<a name="2.8.0"></a>
## 2.8.0 (2020-07-11)


#### Features

* **chore:**  using Github templates for issues and PRs (#610) ([eddc0976](https://github.com/python-zk/kazoo/commit/eddc0976bf1ef9d9fb97990cebbc3f9b1abe9d7d))
* **core:**
  *  Use strict regex to identify lock contenders. ([cc8ce892](https://github.com/python-zk/kazoo/commit/cc8ce8929116a1f0a2f0d088afa82ac9576395dc))
  *  Support additionaal lock contenter patterns ([225eeecb](https://github.com/python-zk/kazoo/commit/225eeecbe66c10d46dc7928681783d17f389f13a))
* **tests:**
  *  Disable problematic hound-flake8-black integration. ([75f62a0d](https://github.com/python-zk/kazoo/commit/75f62a0dd40a9f9bdefcb04cea5ee5fcd3438c0e))
  *  Move to pytest ([de97d74b](https://github.com/python-zk/kazoo/commit/de97d74b50b62cd2f0cddc2a04e150575d9c6bc7))
  *  add Python 3.8 and remove Python 3.6 from the testing suite (#611) ([e4f808f7](https://github.com/python-zk/kazoo/commit/e4f808f7f0fe17e7e01468a2c54684f048e12b52))

#### Performance

* **core:**  Use chain.from_iterable in threading.py (#614) ([13c73ec5](https://github.com/python-zk/kazoo/commit/13c73ec5f4d4f2215deb987a059051bb821674ca))

#### Bug Fixes

* **core:**
  *  handle SSL_WANT_READ/WRITE errors (#619) ([cbdc4749](https://github.com/python-zk/kazoo/commit/cbdc4749edb5879099c1f9b832c055d9eeb52dea), closes [#618](https://github.com/python-zk/kazoo/issues/618))
  *  '"is" with a literal' syntax errors (#609) ([6b6ffe62](https://github.com/python-zk/kazoo/commit/6b6ffe62a073d1ed5413c65c2d8ec94ea2fa1760))
  *  sync() return should be unchrooted ([cbde70ac](https://github.com/python-zk/kazoo/commit/cbde70ac87435afbbacc9806c675184c7f778343), closes [#601](https://github.com/python-zk/kazoo/issues/601))

#### Chore

* **core:**  Update matrix: add pypy3, drop py27 ([522189da](https://github.com/python-zk/kazoo/commit/522189da0f238faafc8f1db34f682f49b15ec503))
* **tests:**  Add coverage report on codecov.io ([bb475843](https://github.com/python-zk/kazoo/commit/bb475843905af1a2d25b1f5834085c85c28bb175))



<a name="2.7.0"></a>
## 2.7.0 (2020-03-13)

#### Features

* **CI:**  Keep only Python 3.{6,7} to CI and bump ZK versions to latests (#574) ([c293aabf](https://github.com/python-zk/kazoo/commit/c293aabf39676b94006cf736f9f75392637b8292))
* **core:**
  *  run SASL Kerberos tests as part of build ([5c461bdf](https://github.com/python-zk/kazoo/commit/5c461bdff50efd762805b40fbe283b194d175c61))
  *  Add create2 support ([1d81f96a](https://github.com/python-zk/kazoo/commit/1d81f96a77a6fd7ae2476cd798a5cb4bf1c1d9a2))
  *  closed states instead of lost states (#573) ([961b2f3b](https://github.com/python-zk/kazoo/commit/961b2f3be557f8314ab41f75444125222638f9cc))
  *  improve SASL interface (#546) ([cd49b3fa](https://github.com/python-zk/kazoo/commit/cd49b3fa01136848c5e6bfafb4c241b9704f249d))
* **recipe:**  add support for curator SharedCount recipe (#559) ([88b657a0](https://github.com/python-zk/kazoo/commit/88b657a0977161f3815657878ba48f82a97a3846), closes [#558](https://github.com/python-zk/kazoo/issues/558))
* **utils:**  extend create_tcp_connection utility (#568) ([ab0cd00c](https://github.com/python-zk/kazoo/commit/ab0cd00c12624b07dcc3b2d62aa96f8f1e658f65))

#### Bug Fixes

* **CI:**  deploying only for 1 job ([0ba3634d](https://github.com/python-zk/kazoo/commit/0ba3634d99740c9ccc2dd01924a36dffff262f8e))
* **core:**
  *  allow requests to be queued in CONNECTING state (#374) (#588) ([a636d7a6](https://github.com/python-zk/kazoo/commit/a636d7a6bb88ab9080e902983b10c8f0f1bf60a8))
  *  Implement proper retry backoff logic with jitter. ([0bb0659c](https://github.com/python-zk/kazoo/commit/0bb0659cf3fd73714a9d75b093a75c7122e116e6))
  *  when connection fails, close the ConnectionHandler (#577) (#579) ([c7e80503](https://github.com/python-zk/kazoo/commit/c7e80503f3be97d26ff2de27f9e424070c8181bb))
* **recipe:**  crash if None in znode (#569) ([ded79467](https://github.com/python-zk/kazoo/commit/ded79467a8254e43841dfeb69f7c3baa1980232c))
* **tests:**
  *  Disable JAAS isInitiator for Server ([933b38b5](https://github.com/python-zk/kazoo/commit/933b38b5506d84e05ed6f6c5c8c208a3367400da))
  *  deactivate TCP port that was enabled by default. ([d7bed550](https://github.com/python-zk/kazoo/commit/d7bed550fee1b861eb2ee81cc685e6d08ee35c34))
  *  capitalize the default_domain value ([7fd22bfd](https://github.com/python-zk/kazoo/commit/7fd22bfd1992b90042db7946949ce992ddfd1821))
  *  weaker crypto when configuring Kerberos ([844df87a](https://github.com/python-zk/kazoo/commit/844df87ac83e72c155367cfe4ff4d52d34d46c99))
  *  prefix with toxinidir variable with a / to ensure path to ensure-zookeeper-env.sh is correct ([c4d42ca7](https://github.com/python-zk/kazoo/commit/c4d42ca7722dec5332ecd4524e8d802a81e2ddca))
  *  specify -Dfile.encoding=UTF-8 when starting the ZK JVM ([5764da0b](https://github.com/python-zk/kazoo/commit/5764da0b3c25556cb6760f68c51b387f2fd8307b))



<a name="2.6.1"></a>
### 2.6.1 (2019-01-22)


#### Bug Fixes

* **client:**  add missing paren (#550) ([1452a48f](https://github.com/python-zk/kazoo/commit/1452a48f3070fe9034314476a6fdb94ca206dede))
* **core:**
  *  support deprecated KazooRetry argument (#545) ([4242da80](https://github.com/python-zk/kazoo/commit/4242da801e8da7b76d7e88e37c3948f97a2b5aae))
  *  reduce timeout for the first Connect() request (#540) ([2ae392e6](https://github.com/python-zk/kazoo/commit/2ae392e69c4b2daca5d8e7f0e79b7ce90423e65c))
* **handlers:**  make AsyncResult call all registered callbacks instantly if the handler has stopped running (#549) ([d9e0e720](https://github.com/python-zk/kazoo/commit/d9e0e7208e56c31f0abec60a3701f8d6ec1e7d32))
* **recipe:**
  *  No more memory leak when ChildrenWatch was stopped (#543) ([37bcda35](https://github.com/python-zk/kazoo/commit/37bcda357463155aba5f2383bc70528413a10f1b))
  *  No more memory leak once TreeCache was closed (#524) ([c48f2733](https://github.com/python-zk/kazoo/commit/c48f2733f2a6b2c2941738e4208e8cfede676730))



<a name="2.6.0"></a>
## 2.6.0 (2018-11-14)


#### Features

* **core:**
  *  add SASL DIGEST-MD5 support ([aa2664b8](https://github.com/python-zk/kazoo/commit/aa2664b880d1456c3ccf6515c6ca42653047e272))
  *  Added SSL support (#513) ([35ce1066](https://github.com/python-zk/kazoo/commit/35ce10669ace9d0d7e787793f0d4937d5d389f69))
* **tests:**
  *  update Zookeeper 3.5.2-alpha to 3.5.4-beta ([30330915](https://github.com/python-zk/kazoo/commit/3033091530b8f0aba13a1b8d031a7297e54006c2), closes [#477](https://github.com/python-zk/kazoo/issues/477))
  *  update Zookeeper version from 3.4.10 to 3.4.13 ([287749b4](https://github.com/python-zk/kazoo/commit/287749b422c886f69e46d108d2ddbb5ad064773e))

#### Bug Fixes

* **core:**
  *  ensure timeout argument is positive (#534) ([8c5ce118](https://github.com/python-zk/kazoo/commit/8c5ce11883a86b15bc6497706cf36abf1b36145f))
  *  get_children with include_data=True uses GetChildren2 types (#514) ([901cba7a](https://github.com/python-zk/kazoo/commit/901cba7a40d67ec96c06abe109e3cf51a992b24d))
  *  allow authentification in RO and RW modes ([2320ab39](https://github.com/python-zk/kazoo/commit/2320ab391f3804a9ddea9c5c86eb86467bb1dbf8))
  *  Use a copy of auth data when reconnecting (#509) ([de20be91](https://github.com/python-zk/kazoo/commit/de20be917855713169863b65a7aa0634fb78b698))
  *  change KazooRetry to uniformly jitter over the whole backoff interval (#521) ([60366d2c](https://github.com/python-zk/kazoo/commit/60366d2c7910fc833991fad8e04bbe33817c0544))
* **recipe:**  Delete lock node in queue recipe if entry already consumed ([7a8167de](https://github.com/python-zk/kazoo/commit/7a8167dea381b3a2015c869a443c96b9d5179411))

#### Doc

*   make badges link to travis and pypi (#528) ([367a1df3](https://github.com/python-zk/kazoo/commit/367a1df35b3b168580327e9f52a4cb9c000ea750))
*   specify description type for pypi to render correctly ([cc4006e6](https://github.com/python-zk/kazoo/commit/cc4006e6a8ea9441b01a631f3350357a8a2e4088))
*   remove broken downloads badge ([47e07a96](https://github.com/python-zk/kazoo/commit/47e07a9674713b0756bce0811545c4442d40b60b))
* **core:**  fix broken zookeeper programmers guide link ([8ecf8a50](https://github.com/python-zk/kazoo/commit/8ecf8a50c746ab7cc588ce9ac10a91ad1d1e5f34))



<a name="2.5.0"></a>
## 2.5.0 (2018-06-01)


#### Performance

* **recipe:**  Give TreeCache standalone queue ([4456f180](https://github.com/python-zk/kazoo/commit/4456f180735a0f8520bfc42474de9d27fa01bb2c))

#### Doc

*   Correctly document supported versions ([f860de52](https://github.com/python-zk/kazoo/commit/f860de5284e8ba7d0ed4171d9e5c5bef41f6b64d))
*   Add license to Wheel ([43d156de](https://github.com/python-zk/kazoo/commit/43d156de3d41173d7baf6e8edb4efa377b3732fc))
*   minor tweaks to contributing.md (#464) ([5837d11b](https://github.com/python-zk/kazoo/commit/5837d11bb541be1296e1b3c1842b11ceb7e743d4))

#### Features

* **recipe:**  allow non ephemeral locking ([6f7a603d](https://github.com/python-zk/kazoo/commit/6f7a603de9f04ec46d9946c6f5b1cb6e2b913b63))

#### Chore

*   drop python 2.6 compatible gevent ([2e8dcd38](https://github.com/python-zk/kazoo/commit/2e8dcd3836d01640f07e8de911cdfb3639f97d20))
*   remove debian packaging (#468) ([a28423aa](https://github.com/python-zk/kazoo/commit/a28423aac7f33111388372dec50653a3091b9045))
*   stop bundling virtualenv ([af9b4cab](https://github.com/python-zk/kazoo/commit/af9b4cab39982d961647afca8119816ffe7bf5e6))
*   remove python 3.3 from tox ([cf66474b](https://github.com/python-zk/kazoo/commit/cf66474b27b4efc9f65e292434c2fcffb697d34d))
*   remove `easy_install` instructions ([6e6627d5](https://github.com/python-zk/kazoo/commit/6e6627d58628dec11d127fc5508f9a1d16e9c317))

#### Bug Fixes

*   Pass watch as keyword arg instead of positional arg (#495) ([23850792](https://github.com/python-zk/kazoo/commit/2385079267db0bea6793c4f20588644381803a98))
*   need gevent >= 1.2, not > 1.1 ([18f3531b](https://github.com/python-zk/kazoo/commit/18f3531b605119a547cfc4d5a4223b4b3f185405))
*   Remove use of "async" as a variable ([225d3369](https://github.com/python-zk/kazoo/commit/225d3369c7a0736125a9375951a079f70fbe9e79), closes [#455](https://github.com/python-zk/kazoo/issues/455))
* **core:**
  *  Fix gevent 1.3b1+ timeout import ([257b5896](https://github.com/python-zk/kazoo/commit/257b58961f7ddd9db04d6efa070739a1b0404487))
  *  Correctly fire multiple callbacks ([0905c47b](https://github.com/python-zk/kazoo/commit/0905c47bff3cfc42382daff0d5ac81189c8ba46d))
  *  resolve race in IAsyncResult.wait() (#487) ([4d268adf](https://github.com/python-zk/kazoo/commit/4d268adf9837836f05dde5ec81be0d7bbd759e78))
* **recipe:**
  *  conn hangs when TreeCache refreshing ([11194137](https://github.com/python-zk/kazoo/commit/111941371daec00a2ecb5d8c29b9b1d35d6aa4ff))
  *  Unexpected exceptions break TreeCache ([db0c2d4f](https://github.com/python-zk/kazoo/commit/db0c2d4f8ab5ecfb367b7b2accfd9c52c1c91fcd))

#### Refactor

*   Unify queue factory in various handlers ([cbd02f5c](https://github.com/python-zk/kazoo/commit/cbd02f5ccc6ea9e6dd6b5da01a0397ea649143a0))



<a name="2.4.0"></a>
## 2.4.0 (2017-06-14)

**PYTHON SUPPORTED VERSIONS CHANGE**: Please note that Kazoo no longer tests
on Python 2.6 or 3.3. Tested versions are 2.7, 3.4, 3.5, 3.6, and PyPy. The
multiple endpoint support for KazooClient may not work correctly on 2.6.

#### Bug Fixes

*   add missed parens to LockingQueue function call. ([88cf4aa7](https://github.com/python-zk/kazoo/commit/88cf4aa7bcd1437a44f6d3aeec34989c467fcf9d))
* **core:**  revert PR #305 SetWatches which caused RuntimeError ([a7b45390](https://github.com/python-zk/kazoo/commit/a7b45390f3720a33c9ad3896a8a185bfb2628839))

#### Features

*   pep8 all the things ([92880342](https://github.com/python-zk/kazoo/commit/928803420721b81962e50d425610e62b0c12e438), closes [#445](https://github.com/python-zk/kazoo/issues/445))
*   drop Python 2.6/3.3 official support, add 3.5/3.6 testing ([2faba9ff](https://github.com/python-zk/kazoo/commit/2faba9ff3bdeff151ac6c922bf65b2dcf9c7bd7b), closes [#441](https://github.com/python-zk/kazoo/issues/441))
* **core:**
  *  allow multiple endpoints in KazooClient hosts arg ([72a8d96c](https://github.com/python-zk/kazoo/commit/72a8d96ca188c3c2e93bd0243283539ebd6c16f1), closes [#411](https://github.com/python-zk/kazoo/issues/411))
  *  use epoll when available to support fds > 1023 ([267e61b4](https://github.com/python-zk/kazoo/commit/267e61b4323bc13505e8933fa9b89d0591af3a69), closes [#171](https://github.com/python-zk/kazoo/issues/171))
* **recipe:**  Add TreeCache recipe ([ec8b337e](https://github.com/python-zk/kazoo/commit/ec8b337e6f1a4ff12e669f4b96ca98fb37ee5d8a))



<a name="2.3.1"></a>
## 2.3.1 (2017-06-01)


#### Chore

*   update MANIFEST.in to reflect changes to filenames ([c9a38c5d](https://github.com/python-zk/kazoo/commit/c9a38c5d650d6d92ff30fd3c1c792fc71db9ce02))
*   add travis deployment and update ZK versions ([7d5d59cb](https://github.com/python-zk/kazoo/commit/7d5d59cb049244b89625d621c9d91d9a44c4b051), closes [#436](https://github.com/python-zk/kazoo/issues/436))

2.3.0 (2017-05-31)
------------------

Please note, there have been a few dozen merges that failed to update the
changelog here. As such, the log here should not be considered conclusive as
to the changes that are arriving in 2.3.0.

Changes being made now to ensure more accuracy in the changelog will appear
in all future versions going forward. Read the commit history for a better
understanding of changes merged between 2.2.1 and 2.3.0.

All future commits must abide by the new CONTRIBUTING.md document describing
how to label commits so they can be automatically used to automatically
generate an accurate changelog.

*WARNING:* THIS IS THE LAST KAZOO RELEASE THAT SUPPORTS PYTHON 2.6. ALL FUTURE
VERSIONS WILL REQUIRE PYTHON 2.7 AND ABOVE.

### Features

-   allow having observers and different sized clusters

### Bug Handling

-   \#372: fully resolve multiple records for hosts in the zookeeper
    connection string

### Documentation

-   Fix the recipe examples, so they actually work by connecting to
    ZooKeeper. Without start() they just hang and can't be killed.

2.2.1 (2015-06-17)
------------------

### Bug Handling

-   handle NameError with basestring on py3k.

### Documentation

2.2 (2015-06-15)
----------------

### Documentation

### Features

-   Issue \#234: Add support for reconfig cluster membership operation

### Bug Handling

-   \#315: multiple acquires of a kazoo lock using the lock recipe would
    block when using acquire even when non-blocking is specified (only
    when the lock was/has been already acquired).
-   \#318: At exit register takes `*args` and `**kwargs` not args and
    kargs

### Documentation

2.1 (2015-05-11)
----------------

### Features

-   Start running tests against Zookeeper 3.5.0 alpha and explicitly
    configure the admin.serverPort in tests to avoid port conflicts. The
    Zookeeper alpha version is not yet officially supported.
-   Integrate eventlet *handler* support into kazoo so that along with
    [gevent, threading] handlers there can now be a dedicated eventlet
    handler for projects that need to (or want to) use eventlet (such as
    those working in the openstack community). The
    `requirements_eventlet.txt` file lists the optional eventlet
    requirement(s) that needs to be satisfied when this new handler is
    used.
-   Use `six` to nicely handle the cross compatibility of kazoo with
    python 2.x and 3.x (reducing/removing the need to have custom
    compatibility code that replicates what six already provides).
-   Add `state_change_event` to
    `kazoo.recipe.partitioner.SetPartitioner` which is set on every
    state change.
-   Add a NonBlockingLease recipe. The recipe allows e.g. cron jobs
    scheduled on multiple machines to ensure that at most N instances
    will run a particular job, with lease timeout for graceful handover
    in case of node failures.

### Bug Handling

-   \#291: Kazoo lock recipe was only partially re-entrant in that
    multiple calls to acquire would obtain the the lock but the first
    call to release would remove the underlying lock. This would leave
    the X - 1 other acquire statements unprotected (and no longer
    holding there expected lock). To fix this the comment about that
    lock recipe being re-entrant has been removed and multiple acquires
    will now block when attempted.
-   \#78: Kazoo now uses socketpairs instead of pipes making it
    compatible with Windows.
-   \#144, \#221: Let client.command work with IPv6 addresses.
-   \#216: Fixed timeout for ConnectionHandler.\_invoke.
-   \#261: Creating a sequential znode under / doesn't work.
-   \#274: Add server\_version() retries (by default 4 attempts will be
    made) to better handle flakey responses.
-   \#271: Fixed handling of KazooState.SUSPENDED in SetPartitioner.
-   \#283: Fixed a race condition in SetPartitioner when party changes
    during handling of lock acquisition.
-   \#303: don't crash on random input as the hosts string.

### Documentation

-   \#222: Document that committed on the transaction is used to ensure
    only one commit and is not an indicator of whether operations in the
    transaction returned desired results.

2.0 (2014-06-19)
----------------

### Documentation

-   Extend 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 Changes

-   Null 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).

### Features

-   Logging levels have been reduced.
    -   Logging previously at the `logging.DEBUG` level is now logged at
    the `kazoo.loggingsupport.BLATHER` level (5).
    -   Some low-level logging previously at the `logging.INFO` level is
    now logged at the `logging.DEBUG` level.
-   Issue \#133: Introduce a new environment variable
    ZOOKEEPER\_PORT\_OFFSET for the testing support, to run the testing
    cluster on a different range.

### Bug Handling

-   When 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.

### Documentation

-   Add 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 KazooClient
    command\_retry argument handling.
-   \#126: Fix KazooRetry.copy to correctly copy sleep function.
-   \#118: Correct session/socket timeout conversion (int vs. float).

### Documentation

-   \#121: Add a note about kazoo.recipe.queue.LockingQueue requiring 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 Handling

-   Issue \#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\_async didn't strip change root
    from the returned path.

1.2 (2013-07-24)
----------------

### Features

-   KazooClient 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 Handling

-   Issue \#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 Changes

-   The kazoo.testing.harness.KazooTestHarness class directly inherits
    from unittest.TestCase and 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)
----------------

### Features

-   Issue \#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 a max\_leases consistency check to the semaphore recipe.
-   Issue \#76: Extend testing helpers to allow customization of the
    Java classpath by specifying the new ZOOKEEPER\_CLASSPATH
    environment variable.
-   Issue \#65: Allow non-blocking semaphore acquisition.

### Bug Handling

-   Issue \#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 Changes

-   KazooClient.create\_async now supports the makepath argument.
-   KazooClient.ensure\_path now has an async version,
    ensure\_path\_async.

1.0 (2013-03-26)
----------------

### Features

-   Added 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 Handling

-   Issue \#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)
------------------

### Features

-   Refactored 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 the retry helper module.
-   Issue \#55: Fix os.pipe file descriptor leak and introduce a
    KazooClient.close method. The method is particular useful in tests,
    where multiple KazooClients are created and closed in the same
    process.

### Bug Handling

-   Issue \#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 Changes

-   When a retry operation ultimately fails, it now raises a
    kazoo.retry.RetryFailedError exception, instead of a general
    Exception instance. RetryFailedError also inherits from the base
    KazooException.

### Features

-   Improvements to Debian packaging rules.

### Bug Handling

-   Issue \#39 / \#41: Handle connection dropped errors during session
    writes. Ensure client connection is re-established to a new ZK node
    if available.
-   Issue \#38: Set CLOEXEC flag on all sockets when available.
-   Issue \#37 / \#40: Handle timeout errors during select calls on
    sockets.
-   Issue \#36: Correctly set ConnectionHandler.writer\_stopped even if
    an exception is raised inside the writer, like a retry operation
    failing.

0.8 (2012-10-26)
----------------

### API Changes

-   The KazooClient.\_\_init\_\_ took as watcher argument as its second
    keyword argument. The argument had no effect anymore since version
    0.5 and was removed.

### Bug Handling

-   Issue \#35: KazooClient.\_\_init\_\_ didn't pass on
    retry\_max\_delay to the retry helper.
-   Issue \#34: Be more careful while handling socket connection errors.

0.7 (2012-10-15)
----------------

### Features

-   DataWatch now has a allow\_missing\_node setting 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 Handling

-   Issue \#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 Changes

-   Node 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 for str under 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.

### Features

-   Add 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 new retry\_max\_delay argument to the client and by default
    limit the retry delay to at most an hour regardless of exponential
    backoff settings.
-   Add new randomize\_hosts argument to KazooClient, allowing one to
    disable host randomization.

### Bug Handling

-   Fix 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.

### Documentation

-   Docs have been restructured to handle the new classes and locations
    of the methods from the pure Python refactor.

### Bug Handling

This 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.

### Features

-   New client.command and client.server\_version API, 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 Changes

-   The testing helpers have been moved from testing.\_\_init\_\_ into a
    testing.harness module. The official API's of KazooTestCase and
    KazooTestHarness can still be directly imported from testing.
-   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 Changes

-   Handler interface now has an rlock\_object for use by recipes.

### Bug Handling

-   Fixed 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)
----------------

### Documentation

-   Fixed doc references to start\_async using an AsyncResult object, it
    uses an Event object.

### Bug Handling

-   Issue \#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 Changes

-   The 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.

### Deprecations

-   connect/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.

### Recipes

-   Added Barrier and DoubleBarrier implementation.

0.2b1 (2012-07-27)
------------------

### Bug Handling

-   ZOOKEEPER-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.

### Features

-   Exponential 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.

