def test_invalid_znode(self):
instance1 = ServiceInstance(Endpoint("host1", 10000))
handler1 = CallbackHandler()
listener1 = ClusterListener(self.client, "/home/my_cluster", instance1,
handler1.promotion_callback,
handler1.demotion_callback,
handler1.master_callback)
listener1.start()
self.client.ensure_path("/home/my_cluster/master")
self.client.create("/home/my_cluster/master/member_",
"Invalid Data",
sequence=True)
# Invalid ZNode data translates into a 'None' return.
assert handler1.detected.get(True, 1) is None
def test_invalid_znode(self):
instance1 = ServiceInstance(Endpoint("host1", 10000))
handler1 = CallbackHandler()
listener1 = ClusterListener(
self.client,
"/home/my_cluster",
instance1,
handler1.promotion_callback,
handler1.demotion_callback,
handler1.master_callback,
)
listener1.start()
self.client.ensure_path("/home/my_cluster/master")
self.client.create("/home/my_cluster/master/member_", "Invalid Data", sequence=True)
# Invalid ZNode data translates into a 'None' return.
assert handler1.detected.get(True, 1) is None
def __init__(self, self_instance, kazoo, cluster_root, installer,
task_control, state_manager):
"""
:param self_instance: The local ServiceInstance associated with this task runner.
:param kazoo: Kazoo client, it should be started before being passed in.
:param cluster_root: The ZooKeeper root path for *this cluster*.
:param installer: The PackageInstaller for MySQL.
:param task_control: The TaskControl that interacts with the task process.
:param state_manager: The StateManager for managing the executor state.
"""
self._installer = installer
self._env = None # The environment variables for the 'task_control' commands. Set by the
# installer.
self._task_control = task_control
self._state_manager = state_manager
self._lock = threading.Lock()
self._popen = None # The singleton task process started by '_task_control'.
self._started = False # Indicates whether start() has already been called.
self._stopping = False # Indicates whether stop() has already been called.
self._exited = threading.Event(
) # Set when the task process has exited.
self._result = Queue.Queue(
) # The returncode returned by the task process or an exception.
# Public events and queue.
self.promoted = threading.Event()
self.demoted = threading.Event()
self.master = Queue.Queue() # Set when a master change is detected.
self._kazoo = kazoo
self._listener = ClusterListener(kazoo,
cluster_root,
self_instance,
promotion_callback=self._on_promote,
demotion_callback=self._on_demote,
master_callback=self._on_master_change
) # Listener started by start().
def test_callbacks(self):
manager = ClusterManager(self.client, "/home/my_cluster")
# Set up 2 listeners.
instance1 = ServiceInstance(Endpoint("host1", 10000))
handler1 = CallbackHandler()
listener1 = ClusterListener(self.client, "/home/my_cluster", instance1,
handler1.promotion_callback,
handler1.demotion_callback,
handler1.master_callback,
handler1.termination_callback)
listener1.start()
member1 = manager.add_member(instance1)
instance2 = ServiceInstance(Endpoint("host2", 10000))
handler2 = CallbackHandler()
listener2 = ClusterListener(self.client, "/home/my_cluster", instance2,
handler2.promotion_callback,
handler2.demotion_callback,
handler2.master_callback)
listener2.start()
member2 = manager.add_member(instance2)
# Test promotion.
manager.promote_member(member1)
assert handler1.promoted.wait(1)
assert handler2.detected.get(True, 1) == instance1
assert (self.storage.paths["/home/my_cluster/master/member_0000000000"]
["data"] == ServiceInstance.pack(instance1))
assert (self.storage.paths["/home/my_cluster/slaves/member_0000000001"]
["data"] == ServiceInstance.pack(instance2))
manager.promote_member(member2)
assert handler1.demoted.wait(1)
assert handler2.promoted.wait(1)
assert (self.storage.paths["/home/my_cluster/master/member_0000000001"]
["data"] == ServiceInstance.pack(instance2))
assert "/home/my_cluster/master/member_0000000000" not in self.storage.paths
manager.remove_member(member2)
assert handler2.demoted.wait(1)
# Test removing cluster.
manager.remove_member(member1)
manager.delete_cluster()
assert handler1.terminated.wait(1)
def __init__(self, self_instance, kazoo, cluster_root, installer, task_control, state_manager):
"""
:param self_instance: The local ServiceInstance associated with this task runner.
:param kazoo: Kazoo client, it should be started before being passed in.
:param cluster_root: The ZooKeeper root path for *this cluster*.
:param installer: The PackageInstaller for MySQL.
:param task_control: The TaskControl that interacts with the task process.
:param state_manager: The StateManager for managing the executor state.
"""
self._installer = installer
self._env = None # The environment variables for the 'task_control' commands. Set by the
# installer.
self._task_control = task_control
self._state_manager = state_manager
self._lock = threading.Lock()
self._popen = None # The singleton task process started by '_task_control'.
self._started = False # Indicates whether start() has already been called.
self._stopping = False # Indicates whether stop() has already been called.
self._exited = threading.Event() # Set when the task process has exited.
self._result = Queue.Queue() # The returncode returned by the task process or an exception.
# Public events and queue.
self.promoted = threading.Event()
self.demoted = threading.Event()
self.master = Queue.Queue() # Set when a master change is detected.
self._kazoo = kazoo
self._listener = ClusterListener(
kazoo,
cluster_root,
self_instance,
promotion_callback=self._on_promote,
demotion_callback=self._on_demote,
master_callback=self._on_master_change) # Listener started by start().
class MysosTaskRunner(TaskRunner):
"""
A runner that manages the lifecycle of a MySQL task (through the provided 'task_control').
The task is executed as a long-running process its return code can be obtained using 'join()'.
Thread-safety:
This class is accessed from the MysosExecutor thread (not the ExecutorDriver thread because
MysosExecutor invokes operations asynchronously) and the ClusterListener thread and is
thread-safe.
TODO(jyx): Push the knowledge of the underlying subprocess down to the task control and stop the
the subprocess using the task control.
"""
def __init__(self, self_instance, kazoo, cluster_root, installer, task_control, state_manager):
"""
:param self_instance: The local ServiceInstance associated with this task runner.
:param kazoo: Kazoo client, it should be started before being passed in.
:param cluster_root: The ZooKeeper root path for *this cluster*.
:param installer: The PackageInstaller for MySQL.
:param task_control: The TaskControl that interacts with the task process.
:param state_manager: The StateManager for managing the executor state.
"""
self._installer = installer
self._env = None # The environment variables for the 'task_control' commands. Set by the
# installer.
self._task_control = task_control
self._state_manager = state_manager
self._lock = threading.Lock()
self._popen = None # The singleton task process started by '_task_control'.
self._started = False # Indicates whether start() has already been called.
self._stopping = False # Indicates whether stop() has already been called.
self._exited = threading.Event() # Set when the task process has exited.
self._result = Queue.Queue() # The returncode returned by the task process or an exception.
# Public events and queue.
self.promoted = threading.Event()
self.demoted = threading.Event()
self.master = Queue.Queue() # Set when a master change is detected.
self._kazoo = kazoo
self._listener = ClusterListener(
kazoo,
cluster_root,
self_instance,
promotion_callback=self._on_promote,
demotion_callback=self._on_demote,
master_callback=self._on_master_change) # Listener started by start().
# --- Public interface. ---
def start(self):
"""
Start the runner in a separate thread and wait for the task process to be forked.
"""
with self._lock:
if self._started:
raise TaskError("Runner already started")
self._started = True
# Can potentially hold the lock for a long time but it's OK since the runner is not accessed
# by multiple threads until after it's started; can be a noop as well, depending on the
# installer implementation.
try:
# 1. Install the application.
self._env = self._installer.install()
log.info("Package installation completed. Resulting environment variables: %s" % self._env)
# 2. Restore/initialize the application state.
self._state_manager.bootstrap(self._task_control, self._env)
log.info("Executor state fully bootstrapped")
# 3. Start the task subprocess.
# Store the process so we can kill it if necessary.
self._popen = self._task_control.start(env=self._env)
log.info("Task started in subprocess %s" % self._popen.pid)
defer(self._wait)
# 4. Start monitoring.
# Only start listening to ZK events after the task subprocess has been successfully started.
self._listener.start()
except (PackageInstaller.Error, StateManager.Error, CalledProcessError) as e:
raise TaskError("Failed to start MySQL task: %s" % e)
def _wait(self):
# Block until the subprocess exits and delivers the return code.
self._result.put(self._popen.wait())
# Notify stop() if it is waiting.
self._exited.set()
def stop(self, timeout=10):
with self._lock:
# stop() could be called by multiple threads. Locking so we only stop the runner once.
if self._stopping:
log.warn("The runner is already stopping/stopped")
return False
else:
log.info("Stopping runner")
self._stopping = True
try:
return self._stop(timeout)
finally:
self._kazoo.stop()
log.info("Runner cleaned up")
def _stop(self, timeout):
"""
Stop the runner and wait for its thread (and the sub-processes) to exit.
:param timeout: The timeout that the process should die before a hard SIGKILL is issued
(SIGTERM is used initially).
:return: True if an active runner is stopped, False if the runner is not started or already
stopping/stopped.
"""
with self._lock:
if not self._started:
log.warn("Cannot stop the runner because it's not started")
return False
if not self._popen:
log.info("The runner task did not start successfully so no need to kill it")
return False
try:
log.info("Terminating process group: %s" % self._popen.pid)
os.killpg(self._popen.pid, signal.SIGTERM)
except OSError as e:
log.info("The sub-processes are already terminated: %s" % e)
return False
log.info("Waiting for process to terminate due to SIGTERM")
# Escalate to SIGKILL if SIGTERM is not sufficient.
if not self._exited.wait(timeout=timeout):
with self._lock:
try:
log.warn("Killing process group %s which failed to terminate cleanly within %s secs" %
(self._popen.pid, timeout))
os.killpg(self._popen.pid, signal.SIGKILL)
except OSError as e:
log.info("The sub-processes are already terminated: %s" % e)
return False
else:
return True
log.info("Waiting for process to terminate due to SIGKILL")
if not self._exited.wait(timeout=timeout):
raise TaskError("Failed to kill process group %s" % self._popen.pid)
return True
def get_log_position(self):
"""
Get the log position of the MySQL slave. Return None if it cannot be obtained.
"""
try:
log_position = self._task_control.get_log_position(env=self._env)
return log_position
except CalledProcessError as e:
raise TaskError("Unable to get the slave's log position: %s" % e)
def join(self):
"""
Wait for the runner to terminate.
:return: The return code of the subprocess. NOTE: A negative value -N indicates that the
child was terminated by signal N (on Unix).
:exception: The TaskError exception due to an error in task control operations.
"""
# Using 'sys.maxint' makes this forever wait interruptible.
result = self._result.get(True, sys.maxint)
if isinstance(result, Exception):
raise result
else:
return result
# --- ClusterListener handlers. ---
def _on_promote(self):
self.promoted.set()
if not self._exited.is_set():
defer(self._promote)
def _promote(self):
try:
self._task_control.promote(env=self._env)
except CalledProcessError as e:
self._result.put(TaskError("Failed to promote the slave: %s" % e))
self.stop()
def _on_demote(self):
"""
Executor shuts itself down when demoted.
"""
self.demoted.set()
# Stop the runner asynchronously.
if not self._exited.is_set():
log.info("Shutting down runner because it is demoted.")
# Call stop() asynchronously because this callback is invoked from the Kazoo thread which we
# don't want to block.
defer(self.stop)
def _on_master_change(self, master):
self.master.put(master)
if not self._exited.is_set():
defer(lambda: self._reparent(master))
def _reparent(self, master):
try:
self._task_control.reparent(
master.service_endpoint.host,
master.service_endpoint.port,
env=self._env)
except CalledProcessError as e:
self._result.put(TaskError("Failed to reparent the slave: %s" % e))
self.stop()
class MysosTaskRunner(TaskRunner):
"""
A runner that manages the lifecycle of a MySQL task (through the provided 'task_control').
The task is executed as a long-running process its return code can be obtained using 'join()'.
Thread-safety:
This class is accessed from the MysosExecutor thread (not the ExecutorDriver thread because
MysosExecutor invokes operations asynchronously) and the ClusterListener thread and is
thread-safe.
TODO(jyx): Push the knowledge of the underlying subprocess down to the task control and stop the
the subprocess using the task control.
"""
def __init__(self, self_instance, kazoo, cluster_root, installer,
task_control, state_manager):
"""
:param self_instance: The local ServiceInstance associated with this task runner.
:param kazoo: Kazoo client, it should be started before being passed in.
:param cluster_root: The ZooKeeper root path for *this cluster*.
:param installer: The PackageInstaller for MySQL.
:param task_control: The TaskControl that interacts with the task process.
:param state_manager: The StateManager for managing the executor state.
"""
self._installer = installer
self._env = None # The environment variables for the 'task_control' commands. Set by the
# installer.
self._task_control = task_control
self._state_manager = state_manager
self._lock = threading.Lock()
self._popen = None # The singleton task process started by '_task_control'.
self._started = False # Indicates whether start() has already been called.
self._stopping = False # Indicates whether stop() has already been called.
self._exited = threading.Event(
) # Set when the task process has exited.
self._result = Queue.Queue(
) # The returncode returned by the task process or an exception.
# Public events and queue.
self.promoted = threading.Event()
self.demoted = threading.Event()
self.master = Queue.Queue() # Set when a master change is detected.
self._kazoo = kazoo
self._listener = ClusterListener(kazoo,
cluster_root,
self_instance,
promotion_callback=self._on_promote,
demotion_callback=self._on_demote,
master_callback=self._on_master_change
) # Listener started by start().
# --- Public interface. ---
def start(self):
"""
Start the runner in a separate thread and wait for the task process to be forked.
"""
with self._lock:
if self._started:
raise TaskError("Runner already started")
self._started = True
# Can potentially hold the lock for a long time but it's OK since the runner is not accessed
# by multiple threads until after it's started; can be a noop as well, depending on the
# installer implementation.
try:
# 1. Install the application.
self._env = self._installer.install()
log.info(
"Package installation completed. Resulting environment variables: %s"
% self._env)
# 2. Restore/initialize the application state.
self._state_manager.bootstrap(self._task_control, self._env)
log.info("Executor state fully bootstrapped")
# 3. Start the task subprocess.
# Store the process so we can kill it if necessary.
self._popen = self._task_control.start(env=self._env)
log.info("Task started in subprocess %s" % self._popen.pid)
defer(self._wait)
# 4. Start monitoring.
# Only start listening to ZK events after the task subprocess has been successfully started.
self._listener.start()
except (PackageInstaller.Error, StateManager.Error,
CalledProcessError) as e:
raise TaskError("Failed to start MySQL task: %s" % e)
def _wait(self):
# Block until the subprocess exits and delivers the return code.
self._result.put(self._popen.wait())
# Notify stop() if it is waiting.
self._exited.set()
def stop(self, timeout=10):
with self._lock:
# stop() could be called by multiple threads. Locking so we only stop the runner once.
if self._stopping:
log.warn("The runner is already stopping/stopped")
return False
else:
log.info("Stopping runner")
self._stopping = True
try:
return self._stop(timeout)
finally:
self._kazoo.stop()
log.info("Runner cleaned up")
def _stop(self, timeout):
"""
Stop the runner and wait for its thread (and the sub-processes) to exit.
:param timeout: The timeout that the process should die before a hard SIGKILL is issued
(SIGTERM is used initially).
:return: True if an active runner is stopped, False if the runner is not started or already
stopping/stopped.
"""
with self._lock:
if not self._started:
log.warn("Cannot stop the runner because it's not started")
return False
if not self._popen:
log.info(
"The runner task did not start successfully so no need to kill it"
)
return False
try:
log.info("Terminating process group: %s" % self._popen.pid)
os.killpg(self._popen.pid, signal.SIGTERM)
except OSError as e:
log.info("The sub-processes are already terminated: %s" % e)
return False
log.info("Waiting for process to terminate due to SIGTERM")
# Escalate to SIGKILL if SIGTERM is not sufficient.
if not self._exited.wait(timeout=timeout):
with self._lock:
try:
log.warn(
"Killing process group %s which failed to terminate cleanly within %s secs"
% (self._popen.pid, timeout))
os.killpg(self._popen.pid, signal.SIGKILL)
except OSError as e:
log.info("The sub-processes are already terminated: %s" %
e)
return False
else:
return True
log.info("Waiting for process to terminate due to SIGKILL")
if not self._exited.wait(timeout=timeout):
raise TaskError("Failed to kill process group %s" %
self._popen.pid)
return True
def get_log_position(self):
"""
Get the log position of the MySQL slave. Return None if it cannot be obtained.
"""
try:
log_position = self._task_control.get_log_position(env=self._env)
return log_position
except CalledProcessError as e:
raise TaskError("Unable to get the slave's log position: %s" % e)
def join(self):
"""
Wait for the runner to terminate.
:return: The return code of the subprocess. NOTE: A negative value -N indicates that the
child was terminated by signal N (on Unix).
:exception: The TaskError exception due to an error in task control operations.
"""
# Using 'sys.maxint' makes this forever wait interruptible.
result = self._result.get(True, sys.maxint)
if isinstance(result, Exception):
raise result
else:
return result
# --- ClusterListener handlers. ---
def _on_promote(self):
self.promoted.set()
if not self._exited.is_set():
defer(self._promote)
def _promote(self):
try:
self._task_control.promote(env=self._env)
except CalledProcessError as e:
self._result.put(TaskError("Failed to promote the slave: %s" % e))
self.stop()
def _on_demote(self):
"""
Executor shuts itself down when demoted.
"""
self.demoted.set()
# Stop the runner asynchronously.
if not self._exited.is_set():
log.info("Shutting down runner because it is demoted.")
# Call stop() asynchronously because this callback is invoked from the Kazoo thread which we
# don't want to block.
defer(self.stop)
def _on_master_change(self, master):
self.master.put(master)
if not self._exited.is_set():
defer(lambda: self._reparent(master))
def _reparent(self, master):
try:
self._task_control.reparent(master.service_endpoint.host,
master.service_endpoint.port,
env=self._env)
except CalledProcessError as e:
self._result.put(TaskError("Failed to reparent the slave: %s" % e))
self.stop()
def test_callbacks(self):
manager = ClusterManager(self.client, "/home/my_cluster")
# Set up 2 listeners.
instance1 = ServiceInstance(Endpoint("host1", 10000))
handler1 = CallbackHandler()
listener1 = ClusterListener(
self.client,
"/home/my_cluster",
instance1,
handler1.promotion_callback,
handler1.demotion_callback,
handler1.master_callback,
handler1.termination_callback,
)
listener1.start()
member1 = manager.add_member(instance1)
instance2 = ServiceInstance(Endpoint("host2", 10000))
handler2 = CallbackHandler()
listener2 = ClusterListener(
self.client,
"/home/my_cluster",
instance2,
handler2.promotion_callback,
handler2.demotion_callback,
handler2.master_callback,
)
listener2.start()
member2 = manager.add_member(instance2)
# Test promotion.
manager.promote_member(member1)
assert handler1.promoted.wait(1)
assert handler2.detected.get(True, 1) == instance1
assert self.storage.paths["/home/my_cluster/master/member_0000000000"]["data"] == ServiceInstance.pack(
instance1
)
assert self.storage.paths["/home/my_cluster/slaves/member_0000000001"]["data"] == ServiceInstance.pack(
instance2
)
manager.promote_member(member2)
assert handler1.demoted.wait(1)
assert handler2.promoted.wait(1)
assert self.storage.paths["/home/my_cluster/master/member_0000000001"]["data"] == ServiceInstance.pack(
instance2
)
assert "/home/my_cluster/master/member_0000000000" not in self.storage.paths
manager.remove_member(member2)
assert handler2.demoted.wait(1)
# Test removing cluster.
manager.remove_member(member1)
manager.delete_cluster()
assert handler1.terminated.wait(1)