剖析Python的Twisted框架的核心特性
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一. reactor 二. twisted简单使用
# 示例一 twisted底层API的使用
from twisted.internet import reacto
from twisted.internet import main
from twisted.internet.interfaces import IReadDescriptor
import socket
class MySocket(IReadDescriptor):
def __init__(self,address):
# 连接服务器
self.address = address
self.sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
self.sock.connect(address)
self.sock.setblocking(0)
# tell the Twisted reactor to monitor this socket for reading
reactor.addReader(self)
# 接口: 告诉reactor 监听的套接字描述符
def fileno(self):
try:
return self.sock.fileno()
except socket.error:
return -1
# 接口: 在连接断开时的回调
def connectionLost(self,reason):
self.sock.close()
reactor.removeReader(self)
# 当应用程序需要终止时 调用:
# reactor.stop()
# 接口: 当套接字描述符有数据可读时
def doRead(self):
bytes = ''
# 尽可能多的读取数据
while True:
try:
bytesread = self.sock.recv(1024)
if not bytesread:
break
else:
bytes += bytesread
except socket.error,e:
if e.args[0] == errno.EWOULDBLOCK:
break
return main.CONNECTION_LOST
if not bytes:
return main.CONNECTION_DONE
else:
# 在这里解析协议并处理数据
print bytes
示例一可以很清晰的看到twisted的reactor本质：添加监听描述符，监听可读/可写事件，当事件来临时回调函数，回调完成之后继续监听事件。 三. twisted抽象
# 示例二 twisted抽象的使用
from twisted.internet import reactor
from twisted.internet.protocol import Protocol,ClientFactory
class MyProtocol(Protocol):
# 接口: Protocols初始化时调用，并传入Transports
# 另外 twisted会自动将Protocols的factory对象成员设为ProtocolsFactory实例的引用
# 如此就可以通过factory来与MyProtocolFactory交互
def makeConnection(self,trans):
print 'make connection: get transport: ',trans
print 'my factory is: ',self.factory
# 接口: 有数据到达
def dataReceived(self,data):
self.poem += data
msg = 'Task %d: got %d bytes of poetry from %s'
print msg % (self.task_num,len(data),self.transport.getPeer())
# 接口: 连接断开
def connectionLost(self,reason):
# 连接断开的处理
class MyProtocolFactory(ClientFactory):
# 接口: 通过protocol类成员指出需要创建的Protocols
protocol = PoetryProtocol # tell base class what proto to build
def __init__(self,address):
self.poetry_count = poetry_count
self.poems = {} # task num -> poem
# 接口: 在创建Protocols的回调
def buildProtocol(self,address):
proto = ClientFactory.buildProtocol(self,address)
# 在这里对proto做一些初始化....
return proto
# 接口: 连接Server失败时的回调
def clientConnectionFailed(self,connector,reason):
print 'Failed to connect to:',connector.getDestination()
def main(address):
factory = MyClientFactory(address)
host,port = address
# 连接服务端时传入ProtocolsFactory
reactor.connectTCP(host,port,factory)
reactor.run()
示例二要比示例一要简单清晰很多，因为它无需处理网络IO，并且逻辑上更为清晰，实际上ClientFactory和Protocol提供了更多的接口用于实现更灵活强大的逻辑控制，具体的接口可参见twisted源代码。 四. twisted Deferred d = Deferred() # 添加正确回调和错误回调 d.addCallbacks(your_ok_callback,your_err_callback) # 添加公共回调函数 d.addBoth(your_common_callback) # 正确返回 将依次调用 your_ok_callback(Res) -> common_callback(Res) d.callback(Res) # 错误返回 将依次调用 your_err_callback(Err) -> common_callback(Err) d.errback(Err) # 注意，对同一个Defered对象，只能返回一次，尝试多次返回将会报错 twisted的defer是异步的一种变现方式，可以这么理解，他和thread的区别是，他是基于时间event的。 五.综合示例 下面的例子，你们自己跑跑，我上面说的都是一些个零散的例子，大家对照下面完整的，走一遍。 twisted理解其实却是有点麻烦，大家只要知道他是基于事件的后，慢慢理解就行了。
#coding:utf-8
#xiaorui.cc
from twisted.internet import reactor,defer
from twisted.internet.threads import deferToThread
import os,sys
from twisted.python import threadable; threadable.init(1)
deferred =deferToThread.__get__
import time
def todoprint_(result):
print result
def running():
"Prints a few dots on stdout while the reactor is running."
# sys.stdout.write("."); sys.stdout.flush()
print '.'
reactor.callLater(.1,running)
@deferred
def sleep(sec):
"A blocking function magically converted in a non-blocking one."
print 'start sleep %s'%sec
time.sleep(sec)
print 'nend sleep %s'%sec
return "ok"
def test(n,m):
print "fun test() is start"
m=m
vals = []
keys = []
for i in xrange(m):
vals.append(i)
keys.append('a%s'%i)
d = None
for i in xrange(n):
d = dict(zip(keys,vals))
print "fun test() is end"
return d
if __name__== "__main__":
#one
sleep(10).addBoth(todoprint_)
reactor.callLater(.1,running)
reactor.callLater(3,reactor.stop)
print "go go !!!"
reactor.run()
#two
aa=time.time()
de = defer.Deferred()
de.addCallback(test)
reactor.callInThread(de.callback,10000000,100 )
print time.time()-aa
print "我这里先做别的事情"
print de
print "go go end"
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