry = KazooRetry(
sleep_func=self.handler.sleep_func,
**retry_keys)
self._conn_retry.interrupt = lambda: self._stopped.is_set()
self._connection = ConnectionHandler(self, self._conn_retry.copy(),
logger=self.logger)
# Every retry call should have its own copy of the retry helper
# to avoid shared retry counts
self._retry = self.retry
def _retry(*args, **kwargs):
return self._retry.copy()(*args, **kwargs)
self.retry = _retry
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
# If we got any unhandled keywords, complain like python would
if kwargs:
raise TypeError('__init__() got unexpected keyword arguments: %s'
% (kwargs.keys(),))
class KazooClient(object):
"""An Apache Zookeeper Python client supporting alternate callback
handlers and high-level functionality.
Watch functions registered with this class will not get session
events, unlike the default Zookeeper watches. They will also be
called with a single argument, a
:class:`~kazoo.protocol.states.WatchedEvent` instance.
"""
def __init__(self, hosts='127.0.0.1:2181',
timeout=10.0, client_id=None, handler=None,
default_acl=None, auth_data=None, read_only=None,
randomize_hosts=True, connection_retry=None,
command_retry=None, logger=None, **kwargs):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
:param connection_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
retrying the connection to Zookeeper. Also can be a dict of
options which will be used for creating one.
:param command_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
the :meth:`KazooClient.retry` method. Also can be a dict of
options which will be used for creating one.
:param logger: A custom logger to use instead of the module
global `log` instance.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
.. versionadded:: 1.2
The connection_retry, command_retry and logger options.
"""
self.logger = logger or log
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts = None
self.chroot = None
self.set_hosts(hosts)
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = self._conn_retry = None
if type(connection_retry) is dict:
self._conn_retry = KazooRetry(**connection_retry)
elif type(connection_retry) is KazooRetry:
self._conn_retry = connection_retry
if type(command_retry) is dict:
self.retry = KazooRetry(**command_retry)
elif type(command_retry) is KazooRetry:
self.retry = command_retry
if type(self._conn_retry) is KazooRetry:
if self.handler.sleep_func != self._conn_retry.sleep_func:
raise ConfigurationError("Retry handler and event handler "
" must use the same sleep func")
if type(self.retry) is KazooRetry:
if self.handler.sleep_func != self.retry.sleep_func:
raise ConfigurationError("Command retry handler and event "
"handler must use the same sleep func")
if self.retry is None or self._conn_retry is None:
old_retry_keys = dict(_RETRY_COMPAT_DEFAULTS)
for key in old_retry_keys:
try:
old_retry_keys[key] = kwargs.pop(key)
warnings.warn('Passing retry configuration param %s to the'
' client directly is deprecated, please pass a'
' configured retry object (using param %s)' % (
key, _RETRY_COMPAT_MAPPING[key]),
DeprecationWarning, stacklevel=2)
except KeyError:
pass
retry_keys = {}
for oldname, value in old_retry_keys.items():
retry_keys[_RETRY_COMPAT_MAPPING[oldname]] = value
if self._conn_retry is None:
self._conn_retry = KazooRetry(
sleep_func=self.handler.sleep_func,
**retry_keys)
if self.retry is None:
self.retry = KazooRetry(
sleep_func=self.handler.sleep_func,
**retry_keys)
self._conn_retry.interrupt = lambda: self._stopped.is_set()
self._connection = ConnectionHandler(self, self._conn_retry.copy(),
logger=self.logger)
# Every retry call should have its own copy of the retry helper
# to avoid shared retry counts
self._retry = self.retry
def _retry(*args, **kwargs):
return self._retry.copy()(*args, **kwargs)
self.retry = _retry
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
# If we got any unhandled keywords, complain like python would
if kwargs:
raise TypeError('__init__() got unexpected keyword arguments: %s'
% (kwargs.keys(),))
def _reset(self):
"""Resets a variety of client states for a new connection."""
self._queue = deque()
self._pending = deque()
self._reset_watchers()
self._reset_session()
self.last_zxid = 0
self._protocol_version = None
def _reset_watchers(self):
self._child_watchers = defaultdict(set)
self._data_watchers = defaultdict(set)
def _reset_session(self):
self._session_id = None
self._session_passwd = b'\x00' * 16
@property
def client_state(self):
"""Returns the last Zookeeper client state
This is the non-simplified state information and is generally
not as useful as the simplified KazooState information.
"""
return self._state
@property
def client_id(self):
"""Returns the client id for this Zookeeper session if
connected.
:returns: client id which consists of the session id and
password.
:rtype: tuple
"""
if self._live.is_set():
return (self._session_id, self._session_passwd)
return None
@property
def connected(self):
"""Returns whether the Zookeeper connection has been
established."""
return self._live.is_set()
def set_hosts(self, hosts, randomize_hosts=None):
""" sets the list of hosts used by this client.
This function accepts the same format hosts parameter as the init
function and sets the client to use the new hosts the next time it
needs to look up a set of hosts. This function does not affect the
current connected status.
It is not currently possible to change the chroot with this function,
setting a host list with a new chroot will raise a ConfigurationError.
:param hosts: see description in :meth:`KazooClient.__init__`
:param randomize_hosts: override client default for host randomization
:raises:
:exc:`ConfigurationError` if the hosts argument changes the chroot
.. versionadded:: 1.4
.. warning::
Using this function to point a client to a completely disparate
zookeeper server cluster has undefined behavior.
"""
if randomize_hosts is None:
randomize_hosts = self.randomize_hosts
self.hosts, chroot = collect_hosts(hosts, randomize_hosts)
if chroot:
new_chroot = normpath(chroot)
else:
new_chroot = ''
if self.chroot is not None and new_chroot != self.chroot:
raise ConfigurationError("Changing chroot at runtime is not "
"currently supported")
self.chroot = new_chroot
def add_listener(self, listener):
"""Add a function to be called for connection state changes.
This function will be called with a
:class:`~kazoo.protocol.states.KazooState` instance indicating
the new connection state on state transitions.
.. warning::
This function must not block. If its at all likely that it
might need data or a value that could result in blocking
than the :meth:`~kazoo.interfaces.IHandler.spawn` method
should be used so that the listener can return immediately.
"""
if not (listener and callable(listener)):
raise ConfigurationError("listener must be callable")
self.state_listeners.add(listener)
def remove_listener(self, listener):
"""Remove a listener function"""
self.state_listeners.discard(listener)
def _make_state_change(self, state):
# skip if state is current
if self.state == state:
return
self.state = state
# Create copy of listeners for iteration in case one needs to
# remove itself
for listener in list(self.state_listeners):
try:
remove = listener(state)
if remove is True:
self.remove_listener(listener)
except Exception:
self.logger.exception("Error in connection state listener")
def _session_callback(self, state):
if state == self._state:
return
# Note that we don't check self.state == LOST since that's also
# the client's initial state
dead_state = self._state in LOST_STATES
self._state = state
# If we were previously closed or had an expired session, and
# are now connecting, don't bother with the rest of the
# transitions since they only apply after
# we've established a connection
if dead_state and state == KeeperState.CONNECTING:
self.logger.log(BLATHER, "Skipping state change")
return
if state in (KeeperState.CONNECTED, KeeperState.CONNECTED_RO):
self.logger.info("Zookeeper connection established, state: %s", state)
self._live.set()
self._make_state_change(KazooState.CONNECTED)
elif state in LOST_STATES:
self.logger.info("Zookeeper session lost, state: %s", state)
self._live.clear()
self._make_state_change(KazooState.LOST)
self._notify_pending(state)
self._reset()
else:
self.logger.info("Zookeeper connection lost")
# Connection lost
self._live.clear()
self._notify_pending(state)
self._make_state_change(KazooState.SUSPENDED)
self._reset_watchers()
def _notify_pending(self, state):
"""Used to clear a pending response queue and request queue
during connection drops."""
if state == KeeperState.AUTH_FAILED:
exc = AuthFailedError()
elif state == KeeperState.EXPIRED_SESSION:
exc = SessionExpiredError()
else:
exc = ConnectionLoss()
while True:
try:
request, async_object, xid = self._pending.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
while True:
try:
request, async_object = self._queue.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
def _safe_close(self):
self.handler.stop()
timeout = self._session_timeout // 1000
if timeout < 10:
timeout = 10
if not self._connection.stop(timeout):
raise WriterNotClosedException(
"Writer still open from prior connection "
"and wouldn't close after %s seconds" % timeout)
def _call(self, request, async_object):
"""Ensure there's an active connection and put the request in
the queue if there is.
Returns False if the call short circuits due to AUTH_FAILED,
CLOSED, EXPIRED_SESSION or CONNECTING state.
"""
if self._state == KeeperState.AUTH_FAILED:
async_object.set_exception(AuthFailedError())
return False
elif self._state == KeeperState.CLOSED:
async_object.set_exception(ConnectionClosedError(
"Connection has been closed"))
return False
elif self._state in (KeeperState.EXPIRED_SESSION,
KeeperState.CONNECTING):
async_object.set_exception(SessionExpiredError())
return False
self._queue.append((request, async_object))
# wake the connection, guarding against a race with close()
write_pipe = self._connection._write_pipe
if write_pipe is None:
async_object.set_exception(ConnectionClosedError(
"Connection has been closed"))
try:
os.write(write_pipe, b'\0')
except:
async_object.set_exception(ConnectionClosedError(
"Connection has been closed"))
def start(self, timeout=15):
"""Initiate connection to ZK.
:param timeout: Time in seconds to wait for connection to
succeed.
:raises: :attr:`~kazoo.interfaces.IHandler.timeout_exception`
if the connection wasn't established within `timeout`
seconds.
"""
event = self.start_async()
event.wait(timeout=timeout)
if not self.connected:
# We time-out, ensure we are disconnected
self.stop()
raise self.handler.timeout_exception("Connection time-out")
if self.chroot and not self.exists("/"):
warnings.warn("No chroot path exists, the chroot path "
"should be created before normal use.")
def start_async(self):
"""Asynchronously initiate connection to ZK.
:returns: An event object that can be checked to see if the
connection is alive.
:rtype: :class:`~threading.Event` compatible object.
"""
# If we're already connected, ignore
if self._live.is_set():
return self._live
# Make sure we're safely closed
self._safe_close()
# We've been asked to connect, clear the stop and our writer
# thread indicator
self._stopped.clear()
self._writer_stopped.clear()
# Start the handler
self.handler.start()
# Start the connection
self._connection.start()
return self._live
def stop(self):
"""Gracefully stop this Zookeeper session.
This method can be called while a reconnection attempt is in
progress, which will then be halted.
Once the connection is closed, its session becomes invalid. All
the ephemeral nodes in the ZooKeeper server associated with the
session will be removed. The watches left on those nodes (and
on their parents) will be triggered.
"""
if self._stopped.is_set():
return
self._stopped.set()
self._queue.append((CloseInstance, None))
os.write(self._connection._write_pipe, b'\0')
self._safe_close()
def restart(self):
"""Stop and restart the Zookeeper session."""
self.stop()
self.start()
def close(self):
"""Free any resources held by the client.
This method should be called on a stopped client before it is
discarded. Not doing so may result in filehandles being leaked.
.. versionadded:: 1.0
"""
self._connection.close()
def command(self, cmd=b'ruok'):
"""Sent a management command to the current ZK server.
Examples are `ruok`, `envi` or `stat`.
:returns: An unstructured textual response.
:rtype: str
:raises:
:exc:`ConnectionLoss` if there is no connection open, or
possibly a :exc:`socket.error` if there's a problem with
the connection used just for this command.
.. versionadded:: 0.5
"""
if not self._live.is_set():
raise ConnectionLoss("No connection to server")
peer = self._connection._socket.getpeername()
sock = self.handler.create_connection(
peer, timeout=self._session_timeout / 1000.0)
sock.sendall(cmd)
result = sock.recv(8192)
sock.close()
return result.decode('utf-8', 'replace')
def server_version(self):
"""Get the version of the currently connected ZK server.
:returns: The server version, for example (3, 4, 3).
:rtype: tuple
.. versionadded:: 0.5
"""
data = self.command(b'envi')
string = ENVI_VERSION.match(data).group(1)
return tuple([int(i) for i in string.split('.')])
def add_auth(self, scheme, credential):
"""Send credentials to server.
:param scheme: authentication scheme (default supported:
"digest").
:param credential: the credential -- value depends on scheme.
:returns: True if it was successful.
:rtype: bool
:raises:
:exc:`~kazoo.exceptions.AuthFailedError` if it failed though
the session state will be set to AUTH_FAILED as well.
"""
return self.add_auth_async(scheme, credential).get()
def add_auth_async(self, scheme, credential):
"""Asynchronously send credentials to server. Takes the same
arguments as :meth:`add_auth`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(scheme, basestring):
raise TypeError("Invalid type for scheme")
if not isinstance(credential, basestring):
raise TypeError("Invalid type for credential")
# we need this auth data to re-authenticate on reconnect
self.auth_data.add((scheme, credential))
async_result = self.handler.async_result()
self._call(Auth(0, scheme, credential), async_result)
return async_result
def unchroot(self, path):
"""Strip the chroot if applicable from the path."""
if not self.chroot:
return path
if path.startswith(self.chroot):
return path[len(self.chroot):]
else:
return path
def sync_async(self, path):
"""Asynchronous sync.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
async_result = self.handler.async_result()
self._call(Sync(_prefix_root(self.chroot, path)), async_result)
return async_result
def sync(self, path):
"""Sync, blocks until response is acknowledged.
Flushes channel between process and leader.
:param path: path of node.
:returns: The node path that was synced.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.sync_async(path).get()
def create(self, path, value=b"", acl=None, ephemeral=False,
sequence=False, makepath=False):
"""Create a node with the given value as its data. Optionally
set an ACL on the node.
The ephemeral and sequence arguments determine the type of the
node.
An ephemeral node will be automatically removed by ZooKeeper
when the session associated with the creation of the node
expires.
A sequential node will be given the specified path plus a
suffix `i` where i is the current sequential number of the
node. The sequence number is always fixed length of 10 digits,
0 padded. Once such a node is created, the sequential number
will be incremented by one.
If a node with the same actual path already exists in
ZooKeeper, a NodeExistsError will be raised. Note that since a
different actual path is used for each invocation of creating
sequential nodes with the same path argument, the call will
never raise NodeExistsError.
If the parent node does not exist in ZooKeeper, a NoNodeError
will be raised. Setting the optional `makepath` argument to
`True` will create all missing parent nodes instead.
An ephemeral node cannot have children. If the parent node of
the given path is ephemeral, a NoChildrenForEphemeralsError
will be raised.
This operation, if successful, will trigger all the watches
left on the node of the given path by :meth:`exists` and
:meth:`get` API calls, and the watches left on the parent node
by :meth:`get_children` API calls.
The maximum allowable size of the node value is 1 MB. Values
larger than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: Initial bytes value of node.
:param acl: :class:`~kazoo.security.ACL` list.
:param ephemeral: Boolean indicating whether node is ephemeral
(tied to this session).
:param sequence: Boolean indicating whether path is suffixed
with a unique index.
:param makepath: Whether the path should be created if it
doesn't exist.
:returns: Real path of the new node.
:rtype: str
:raises:
:exc:`~kazoo.exceptions.NodeExistsError` if the node
already exists.
:exc:`~kazoo.exceptions.NoNodeError` if parent nodes are
missing.
:exc:`~kazoo.exceptions.NoChildrenForEphemeralsError` if
the parent node is an ephemeral node.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
acl = acl or self.default_acl
return self.create_async(path, value, acl=acl, ephemeral=ephemeral,
sequence=sequence, makepath=makepath).get()
def create_async(self, path, value=b"", acl=None, ephemeral=False,
sequence=False, makepath=False):
"""Asynchronously create a ZNode. Takes the same arguments as
:meth:`create`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
.. versionadded:: 1.1
The makepath option.
"""
if acl is None and self.default_acl:
acl = self.default_acl
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if acl and (isinstance(acl, ACL) or
not isinstance(acl, (tuple, list))):
raise TypeError("acl must be a tuple/list of ACL's")
if value is not None and not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(ephemeral, bool):
raise TypeError("ephemeral must be a bool")
if not isinstance(sequence, bool):
raise TypeError("sequence must be a bool")
if not isinstance(makepath, bool):
raise TypeError("makepath must be a bool")
flags = 0
if ephemeral:
flags |= 1
if sequence:
flags |= 2
if acl is None:
acl = OPEN_ACL_UNSAFE
async_result = self.handler.async_result()
@capture_exceptions(async_result)
def do_create():
result = self._create_async_inner(path, value, acl, flags, trailing=sequence)
result.rawlink(create_completion)
@capture_exceptions(async_result)
def retry_completion(result):
result.get()
do_create()
@wrap(async_result)
def create_completion(result):
try:
return self.unchroot(result.get())
except NoNodeError:
if not makepath:
raise
if sequence and path.endswith('/'):
parent = path.rstrip('/')
else:
parent, _ = split(path)
self.ensure_path_async(parent, acl).rawlink(retry_completion)
do_create()
return async_result
def _create_async_inner(self, path, value, acl, flags, trailing=False):
async_result = self.handler.async_result()
call_result = self._call(
Create(_prefix_root(self.chroot, path, trailing=trailing),
value, acl, flags), async_result)
if call_result is False:
# We hit a short-circuit exit on the _call. Because we are
# not using the original async_result here, we bubble the
# exception upwards to the do_create function in
# KazooClient.create so that it gets set on the correct
# async_result object
raise async_result.exception
return async_result
def ensure_path(self, path, acl=None):
"""Recursively create a path if it doesn't exist.
:param path: Path of node.
:param acl: Permissions for node.
"""
return self.ensure_path_async(path, acl).get()
def ensure_path_async(self, path, acl=None):
"""Recursively create a path asynchronously if it doesn't
exist. Takes the same arguments as :meth:`ensure_path`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
.. versionadded:: 1.1
"""
acl = acl or self.default_acl
async_result = self.handler.async_result()
@wrap(async_result)
def create_completion(result):
try:
return result.get()
except NodeExistsError:
return True
@capture_exceptions(async_result)
def prepare_completion(next_path, result):
result.get()
self.create_async(next_path, acl=acl).rawlink(create_completion)
@wrap(async_result)
def exists_completion(path, result):
if result.get():
return True
parent, node = split(path)
if node:
self.ensure_path_async(parent, acl=acl).rawlink(
partial(prepare_completion, path))
else:
self.create_async(path, acl=acl).rawlink(create_completion)
self.exists_async(path).rawlink(partial(exists_completion, path))
return async_result
def exists(self, path, watch=None):
"""Check if a node exists.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that creates/deletes the node or sets the data on the
node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns: ZnodeStat of the node if it exists, else None if the
node does not exist.
:rtype: :class:`~kazoo.protocol.states.ZnodeStat` or `None`.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.exists_async(path, watch).get()
def exists_async(self, path, watch=None):
"""Asynchronously check if a node exists. Takes the same
arguments as :meth:`exists`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(Exists(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get(self, path, watch=None):
"""Get the value of a node.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that sets data on the node, or deletes the node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns:
Tuple (value, :class:`~kazoo.protocol.states.ZnodeStat`) of
node.
:rtype: tuple
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
"""
return self.get_async(path, watch).get()
def get_async(self, path, watch=None):
"""Asynchronously get the value of a node. Takes the same
arguments as :meth:`get`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(GetData(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get_children(self, path, watch=None, include_data=False):
"""Get a list of child nodes of a path.
If a watch is provided it will be left on the node with the
given path. The watch will be triggered by a successful
operation that deletes the node of the given path or
creates/deletes a child under the node.
The list of children returned is not sorted and no guarantee is
provided as to its natural or lexical order.
:param path: Path of node to list.
:param watch: Optional watch callback to set for future changes
to this path.
:param include_data:
Include the :class:`~kazoo.protocol.states.ZnodeStat` of
the node in addition to the children. This option changes
the return value to be a tuple of (children, stat).
:returns: List of child node names, or tuple if `include_data`
is `True`.
:rtype: list
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
The `include_data` option.
"""
return self.get_children_async(path, watch, include_data).get()
def get_children_async(self, path, watch=None, include_data=False):
"""Asynchronously get a list of child nodes of a path. Takes
the same arguments as :meth:`get_children`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
if not isinstance(include_data, bool):
raise TypeError("include_data must be a bool")
async_result = self.handler.async_result()
if include_data:
req = GetChildren2(_prefix_root(self.chroot, path), watch)
else:
req = GetChildren(_prefix_root(self.chroot, path), watch)
self._call(req, async_result)
return async_result
def get_acls(self, path):
"""Return the ACL and stat of the node of the given path.
:param path: Path of the node.
:returns: The ACL array of the given node and its
:class:`~kazoo.protocol.states.ZnodeStat`.
:rtype: tuple of (:class:`~kazoo.security.ACL` list,
:class:`~kazoo.protocol.states.ZnodeStat`)
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
.. versionadded:: 0.5
"""
return self.get_acls_async(path).get()
def get_acls_async(self, path):
"""Return the ACL and stat of the node of the given path. Takes
the same arguments as :meth:`get_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
async_result = self.handler.async_result()
self._call(GetACL(_prefix_root(self.chroot, path)), async_result)
return async_result
def set_acls(self, path, acls, version=-1):
"""Set the ACL for the node of the given path.
Set the ACL for the node of the given path if such a node
exists and the given version matches the version of the node.
:param path: Path for the node.
:param acls: List of :class:`~kazoo.security.ACL` objects to
set.
:param version: The expected node version that must match.
:returns: The stat of the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.InvalidACLError` if the ACL is
invalid.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.set_acls_async(path, acls, version).get()
def set_acls_async(self, path, acls, version=-1):
"""Set the ACL for the node of the given path. Takes the same
arguments as :meth:`set_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if isinstance(acls, ACL) or not isinstance(acls, (tuple, list)):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetACL(_prefix_root(self.chroot, path), acls, version),
async_result)
return async_result
def set(self, path, value, version=-1):
"""Set the value of a node.
If the version of the node being updated is newer than the
supplied version (and the supplied version is not -1), a
BadVersionError will be raised.
This operation, if successful, will trigger all the watches on
the node of the given path left by :meth:`get` API calls.
The maximum allowable size of the value is 1 MB. Values larger
than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: New data value.
:param version: Version of node being updated, or -1.
:returns: Updated :class:`~kazoo.protocol.states.ZnodeStat` of
the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.set_async(path, value, version).get()
def set_async(self, path, value, version=-1):
"""Set the value of a node. Takes the same arguments as
:meth:`set`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if value is not None and not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetData(_prefix_root(self.chroot, path), value, version),
async_result)
return async_result
def transaction(self):
"""Create and return a :class:`TransactionRequest` object
Creates a :class:`TransactionRequest` object. A Transaction can
consist of multiple operations which can be committed as a
single atomic unit. Either all of the operations will succeed
or none of them.
:returns: A TransactionRequest.
:rtype: :class:`TransactionRequest`
.. versionadded:: 0.6
Requires Zookeeper 3.4+
"""
return TransactionRequest(self)
def delete(self, path, version=-1, recursive=False):
"""Delete a node.
The call will succeed if such a node exists, and the given
version matches the node's version (if the given version is -1,
the default, it matches any node's versions).
This operation, if successful, will trigger all the watches on
the node of the given path left by `exists` API calls, and the
watches on the parent node left by `get_children` API calls.
:param path: Path of node to delete.
:param version: Version of node to delete, or -1 for any.
:param recursive: Recursively delete node and all its children,
defaults to False.
:type recursive: bool
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.NotEmptyError` if the node has
children.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
if not isinstance(recursive, bool):
raise TypeError("recursive must be a bool")
if recursive:
return self._delete_recursive(path)
else:
return self.delete_async(path, version).get()
def delete_async(self, path, version=-1):
"""Asynchronously delete a node. Takes the same arguments as
:meth:`delete`, with the exception of `recursive`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(Delete(_prefix_root(self.chroot, path), version),
async_result)
return async_result
def _delete_recursive(self, path):
try:
children = self.get_children(path)
except NoNodeError:
return True
if children:
for child in children:
if path == "/":
child_path = path + child
else:
child_path = path + "/" + child
self._delete_recursive(child_path)
try:
self.delete(path)
except NoNodeError: # pragma: nocover
pass
class KazooClient(object):
"""An Apache Zookeeper Python client supporting alternate callback
handlers and high-level functionality.
Watch functions registered with this class will not get session
events, unlike the default Zookeeper watches. They will also be
called with a single argument, a
:class:`~kazoo.protocol.states.WatchedEvent` instance.
"""
def __init__(self, hosts='127.0.0.1:2181', watcher=None,
timeout=10.0, client_id=None, max_retries=None, retry_delay=0.1,
retry_backoff=2, retry_jitter=0.8, handler=None,
default_acl=None, auth_data=None, read_only=None):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182).
:param watcher:
Set a default watcher. This will be called by the actual
default watcher that :class:`KazooClient` establishes.
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param max_retries: Maximum retries when using the
:meth:`KazooClient.retry` method.
:param retry_delay: Initial delay when retrying a call.
:param retry_backoff:
Backoff multiplier between retry attempts. Defaults to 2
for exponential back-off.
:param retry_jitter:
How much jitter delay to introduce per call. An amount of
time up to this will be added per retry call to avoid
hammering the server.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
Retry parameters will be used for connection establishment
attempts and reconnects.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
"""
self.log_debug = logging.DEBUG >= log.getEffectiveLevel()
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.hosts, chroot = collect_hosts(hosts)
if chroot:
self.chroot = normpath(chroot)
else:
self.chroot = ''
# Curator like simplified state tracking, and listeners for
# state transitions
self._state_lock = self.handler.rlock_object()
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._session_id = None
self._session_passwd = str(bytearray([0] * 16))
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = KazooRetry(
max_tries=max_retries,
delay=retry_delay,
backoff=retry_backoff,
max_jitter=retry_jitter,
sleep_func=self.handler.sleep_func
)
self.retry_sleeper = self.retry.retry_sleeper.copy()
self._connection = ConnectionHandler(
self, self.retry.retry_sleeper.copy(), log_debug=self.log_debug)
# convenience API
from kazoo.recipe.barrier import Barrier
from kazoo.recipe.barrier import DoubleBarrier
from kazoo.recipe.election import Election
from kazoo.recipe.lock import Lock
from kazoo.recipe.partitioner import SetPartitioner
from kazoo.recipe.party import Party
from kazoo.recipe.party import ShallowParty
from kazoo.recipe.watchers import ChildrenWatch
from kazoo.recipe.watchers import DataWatch
self.Barrier = partial(Barrier, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.ShallowParty = partial(ShallowParty, self)
def _reset(self):
"""Resets a variety of client states for a new connection."""
with self._state_lock:
self._queue = self.handler.peekable_queue()
self._pending = self.handler.peekable_queue()
self._child_watchers = defaultdict(list)
self._data_watchers = defaultdict(list)
self._session_id = None
self._session_passwd = str(bytearray([0] * 16))
self.last_zxid = 0
@property
def client_state(self):
"""Returns the last Zookeeper client state
This is the non-simplified state information and is generally
not as useful as the simplified KazooState information.
"""
return self._state
@property
def client_id(self):
"""Returns the client id for this Zookeeper session if
connected.
:returns: client id which consists of the session id and
password.
:rtype: tuple
"""
if self._live.is_set():
return (self._session_id, self._session_passwd)
return None
@property
def connected(self):
"""Returns whether the Zookeeper connection has been
established."""
return self._live.is_set()
def add_listener(self, listener):
"""Add a function to be called for connection state changes.
This function will be called with a
:class:`~kazoo.protocol.states.KazooState` instance indicating
the new connection state on state transitions.
.. warning::
This function must not block. If its at all likely that it
might need data or a value that could result in blocking
than the :meth:`~kazoo.interfaces.IHandler.spawn` method
should be used so that the listener can return immediately.
"""
if not (listener and callable(listener)):
raise ConfigurationError("listener must be callable")
self.state_listeners.add(listener)
def remove_listener(self, listener):
"""Remove a listener function"""
self.state_listeners.discard(listener)
def _make_state_change(self, state):
# skip if state is current
if self.state == state:
return
self.state = state
# Create copy of listeners for iteration in case one needs to
# remove itself
for listener in list(self.state_listeners):
try:
remove = listener(state)
if remove is True:
self.remove_listener(listener)
except Exception:
log.exception("Error in connection state listener")
def _session_callback(self, state):
if state == self._state:
return
# Note that we don't check self.state == LOST since thats also
# the clients initial state
dead_state = self._state in LOST_STATES
self._state = state
# If we were previously closed or had an expired session, and
# are now connecting, don't bother with the rest of the
# transitions since they only apply after
# we've established a connection
if dead_state and state == KeeperState.CONNECTING:
return
if state in (KeeperState.CONNECTED, KeeperState.CONNECTED_RO):
log.info("Zookeeper connection established, state: %s",
state)
self._live.set()
self._make_state_change(KazooState.CONNECTED)
elif state in LOST_STATES:
log.info("Zookeeper session lost, state: %s", state)
self._live.clear()
self._make_state_change(KazooState.LOST)
self._notify_pending(state)
self._reset()
else:
log.info("Zookeeper connection lost")
# Connection lost
self._live.clear()
self._notify_pending(state)
self._make_state_change(KazooState.SUSPENDED)
def _notify_pending(self, state):
"""Used to clear a pending response queue and request queue
during connection drops."""
if state == KeeperState.AUTH_FAILED:
exc = AuthFailedError()
elif state == KeeperState.EXPIRED_SESSION:
exc = SessionExpiredError()
else:
exc = ConnectionLoss()
while not self._pending.empty():
request, async_object, xid = self._pending.get()
if async_object:
async_object.set_exception(exc)
while not self._queue.empty():
request, async_object = self._queue.get()
if async_object:
async_object.set_exception(exc)
def _safe_close(self):
self.handler.stop()
if not self._connection.stop(10):
raise Exception("Writer still open from prior connection"
" and wouldn't close after 10 seconds")
def _call(self, request, async_object):
"""Ensure there's an active connection and put the request in
the queue if there is."""
with self._state_lock:
if self._state == KeeperState.AUTH_FAILED:
raise AuthFailedError()
elif self._state == KeeperState.CLOSED:
raise ConnectionClosedError("Connection has been closed")
elif self._state in (KeeperState.EXPIRED_SESSION,
KeeperState.CONNECTING):
raise SessionExpiredError()
self._queue.put((request, async_object))
def start(self, timeout=15):
"""Initiate connection to ZK.
:param timeout: Time in seconds to wait for connection to
succeed.
:raises: :attr:`~kazoo.interfaces.IHandler.timeout_exception`
if the connection wasn't established within `timeout`
seconds.
"""
event = self.start_async()
event.wait(timeout=timeout)
if not self.connected:
# We time-out, ensure we are disconnected
self.stop()
raise self.handler.timeout_exception("Connection time-out")
def start_async(self):
"""Asynchronously initiate connection to ZK.
:returns: An event object that can be checked to see if the
connection is alive.
:rtype: :class:`~threading.Event` compatible object.
"""
# If we're already connected, ignore
if self._live.is_set():
return self._live
# Make sure we're safely closed
self._safe_close()
# We've been asked to connect, clear the stop and our writer
# thread indicator
self._stopped.clear()
self._writer_stopped.clear()
# Start the handler
self.handler.start()
# Start the connection
self._connection.start()
return self._live
def stop(self):
"""Gracefully stop this Zookeeper session.
This method can be called while a reconnection attempt is in
progress, which will then be halted.
Once the connection is closed, its session becomes invalid. All
the ephemeral nodes in the ZooKeeper server associated with the
session will be removed. The watches left on those nodes (and
on their parents) will be triggered.
"""
if self._stopped.is_set():
return
self._stopped.set()
self._queue.put((Close(), None))
self._safe_close()
def restart(self):
"""Stop and restart the Zookeeper session."""
self.stop()
self.start()
def command(self, cmd=b'ruok'):
"""Sent a management command to the current ZK server.
Examples are `ruok`, `envi` or `stat`.
:returns: An unstructured textual response.
:rtype: unicode
:raises:
:exc:`ConnectionLoss` if there is no connection open, or
possibly a :exc:`socket.error` if there's a problem with
the connection used just for this command.
.. versionadded:: 0.5
"""
if not self._live.is_set():
raise ConnectionLoss("No connection to server")
sock = self.handler.socket()
sock.settimeout(self._session_timeout)
peer = self._connection._socket.getpeername()
sock.connect(peer)
sock.sendall(cmd)
result = sock.recv(8192)
sock.close()
return result.decode('utf-8', 'replace')
def server_version(self):
"""Get the version of the currently connected ZK server.
:returns: The server version, for example (3, 4, 3).
:rtype: tuple
.. versionadded:: 0.5
"""
data = self.command(b'envi')
string = ENVI_VERSION.match(data).group(1)
return tuple([int(i) for i in string.split('.')])
def add_auth(self, scheme, credential):
"""Send credentials to server.
:param scheme: authentication scheme (default supported:
"digest").
:param credential: the credential -- value depends on scheme.
"""
return self.add_auth_async(scheme, credential)
def add_auth_async(self, scheme, credential):
"""Asynchronously send credentials to server. Takes the same
arguments as :meth:`add_auth`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(scheme, basestring):
raise TypeError("Invalid type for scheme")
if not isinstance(credential, basestring):
raise TypeError("Invalid type for credential")
self._call(Auth(0, scheme, credential), None)
return True
def unchroot(self, path):
"""Strip the chroot if applicable from the path."""
if not self.chroot:
return path
if path.startswith(self.chroot):
return path[len(self.chroot):]
else:
return path
def sync_async(self, path):
"""Asynchronous sync.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
async_result = self.handler.async_result()
self._call(Sync(_prefix_root(self.chroot, path)), async_result)
return async_result
def sync(self, path):
"""Sync, blocks until response is acknowledged.
Flushes channel between process and leader.
:param path: path of node.
:returns: The node path that was synced.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.sync_async(path).get()
def create(self, path, value="", acl=None, ephemeral=False,
sequence=False, makepath=False):
"""Create a node with the given value as its data. Optionally
set an ACL on the node.
The ephemeral and sequence arguments determine the type of the
node.
An ephemeral node will be automatically removed by ZooKeeper
when the session associated with the creation of the node
expires.
A sequential node will be given the specified path plus a
suffix `i` where i is the current sequential number of the
node. The sequence number is always fixed length of 10 digits,
0 padded. Once such a node is created, the sequential number
will be incremented by one.
If a node with the same actual path already exists in
ZooKeeper, a NodeExistsError will be raised. Note that since a
different actual path is used for each invocation of creating
sequential nodes with the same path argument, the call will
never raise NodeExistsError.
If the parent node does not exist in ZooKeeper, a NoNodeError
will be raised. Setting the optional `makepath` argument to
`True` will create all missing parent nodes instead.
An ephemeral node cannot have children. If the parent node of
the given path is ephemeral, a NoChildrenForEphemeralsError
will be raised.
This operation, if successful, will trigger all the watches
left on the node of the given path by :meth:`exists` and
:meth:`get` API calls, and the watches left on the parent node
by :meth:`get_children` API calls.
The maximum allowable size of the node value is 1 MB. Values
larger than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: Initial bytes value of node.
:param acl: :class:`~kazoo.security.ACL` list.
:param ephemeral: Boolean indicating whether node is ephemeral
(tied to this session).
:param sequence: Boolean indicating whether path is suffixed
with a unique index.
:param makepath: Whether the path should be created if it
doesn't exist.
:returns: Real path of the new node.
:rtype: str
:raises:
:exc:`~kazoo.exceptions.NodeExistsError` if the node
already exists.
:exc:`~kazoo.exceptions.NoNodeError` if parent nodes are
missing.
:exc:`~kazoo.exceptions.NoChildrenForEphemeralsError` if
the parent node is an ephemeral node.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
try:
realpath = self.create_async(path, value, acl=acl,
ephemeral=ephemeral, sequence=sequence).get()
except NoNodeError:
# some or all of the parent path doesn't exist. if makepath is set
# we will create it and retry. If it fails again, someone must be
# actively deleting ZNodes and we'd best bail out.
if not makepath:
raise
parent, _ = split(path)
# using the inner call directly because path is already namespaced
self._inner_ensure_path(parent, acl)
# now retry
realpath = self.create_async(path, value, acl=acl,
ephemeral=ephemeral, sequence=sequence).get()
return self.unchroot(realpath)
def create_async(self, path, value="", acl=None, ephemeral=False,
sequence=False):
"""Asynchronously create a ZNode. Takes the same arguments as
:meth:`create`, with the exception of `makepath`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if acl is None and self.default_acl:
acl = self.default_acl
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if acl and (isinstance(acl, ACL) or
not isinstance(acl, (tuple, list))):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(value, str):
raise TypeError("value must be a byte string")
if not isinstance(ephemeral, bool):
raise TypeError("ephemeral must be a bool")
if not isinstance(sequence, bool):
raise TypeError("sequence must be a bool")
flags = 0
if ephemeral:
flags |= 1
if sequence:
flags |= 2
if acl is None:
acl = OPEN_ACL_UNSAFE
async_result = self.handler.async_result()
self._call(Create(_prefix_root(self.chroot, path), value, acl, flags),
async_result)
return async_result
def ensure_path(self, path, acl=None):
"""Recursively create a path if it doesn't exist.
:param path: Path of node.
:param acl: Permissions for node.
"""
self._inner_ensure_path(path, acl)
def _inner_ensure_path(self, path, acl):
if self.exists(path):
return
if acl is None and self.default_acl:
acl = self.default_acl
parent, node = split(path)
if node:
self._inner_ensure_path(parent, acl)
try:
self.create_async(path, "", acl=acl).get()
except NodeExistsError:
# someone else created the node. how sweet!
pass
def exists(self, path, watch=None):
"""Check if a node exists.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that creates/deletes the node or sets the data on the
node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns: ZnodeStat of the node if it exists, else None if the
node does not exist.
:rtype: :class:`~kazoo.protocol.states.ZnodeStat` or `None`.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.exists_async(path, watch).get()
def exists_async(self, path, watch=None):
"""Asynchronously check if a node exists. Takes the same
arguments as :meth:`exists`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(Exists(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get(self, path, watch=None):
"""Get the value of a node.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that sets data on the node, or deletes the node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns:
Tuple (value, :class:`~kazoo.protocol.states.ZnodeStat`) of
node.
:rtype: tuple
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
"""
return self.get_async(path, watch).get()
def get_async(self, path, watch=None):
"""Asynchronously get the value of a node. Takes the same
arguments as :meth:`get`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(GetData(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get_children(self, path, watch=None, include_data=False):
"""Get a list of child nodes of a path.
If a watch is provided it will be left on the node with the
given path. The watch will be triggered by a successful
operation that deletes the node of the given path or
creates/deletes a child under the node.
The list of children returned is not sorted and no guarantee is
provided as to its natural or lexical order.
:param path: Path of node to list.
:param watch: Optional watch callback to set for future changes
to this path.
:param include_data:
Include the :class:`~kazoo.protocol.states.ZnodeStat` of
the node in addition to the children. This option changes
the return value to be a tuple of (children, stat).
:returns: List of child node names, or tuple if `include_data`
is `True`.
:rtype: list
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
The `include_data` option.
"""
return self.get_children_async(path, watch, include_data).get()
def get_children_async(self, path, watch=None, include_data=False):
"""Asynchronously get a list of child nodes of a path. Takes
the same arguments as :meth:`get_children`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
if not isinstance(include_data, bool):
raise TypeError("include_data must be a bool")
async_result = self.handler.async_result()
if include_data:
req = GetChildren2(_prefix_root(self.chroot, path), watch)
else:
req = GetChildren(_prefix_root(self.chroot, path), watch)
self._call(req, async_result)
return async_result
def get_acls(self, path):
"""Return the ACL and stat of the node of the given path.
:param path: Path of the node.
:returns: The ACL array of the given node and its
:class:`~kazoo.protocol.states.ZnodeStat`.
:rtype: tuple of (:class:`~kazoo.security.ACL` list,
:class:`~kazoo.protocol.states.ZnodeStat`)
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
.. versionadded:: 0.5
"""
return self.get_acls_async(path).get()
def get_acls_async(self, path):
"""Return the ACL and stat of the node of the given path. Takes
the same arguments as :meth:`get_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
async_result = self.handler.async_result()
self._call(GetACL(_prefix_root(self.chroot, path)), async_result)
return async_result
def set_acls(self, path, acls, version=-1):
"""Set the ACL for the node of the given path.
Set the ACL for the node of the given path if such a node
exists and the given version matches the version of the node.
:param path: Path for the node.
:param acls: List of :class:`~kazoo.security.ACL` objects to
set.
:param version: The expected node version that must match.
:returns: The stat of the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.InvalidACLError` if the ACL is
invalid.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.set_acls_async(path, acls, version).get()
def set_acls_async(self, path, acls, version=-1):
"""Set the ACL for the node of the given path. Takes the same
arguments as :meth:`set_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if isinstance(acls, ACL) or not isinstance(acls, (tuple, list)):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetACL(_prefix_root(self.chroot, path), acls, version),
async_result)
return async_result
def set(self, path, data, version=-1):
"""Set the value of a node.
If the version of the node being updated is newer than the
supplied version (and the supplied version is not -1), a
BadVersionError will be raised.
This operation, if successful, will trigger all the watches on
the node of the given path left by :meth:`get` API calls.
The maximum allowable size of the value is 1 MB. Values larger
than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param data: New data value.
:param version: Version of node being updated, or -1.
:returns: Updated :class:`~kazoo.protocol.states.ZnodeStat` of
the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.set_async(path, data, version).get()
def set_async(self, path, data, version=-1):
"""Set the value of a node. Takes the same arguments as
:meth:`set`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(data, basestring):
raise TypeError("data must be a string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetData(_prefix_root(self.chroot, path), data, version),
async_result)
return async_result
def transaction(self):
"""Create and return a :class:`TransactionRequest` object
Creates a :class:`TransactionRequest` object. A Transaction can
consist of multiple operations which can be committed as a
single atomic unit. Either all of the operations will succeed
or none of them.
:returns: A TransactionRequest.
:rtype: :class:`TransactionRequest`
"""
return TransactionRequest(self)
def delete(self, path, version=-1, recursive=False):
"""Delete a node.
The call will succeed if such a node exists, and the given
version matches the node's version (if the given version is -1,
the default, it matches any node's versions).
This operation, if successful, will trigger all the watches on
the node of the given path left by `exists` API calls, and the
watches on the parent node left by `get_children` API calls.
:param path: Path of node to delete.
:param version: Version of node to delete, or -1 for any.
:param recursive: Recursively delete node and all its children,
defaults to False.
:type recursive: bool
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.NotEmptyError` if the node has
children.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
if not isinstance(recursive, bool):
raise TypeError("recursive must be a bool")
if recursive:
return self._delete_recursive(path)
else:
return self.delete_async(path, version).get()
def delete_async(self, path, version=-1):
"""Asynchronously delete a node. Takes the same arguments as
:meth:`delete`, with the exception of `recursive`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(Delete(_prefix_root(self.chroot, path), version),
async_result)
return async_result
def _delete_recursive(self, path):
try:
children = self.get_children(path)
except NoNodeError:
return True
if children:
for child in children:
if path == "/":
child_path = path + child
else:
child_path = path + "/" + child
self._delete_recursive(child_path)
try:
self.delete(path)
except NoNodeError: # pragma: nocover
pass
def __init__(self, hosts='127.0.0.1:2181', watcher=None,
timeout=10.0, client_id=None, max_retries=None, retry_delay=0.1,
retry_backoff=2, retry_jitter=0.8, handler=None,
default_acl=None, auth_data=None, read_only=None):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182).
:param watcher:
Set a default watcher. This will be called by the actual
default watcher that :class:`KazooClient` establishes.
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param max_retries: Maximum retries when using the
:meth:`KazooClient.retry` method.
:param retry_delay: Initial delay when retrying a call.
:param retry_backoff:
Backoff multiplier between retry attempts. Defaults to 2
for exponential back-off.
:param retry_jitter:
How much jitter delay to introduce per call. An amount of
time up to this will be added per retry call to avoid
hammering the server.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
Retry parameters will be used for connection establishment
attempts and reconnects.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
"""
self.log_debug = logging.DEBUG >= log.getEffectiveLevel()
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.hosts, chroot = collect_hosts(hosts)
if chroot:
self.chroot = normpath(chroot)
else:
self.chroot = ''
# Curator like simplified state tracking, and listeners for
# state transitions
self._state_lock = self.handler.rlock_object()
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._session_id = None
self._session_passwd = str(bytearray([0] * 16))
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = KazooRetry(
max_tries=max_retries,
delay=retry_delay,
backoff=retry_backoff,
max_jitter=retry_jitter,
sleep_func=self.handler.sleep_func
)
self.retry_sleeper = self.retry.retry_sleeper.copy()
self._connection = ConnectionHandler(
self, self.retry.retry_sleeper.copy(), log_debug=self.log_debug)
# convenience API
from kazoo.recipe.barrier import Barrier
from kazoo.recipe.barrier import DoubleBarrier
from kazoo.recipe.election import Election
from kazoo.recipe.lock import Lock
from kazoo.recipe.partitioner import SetPartitioner
from kazoo.recipe.party import Party
from kazoo.recipe.party import ShallowParty
from kazoo.recipe.watchers import ChildrenWatch
from kazoo.recipe.watchers import DataWatch
self.Barrier = partial(Barrier, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.ShallowParty = partial(ShallowParty, self)
def __init__(self,
hosts='127.0.0.1:2181',
timeout=10.0,
client_id=None,
handler=None,
default_acl=None,
auth_data=None,
read_only=None,
randomize_hosts=True,
connection_retry=None,
command_retry=None,
logger=None,
**kwargs):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
:param connection_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
retrying the connection to Zookeeper. Also can be a dict of
options which will be used for creating one.
:param command_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
the :meth:`KazooClient.retry` method. Also can be a dict of
options which will be used for creating one.
:param logger: A custom logger to use instead of the module
global `log` instance.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
.. versionadded:: 1.2
The connection_retry, command_retry and logger options.
"""
self.logger = logger or log
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts = None
self.chroot = None
self.set_hosts(hosts)
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = self._conn_retry = None
if type(connection_retry) is dict:
self._conn_retry = KazooRetry(**connection_retry)
elif type(connection_retry) is KazooRetry:
self._conn_retry = connection_retry
if type(command_retry) is dict:
self.retry = KazooRetry(**command_retry)
elif type(command_retry) is KazooRetry:
self.retry = command_retry
if type(self._conn_retry) is KazooRetry:
if self.handler.sleep_func != self._conn_retry.sleep_func:
raise ConfigurationError("Retry handler and event handler "
" must use the same sleep func")
if type(self.retry) is KazooRetry:
if self.handler.sleep_func != self.retry.sleep_func:
raise ConfigurationError(
"Command retry handler and event "
"handler must use the same sleep func")
if self.retry is None or self._conn_retry is None:
old_retry_keys = dict(_RETRY_COMPAT_DEFAULTS)
for key in old_retry_keys:
try:
old_retry_keys[key] = kwargs.pop(key)
warnings.warn(
'Passing retry configuration param %s to the'
' client directly is deprecated, please pass a'
' configured retry object (using param %s)' %
(key, _RETRY_COMPAT_MAPPING[key]),
DeprecationWarning,
stacklevel=2)
except KeyError:
pass
retry_keys = {}
for oldname, value in old_retry_keys.items():
retry_keys[_RETRY_COMPAT_MAPPING[oldname]] = value
if self._conn_retry is None:
self._conn_retry = KazooRetry(
sleep_func=self.handler.sleep_func, **retry_keys)
if self.retry is None:
self.retry = KazooRetry(sleep_func=self.handler.sleep_func,
**retry_keys)
self._conn_retry.interrupt = lambda: self._stopped.is_set()
self._connection = ConnectionHandler(self,
self._conn_retry.copy(),
logger=self.logger)
# Every retry call should have its own copy of the retry helper
# to avoid shared retry counts
self._retry = self.retry
def _retry(*args, **kwargs):
return self._retry.copy()(*args, **kwargs)
self.retry = _retry
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
# If we got any unhandled keywords, complain like python would
if kwargs:
raise TypeError('__init__() got unexpected keyword arguments: %s' %
(kwargs.keys(), ))
class KazooClient(object):
"""An Apache Zookeeper Python client supporting alternate callback
handlers and high-level functionality.
Watch functions registered with this class will not get session
events, unlike the default Zookeeper watches. They will also be
called with a single argument, a
:class:`~kazoo.protocol.states.WatchedEvent` instance.
"""
def __init__(self,
hosts='127.0.0.1:2181',
timeout=10.0,
client_id=None,
handler=None,
default_acl=None,
auth_data=None,
read_only=None,
randomize_hosts=True,
connection_retry=None,
command_retry=None,
logger=None,
**kwargs):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
:param connection_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
retrying the connection to Zookeeper. Also can be a dict of
options which will be used for creating one.
:param command_retry:
A :class:`kazoo.retry.KazooRetry` object to use for
the :meth:`KazooClient.retry` method. Also can be a dict of
options which will be used for creating one.
:param logger: A custom logger to use instead of the module
global `log` instance.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
.. versionadded:: 1.2
The connection_retry, command_retry and logger options.
"""
self.logger = logger or log
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts = None
self.chroot = None
self.set_hosts(hosts)
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = self._conn_retry = None
if type(connection_retry) is dict:
self._conn_retry = KazooRetry(**connection_retry)
elif type(connection_retry) is KazooRetry:
self._conn_retry = connection_retry
if type(command_retry) is dict:
self.retry = KazooRetry(**command_retry)
elif type(command_retry) is KazooRetry:
self.retry = command_retry
if type(self._conn_retry) is KazooRetry:
if self.handler.sleep_func != self._conn_retry.sleep_func:
raise ConfigurationError("Retry handler and event handler "
" must use the same sleep func")
if type(self.retry) is KazooRetry:
if self.handler.sleep_func != self.retry.sleep_func:
raise ConfigurationError(
"Command retry handler and event "
"handler must use the same sleep func")
if self.retry is None or self._conn_retry is None:
old_retry_keys = dict(_RETRY_COMPAT_DEFAULTS)
for key in old_retry_keys:
try:
old_retry_keys[key] = kwargs.pop(key)
warnings.warn(
'Passing retry configuration param %s to the'
' client directly is deprecated, please pass a'
' configured retry object (using param %s)' %
(key, _RETRY_COMPAT_MAPPING[key]),
DeprecationWarning,
stacklevel=2)
except KeyError:
pass
retry_keys = {}
for oldname, value in old_retry_keys.items():
retry_keys[_RETRY_COMPAT_MAPPING[oldname]] = value
if self._conn_retry is None:
self._conn_retry = KazooRetry(
sleep_func=self.handler.sleep_func, **retry_keys)
if self.retry is None:
self.retry = KazooRetry(sleep_func=self.handler.sleep_func,
**retry_keys)
self._conn_retry.interrupt = lambda: self._stopped.is_set()
self._connection = ConnectionHandler(self,
self._conn_retry.copy(),
logger=self.logger)
# Every retry call should have its own copy of the retry helper
# to avoid shared retry counts
self._retry = self.retry
def _retry(*args, **kwargs):
return self._retry.copy()(*args, **kwargs)
self.retry = _retry
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
# If we got any unhandled keywords, complain like python would
if kwargs:
raise TypeError('__init__() got unexpected keyword arguments: %s' %
(kwargs.keys(), ))
def _reset(self):
"""Resets a variety of client states for a new connection."""
self._queue = deque()
self._pending = deque()
self._reset_watchers()
self._reset_session()
self.last_zxid = 0
self._protocol_version = None
def _reset_watchers(self):
self._child_watchers = defaultdict(set)
self._data_watchers = defaultdict(set)
def _reset_session(self):
self._session_id = None
self._session_passwd = b'\x00' * 16
@property
def client_state(self):
"""Returns the last Zookeeper client state
This is the non-simplified state information and is generally
not as useful as the simplified KazooState information.
"""
return self._state
@property
def client_id(self):
"""Returns the client id for this Zookeeper session if
connected.
:returns: client id which consists of the session id and
password.
:rtype: tuple
"""
if self._live.is_set():
return (self._session_id, self._session_passwd)
return None
@property
def connected(self):
"""Returns whether the Zookeeper connection has been
established."""
return self._live.is_set()
def set_hosts(self, hosts, randomize_hosts=None):
""" sets the list of hosts used by this client.
This function accepts the same format hosts parameter as the init
function and sets the client to use the new hosts the next time it
needs to look up a set of hosts. This function does not affect the
current connected status.
It is not currently possible to change the chroot with this function,
setting a host list with a new chroot will raise a ConfigurationError.
:param hosts: see description in :meth:`KazooClient.__init__`
:param randomize_hosts: override client default for host randomization
:raises:
:exc:`ConfigurationError` if the hosts argument changes the chroot
.. versionadded:: 1.4
.. warning::
Using this function to point a client to a completely disparate
zookeeper server cluster has undefined behavior.
"""
if randomize_hosts is None:
randomize_hosts = self.randomize_hosts
self.hosts, chroot = collect_hosts(hosts, randomize_hosts)
if chroot:
new_chroot = normpath(chroot)
else:
new_chroot = ''
if self.chroot is not None and new_chroot != self.chroot:
raise ConfigurationError("Changing chroot at runtime is not "
"currently supported")
self.chroot = new_chroot
def add_listener(self, listener):
"""Add a function to be called for connection state changes.
This function will be called with a
:class:`~kazoo.protocol.states.KazooState` instance indicating
the new connection state on state transitions.
.. warning::
This function must not block. If its at all likely that it
might need data or a value that could result in blocking
than the :meth:`~kazoo.interfaces.IHandler.spawn` method
should be used so that the listener can return immediately.
"""
if not (listener and callable(listener)):
raise ConfigurationError("listener must be callable")
self.state_listeners.add(listener)
def remove_listener(self, listener):
"""Remove a listener function"""
self.state_listeners.discard(listener)
def _make_state_change(self, state):
# skip if state is current
if self.state == state:
return
self.state = state
# Create copy of listeners for iteration in case one needs to
# remove itself
for listener in list(self.state_listeners):
try:
remove = listener(state)
if remove is True:
self.remove_listener(listener)
except Exception:
self.logger.exception("Error in connection state listener")
def _session_callback(self, state):
if state == self._state:
return
# Note that we don't check self.state == LOST since that's also
# the client's initial state
dead_state = self._state in LOST_STATES
self._state = state
# If we were previously closed or had an expired session, and
# are now connecting, don't bother with the rest of the
# transitions since they only apply after
# we've established a connection
if dead_state and state == KeeperState.CONNECTING:
self.logger.log(BLATHER, "Skipping state change")
return
if state in (KeeperState.CONNECTED, KeeperState.CONNECTED_RO):
self.logger.info("Zookeeper connection established, state: %s",
state)
self._live.set()
self._make_state_change(KazooState.CONNECTED)
elif state in LOST_STATES:
self.logger.info("Zookeeper session lost, state: %s", state)
self._live.clear()
self._make_state_change(KazooState.LOST)
self._notify_pending(state)
self._reset()
else:
self.logger.info("Zookeeper connection lost")
# Connection lost
self._live.clear()
self._notify_pending(state)
self._make_state_change(KazooState.SUSPENDED)
self._reset_watchers()
def _notify_pending(self, state):
"""Used to clear a pending response queue and request queue
during connection drops."""
if state == KeeperState.AUTH_FAILED:
exc = AuthFailedError()
elif state == KeeperState.EXPIRED_SESSION:
exc = SessionExpiredError()
else:
exc = ConnectionLoss()
while True:
try:
request, async_object, xid = self._pending.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
while True:
try:
request, async_object = self._queue.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
def _safe_close(self):
self.handler.stop()
timeout = self._session_timeout // 1000
if timeout < 10:
timeout = 10
if not self._connection.stop(timeout):
raise WriterNotClosedException(
"Writer still open from prior connection "
"and wouldn't close after %s seconds" % timeout)
def _call(self, request, async_object):
"""Ensure there's an active connection and put the request in
the queue if there is.
Returns False if the call short circuits due to AUTH_FAILED,
CLOSED, EXPIRED_SESSION or CONNECTING state.
"""
if self._state == KeeperState.AUTH_FAILED:
async_object.set_exception(AuthFailedError())
return False
elif self._state == KeeperState.CLOSED:
async_object.set_exception(
ConnectionClosedError("Connection has been closed"))
return False
elif self._state in (KeeperState.EXPIRED_SESSION,
KeeperState.CONNECTING):
async_object.set_exception(SessionExpiredError())
return False
self._queue.append((request, async_object))
# wake the connection, guarding against a race with close()
write_pipe = self._connection._write_pipe
if write_pipe is None:
async_object.set_exception(
ConnectionClosedError("Connection has been closed"))
try:
os.write(write_pipe, b'\0')
except:
async_object.set_exception(
ConnectionClosedError("Connection has been closed"))
def start(self, timeout=15):
"""Initiate connection to ZK.
:param timeout: Time in seconds to wait for connection to
succeed.
:raises: :attr:`~kazoo.interfaces.IHandler.timeout_exception`
if the connection wasn't established within `timeout`
seconds.
"""
event = self.start_async()
event.wait(timeout=timeout)
if not self.connected:
# We time-out, ensure we are disconnected
self.stop()
raise self.handler.timeout_exception("Connection time-out")
if self.chroot and not self.exists("/"):
warnings.warn("No chroot path exists, the chroot path "
"should be created before normal use.")
def start_async(self):
"""Asynchronously initiate connection to ZK.
:returns: An event object that can be checked to see if the
connection is alive.
:rtype: :class:`~threading.Event` compatible object.
"""
# If we're already connected, ignore
if self._live.is_set():
return self._live
# Make sure we're safely closed
self._safe_close()
# We've been asked to connect, clear the stop and our writer
# thread indicator
self._stopped.clear()
self._writer_stopped.clear()
# Start the handler
self.handler.start()
# Start the connection
self._connection.start()
return self._live
def stop(self):
"""Gracefully stop this Zookeeper session.
This method can be called while a reconnection attempt is in
progress, which will then be halted.
Once the connection is closed, its session becomes invalid. All
the ephemeral nodes in the ZooKeeper server associated with the
session will be removed. The watches left on those nodes (and
on their parents) will be triggered.
"""
if self._stopped.is_set():
return
self._stopped.set()
self._queue.append((CloseInstance, None))
os.write(self._connection._write_pipe, b'\0')
self._safe_close()
def restart(self):
"""Stop and restart the Zookeeper session."""
self.stop()
self.start()
def close(self):
"""Free any resources held by the client.
This method should be called on a stopped client before it is
discarded. Not doing so may result in filehandles being leaked.
.. versionadded:: 1.0
"""
self._connection.close()
def command(self, cmd=b'ruok'):
"""Sent a management command to the current ZK server.
Examples are `ruok`, `envi` or `stat`.
:returns: An unstructured textual response.
:rtype: str
:raises:
:exc:`ConnectionLoss` if there is no connection open, or
possibly a :exc:`socket.error` if there's a problem with
the connection used just for this command.
.. versionadded:: 0.5
"""
if not self._live.is_set():
raise ConnectionLoss("No connection to server")
peer = self._connection._socket.getpeername()
sock = self.handler.create_connection(peer,
timeout=self._session_timeout /
1000.0)
sock.sendall(cmd)
result = sock.recv(8192)
sock.close()
return result.decode('utf-8', 'replace')
def server_version(self):
"""Get the version of the currently connected ZK server.
:returns: The server version, for example (3, 4, 3).
:rtype: tuple
.. versionadded:: 0.5
"""
data = self.command(b'envi')
string = ENVI_VERSION.match(data).group(1)
return tuple([int(i) for i in string.split('.')])
def add_auth(self, scheme, credential):
"""Send credentials to server.
:param scheme: authentication scheme (default supported:
"digest").
:param credential: the credential -- value depends on scheme.
:returns: True if it was successful.
:rtype: bool
:raises:
:exc:`~kazoo.exceptions.AuthFailedError` if it failed though
the session state will be set to AUTH_FAILED as well.
"""
return self.add_auth_async(scheme, credential).get()
def add_auth_async(self, scheme, credential):
"""Asynchronously send credentials to server. Takes the same
arguments as :meth:`add_auth`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(scheme, basestring):
raise TypeError("Invalid type for scheme")
if not isinstance(credential, basestring):
raise TypeError("Invalid type for credential")
# we need this auth data to re-authenticate on reconnect
self.auth_data.add((scheme, credential))
async_result = self.handler.async_result()
self._call(Auth(0, scheme, credential), async_result)
return async_result
def unchroot(self, path):
"""Strip the chroot if applicable from the path."""
if not self.chroot:
return path
if path.startswith(self.chroot):
return path[len(self.chroot):]
else:
return path
def sync_async(self, path):
"""Asynchronous sync.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
async_result = self.handler.async_result()
self._call(Sync(_prefix_root(self.chroot, path)), async_result)
return async_result
def sync(self, path):
"""Sync, blocks until response is acknowledged.
Flushes channel between process and leader.
:param path: path of node.
:returns: The node path that was synced.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.sync_async(path).get()
def create(self,
path,
value=b"",
acl=None,
ephemeral=False,
sequence=False,
makepath=False):
"""Create a node with the given value as its data. Optionally
set an ACL on the node.
The ephemeral and sequence arguments determine the type of the
node.
An ephemeral node will be automatically removed by ZooKeeper
when the session associated with the creation of the node
expires.
A sequential node will be given the specified path plus a
suffix `i` where i is the current sequential number of the
node. The sequence number is always fixed length of 10 digits,
0 padded. Once such a node is created, the sequential number
will be incremented by one.
If a node with the same actual path already exists in
ZooKeeper, a NodeExistsError will be raised. Note that since a
different actual path is used for each invocation of creating
sequential nodes with the same path argument, the call will
never raise NodeExistsError.
If the parent node does not exist in ZooKeeper, a NoNodeError
will be raised. Setting the optional `makepath` argument to
`True` will create all missing parent nodes instead.
An ephemeral node cannot have children. If the parent node of
the given path is ephemeral, a NoChildrenForEphemeralsError
will be raised.
This operation, if successful, will trigger all the watches
left on the node of the given path by :meth:`exists` and
:meth:`get` API calls, and the watches left on the parent node
by :meth:`get_children` API calls.
The maximum allowable size of the node value is 1 MB. Values
larger than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: Initial bytes value of node.
:param acl: :class:`~kazoo.security.ACL` list.
:param ephemeral: Boolean indicating whether node is ephemeral
(tied to this session).
:param sequence: Boolean indicating whether path is suffixed
with a unique index.
:param makepath: Whether the path should be created if it
doesn't exist.
:returns: Real path of the new node.
:rtype: str
:raises:
:exc:`~kazoo.exceptions.NodeExistsError` if the node
already exists.
:exc:`~kazoo.exceptions.NoNodeError` if parent nodes are
missing.
:exc:`~kazoo.exceptions.NoChildrenForEphemeralsError` if
the parent node is an ephemeral node.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
acl = acl or self.default_acl
return self.create_async(path,
value,
acl=acl,
ephemeral=ephemeral,
sequence=sequence,
makepath=makepath).get()
def create_async(self,
path,
value=b"",
acl=None,
ephemeral=False,
sequence=False,
makepath=False):
"""Asynchronously create a ZNode. Takes the same arguments as
:meth:`create`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
.. versionadded:: 1.1
The makepath option.
"""
if acl is None and self.default_acl:
acl = self.default_acl
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if acl and (isinstance(acl, ACL) or not isinstance(acl,
(tuple, list))):
raise TypeError("acl must be a tuple/list of ACL's")
if value is not None and not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(ephemeral, bool):
raise TypeError("ephemeral must be a bool")
if not isinstance(sequence, bool):
raise TypeError("sequence must be a bool")
if not isinstance(makepath, bool):
raise TypeError("makepath must be a bool")
flags = 0
if ephemeral:
flags |= 1
if sequence:
flags |= 2
if acl is None:
acl = OPEN_ACL_UNSAFE
async_result = self.handler.async_result()
@capture_exceptions(async_result)
def do_create():
result = self._create_async_inner(path,
value,
acl,
flags,
trailing=sequence)
result.rawlink(create_completion)
@capture_exceptions(async_result)
def retry_completion(result):
result.get()
do_create()
@wrap(async_result)
def create_completion(result):
try:
return self.unchroot(result.get())
except NoNodeError:
if not makepath:
raise
if sequence and path.endswith('/'):
parent = path.rstrip('/')
else:
parent, _ = split(path)
self.ensure_path_async(parent, acl).rawlink(retry_completion)
do_create()
return async_result
def _create_async_inner(self, path, value, acl, flags, trailing=False):
async_result = self.handler.async_result()
call_result = self._call(
Create(_prefix_root(self.chroot, path, trailing=trailing), value,
acl, flags), async_result)
if call_result is False:
# We hit a short-circuit exit on the _call. Because we are
# not using the original async_result here, we bubble the
# exception upwards to the do_create function in
# KazooClient.create so that it gets set on the correct
# async_result object
raise async_result.exception
return async_result
def ensure_path(self, path, acl=None):
"""Recursively create a path if it doesn't exist.
:param path: Path of node.
:param acl: Permissions for node.
"""
return self.ensure_path_async(path, acl).get()
def ensure_path_async(self, path, acl=None):
"""Recursively create a path asynchronously if it doesn't
exist. Takes the same arguments as :meth:`ensure_path`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
.. versionadded:: 1.1
"""
acl = acl or self.default_acl
async_result = self.handler.async_result()
@wrap(async_result)
def create_completion(result):
try:
return result.get()
except NodeExistsError:
return True
@capture_exceptions(async_result)
def prepare_completion(next_path, result):
result.get()
self.create_async(next_path, acl=acl).rawlink(create_completion)
@wrap(async_result)
def exists_completion(path, result):
if result.get():
return True
parent, node = split(path)
if node:
self.ensure_path_async(parent, acl=acl).rawlink(
partial(prepare_completion, path))
else:
self.create_async(path, acl=acl).rawlink(create_completion)
self.exists_async(path).rawlink(partial(exists_completion, path))
return async_result
def exists(self, path, watch=None):
"""Check if a node exists.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that creates/deletes the node or sets the data on the
node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns: ZnodeStat of the node if it exists, else None if the
node does not exist.
:rtype: :class:`~kazoo.protocol.states.ZnodeStat` or `None`.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.exists_async(path, watch).get()
def exists_async(self, path, watch=None):
"""Asynchronously check if a node exists. Takes the same
arguments as :meth:`exists`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(Exists(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get(self, path, watch=None):
"""Get the value of a node.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that sets data on the node, or deletes the node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns:
Tuple (value, :class:`~kazoo.protocol.states.ZnodeStat`) of
node.
:rtype: tuple
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
"""
return self.get_async(path, watch).get()
def get_async(self, path, watch=None):
"""Asynchronously get the value of a node. Takes the same
arguments as :meth:`get`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(GetData(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get_children(self, path, watch=None, include_data=False):
"""Get a list of child nodes of a path.
If a watch is provided it will be left on the node with the
given path. The watch will be triggered by a successful
operation that deletes the node of the given path or
creates/deletes a child under the node.
The list of children returned is not sorted and no guarantee is
provided as to its natural or lexical order.
:param path: Path of node to list.
:param watch: Optional watch callback to set for future changes
to this path.
:param include_data:
Include the :class:`~kazoo.protocol.states.ZnodeStat` of
the node in addition to the children. This option changes
the return value to be a tuple of (children, stat).
:returns: List of child node names, or tuple if `include_data`
is `True`.
:rtype: list
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
The `include_data` option.
"""
return self.get_children_async(path, watch, include_data).get()
def get_children_async(self, path, watch=None, include_data=False):
"""Asynchronously get a list of child nodes of a path. Takes
the same arguments as :meth:`get_children`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
if not isinstance(include_data, bool):
raise TypeError("include_data must be a bool")
async_result = self.handler.async_result()
if include_data:
req = GetChildren2(_prefix_root(self.chroot, path), watch)
else:
req = GetChildren(_prefix_root(self.chroot, path), watch)
self._call(req, async_result)
return async_result
def get_acls(self, path):
"""Return the ACL and stat of the node of the given path.
:param path: Path of the node.
:returns: The ACL array of the given node and its
:class:`~kazoo.protocol.states.ZnodeStat`.
:rtype: tuple of (:class:`~kazoo.security.ACL` list,
:class:`~kazoo.protocol.states.ZnodeStat`)
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
.. versionadded:: 0.5
"""
return self.get_acls_async(path).get()
def get_acls_async(self, path):
"""Return the ACL and stat of the node of the given path. Takes
the same arguments as :meth:`get_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
async_result = self.handler.async_result()
self._call(GetACL(_prefix_root(self.chroot, path)), async_result)
return async_result
def set_acls(self, path, acls, version=-1):
"""Set the ACL for the node of the given path.
Set the ACL for the node of the given path if such a node
exists and the given version matches the version of the node.
:param path: Path for the node.
:param acls: List of :class:`~kazoo.security.ACL` objects to
set.
:param version: The expected node version that must match.
:returns: The stat of the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.InvalidACLError` if the ACL is
invalid.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.set_acls_async(path, acls, version).get()
def set_acls_async(self, path, acls, version=-1):
"""Set the ACL for the node of the given path. Takes the same
arguments as :meth:`set_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if isinstance(acls, ACL) or not isinstance(acls, (tuple, list)):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetACL(_prefix_root(self.chroot, path), acls, version),
async_result)
return async_result
def set(self, path, value, version=-1):
"""Set the value of a node.
If the version of the node being updated is newer than the
supplied version (and the supplied version is not -1), a
BadVersionError will be raised.
This operation, if successful, will trigger all the watches on
the node of the given path left by :meth:`get` API calls.
The maximum allowable size of the value is 1 MB. Values larger
than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: New data value.
:param version: Version of node being updated, or -1.
:returns: Updated :class:`~kazoo.protocol.states.ZnodeStat` of
the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.set_async(path, value, version).get()
def set_async(self, path, value, version=-1):
"""Set the value of a node. Takes the same arguments as
:meth:`set`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if value is not None and not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetData(_prefix_root(self.chroot, path), value, version),
async_result)
return async_result
def transaction(self):
"""Create and return a :class:`TransactionRequest` object
Creates a :class:`TransactionRequest` object. A Transaction can
consist of multiple operations which can be committed as a
single atomic unit. Either all of the operations will succeed
or none of them.
:returns: A TransactionRequest.
:rtype: :class:`TransactionRequest`
.. versionadded:: 0.6
Requires Zookeeper 3.4+
"""
return TransactionRequest(self)
def delete(self, path, version=-1, recursive=False):
"""Delete a node.
The call will succeed if such a node exists, and the given
version matches the node's version (if the given version is -1,
the default, it matches any node's versions).
This operation, if successful, will trigger all the watches on
the node of the given path left by `exists` API calls, and the
watches on the parent node left by `get_children` API calls.
:param path: Path of node to delete.
:param version: Version of node to delete, or -1 for any.
:param recursive: Recursively delete node and all its children,
defaults to False.
:type recursive: bool
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.NotEmptyError` if the node has
children.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
if not isinstance(recursive, bool):
raise TypeError("recursive must be a bool")
if recursive:
return self._delete_recursive(path)
else:
return self.delete_async(path, version).get()
def delete_async(self, path, version=-1):
"""Asynchronously delete a node. Takes the same arguments as
:meth:`delete`, with the exception of `recursive`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(Delete(_prefix_root(self.chroot, path), version),
async_result)
return async_result
def _delete_recursive(self, path):
try:
children = self.get_children(path)
except NoNodeError:
return True
if children:
for child in children:
if path == "/":
child_path = path + child
else:
child_path = path + "/" + child
self._delete_recursive(child_path)
try:
self.delete(path)
except NoNodeError: # pragma: nocover
pass
def __init__(self, hosts='127.0.0.1:2181',
timeout=10.0, client_id=None, max_retries=None,
retry_delay=0.1, retry_backoff=2, retry_jitter=0.8,
retry_max_delay=3600, handler=None, default_acl=None,
auth_data=None, read_only=None, randomize_hosts=True):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param max_retries: Maximum retries when using the
:meth:`KazooClient.retry` method.
:param retry_delay: Initial delay when retrying a call.
:param retry_backoff:
Backoff multiplier between retry attempts. Defaults to 2
for exponential back-off.
:param retry_jitter:
How much jitter delay to introduce per call. An amount of
time up to this will be added per retry call to avoid
hammering the server.
:param retry_max_delay:
Maximum delay in seconds, regardless of other backoff
settings. Defaults to one hour.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
Retry parameters will be used for connection establishment
attempts and reconnects.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
"""
self.log_debug = logging.DEBUG >= log.getEffectiveLevel()
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts, chroot = collect_hosts(hosts, randomize_hosts)
if chroot:
self.chroot = normpath(chroot)
else:
self.chroot = ''
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = KazooRetry(
max_tries=max_retries,
delay=retry_delay,
backoff=retry_backoff,
max_jitter=retry_jitter,
max_delay=retry_max_delay,
sleep_func=self.handler.sleep_func
)
self.retry_sleeper = self.retry.retry_sleeper.copy()
self._connection = ConnectionHandler(
self, self.retry.retry_sleeper.copy(), log_debug=self.log_debug)
# convenience API
from kazoo.recipe.barrier import Barrier
from kazoo.recipe.barrier import DoubleBarrier
from kazoo.recipe.counter import Counter
from kazoo.recipe.election import Election
from kazoo.recipe.lock import Lock
from kazoo.recipe.lock import Semaphore
from kazoo.recipe.partitioner import SetPartitioner
from kazoo.recipe.party import Party
from kazoo.recipe.party import ShallowParty
from kazoo.recipe.queue import Queue
from kazoo.recipe.queue import LockingQueue
from kazoo.recipe.watchers import ChildrenWatch
from kazoo.recipe.watchers import DataWatch
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
class KazooClient(object):
"""An Apache Zookeeper Python client supporting alternate callback
handlers and high-level functionality.
Watch functions registered with this class will not get session
events, unlike the default Zookeeper watches. They will also be
called with a single argument, a
:class:`~kazoo.protocol.states.WatchedEvent` instance.
"""
def __init__(self, hosts='127.0.0.1:2181',
timeout=10.0, client_id=None, max_retries=None,
retry_delay=0.1, retry_backoff=2, retry_jitter=0.8,
retry_max_delay=3600, handler=None, default_acl=None,
auth_data=None, read_only=None, randomize_hosts=True):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param max_retries: Maximum retries when using the
:meth:`KazooClient.retry` method.
:param retry_delay: Initial delay when retrying a call.
:param retry_backoff:
Backoff multiplier between retry attempts. Defaults to 2
for exponential back-off.
:param retry_jitter:
How much jitter delay to introduce per call. An amount of
time up to this will be added per retry call to avoid
hammering the server.
:param retry_max_delay:
Maximum delay in seconds, regardless of other backoff
settings. Defaults to one hour.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
Retry parameters will be used for connection establishment
attempts and reconnects.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
"""
self.log_debug = logging.DEBUG >= log.getEffectiveLevel()
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts, chroot = collect_hosts(hosts, randomize_hosts)
if chroot:
self.chroot = normpath(chroot)
else:
self.chroot = ''
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.event_object()
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
self.retry = KazooRetry(
max_tries=max_retries,
delay=retry_delay,
backoff=retry_backoff,
max_jitter=retry_jitter,
max_delay=retry_max_delay,
sleep_func=self.handler.sleep_func
)
self.retry_sleeper = self.retry.retry_sleeper.copy()
self._connection = ConnectionHandler(
self, self.retry.retry_sleeper.copy(), log_debug=self.log_debug)
# convenience API
from kazoo.recipe.barrier import Barrier
from kazoo.recipe.barrier import DoubleBarrier
from kazoo.recipe.counter import Counter
from kazoo.recipe.election import Election
from kazoo.recipe.lock import Lock
from kazoo.recipe.lock import Semaphore
from kazoo.recipe.partitioner import SetPartitioner
from kazoo.recipe.party import Party
from kazoo.recipe.party import ShallowParty
from kazoo.recipe.queue import Queue
from kazoo.recipe.queue import LockingQueue
from kazoo.recipe.watchers import ChildrenWatch
from kazoo.recipe.watchers import DataWatch
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
def _reset(self):
"""Resets a variety of client states for a new connection."""
self._queue = deque()
self._pending = deque()
self._child_watchers = defaultdict(list)
self._data_watchers = defaultdict(list)
self._reset_session()
self.last_zxid = 0
def _reset_session(self):
self._session_id = None
self._session_passwd = b'\x00' * 16
@property
def client_state(self):
"""Returns the last Zookeeper client state
This is the non-simplified state information and is generally
not as useful as the simplified KazooState information.
"""
return self._state
@property
def client_id(self):
"""Returns the client id for this Zookeeper session if
connected.
:returns: client id which consists of the session id and
password.
:rtype: tuple
"""
if self._live.is_set():
return (self._session_id, self._session_passwd)
return None
@property
def connected(self):
"""Returns whether the Zookeeper connection has been
established."""
return self._live.is_set()
def add_listener(self, listener):
"""Add a function to be called for connection state changes.
This function will be called with a
:class:`~kazoo.protocol.states.KazooState` instance indicating
the new connection state on state transitions.
.. warning::
This function must not block. If its at all likely that it
might need data or a value that could result in blocking
than the :meth:`~kazoo.interfaces.IHandler.spawn` method
should be used so that the listener can return immediately.
"""
if not (listener and callable(listener)):
raise ConfigurationError("listener must be callable")
self.state_listeners.add(listener)
def remove_listener(self, listener):
"""Remove a listener function"""
self.state_listeners.discard(listener)
def _make_state_change(self, state):
# skip if state is current
if self.state == state:
return
self.state = state
# Create copy of listeners for iteration in case one needs to
# remove itself
for listener in list(self.state_listeners):
try:
remove = listener(state)
if remove is True:
self.remove_listener(listener)
except Exception:
log.exception("Error in connection state listener")
def _session_callback(self, state):
if state == self._state:
return
# Note that we don't check self.state == LOST since thats also
# the clients initial state
dead_state = self._state in LOST_STATES
self._state = state
# If we were previously closed or had an expired session, and
# are now connecting, don't bother with the rest of the
# transitions since they only apply after
# we've established a connection
if dead_state and state == KeeperState.CONNECTING:
log.info("Skipping state change")
return
if state in (KeeperState.CONNECTED, KeeperState.CONNECTED_RO):
log.info("Zookeeper connection established, state: %s", state)
self._live.set()
self._make_state_change(KazooState.CONNECTED)
elif state in LOST_STATES:
log.info("Zookeeper session lost, state: %s", state)
self._live.clear()
self._make_state_change(KazooState.LOST)
self._notify_pending(state)
self._reset()
else:
log.info("Zookeeper connection lost")
# Connection lost
self._live.clear()
self._notify_pending(state)
self._make_state_change(KazooState.SUSPENDED)
def _notify_pending(self, state):
"""Used to clear a pending response queue and request queue
during connection drops."""
if state == KeeperState.AUTH_FAILED:
exc = AuthFailedError()
elif state == KeeperState.EXPIRED_SESSION:
exc = SessionExpiredError()
else:
exc = ConnectionLoss()
while True:
try:
request, async_object, xid = self._pending.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
while True:
try:
request, async_object = self._queue.popleft()
if async_object:
async_object.set_exception(exc)
except IndexError:
break
def _safe_close(self):
self.handler.stop()
if not self._connection.stop(10):
raise Exception("Writer still open from prior connection"
" and wouldn't close after 10 seconds")
def _call(self, request, async_object):
"""Ensure there's an active connection and put the request in
the queue if there is."""
if self._state == KeeperState.AUTH_FAILED:
raise AuthFailedError()
elif self._state == KeeperState.CLOSED:
raise ConnectionClosedError("Connection has been closed")
elif self._state in (KeeperState.EXPIRED_SESSION,
KeeperState.CONNECTING):
raise SessionExpiredError()
self._queue.append((request, async_object))
# wake the connection, guarding against a race with close()
write_pipe = self._connection._write_pipe
if write_pipe is None:
raise ConnectionClosedError("Connection has been closed")
try:
os.write(write_pipe, b'\0')
except OSError as e:
if e.errno == errno.EBADF:
raise ConnectionClosedError("Connection has been closed")
raise
def start(self, timeout=15):
"""Initiate connection to ZK.
:param timeout: Time in seconds to wait for connection to
succeed.
:raises: :attr:`~kazoo.interfaces.IHandler.timeout_exception`
if the connection wasn't established within `timeout`
seconds.
"""
event = self.start_async()
event.wait(timeout=timeout)
if not self.connected:
# We time-out, ensure we are disconnected
self.stop()
raise self.handler.timeout_exception("Connection time-out")
def start_async(self):
"""Asynchronously initiate connection to ZK.
:returns: An event object that can be checked to see if the
connection is alive.
:rtype: :class:`~threading.Event` compatible object.
"""
# If we're already connected, ignore
if self._live.is_set():
return self._live
# Make sure we're safely closed
self._safe_close()
# We've been asked to connect, clear the stop and our writer
# thread indicator
self._stopped.clear()
self._writer_stopped.clear()
# Start the handler
self.handler.start()
# Start the connection
self._connection.start()
return self._live
def stop(self):
"""Gracefully stop this Zookeeper session.
This method can be called while a reconnection attempt is in
progress, which will then be halted.
Once the connection is closed, its session becomes invalid. All
the ephemeral nodes in the ZooKeeper server associated with the
session will be removed. The watches left on those nodes (and
on their parents) will be triggered.
"""
if self._stopped.is_set():
return
self._stopped.set()
self._queue.append((Close(), None))
os.write(self._connection._write_pipe, b'\0')
self._safe_close()
def restart(self):
"""Stop and restart the Zookeeper session."""
self.stop()
self.start()
def close(self):
"""Free any resources held by the client.
This method should be called on a stopped client before it is
discarded. Not doing so may result in filehandles being leaked.
.. versionadded:: 1.0
"""
self._connection.close()
def command(self, cmd=b'ruok'):
"""Sent a management command to the current ZK server.
Examples are `ruok`, `envi` or `stat`.
:returns: An unstructured textual response.
:rtype: str
:raises:
:exc:`ConnectionLoss` if there is no connection open, or
possibly a :exc:`socket.error` if there's a problem with
the connection used just for this command.
.. versionadded:: 0.5
"""
if not self._live.is_set():
raise ConnectionLoss("No connection to server")
sock = self.handler.socket()
sock.settimeout(self._session_timeout)
peer = self._connection._socket.getpeername()
sock.connect(peer)
sock.sendall(cmd)
result = sock.recv(8192)
sock.close()
return result.decode('utf-8', 'replace')
def server_version(self):
"""Get the version of the currently connected ZK server.
:returns: The server version, for example (3, 4, 3).
:rtype: tuple
.. versionadded:: 0.5
"""
data = self.command(b'envi')
string = ENVI_VERSION.match(data).group(1)
return tuple([int(i) for i in string.split('.')])
def add_auth(self, scheme, credential):
"""Send credentials to server.
:param scheme: authentication scheme (default supported:
"digest").
:param credential: the credential -- value depends on scheme.
"""
return self.add_auth_async(scheme, credential)
def add_auth_async(self, scheme, credential):
"""Asynchronously send credentials to server. Takes the same
arguments as :meth:`add_auth`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(scheme, basestring):
raise TypeError("Invalid type for scheme")
if not isinstance(credential, basestring):
raise TypeError("Invalid type for credential")
self._call(Auth(0, scheme, credential), None)
return True
def unchroot(self, path):
"""Strip the chroot if applicable from the path."""
if not self.chroot:
return path
if path.startswith(self.chroot):
return path[len(self.chroot):]
else:
return path
def sync_async(self, path):
"""Asynchronous sync.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
async_result = self.handler.async_result()
self._call(Sync(_prefix_root(self.chroot, path)), async_result)
return async_result
def sync(self, path):
"""Sync, blocks until response is acknowledged.
Flushes channel between process and leader.
:param path: path of node.
:returns: The node path that was synced.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.sync_async(path).get()
def create(self, path, value=b"", acl=None, ephemeral=False,
sequence=False, makepath=False):
"""Create a node with the given value as its data. Optionally
set an ACL on the node.
The ephemeral and sequence arguments determine the type of the
node.
An ephemeral node will be automatically removed by ZooKeeper
when the session associated with the creation of the node
expires.
A sequential node will be given the specified path plus a
suffix `i` where i is the current sequential number of the
node. The sequence number is always fixed length of 10 digits,
0 padded. Once such a node is created, the sequential number
will be incremented by one.
If a node with the same actual path already exists in
ZooKeeper, a NodeExistsError will be raised. Note that since a
different actual path is used for each invocation of creating
sequential nodes with the same path argument, the call will
never raise NodeExistsError.
If the parent node does not exist in ZooKeeper, a NoNodeError
will be raised. Setting the optional `makepath` argument to
`True` will create all missing parent nodes instead.
An ephemeral node cannot have children. If the parent node of
the given path is ephemeral, a NoChildrenForEphemeralsError
will be raised.
This operation, if successful, will trigger all the watches
left on the node of the given path by :meth:`exists` and
:meth:`get` API calls, and the watches left on the parent node
by :meth:`get_children` API calls.
The maximum allowable size of the node value is 1 MB. Values
larger than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: Initial bytes value of node.
:param acl: :class:`~kazoo.security.ACL` list.
:param ephemeral: Boolean indicating whether node is ephemeral
(tied to this session).
:param sequence: Boolean indicating whether path is suffixed
with a unique index.
:param makepath: Whether the path should be created if it
doesn't exist.
:returns: Real path of the new node.
:rtype: str
:raises:
:exc:`~kazoo.exceptions.NodeExistsError` if the node
already exists.
:exc:`~kazoo.exceptions.NoNodeError` if parent nodes are
missing.
:exc:`~kazoo.exceptions.NoChildrenForEphemeralsError` if
the parent node is an ephemeral node.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
try:
realpath = self.create_async(path, value, acl=acl,
ephemeral=ephemeral, sequence=sequence).get()
except NoNodeError:
# some or all of the parent path doesn't exist. if makepath is set
# we will create it and retry. If it fails again, someone must be
# actively deleting ZNodes and we'd best bail out.
if not makepath:
raise
parent, _ = split(path)
# using the inner call directly because path is already namespaced
self._inner_ensure_path(parent, acl)
# now retry
realpath = self.create_async(path, value, acl=acl,
ephemeral=ephemeral, sequence=sequence).get()
return self.unchroot(realpath)
def create_async(self, path, value=b"", acl=None, ephemeral=False,
sequence=False):
"""Asynchronously create a ZNode. Takes the same arguments as
:meth:`create`, with the exception of `makepath`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if acl is None and self.default_acl:
acl = self.default_acl
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if acl and (isinstance(acl, ACL) or
not isinstance(acl, (tuple, list))):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(ephemeral, bool):
raise TypeError("ephemeral must be a bool")
if not isinstance(sequence, bool):
raise TypeError("sequence must be a bool")
flags = 0
if ephemeral:
flags |= 1
if sequence:
flags |= 2
if acl is None:
acl = OPEN_ACL_UNSAFE
async_result = self.handler.async_result()
self._call(Create(_prefix_root(self.chroot, path), value, acl, flags),
async_result)
return async_result
def ensure_path(self, path, acl=None):
"""Recursively create a path if it doesn't exist.
:param path: Path of node.
:param acl: Permissions for node.
"""
self._inner_ensure_path(path, acl)
def _inner_ensure_path(self, path, acl):
if self.exists(path):
return
if acl is None and self.default_acl:
acl = self.default_acl
parent, node = split(path)
if node:
self._inner_ensure_path(parent, acl)
try:
self.create_async(path, acl=acl).get()
except NodeExistsError:
# someone else created the node. how sweet!
pass
def exists(self, path, watch=None):
"""Check if a node exists.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that creates/deletes the node or sets the data on the
node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns: ZnodeStat of the node if it exists, else None if the
node does not exist.
:rtype: :class:`~kazoo.protocol.states.ZnodeStat` or `None`.
:raises:
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.exists_async(path, watch).get()
def exists_async(self, path, watch=None):
"""Asynchronously check if a node exists. Takes the same
arguments as :meth:`exists`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(Exists(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get(self, path, watch=None):
"""Get the value of a node.
If a watch is provided, it will be left on the node with the
given path. The watch will be triggered by a successful
operation that sets data on the node, or deletes the node.
:param path: Path of node.
:param watch: Optional watch callback to set for future changes
to this path.
:returns:
Tuple (value, :class:`~kazoo.protocol.states.ZnodeStat`) of
node.
:rtype: tuple
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
"""
return self.get_async(path, watch).get()
def get_async(self, path, watch=None):
"""Asynchronously get the value of a node. Takes the same
arguments as :meth:`get`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
async_result = self.handler.async_result()
self._call(GetData(_prefix_root(self.chroot, path), watch),
async_result)
return async_result
def get_children(self, path, watch=None, include_data=False):
"""Get a list of child nodes of a path.
If a watch is provided it will be left on the node with the
given path. The watch will be triggered by a successful
operation that deletes the node of the given path or
creates/deletes a child under the node.
The list of children returned is not sorted and no guarantee is
provided as to its natural or lexical order.
:param path: Path of node to list.
:param watch: Optional watch callback to set for future changes
to this path.
:param include_data:
Include the :class:`~kazoo.protocol.states.ZnodeStat` of
the node in addition to the children. This option changes
the return value to be a tuple of (children, stat).
:returns: List of child node names, or tuple if `include_data`
is `True`.
:rtype: list
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
The `include_data` option.
"""
return self.get_children_async(path, watch, include_data).get()
def get_children_async(self, path, watch=None, include_data=False):
"""Asynchronously get a list of child nodes of a path. Takes
the same arguments as :meth:`get_children`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if watch and not callable(watch):
raise TypeError("watch must be a callable")
if not isinstance(include_data, bool):
raise TypeError("include_data must be a bool")
async_result = self.handler.async_result()
if include_data:
req = GetChildren2(_prefix_root(self.chroot, path), watch)
else:
req = GetChildren(_prefix_root(self.chroot, path), watch)
self._call(req, async_result)
return async_result
def get_acls(self, path):
"""Return the ACL and stat of the node of the given path.
:param path: Path of the node.
:returns: The ACL array of the given node and its
:class:`~kazoo.protocol.states.ZnodeStat`.
:rtype: tuple of (:class:`~kazoo.security.ACL` list,
:class:`~kazoo.protocol.states.ZnodeStat`)
:raises:
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code
.. versionadded:: 0.5
"""
return self.get_acls_async(path).get()
def get_acls_async(self, path):
"""Return the ACL and stat of the node of the given path. Takes
the same arguments as :meth:`get_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
async_result = self.handler.async_result()
self._call(GetACL(_prefix_root(self.chroot, path)), async_result)
return async_result
def set_acls(self, path, acls, version=-1):
"""Set the ACL for the node of the given path.
Set the ACL for the node of the given path if such a node
exists and the given version matches the version of the node.
:param path: Path for the node.
:param acls: List of :class:`~kazoo.security.ACL` objects to
set.
:param version: The expected node version that must match.
:returns: The stat of the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.InvalidACLError` if the ACL is
invalid.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
.. versionadded:: 0.5
"""
return self.set_acls_async(path, acls, version).get()
def set_acls_async(self, path, acls, version=-1):
"""Set the ACL for the node of the given path. Takes the same
arguments as :meth:`set_acls`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if isinstance(acls, ACL) or not isinstance(acls, (tuple, list)):
raise TypeError("acl must be a tuple/list of ACL's")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetACL(_prefix_root(self.chroot, path), acls, version),
async_result)
return async_result
def set(self, path, value, version=-1):
"""Set the value of a node.
If the version of the node being updated is newer than the
supplied version (and the supplied version is not -1), a
BadVersionError will be raised.
This operation, if successful, will trigger all the watches on
the node of the given path left by :meth:`get` API calls.
The maximum allowable size of the value is 1 MB. Values larger
than this will cause a ZookeeperError to be raised.
:param path: Path of node.
:param value: New data value.
:param version: Version of node being updated, or -1.
:returns: Updated :class:`~kazoo.protocol.states.ZnodeStat` of
the node.
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.ZookeeperError` if the provided
value is too large.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
return self.set_async(path, value, version).get()
def set_async(self, path, value, version=-1):
"""Set the value of a node. Takes the same arguments as
:meth:`set`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(value, bytes):
raise TypeError("value must be a byte string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(SetData(_prefix_root(self.chroot, path), value, version),
async_result)
return async_result
def transaction(self):
"""Create and return a :class:`TransactionRequest` object
Creates a :class:`TransactionRequest` object. A Transaction can
consist of multiple operations which can be committed as a
single atomic unit. Either all of the operations will succeed
or none of them.
:returns: A TransactionRequest.
:rtype: :class:`TransactionRequest`
.. versionadded:: 0.6
Requires Zookeeper 3.4+
"""
return TransactionRequest(self)
def delete(self, path, version=-1, recursive=False):
"""Delete a node.
The call will succeed if such a node exists, and the given
version matches the node's version (if the given version is -1,
the default, it matches any node's versions).
This operation, if successful, will trigger all the watches on
the node of the given path left by `exists` API calls, and the
watches on the parent node left by `get_children` API calls.
:param path: Path of node to delete.
:param version: Version of node to delete, or -1 for any.
:param recursive: Recursively delete node and all its children,
defaults to False.
:type recursive: bool
:raises:
:exc:`~kazoo.exceptions.BadVersionError` if version doesn't
match.
:exc:`~kazoo.exceptions.NoNodeError` if the node doesn't
exist.
:exc:`~kazoo.exceptions.NotEmptyError` if the node has
children.
:exc:`~kazoo.exceptions.ZookeeperError` if the server
returns a non-zero error code.
"""
if not isinstance(recursive, bool):
raise TypeError("recursive must be a bool")
if recursive:
return self._delete_recursive(path)
else:
return self.delete_async(path, version).get()
def delete_async(self, path, version=-1):
"""Asynchronously delete a node. Takes the same arguments as
:meth:`delete`, with the exception of `recursive`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`
"""
if not isinstance(path, basestring):
raise TypeError("path must be a string")
if not isinstance(version, int):
raise TypeError("version must be an int")
async_result = self.handler.async_result()
self._call(Delete(_prefix_root(self.chroot, path), version),
async_result)
return async_result
def _delete_recursive(self, path):
try:
children = self.get_children(path)
except NoNodeError:
return True
if children:
for child in children:
if path == "/":
child_path = path + child
else:
child_path = path + "/" + child
self._delete_recursive(child_path)
try:
self.delete(path)
except NoNodeError: # pragma: nocover
pass
def __init__(self, hosts='127.0.0.1:2181',
timeout=10.0, client_id=None, handler=None, default_acl=None,
auth_data=None, read_only=None, randomize_hosts=True,
retry=None, logger=None, **kwargs):
"""Create a :class:`KazooClient` instance. All time arguments
are in seconds.
:param hosts: Comma-separated list of hosts to connect to
(e.g. 127.0.0.1:2181,127.0.0.1:2182).
:param timeout: The longest to wait for a Zookeeper connection.
:param client_id: A Zookeeper client id, used when
re-establishing a prior session connection.
:param handler: An instance of a class implementing the
:class:`~kazoo.interfaces.IHandler` interface
for callback handling.
:param default_acl: A default ACL used on node creation.
:param auth_data:
A list of authentication credentials to use for the
connection. Should be a list of (scheme, credential)
tuples as :meth:`add_auth` takes.
:param read_only: Allow connections to read only servers.
:param randomize_hosts: By default randomize host selection.
:param retry: The configured retry object to use.
Retry parameters will be used for connection establishment
attempts and reconnects.
Basic Example:
.. code-block:: python
zk = KazooClient()
zk.start()
children = zk.get_children('/')
zk.stop()
As a convenience all recipe classes are available as attributes
and get automatically bound to the client. For example::
zk = KazooClient()
zk.start()
lock = zk.Lock('/lock_path')
.. versionadded:: 0.6
The read_only option. Requires Zookeeper 3.4+
.. versionadded:: 0.6
The retry_max_delay option.
.. versionadded:: 0.6
The randomize_hosts option.
.. versionchanged:: 0.8
Removed the unused watcher argument (was second argument).
"""
self.logger = logger or log
# Record the handler strategy used
self.handler = handler if handler else SequentialThreadingHandler()
if inspect.isclass(self.handler):
raise ConfigurationError("Handler must be an instance of a class, "
"not the class: %s" % self.handler)
self.auth_data = auth_data if auth_data else set([])
self.default_acl = default_acl
self.randomize_hosts = randomize_hosts
self.hosts, chroot = collect_hosts(hosts, randomize_hosts)
if chroot:
self.chroot = normpath(chroot)
else:
self.chroot = ''
# Curator like simplified state tracking, and listeners for
# state transitions
self._state = KeeperState.CLOSED
self.state = KazooState.LOST
self.state_listeners = set()
self._reset()
self.read_only = read_only
if client_id:
self._session_id = client_id[0]
self._session_passwd = client_id[1]
else:
self._reset_session()
# ZK uses milliseconds
self._session_timeout = int(timeout * 1000)
# We use events like twitter's client to track current and
# desired state (connected, and whether to shutdown)
self._live = self.handler.async_result()
self._live.set(False)
self._writer_stopped = self.handler.event_object()
self._stopped = self.handler.event_object()
self._stopped.set()
self._writer_stopped.set()
if retry is not None:
self.retry = retry
assert self.handler.sleep_func == self.retry.sleep_func, \
'retry handler and event handler must use the same sleep func'
else:
retry_keys = dict(_RETRY_COMPAT_DEFAULTS)
for key in retry_keys:
try:
retry_keys[key] = kwargs.pop(key)
warnings.warn('Passing retry configuration param %s to the'
' client directly is deprecated, please pass a'
' configured retry object (using param %s)' % (
key, _RETRY_COMPAT_MAPPING[key]),
DeprecationWarning, stacklevel=2)
except KeyError:
pass
retry_keys = {_RETRY_COMPAT_MAPPING[oldname]: value for oldname, value in retry_keys.items()}
self.retry = KazooRetry(
sleep_func=self.handler.sleep_func,
**retry_keys)
self._connection = ConnectionHandler(
self, self.retry.copy(),
logger=self.logger)
# convenience API
from kazoo.recipe.barrier import Barrier
from kazoo.recipe.barrier import DoubleBarrier
from kazoo.recipe.counter import Counter
from kazoo.recipe.election import Election
from kazoo.recipe.lock import Lock
from kazoo.recipe.lock import Semaphore
from kazoo.recipe.partitioner import SetPartitioner
from kazoo.recipe.party import Party
from kazoo.recipe.party import ShallowParty
from kazoo.recipe.queue import Queue
from kazoo.recipe.queue import LockingQueue
from kazoo.recipe.watchers import ChildrenWatch
from kazoo.recipe.watchers import DataWatch
self.Barrier = partial(Barrier, self)
self.Counter = partial(Counter, self)
self.DoubleBarrier = partial(DoubleBarrier, self)
self.ChildrenWatch = partial(ChildrenWatch, self)
self.DataWatch = partial(DataWatch, self)
self.Election = partial(Election, self)
self.Lock = partial(Lock, self)
self.Party = partial(Party, self)
self.Queue = partial(Queue, self)
self.LockingQueue = partial(LockingQueue, self)
self.SetPartitioner = partial(SetPartitioner, self)
self.Semaphore = partial(Semaphore, self)
self.ShallowParty = partial(ShallowParty, self)
# If we got any unhandled keywords, complain like python would
if kwargs:
raise TypeError('__init__() got unexpected keyword arguments: %s' % (kwargs.keys(),))
