def __init__(self, cluster, nodes):
"""
Initializes the client
"""
cleaned_nodes = {}
for node, info in nodes.iteritems():
cleaned_nodes[str(node)] = ([str(entry) for entry in info[0]], int(info[1]))
self._config = ArakoonClientConfig(str(cluster), cleaned_nodes)
self._client = ArakoonClient(self._config)
self._identifier = int(round(random.random() * 10000000))
self._lock = Lock()
self._batch_size = 500
self._sequences = {}
class PyrakoonClient(object):
"""
Arakoon client wrapper:
* Uses json serialisation
* Raises generic exception
"""
_logger = LogHandler.get('extensions', name='pyrakoon_client')
def __init__(self, cluster, nodes):
"""
Initializes the client
"""
cleaned_nodes = {}
for node, info in nodes.iteritems():
cleaned_nodes[str(node)] = ([str(entry) for entry in info[0]], int(info[1]))
self._config = ArakoonClientConfig(str(cluster), cleaned_nodes)
self._client = ArakoonClient(self._config)
self._identifier = int(round(random.random() * 10000000))
self._lock = Lock()
self._batch_size = 500
self._sequences = {}
@locked()
def get(self, key, consistency=None):
"""
Retrieves a certain value for a given key
"""
return PyrakoonClient._try(self._identifier, self._client.get, key, consistency)
@locked()
def get_multi(self, keys):
"""
Get multiple keys at once
"""
for item in PyrakoonClient._try(self._identifier, self._client.multiGet, keys):
yield item
@locked()
def set(self, key, value, transaction=None):
"""
Sets the value for a key to a given value
"""
if transaction is not None:
return self._sequences[transaction].addSet(key, value)
return PyrakoonClient._try(self._identifier, self._client.set, key, value,)
@locked()
def prefix(self, prefix):
"""
Lists all keys starting with the given prefix
"""
next_prefix = PyrakoonClient._next_key(prefix)
batch = None
while batch is None or len(batch) > 0:
batch = PyrakoonClient._try(self._identifier,
self._client.range,
beginKey=prefix if batch is None else batch[-1],
beginKeyIncluded=batch is None,
endKey=next_prefix,
endKeyIncluded=False,
maxElements=self._batch_size)
for item in batch:
yield item
@locked()
def prefix_entries(self, prefix):
"""
Lists all keys starting with the given prefix
"""
next_prefix = PyrakoonClient._next_key(prefix)
batch = None
while batch is None or len(batch) > 0:
batch = PyrakoonClient._try(self._identifier,
self._client.range_entries,
beginKey=prefix if batch is None else batch[-1][0],
beginKeyIncluded=batch is None,
endKey=next_prefix,
endKeyIncluded=False,
maxElements=self._batch_size)
for item in batch:
yield item
@locked()
def delete(self, key, must_exist=True, transaction=None):
"""
Deletes a given key from the store
"""
if transaction is not None:
if must_exist is True:
return self._sequences[transaction].addDelete(key)
else:
return self._sequences[transaction].addReplace(key, None)
if must_exist is True:
return PyrakoonClient._try(self._identifier, self._client.delete, key)
else:
return PyrakoonClient._try(self._identifier, self._client.replace, key, None)
@locked()
def delete_prefix(self, prefix):
"""
Removes a given prefix from the store
"""
return PyrakoonClient._try(self._identifier, self._client.deletePrefix, prefix)
@locked()
def nop(self):
"""
Executes a nop command
"""
return PyrakoonClient._try(self._identifier, self._client.nop)
@locked()
def exists(self, key):
"""
Check if key exists
"""
return PyrakoonClient._try(self._identifier, self._client.exists, key)
@locked()
def assert_value(self, key, value, transaction=None):
"""
Asserts a key-value pair
"""
if transaction is not None:
return self._sequences[transaction].addAssert(key, value)
return PyrakoonClient._try(self._identifier, self._client.aSSert, key, value)
@locked()
def assert_exists(self, key, transaction=None):
"""
Asserts that a given key exists
"""
if transaction is not None:
return self._sequences[transaction].addAssertExists(key)
return PyrakoonClient._try(self._identifier, self._client.aSSert_exists, key)
def begin_transaction(self):
"""
Creates a transaction (wrapper around Arakoon sequences)
"""
key = str(uuid.uuid4())
self._sequences[key] = self._client.makeSequence()
return key
def apply_transaction(self, transaction):
"""
Applies a transaction
"""
return PyrakoonClient._try(self._identifier, self._client.sequence, self._sequences[transaction])
@staticmethod
def _try(identifier, method, *args, **kwargs):
"""
Tries to call a given method, retry-ing if Arakoon is temporary unavailable
"""
try:
start = time.time()
try:
return_value = method(*args, **kwargs)
except (ArakoonSockNotReadable, ArakoonSockReadNoBytes, ArakoonSockSendError):
PyrakoonClient._logger.debug('Error during arakoon call {0}, retry'.format(method.__name__))
time.sleep(1)
return_value = method(*args, **kwargs)
duration = time.time() - start
if duration > 0.5:
PyrakoonClient._logger.warning('Arakoon call {0} took {1}s'.format(method.__name__, round(duration, 2)))
return return_value
except (ArakoonNotFound, ArakoonAssertionFailed):
# No extra logging for some errors
raise
except Exception:
PyrakoonClient._logger.error('Error during {0}. Process {1}, thread {2}, clientid {3}'.format(
method.__name__, os.getpid(), current_thread().ident, identifier
))
raise
@staticmethod
def _next_key(key):
"""
Calculates the next key (to be used in range queries)
"""
encoding = 'ascii' # For future python 3 compatibility
array = bytearray(str(key), encoding)
for index in range(len(array) - 1, -1, -1):
array[index] += 1
if array[index] < 128:
while array[-1] == 0:
array = array[:-1]
return str(array.decode(encoding))
array[index] = 0
return '\xff'
