Package: kazoo.yandex
kazooimplements a higher level API toApache Zookeeperfor Python
clients.Seethe full docsfor more information.Licensekazoois offered under the Apache License 2.0.Authorskazoostarted under theNimbus Projectand through collaboration with
the open-source community has been merged with code fromMozillaand theZope Corporation. It has since gathered an active community of over two
dozen contributors.Changelog2.0.1 (unreleased)2.0 (2014-06-19)DocumentationExtend support to Python 3.4, deprecating Python 3.2.Issue #198: Mention Zake as a sophisticated kazoo mock testing library.Issue #181: Add documentation on basic logging setup.2.0b1 (2014-04-24)API ChangesNull or None data is no longer treated as “”. Pull req #165, patch by
Raul Gutierrez S. This will affect how you should treat null data in a
znode vs. an empty string.Passing acl=[] to create() now works properly instead of an InvalidACLError
as it returned before. Patch by Raul Gutierrez S in PR #164.Removed the dependency on zope.interface. The classes in the interfaces
module are left for documentation purposes only (issue #131).FeaturesLogging levels have been reduced.Logging previously at thelogging.DEBUGlevel is now logged at
thekazoo.loggingsupport.BLATHERlevel (5).Some low-level logging previously at thelogging.INFOlevel is
now logged at thelogging.DEBUGlevel.Issue #133: Introduce a new environment variableZOOKEEPER_PORT_OFFSETfor the testing support, to run the testing cluster on a different range.Bug HandlingWhen authenticating via add_auth() the auth data will be saved to ensure that
the authentication happens on reconnect (as is the case when feeding auth
data via KazooClient’s constructor). PR #172, patch by Raul Gutierrez S.Change gevent import to remove deprecation warning when newer gevent is
used. PR #191, patch by Hiroaki Kawai.Lock recipe was failing to use the client’s sleep_func causing issues with
gevent. Issue #150.Calling a DataWatch or ChildrenWatch instance twice (decorator) now throws
an exception as only a single function can be associated with a single
watcher. Issue #154.Another fix for atexit handling so that when disposing of connections the
atexit handler is removed. PR #190, patch by Devaev Maxim.Fix atexit handling for kazoo threading handler, PR #183. Patch by
Brian Wickman.Partitioner should handle a suspended connection properly and restore
an allocated state if it was allocated previously. Patch by Manish Tomar.Issue #167: Closing a client that was never started throws a type error.
Patch by Joshua Harlow.Passing dictionaries to KazooClient.__init__() wasn’t actually working
properly. Patch by Ryan Uber.Issue #119: Handler timeout takes the max of the random interval or
the read timeout to ensure a negative number isn’t used for the read
timeout.Fix ordering of exception catches in lock.acquire as it was capturing a
parent exception before the child. Patch by ReneSac.Fix issue with client.stop() not always setting the client state to
KeeperState.CLOSED. Patch by Jyrki Pulliainen in PR #174.Issue #169: Fixed pipes leaking into child processes.DocumentationAdd section on contributing recipes, add maintainer/status information for
existing recipes.Add note about alternate use of DataWatch.1.3.1 (2013-09-25)Bug Handling#118, #125, #128: Fix unknown variable in KazooClientcommand_retryargument handling.#126: FixKazooRetry.copyto correctly copy sleep function.#118: Correct session/socket timeout conversion (int vs. float).Documentation#121: Add a note aboutkazoo.recipe.queue.LockingQueuerequiring a
Zookeeper 3.4+ server.1.3 (2013-09-05)Features#115: Limit the backends we use for SLF4J during tests.#112: Add IPv6 support. Patch by Dan Kruchinin.1.2.1 (2013-08-01)Bug HandlingIssue #108: Circular import fail when importing kazoo.recipe.watchers
directly has now been resolved. Watchers and partitioner properly import
the KazooState from kazoo.protocol.states rather than kazoo.client.Issue #109: Partials not usable properly as a datawatch call can now be
used. All funcs will be called with 3 args and fall back to 2 args if
there’s an argument error.Issue #106, #107:client.create_asyncdidn’t strip change root from the
returned path.1.2 (2013-07-24)FeaturesKazooClient can now be stopped more reliably even if its in the middle
of a long retry sleep. This utilizes the new interrupt feature of
KazooRetry which lets the sleep be broken down into chunks and an
interrupt function called to determine if the retry should fail early.Issue #62, #92, #89, #101, #102: Allow KazooRetry to have a
max deadline, transition properly when connection fails to LOST, and
setup separate connection retry behavior from client command retry
behavior. Patches by Mike Lundy.Issue #100: Make it easier to see exception context in threading and
connection modules.Issue #85: Increase information density of logs and don’t prevent
dynamic reconfiguration of log levels at runtime.Data-watchers for the same node are no longer ‘stacked’. That is, if
a get and an exists call occur for the same node with the same watch
function, then it will be registered only once. This change results in
Kazoo behaving per Zookeeper client spec regarding repeat watch use.Bug HandlingIssue #53: Throw a warning upon starting if the chroot path doesn’t exist
so that it’s more obvious when the chroot should be created before
performing more operations.Kazoo previously would let the same function be registered as a data-watch
or child-watch multiple times, and then call it multiple times upon being
triggered. This was non-compliant Zookeeper client behavior, the same
watch can now only be registered once for the same znode path per Zookeeper
client documentation.Issue #105: Avoid rare import lock problems by moving module imports in
client.py to the module scope.Issue #103: Allow prefix-less sequential znodes.Issue #98: Extend testing ZK harness to work with different file locations
on some versions of Debian/Ubuntu.Issue #97: Update some docstrings to reflect current state of handlers.Issue #62, #92, #89, #101, #102: Allow KazooRetry to have a
max deadline, transition properly when connection fails to LOST, and
setup separate connection retry behavior from client command retry
behavior. Patches by Mike Lundy.API ChangesThekazoo.testing.harness.KazooTestHarnessclass directly inherits fromunittest.TestCaseand you need to ensure to call its__init__method.DataWatch no longer takes any parameters besides for the optional function
during instantiation. The additional options are now implicitly True, with
the user being left to ignore events as they choose. See the DataWatch
API docs for more information.Issue #99: Better exception raised when the writer fails to close. A
WriterNotClosedException that inherits from KazooException is now raised
when the writer fails to close in time.1.1 (2013-06-08)FeaturesIssue #93: Add timeout option to lock/semaphore acquire methods.Issue #79 / #90: Add ability to pass the WatchedEvent to DataWatch and
ChildWatch functions.Respect large client timeout values when closing the connection.Add amax_leasesconsistency check to the semaphore recipe.Issue #76: Extend testing helpers to allow customization of the Java
classpath by specifying the newZOOKEEPER_CLASSPATHenvironment variable.Issue #65: Allow non-blocking semaphore acquisition.Bug HandlingIssue #96: Provide Windows compatibility in testing harness.Issue #95: Handle errors deserializing connection response.Issue #94: Clean up stray bytes in connection pipe.Issue #87 / #88: Allow re-acquiring lock after cancel.Issue #77: Use timeout in initial socket connection.Issue #69: Only ensure path once in lock and semaphore recipes.Issue #68: Closing the connection causes exceptions to be raised by watchers
which assume the connection won’t be closed when running commands.Issue #66: Require ping reply before sending another ping, otherwise the
connection will be considered dead and a ConnectionDropped will be raised
to trigger a reconnect.Issue #63: Watchers weren’t reset on lost connection.Issue #58: DataWatcher failed to re-register for changes after non-existent
node was created then deleted.API ChangesKazooClient.create_async now supports the makepath argument.KazooClient.ensure_path now has an async version, ensure_path_async.1.0 (2013-03-26)FeaturesAdded a LockingQueue recipe. The queue first locks an item and removes it
from the queue only after the consume() method is called. This enables other
nodes to retake the item if an error occurs on the first node.Bug HandlingIssue #50: Avoid problems with sleep function in mixed gevent/threading
setup.Issue #56: Avoid issues with watch callbacks evaluating to false.1.0b1 (2013-02-24)FeaturesRefactored the internal connection handler to use a single thread. It now
uses a deque and pipe to signal the ZK thread that there’s a new command to
send, so that the ZK thread can send it, or retrieve a response.
Processing ZK requests and responses serially in a single thread eliminates
the need for a bunch of the locking, the peekable queue and two threads
working on the same underlying socket.Issue #48: Added documentation for theretryhelper module.Issue #55: Fixos.pipefile descriptor leak and introduce aKazooClient.closemethod. The method is particular useful in tests, where
multiple KazooClients are created and closed in the same process.Bug HandlingIssue #46: Avoid TypeError in GeneratorContextManager on process shutdown.Issue #43: Let DataWatch return node data if allow_missing_node is used.0.9 (2013-01-07)API ChangesWhen a retry operation ultimately fails, it now raises akazoo.retry.RetryFailedErrorexception, instead of a generalExceptioninstance.RetryFailedErroralso inherits from the baseKazooException.FeaturesImprovements to Debian packaging rules.Bug HandlingIssue #39 / #41: Handle connection dropped errors during session writes.
Ensure client connection is re-established to a new ZK node if available.Issue #38: SetCLOEXECflag on all sockets when available.Issue #37 / #40: Handle timeout errors duringselectcalls on sockets.Issue #36: Correctly setConnectionHandler.writer_stoppedeven if an
exception is raised inside the writer, like a retry operation failing.0.8 (2012-10-26)API ChangesTheKazooClient.__init__took aswatcherargument as its second keyword
argument. The argument had no effect anymore since version 0.5 and was
removed.Bug HandlingIssue #35:KazooClient.__init__didn’t pass onretry_max_delayto the
retry helper.Issue #34: Be more careful while handling socket connection errors.0.7 (2012-10-15)FeaturesDataWatch now has aallow_missing_nodesetting that allows a watch to be
set on a node that doesn’t exist when the DataWatch is created.Add new Queue recipe, with optional priority support.Add new Counter recipe.Added debian packaging rules.Bug HandlingIssue #31 fixed: Only catch KazooExceptions in catch-all calls.Issue #15 fixed again: Force sleep delay to be a float to appease gevent.Issue #29 fixed: DataWatch and ChildrenWatch properly re-register their
watches on server disconnect.0.6 (2012-09-27)API ChangesNode paths are assumed to be Unicode objects. Under Python 2 pure-ascii
strings will also be accepted. Node values are considered bytes. The byte
type is an alias forstrunder Python 2.New KeeperState.CONNECTED_RO state for Zookeeper servers connected in
read-only mode.New NotReadOnlyCallError exception when issuing a write change against a
server thats currently read-only.FeaturesAdd support for Python 3.2, 3.3 and PyPy (only for the threading handler).Handles connecting to Zookeeper 3.4+ read-only servers.Automatic background scanning for a Read/Write server when connected to a
server in read-only mode.Add new Semaphore recipe.Add a newretry_max_delayargument to the client and by default limit the
retry delay to at most an hour regardless of exponential backoff settings.Add newrandomize_hostsargument toKazooClient, allowing one to disable
host randomization.Bug HandlingFix bug with locks not handling intermediary lock contenders disappearing.Fix bug with set_data type check failing to catch unicode values.Fix bug with gevent 0.13.x backport of peekable queue.Fix PatientChildrenWatch to use handler specific sleep function.0.5 (2012-09-06)Skipping a version to reflect the magnitude of the change. Kazoo is now a pure
Python client with no C bindings. This release should run without a problem
on alternate Python implementations such as PyPy and Jython. Porting to Python
3 in the future should also be much easier.DocumentationDocs have been restructured to handle the new classes and locations of the
methods from the pure Python refactor.Bug HandlingThis change may introduce new bugs, however there is no longer the possibility
of a complete Python segfault due to errors in the C library and/or the C
binding.Possible segfaults from the C lib are gone.Password mangling due to the C lib is gone.The party recipes didn’t set their participating flag to False after
leaving.FeaturesNewclient.commandandclient.server_versionAPI, exposing Zookeeper’s
four letter commands and giving access to structured version information.Added ‘include_data’ option for get_children to include the node’s Stat
object.Substantial increase in logging data with debug mode. All correspondence with
the Zookeeper server can now be seen to help in debugging.API ChangesThe testing helpers have been moved fromtesting.__init__into atesting.harnessmodule. The official API’s ofKazooTestCaseandKazooTestHarnesscan still be directly imported fromtesting.The kazoo.handlers.util module was removed.Backwards compatible exception class aliases are provided for now in kazoo
exceptions for the prior C exception names.Unicode strings now work fine for node names and are properly converted to
and from unicode objects.The data value argument for the create and create_async methods of the
client was made optional and defaults to an empty byte string. The data
value must be a byte string. Unicode values are no longer allowed and
will raise a TypeError.0.3 (2012-08-23)API ChangesHandler interface now has an rlock_object for use by recipes.Bug HandlingFixed password bug with updated zc-zookeeper-static release, which retains
null bytes in the password properly.Fixed reconnect hammering, so that the reconnection follows retry jitter and
retry backoff’s.Fixed possible bug with using a threading.Condition in the set partitioner.
Set partitioner uses new rlock_object handler API to get an appropriate RLock
for gevent.Issue #17 fixed: Wrap timeout exceptions with staticmethod so they can be
used directly as intended. Patch by Bob Van Zant.Fixed bug with client reconnection looping indefinitely using an expired
session id.0.2 (2012-08-12)DocumentationFixed doc references to start_async using an AsyncResult object, it uses
an Event object.Bug HandlingIssue #16 fixed: gevent zookeeper logging failed to handle a monkey patched
logging setup. Logging is now setup such that a greenlet is used for logging
messages under gevent, and the thread one is used otherwise.Fixed bug similar to #14 for ChildrenWatch on the session listener.Issue #14 fixed: DataWatch had inconsistent handling of the node it was
watching not existing. DataWatch also properly spawns its _get_data function
to avoid blocking session events.Issue #15 fixed: sleep_func for SequentialGeventHandler was not set on the
class appropriately leading to additional arguments being passed to
gevent.sleep.Issue #9 fixed: Threads/greenlets didn’t gracefully shut down. Handler now
has a start/stop that is used by the client when calling start and stop that
shuts down the handler workers. This addresses errors and warnings that could
be emitted upon process shutdown regarding a clean exit of the workers.Issue #12 fixed: gevent 0.13 doesn’t use the same start_new_thread as gevent
1.0 which resulted in a fully monkey-patched environment halting due to the
wrong thread. Updated to use the older kazoo method of getting the real thread
module object.API ChangesThe KazooClient handler is now officially exposed as KazooClient.handler
so that the appropriate sync objects can be used by end-users.Refactored ChildrenWatcher used by SetPartitioner into a publicly exposed
PatientChildrenWatch under recipe.watchers.Deprecationsconnect/connect_async has been renamed to start/start_async to better match
the stop to indicate connection handling. The prior names are aliased for
the time being.RecipesAdded Barrier and DoubleBarrier implementation.0.2b1 (2012-07-27)Bug HandlingZOOKEEPER-1318: SystemError is caught and rethrown as the proper invalid
state exception in older zookeeper python bindings where this issue is still
valid.ZOOKEEPER-1431: Install the latest zc-zookeeper-static library or use the
packaged ubuntu one for ubuntu 12.04 or later.ZOOKEEPER-553: State handling isn’t checked via this method, we track it in
a simpler manner with the watcher to ensure we know the right state.FeaturesExponential backoff with jitter for retrying commands.Gevent 0.13 and 1.0b support.Lock, Party, SetPartitioner, and Election recipe implementations.Data and Children watching API’s.State transition handling with listener registering to handle session state
changes (choose to fatal the app on session expiration, etc.)Zookeeper logging stream redirected into Python logging channel under the
name ‘Zookeeper’.Base client library with handler support for threading and gevent async
environments.