zookeeper python接口实例详解

Python  /  管理员 发布于 7年前   227

本文主要讲python支持zookeeper的接口库安装和使用。zk的python接口库有zkpython，还有kazoo，下面是zkpython，是基于zk的C库的python接口。

zkpython安装

前提是zookeeper安装包已经在/usr/local/zookeeper下

cd /usr/local/zookeeper/src/c./configuremakemake installwget --no-check-certificate http://pypi.python.org/packages/source/z/zkpython/zkpython-0.4.tar.gztar -zxvf zkpython-0.4.tar.gzcd zkpython-0.4sudo python setup.py install

zkpython应用

下面是网上一个zkpython的类，用的时候只要import进去就行
vim zkclient.py

#!/usr/bin/env python2.7# -*- coding: UTF-8 -*-import zookeeper, time, threadingfrom collections import namedtupleDEFAULT_TIMEOUT = 30000VERBOSE = TrueZOO_OPEN_ACL_UNSAFE = {"perms":0x1f, "scheme":"world", "id" :"anyone"}# Mapping of connection state values to human strings.STATE_NAME_MAPPING = {  zookeeper.ASSOCIATING_STATE: "associating",  zookeeper.AUTH_FAILED_STATE: "auth-failed",  zookeeper.CONNECTED_STATE: "connected",  zookeeper.CONNECTING_STATE: "connecting",  zookeeper.EXPIRED_SESSION_STATE: "expired",}# Mapping of event type to human string.TYPE_NAME_MAPPING = {  zookeeper.NOTWATCHING_EVENT: "not-watching",  zookeeper.SESSION_EVENT: "session",  zookeeper.CREATED_EVENT: "created",  zookeeper.DELETED_EVENT: "deleted",  zookeeper.CHANGED_EVENT: "changed",  zookeeper.CHILD_EVENT: "child", }class ZKClientError(Exception):  def __init__(self, value):    self.value = value  def __str__(self):    return repr(self.value)class ClientEvent(namedtuple("ClientEvent", 'type, connection_state, path')):  """  A client event is returned when a watch deferred fires. It denotes  some event on the zookeeper client that the watch was requested on.  """  @property  def type_name(self):    return TYPE_NAME_MAPPING[self.type]  @property  def state_name(self):    return STATE_NAME_MAPPING[self.connection_state]  def __repr__(self):    return "<ClientEvent %s at %r state: %s>" % (      self.type_name, self.path, self.state_name)def watchmethod(func):  def decorated(handle, atype, state, path):    event = ClientEvent(atype, state, path)    return func(event)  return decoratedclass ZKClient(object):  def __init__(self, servers, timeout=DEFAULT_TIMEOUT):    self.timeout = timeout    self.connected = False    self.conn_cv = threading.Condition( )    self.handle = -1    self.conn_cv.acquire()    if VERBOSE: print("Connecting to %s" % (servers))    start = time.time()    self.handle = zookeeper.init(servers, self.connection_watcher, timeout)    self.conn_cv.wait(timeout/1000)    self.conn_cv.release()    if not self.connected:      raise ZKClientError("Unable to connect to %s" % (servers))    if VERBOSE:      print("Connected in %d ms, handle is %d"         % (int((time.time() - start) * 1000), self.handle))  def connection_watcher(self, h, type, state, path):    self.handle = h    self.conn_cv.acquire()    self.connected = True    self.conn_cv.notifyAll()    self.conn_cv.release()  def close(self):    return zookeeper.close(self.handle)  def create(self, path, data="", flags=0, acl=[ZOO_OPEN_ACL_UNSAFE]):    start = time.time()    result = zookeeper.create(self.handle, path, data, acl, flags)    if VERBOSE:      print("Node %s created in %d ms"         % (path, int((time.time() - start) * 1000)))    return result  def delete(self, path, version=-1):    start = time.time()    result = zookeeper.delete(self.handle, path, version)    if VERBOSE:      print("Node %s deleted in %d ms"         % (path, int((time.time() - start) * 1000)))    return result  def get(self, path, watcher=None):    return zookeeper.get(self.handle, path, watcher)  def exists(self, path, watcher=None):    return zookeeper.exists(self.handle, path, watcher)  def set(self, path, data="", version=-1):    return zookeeper.set(self.handle, path, data, version)  def set2(self, path, data="", version=-1):    return zookeeper.set2(self.handle, path, data, version)  def get_children(self, path, watcher=None):    return zookeeper.get_children(self.handle, path, watcher)  def async(self, path = "/"):    return zookeeper.async(self.handle, path)  def acreate(self, path, callback, data="", flags=0, acl=[ZOO_OPEN_ACL_UNSAFE]):    result = zookeeper.acreate(self.handle, path, data, acl, flags, callback)    return result  def adelete(self, path, callback, version=-1):    return zookeeper.adelete(self.handle, path, version, callback)  def aget(self, path, callback, watcher=None):    return zookeeper.aget(self.handle, path, watcher, callback)  def aexists(self, path, callback, watcher=None):    return zookeeper.aexists(self.handle, path, watcher, callback)  def aset(self, path, callback, data="", version=-1):    return zookeeper.aset(self.handle, path, data, version, callback)watch_count = 0"""Callable watcher that counts the number of notifications"""class CountingWatcher(object):  def __init__(self):    self.count = 0    global watch_count    self.id = watch_count    watch_count += 1  def waitForExpected(self, count, maxwait):    """Wait up to maxwait for the specified count,    return the count whether or not maxwait reached.    Arguments:    - `count`: expected count    - `maxwait`: max milliseconds to wait    """    waited = 0    while (waited < maxwait):      if self.count >= count:        return self.count      time.sleep(1.0);      waited += 1000    return self.count  def __call__(self, handle, typ, state, path):    self.count += 1    if VERBOSE:      print("handle %d got watch for %s in watcher %d, count %d" %         (handle, path, self.id, self.count))"""Callable watcher that counts the number of notificationsand verifies that the paths are sequential"""class SequentialCountingWatcher(CountingWatcher):  def __init__(self, child_path):    CountingWatcher.__init__(self)    self.child_path = child_path  def __call__(self, handle, typ, state, path):    if not self.child_path(self.count) == path:      raise ZKClientError("handle %d invalid path order %s" % (handle, path))    CountingWatcher.__call__(self, handle, typ, state, path)class Callback(object):  def __init__(self):    self.cv = threading.Condition()    self.callback_flag = False    self.rc = -1  def callback(self, handle, rc, handler):    self.cv.acquire()    self.callback_flag = True    self.handle = handle    self.rc = rc    handler()    self.cv.notify()    self.cv.release()  def waitForSuccess(self):    while not self.callback_flag:      self.cv.wait()    self.cv.release()    if not self.callback_flag == True:      raise ZKClientError("asynchronous operation timed out on handle %d" %   (self.handle))    if not self.rc == zookeeper.OK:      raise ZKClientError(        "asynchronous operation failed on handle %d with rc %d" %        (self.handle, self.rc))class GetCallback(Callback):  def __init__(self):    Callback.__init__(self)  def __call__(self, handle, rc, value, stat):    def handler():      self.value = value      self.stat = stat    self.callback(handle, rc, handler)class SetCallback(Callback):  def __init__(self):    Callback.__init__(self)  def __call__(self, handle, rc, stat):    def handler():      self.stat = stat    self.callback(handle, rc, handler)class ExistsCallback(SetCallback):  passclass CreateCallback(Callback):  def __init__(self):    Callback.__init__(self)  def __call__(self, handle, rc, path):    def handler():      self.path = path    self.callback(handle, rc, handler)class DeleteCallback(Callback):  def __init__(self):    Callback.__init__(self)  def __call__(self, handle, rc):    def handler():      pass    self.callback(handle, rc, handler)

总结

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