Python(十一)异步IO

1.生产者消费者模型
生产者生产消息后，直接通过yield跳转到消费者开始执行，待消费者执行完毕后，切换回生产者继续生产，效率极高

import socket
#创建一个socket
s=socket.socket(socket.AF_INET,socker.SOCK_STREAM)
#建立连接:
s.connect(('www.sina.com.cn',80))
# 发送数据:
s.send(b'GET / HTTP/1.1\r\nHost: www.sina.com.cn\r\nConnection: close\r\n\r\n')
# 接收数据:
buffer = []
while True:
    # 每次最多接收1k字节:
    d = s.recv(1024)
    if d:
        buffer.append(d)
    else:
        break
data = b''.join(buffer)
# 关闭连接:
s.close()

2.asyncio

import asyncio

@asyncio.coroutine
def hello():
    print("Hello world!")
    # 异步调用asyncio.sleep(1):
    r = yield from asyncio.sleep(1)
    print("Hello again!")

# 获取EventLoop:
loop = asyncio.get_event_loop()
# 执行coroutine
loop.run_until_complete(hello())
loop.close()

异步连接获得首页

import asyncio

@asyncio.coroutine
def wget(host):
    print('wget %s...' % host)
    connect = asyncio.open_connection(host, 80)
    reader, writer = yield from connect
    header = 'GET / HTTP/1.0\r\nHost: %s\r\n\r\n' % host
    writer.write(header.encode('utf-8'))
    yield from writer.drain()
    while True:
        line = yield from reader.readline()
        if line == b'\r\n':
            break
        print('%s header > %s' % (host, line.decode('utf-8').rstrip()))
    # Ignore the body, close the socket
    writer.close()

loop = asyncio.get_event_loop()
tasks = [wget(host) for host in ['www.sina.com.cn', 'www.sohu.com', 'www.163.com']]
loop.run_until_complete(asyncio.wait(tasks))
loop.close()

wget www.sohu.com...
wget www.sina.com.cn...
wget www.163.com...
www.sohu.com header > HTTP/1.1 200 OK
www.sohu.com header > Content-Type: text/html;charset=UTF-8
www.sohu.com header > Connection: close
www.sohu.com header > Server: nginx
www.sohu.com header > Date: Thu, 14 Mar 2019 13:42:47 GMT
www.sohu.com header > Cache-Control: max-age=60
www.sohu.com header > X-From-Sohu: X-SRC-Cached
www.sohu.com header > Content-Encoding: gzip
www.sohu.com header > FSS-Cache: HIT from 4098995.6785981.4852700
www.sohu.com header > FSS-Proxy: Powered by 2330267.3247781.3084713
www.sina.com.cn header > HTTP/1.1 302 Moved Temporarily
www.sina.com.cn header > Server: nginx
www.sina.com.cn header > Date: Thu, 14 Mar 2019 13:43:22 GMT
www.sina.com.cn header > Content-Type: text/html
www.sina.com.cn header > Content-Length: 154
www.sina.com.cn header > Connection: close
www.sina.com.cn header > Location: https://www.sina.com.cn/
www.sina.com.cn header > X-Via-CDN: f=edge,s=cnc.qinhuangdao.ha2ts4.54.nb.sinaedge.com,c=121.22.24.9;
www.sina.com.cn header > X-Via-Edge: 1552571002306091816791d0416791ea2e615
www.163.com header > HTTP/1.0 302 Moved Temporarily
www.163.com header > Server: Cdn Cache Server V2.0
www.163.com header > Date: Thu, 14 Mar 2019 13:43:22 GMT
www.163.com header > Content-Length: 0
www.163.com header > Location: http://www.163.com/special/0077jt/error_isp.html
www.163.com header > X-Via: 1.0 dingwtong92:7 (Cdn Cache Server V2.0)
www.163.com header > Connection: close

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