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。
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 import re
4 import socket
5 import select
6 import time
7
8
9 class HttpResponse(object):
10 """
11 封装响应信息
12 """
13 def __init__(self, content=‘‘):
14 self.content = content
15
16 self.headers = {}
17 self.cookies = {}
18
19 def response(self):
20 return bytes(self.content, encoding=‘utf-8‘)
21
22
23 class HttpNotFound(HttpResponse):
24 """
25 404时的错误提示
26 """
27 def __init__(self):
28 super(HttpNotFound, self).__init__(‘404 Not Found‘)
29
30
31 class HttpRequest(object):
32 """
33 用户封装用户请求信息
34 """
35 def __init__(self, conn):
36 self.conn = conn
37
38 self.header_bytes = bytes()
39 self.header_dict = {}
40 self.body_bytes = bytes()
41
42 self.method = ""
43 self.url = ""
44 self.protocol = ""
45
46 self.initialize()
47 self.initialize_headers()
48
49 def initialize(self):
50
51 header_flag = False
52 while True:
53 try:
54 received = self.conn.recv(8096)
55 except Exception as e:
56 received = None
57 if not received:
58 break
59 if header_flag:
60 self.body_bytes += received
61 continue
62 temp = received.split(b‘\r\n\r\n‘, 1)
63 if len(temp) == 1:
64 self.header_bytes += temp
65 else:
66 h, b = temp
67 self.header_bytes += h
68 self.body_bytes += b
69 header_flag = True
70
71 @property
72 def header_str(self):
73 return str(self.header_bytes, encoding=‘utf-8‘)
74
75 def initialize_headers(self):
76 headers = self.header_str.split(‘\r\n‘)
77 first_line = headers[0].split(‘ ‘)
78 if len(first_line) == 3:
79 self.method, self.url, self.protocol = headers[0].split(‘ ‘)
80 for line in headers:
81 kv = line.split(‘:‘)
82 if len(kv) == 2:
83 k, v = kv
84 self.header_dict[k] = v
85
86
87 class Future(object):
88 """
89 异步非阻塞模式时封装回调函数以及是否准备就绪
90 """
91 def __init__(self, callback):
92 self.callback = callback
93 self._ready = False
94 self.value = None
95
96 def set_result(self, value=None):
97 self.value = value
98 self._ready = True
99
100 @property
101 def ready(self):
102 return self._ready
103
104
105 class TimeoutFuture(Future):
106 """
107 异步非阻塞超时
108 """
109 def __init__(self, timeout):
110 super(TimeoutFuture, self).__init__(callback=None)
111 self.timeout = timeout
112 self.start_time = time.time()
113
114 @property
115 def ready(self):
116 current_time = time.time()
117 if current_time > self.start_time + self.timeout:
118 self._ready = True
119 return self._ready
120
121
122 class Snow(object):
123 """
124 微型Web框架类
125 """
126 def __init__(self, routes):
127 self.routes = routes
128 self.inputs = set()
129 self.request = None
130 self.async_request_handler = {}
131
132 def run(self, host=‘localhost‘, port=9999):
133 """
134 事件循环
135 :param host:
136 :param port:
137 :return:
138 """
139 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
140 sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
141 sock.bind((host, port,))
142 sock.setblocking(False)
143 sock.listen(128)
144 sock.setblocking(0)
145 self.inputs.add(sock)
146 try:
147 while True:
148 readable_list, writeable_list, error_list = select.select(self.inputs, [], self.inputs,0.005)
149 for conn in readable_list:
150 if sock == conn:
151 client, address = conn.accept()
152 client.setblocking(False)
153 self.inputs.add(client)
154 else:
155 gen = self.process(conn)
156 if isinstance(gen, HttpResponse):
157 conn.sendall(gen.response())
158 self.inputs.remove(conn)
159 conn.close()
160 else:
161 yielded = next(gen)
162 self.async_request_handler[conn] = yielded
163 self.polling_callback()
164
165 except Exception as e:
166 pass
167 finally:
168 sock.close()
169
170 def polling_callback(self):
171 """
172 遍历触发异步非阻塞的回调函数
173 :return:
174 """
175 for conn in list(self.async_request_handler.keys()):
176 yielded = self.async_request_handler[conn]
177 if not yielded.ready:
178 continue
179 if yielded.callback:
180 ret = yielded.callback(self.request, yielded)
181 conn.sendall(ret.response())
182 self.inputs.remove(conn)
183 del self.async_request_handler[conn]
184 conn.close()
185
186 def process(self, conn):
187 """
188 处理路由系统以及执行函数
189 :param conn:
190 :return:
191 """
192 self.request = HttpRequest(conn)
193 func = None
194 for route in self.routes:
195 if re.match(route[0], self.request.url):
196 func = route[1]
197 break
198 if not func:
199 return HttpNotFound()
200 else:
201 return func(self.request)
snow.py
二、使用
1. 基本使用
1 from snow import Snow 2 from snow import HttpResponse 3 4 5 def index(request): 6 return HttpResponse(‘OK‘) 7 8 9 routes = [ 10 (r‘/index/‘, index), 11 ] 12 13 app = Snow(routes) 14 app.run(port=8012)
2.异步非阻塞：超时
1 from snow import Snow 2 from snow import HttpResponse 3 from snow import TimeoutFuture 4 5 request_list = [] 6 7 8 def async(request): 9 obj = TimeoutFuture(5) 10 yield obj 11 12 13 def home(request): 14 return HttpResponse(‘home‘) 15 16 17 routes = [ 18 (r‘/home/‘, home), 19 (r‘/async/‘, async), 20 ] 21 22 app = Snow(routes) 23 app.run(port=8012)
3.异步非阻塞：等待
基于等待模式可以完成自定制操作
1 from snow import Snow 2 from snow import HttpResponse 3 from snow import Future 4 5 request_list = [] 6 7 8 def callback(request, future): 9 return HttpResponse(future.value) 10 11 12 def req(request): 13 obj = Future(callback=callback) 14 request_list.append(obj) 15 yield obj 16 17 18 def stop(request): 19 obj = request_list[0] 20 del request_list[0] 21 obj.set_result(‘done‘) 22 return HttpResponse(‘stop‘) 23 24 25 routes = [ 26 (r‘/req/‘, req), 27 (r‘/stop/‘, stop), 28 ] 29 30 app = Snow(routes) 31 app.run(port=8012)
时间： 2024-07-28 15:57:42