200行自定义异步非阻塞Web框架


老男孩IT教育Python培训教你如何使用python 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。

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#!/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.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)                        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)
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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)
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