Python recipe(16):ReadWriteLock
代码何在？Example Source Code
'''
Created on 2010-5-28
@author: lk
'''
import threading
class ReadWriteLock:
def __init__(self):
self._read_ready = threading.Condition()
self._readers = 0
def acquire_read(self):
self._read_ready.acquire()
try:
self._readers+=1
finally:
self._read_ready.release()
def release_read(self):
self._read_ready.acquire()
try:
self._readers-=1
if not self._readers:
self._read_ready.notifyAll()
finally:
self._read_ready.release()
def acquire_write(self):
self._read_ready.acquire()
while self._readers:
self._read_ready.wait()
def release_write(self):
self._read_ready.release()
if __name__ == '__main__':
pass
以上代码改写自Python Cookbook 6-4
概述：
不必多说，用Python实现的读写锁（ReadWriteLock）：允许同时多个reader，但只能有一个writer，并且writer工作时reader也不能读
代码说明：
1.实现方法和其他语言没有太大区别，这里threading模块是python实现的高级多线程模块（相对low-level的thread模块而言）
2.python中的condition信号量对象其实还被委托了lock的一些列操作，如acquire和release等，比较方便
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