自定制异步非阻塞web框架
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。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
import re import socket import select import time """ 异步非阻塞内部原理剖析: 正常情况下,服务端处在一个单线程事件循环的过程中。一旦有人链接进来,则将這个链接加入到select的监听对象,只要该 队列中某一个链接发生变化,我们就能及时处理该请求链接。 当一个链接进来,如果服务端函数处理的结果是一个HttpResponse对象,也就是说,這个请求,服务端已经处理完毕了,可以直接返回。那么服务端直接 通过conn.sendall()将响应的数据全部发送给客户端。如果服务端函数处理的结果是一个Future对象,这就给服务端发送一个信号 意思是我這个请求还没有结束,你别给我断开链接了。此时服务端要完成以下事情:第一,将返回的Future对象放入一个队列中 第二,继续监听其它请求,也就是说,在這个地方,我服务端并不会阻塞等待处理完毕,而是直接进入到时间循环。等待新的链接。 第三,在事件循环的过程中,除了要监听链接的变化之外,还得监听上面的阻塞队列的中变化。至于阻塞队列如何变化,這个得通过 set_result()信号,一旦這个被设置了,说明我這个阻塞的链接是时候返回了. 整个过程,只用了一个线程在监听,完成了异步非阻塞的强大功能。 """ class 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] = v class 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 # 返回与否的标识,False不返回,True返回 self.value = None def set_result(self, value=None): self.value = value self._ready = True @property def ready(self): return self._ready class 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._ready class 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 = {} # 存放等待返回的Future对象 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.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 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) # 返回有两种可能:1.HttpResponse对象,2.生成器对象 if isinstance(gen, HttpResponse): # 返回HttpResponse对象 conn.sendall(gen.response()) self.inputs.remove(conn) conn.close() else: # 返回生成器对象 yielded = next(gen) # 取第一个yield self.async_request_handler[conn] = yielded #{conn:Future对象} self.polling_callback() # 循环检测async_request_handler中等待返回的Future对象 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: """ # 循环检测async_request_handler中等待返回的Future对象 ,一旦某个Future对象set_result()被设置了,该对象就应该返回了 for conn in list(self.async_request_handler.keys()): yielded = self.async_request_handler[conn] # Future对象 if not yielded.ready: # 判断ready是否被设置为True,如果 被设置为True,则应该执行回调函数 continue if yielded.callback: ret = yielded.callback(self.request, yielded) conn.sendall(ret.response()) self.inputs.remove(conn) del self.async_request_handler[conn] # Http应该返回了 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)
二、使用
1、基本使用
from snow import Snow from snow import HttpResponse def index(request): return HttpResponse('OK') routes = [ (r'/index/', index), ] app = Snow(routes) app.run(port=8012)
2、异步非阻塞:超时
from snow import Snow from snow import HttpResponse from snow import TimeoutFuture request_list = [] def async(request): obj = TimeoutFuture(5) yield obj def home(request): return HttpResponse('home') routes = [ (r'/home/', home), (r'/async/', async), ] app = Snow(routes) 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
from snow import Snow from snow import HttpResponse from snow import Future request_list = [] def callback(request, future): return HttpResponse(future.value) def req(request): obj = Future(callback=callback) request_list.append(obj) yield obj def stop(request): obj = request_list[0] del request_list[0] obj.set_result('done') return HttpResponse('stop') routes = [ (r'/req/', req), (r'/stop/', stop), ] app = Snow(routes) app.run(port=8012)