上文讲了zookeeper集群安装配置，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
./configure
make
make install
wget --no-check-certificate http://pypi.python.org/packages/source/z/zkpython/zkpython-0.4.tar.gz
tar -zxvf zkpython-0.4.tar.gz
cd zkpython-0.4
sudo python setup.py installzkpython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, threading
from collections import namedtuple
DEFAULT_TIMEOUT = 30000
VERBOSE = True
ZOO_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 "" % (
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 decorated
class 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 notifications
and 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):
pass
class 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)