200行自定义python异步非阻塞Web框架

Python的Web框架中Tornado以异步非阻塞而闻名。本篇将使用200行代码完成一个微型异步非阻塞Web框架：Snow。

一、源码

本文基于非阻塞的Socket以及IO多路复用从而实现异步非阻塞的Web框架，其中便是众多异步非阻塞Web框架内部原理。

#!/usr/bin/env python# -*- coding:utf-8 -*-import reimport socketimport selectimport timeclass HttpResponse(object): """ 封装响应信息 """ def __init__(self, content=''):  self.content = content  self.headers = {}  self.cookies = {} def response(self):  return bytes(self.content, encoding='utf-8')class HttpNotFound(HttpResponse): """ 404时的错误提示 """ def __init__(self):  super(HttpNotFound, self).__init__('404 Not Found')class HttpRequest(object): """ 用户封装用户请求信息 """ def __init__(self, conn):  self.conn = conn  self.header_bytes = bytes()  self.header_dict = {}  self.body_bytes = bytes()  self.method = ""  self.url = ""  self.protocol = ""  self.initialize()  self.initialize_headers() def initialize(self):  header_flag = False  while True:   try:    received = self.conn.recv(8096)   except Exception as e:    received = None   if not received:    break   if header_flag:    self.body_bytes += received    continue   temp = received.split(b'/r/n/r/n', 1)   if len(temp) == 1:    self.header_bytes += temp   else:    h, b = temp    self.header_bytes += h    self.body_bytes += b    header_flag = True @property def header_str(self):  return str(self.header_bytes, encoding='utf-8') def initialize_headers(self):  headers = self.header_str.split('/r/n')  first_line = headers[0].split(' ')  if len(first_line) == 3:   self.method, self.url, self.protocol = headers[0].split(' ')   for line in headers:    kv = line.split(':')    if len(kv) == 2:     k, v = kv     self.header_dict[k] = vclass Future(object): """ 异步非阻塞模式时封装回调函数以及是否准备就绪 """ def __init__(self, callback):  self.callback = callback  self._ready = False  self.value = None def set_result(self, value=None):  self.value = value  self._ready = True @property def ready(self):  return self._readyclass TimeoutFuture(Future): """ 异步非阻塞超时 """ def __init__(self, timeout):  super(TimeoutFuture, self).__init__(callback=None)  self.timeout = timeout  self.start_time = time.time() @property def ready(self):  current_time = time.time()  if current_time > self.start_time + self.timeout:   self._ready = True  return self._readyclass Snow(object): """ 微型Web框架类 """ def __init__(self, routes):  self.routes = routes  self.inputs = set()  self.request = None  self.async_request_handler = {} def run(self, host='localhost', port=9999):  """  事件循环  :param host:  :param port:  :return:  """  sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  sock.bind((host, port,))  sock.setblocking(False)  sock.listen(128)  sock.setblocking(0)  self.inputs.add(sock)  try:   while True:    readable_list, writeable_list, error_list = select.select(self.inputs, [], self.inputs,0.005)    for conn in readable_list:     if sock == conn:      client, address = conn.accept()      client.setblocking(False)      self.inputs.add(client)     else:      gen = self.process(conn)      if isinstance(gen, HttpResponse):       conn.sendall(gen.response())       self.inputs.remove(conn)       conn.close()      else:       yielded = next(gen)self.async_request_handler[conn] = yielded    self.polling_callback()except Exception as e:   pass  finally:   sock.close()def polling_callback(self):  """  遍历触发异步非阻塞的回调函数  :return:  """  for conn in list(self.async_request_handler.keys()):   yielded = self.async_request_handler[conn]   if not yielded.ready:    continue   if yielded.callback:    ret = yielded.callback(self.request, yielded)    conn.sendall(ret.response())   self.inputs.remove(conn)   del self.async_request_handler[conn]   conn.close() def process(self, conn):  """  处理路由系统以及执行函数  :param conn:  :return:  """  self.request = HttpRequest(conn)  func = None  for route in self.routes:   if re.match(route[0], self.request.url):    func = route[1]    break  if not func:   return HttpNotFound()  else:   return func(self.request)snow.py