• 自定义异步IO框架


    异步就是回调

    异步 = 非阻塞+循环

    select只能完成IO多路复用,不能完成异步

    IO多路复用--->监听多个socket对象,这个过程是同步的

    利用其特性可以开发异步模块

    异步IO:非阻塞的socket + IO多路复用

    自定义异步框架

    import socket
    import select
    
    
    class HttpRequest(object):
        def __init__(self, sk, host, callback):
            self.socket = sk
            self.host = host
            self.callback = callback
        def fileno(self): # select监听的对象,只要内部有fileno()方法,并且返回fileno
            return self.socket.fileno()
    
    class HttpResponse(object):
        def __init__(self, recv_data):
            self.recv_data = recv_data
            self.header_dict = {}
            self.body = None
            self.initialize()
    
        def initialize(self):
            headers, body = self.recv_data.split(b'
    
    ', 1)
            self.body = body
            header_list = headers.split(b'
    ')
            for h in header_list:
                h_str = str(h, encoding='utf-8')
                v = h_str.split(':', 1)
                if len(v) == 2:
                    self.header_dict[v[0]] = v[1]
    
    
    class AsyncRequest(object):
        def __init__(self):
            self.conn = []
            self.connection = []
        def add_request(self, host, callback):
            try:
                sk = socket.socket()
                sk.setblocking(0)
                sk.connect((host, 80),)
            except BlockingIOError as e:
                pass
            # 把sk、host和callback封装起来,返回fd给select
            request = HttpRequest(sk, host, callback)
            self.conn.append(request)
            self.connection.append(request)
    
        def run(self):
            while True:
                rlist, wlist, elist = select.select(self.conn, self.connection, self.conn, 0.05)
                for w in wlist:
                    # 只要能循环到,表示socket和服务端已经连接成功
                    print(w.host, '连接成功...')
                    tpl = "GET / HTTP/1.0
    Host:%s
    
    " % (w.host,)
                    w.socket.send(bytes(tpl, encoding='utf-8'))
                    self.connection.remove(w)
                for r in rlist:
                    recv_data = bytes()
                    while True:
                        try:
                            chunck = r.socket.recv(8096)
                            recv_data += chunck
                        except Exception as e:
                            break
                    # 把返回的数据进行处理,然后交给回调函数
                    response = HttpResponse(recv_data)
                    r.callback(response)
                    r.socket.close()
                    self.conn.remove(r)
                if len(self.conn) == 0:
                    break
    
    
    def f1(response):
        print('保存到文件',response.header_dict)
    
    def f2(response):
        print('保存到数据库', response.header_dict)
    
    url_list = [
        {'host':'www.baidu.com','callback': f1},
        {'host':'cn.bing.com','callback': f2},
        {'host':'www.cnblogs.com','callback': f2},
    ]
    
    req = AsyncRequest()
    for item in url_list:
        req.add_request(item['host'],item['callback'])
    
    req.run()
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  • 原文地址:https://www.cnblogs.com/linyuhong/p/10351333.html
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