一、Tornado异步非阻塞
一般的web框架，可以分为两类：
阻塞式：（Django，Flask，Tornado，Bottle）
一个请求到来未处理完成，后续一直等待
解决方案：多线程或多进程
异步非阻塞（存在IO请求）：Tornado （单进程+单线程）
- 使用
- @gen.coroutine
- yield Future对象
1.简单的异步例子
import tornado.ioloop
import tornado.web
from tornado.web import RequestHandler
from tornado import gen
from tornado.concurrent import Future
import time
class IndexHandler(RequestHandler):
@gen.coroutine
def get(self):
print('开始')
future = Future()
#从当前时间开始夯住10S,当时间结束执行 self.doing方法
tornado.ioloop.IOLoop.current().add_timeout(time.time() + 10, self.doing)
yield future
def doing(self, *args, **kwargs):
self.write('async')
#关闭连接
self.finish()
application = tornado.web.Application([
(r"/index", IndexHandler),
])
if __name__ == "__main__":
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
在内部中，Select循环检测Future，当有返回值时，Future内部会作出变化，此时即可释放向自己发送请求的链接
2.作为中转，接收用户对自己的请求，而自己需要向另一个API发送请求处理，在发送请求的过程中，占用大量时间，这时候就可以使用异步非阻塞的形式。
比如一个购物网站，用户向自己发来购买订单，自己再向预定的后台处理API发送处理请求，在这段时间内可以接收其它用户发来的订单请求，这将大大提升处理的效率。
import tornado.ioloop
import tornado.web
from tornado.web import RequestHandler
from tornado import gen
from tornado.concurrent import Future
import time
from tornado import httpclient
class IndexHandler(RequestHandler):
@gen.coroutine
def get(self):
print('收到订单')
#开启一个非阻塞HTTP客户端对象
http = httpclient.AsyncHTTPClient()
# 执行请求，异步返回HTTPResponse。在向另一url请求的过程中，可以继续接收其它对自己的请求
yield http.fetch("http://www.github.com", self.done,)
def done(self, response): #异步方法接收HTTPResponse,并可以继续执行其它代码
print(response)
self.write('订单成功')
#关闭此连接
self.finish()
application = tornado.web.Application([
(r"/index", IndexHandler),
])
if __name__ == "__main__":
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
fetch（request，callback = None，raise_error = True，** kwargs ）[source]
执行请求，异步返回HTTPResponse。
请求可以是字符串URL或HTTPRequest对象。如果它是一个字符串，我们构造一个HTTPRequest使用任何额外的kwargs：HTTPRequest(request, **kwargs)
该方法return一个Future结果是一个 HTTPResponse。默认情况下，Future将引发一个HTTPError，如果该请求返回一个非200响应代码（其他错误也可以得到提升，如果服务器无法联系）。相反，如果raise_error设置为False，则无论响应代码如何，都将始终返回响应。
如果callback给出一个，它将被调用HTTPResponse。在回调界面中，HTTPError不会自动提出。相反，您必须检查响应的error属性或调用其rethrow方法。
3.模拟异步非阻塞执行的流程：
import tornado.ioloop
import tornado.web
from tornado.web import RequestHandler
from tornado import gen
from tornado.concurrent import Future
import time
from tornado import httpclient
fu = None
class IndexHandler(RequestHandler):
@gen.coroutine
def get(self):
#将fu设置为全局变量
global fu
print('疯狂的追求')
fu = Future()
#添加一个回调，如果完成运行并且其结果可用时，它将作为其参数被调用
fu.add_done_callback(self.done)
yield fu
def done(self, response):
self.write('终于等到你')
self.finish()
class TestHandler(RequestHandler):
def get(self):
#手动设置Future结果
fu.set_result(666)
self.write('我只能帮你到这里了')
application = tornado.web.Application([
(r"/index", IndexHandler),
(r"/test", TestHandler),
])
if __name__ == "__main__":
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
当return一个Future时，可以添加一个回调函数，而这个回调函数，只有在请求成功接收到结果时才会执行，否则将一直夯住，而Future内部则是通过set_result()方法使其得到一个成功返回的信号从而执行回调。正常情况下set_result()的值是正确的返回结果，这里通过伪造结果达到异步的效果。done()方法中的response即set_result()的值。
3.1 多线程自动执行:
import tornado.ioloop
import tornado.web
from tornado.web import RequestHandler
from tornado import gen
from tornado.concurrent import Future
import time
from threading import Thread
def waiting(future):
import time
time.sleep(10)
#10S后执行set_result使回调生效。
future.set_result(666)
class IndexHandler(RequestHandler):
@gen.coroutine
def get(self):
global fu
print('疯狂的追求')
fu = Future()
fu.add_done_callback(self.done)
#开启线程执行waiting函数，
thread = Thread(target=waiting,args=(fu,))
thread.start()
yield fu
def done(self, response):
self.write('终于等到你')
self.finish()
application = tornado.web.Application([
(r"/index", IndexHandler),
])
if __name__ == "__main__":
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
4.使用Tornado异步非阻塞模拟用户登录
import tornado.web
from tornado import gen
import tornado_mysql
#必须要使用支持的类库，如tornado_mysql ，sqlalchemy以及pymysql都不支持
@gen.coroutine
def get_user(user):
#连接时会有IO耗时
conn = yield tornado_mysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='cmdb',
charset='utf8')
cur = conn.cursor()
#查询时也会有IO耗时
# yield cur.execute("SELECT name,email FROM web_models_userprofile where name=%s", (user,))
yield cur.execute("select sleep(10)")
row = cur.fetchone()
cur.close()
conn.close()
#gen.Task特有的return方式，通过捕捉异常获取数据库查询的值
raise gen.Return(row)
class LoginHandler(tornado.web.RequestHandler):
def get(self, *args, **kwargs):
self.render('login.html')
@gen.coroutine
def post(self, *args, **kwargs):
user = self.get_argument('user')
#yield一个Task任务，封装数据库查询的函数，当查询遇到IO操作时不会阻塞，可以接收其它请求。
data = yield gen.Task(get_user, user)
if data:
print(data)
self.redirect('http://www.baidu.com')
else:
self.render('login.html')
二、自定义简易非阻塞框架
1.socket服务端基本（阻塞式）：
import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(("127.0.0.1", 9999,))
sock.listen(5)
while True:
client, address = sock.accept()
data = client.recv(8096)
print(data)
# /r/n/r/n
# 请求头中URL
# 请求体中数据
# URL去路由关系中匹配 （请求体中数据）
# response = func()
import time
time.sleep(10)
client.sendall(b'uuuuuuuuuuuuuu')
client.close()
2.应用select模拟非阻塞web框架的基本流程：
import socket
import select
def f1(request):
return "内容1"
def f2(request):
return "内容2"
#路由匹配系统
urls = [
('/index.html',f1),
('/home.html',f2),
]
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
#设置非阻塞
sock.setblocking(False)
sock.bind(("127.0.0.1", 9999,))
sock.listen(5)
input_list = [sock,]
while True:
"""
客户端第一次建立连接以及后续的请求发来数据都会对rlist有变动，对rlist进行循环，
如果等于sock即是建立连接的请求，否则就是客户端后续发来数据，因此进行不同的操作
"""
rlist,wlist,elist = select.select(input_list,[],[],0.005)
for sk in rlist:
# 有新人来连接：sock 进行accept,接收连接，等待客户来连接
if sk == sock:
client, address = sock.accept()
client.setblocking(False)
input_list.append(client) #将客户端连接添加到循环列表中
# 老人发来数据： client 建立连接并接收数据
else:
data = sk.recv(8096)
# /r/n/r/n (分割请求头跟请求体)
# 请求头中URL
# 请求体中数据 (提取URL跟数据)
# URL去路由关系中匹配 （请求体中数据）
# response = func()
#根据数据匹配URL，服务器做相应的视图处理，处理后的数据返回给客户端
response = f1(data)
sk.sendall(response.encode('utf-8'))
sk.close()
3.简单的web框架基本实现原理
import re
import socket
import select
import time
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
self.value = None
def set_result(self, value=None):
self.value = value
self._ready = True
@property
def ready(self):
return self._ready
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):
"""
:param conn: 客户端的连接
"""
self.conn = conn
self.header_bytes = bytes()
self.body_bytes = bytes()
self.header_dict = {}
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'
', 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('
')
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 Snow(object):
"""
微型Web框架类,
"""
def __init__(self, routes):
"""
:param routes: url路由匹配
"""
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: IP地址
:param port: 端口
: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:
# 连接
client, address = conn.accept()
client.setblocking(False)
self.inputs.add(client)
else:
# 发送请求
# HttpResponse
# 生成器
"""
gen=HttpResponse对象，执行了三件事，
1.HttpRequest类，将客户端拿到，分割请求头与请求体，将请求头信息处理成header_dict {'method':xxx,'url':xxx}
2.循环路由，实例化HttpRequest类， .url与其进行匹配，匹配成功将self.fun 赋值称为路由系统填写的func函数。
3.处理func视图,返回2种类型，HttpResponse对象或者Future对象。如果是HttpResponse()对象，封装了将字符串转换
成字节的方法，即还是一种阻塞式，即一般的如Django类web框架的处理流程，
"""
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
for conn,fur in self.async_request_handler.items():
if not fur.ready:
continue
response = fur.callback(fur.value)
conn.sendall(response)
conn.close()
del self.async_request_handler[conn]
except Exception as e:
pass
finally:
sock.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)
def index(request):
return HttpResponse('OK')
def asynccccc(request):
fur = Future(callback=done)
yield fur
def done(arg):
pass
routes = [
(r'/index/', index),
(r'/async/', asynccccc),
]
if __name__ == '__main__':
app = Snow(routes)
app.run(port=8012)
gen对象中，如果返回的是一个Future对象，则内部会将封装的Future对象yield给回调函数，或者说是交给中转站，由中转站向基础平台的API发送IO请求，这时不会阻塞，会在循环中继续yield新的请求，并生成一个字典，{conn:yield Future的对象},而在外层的循环中监听这个对象，一旦对象发送的IO请求处理完成，将执行set_result方法，将ready设置成True，并拿到请求接收的值即赋值给value,再把value传递给回调函数中进行相应处理， 获得一个最后的值，将conn从字典中移除，将处理后的值返回给用户。
4.最后整理后的简单异步非阻塞web框架
import re
import socket
import select
import time
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'
', 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('
')
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
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 = {}
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)
使用：
基本使用(没有使用异步非阻塞)：
from s4 import Snow
from s4 import HttpResponse
def index(request):
return HttpResponse('OK')
routes = [
(r'/index/', index),
]
app = Snow(routes)
app.run(port=8012)
手动的异步非阻塞使用
from s4 import Snow
from s4 import HttpResponse
from s4 import Future
request_list = []
def callback(request, future):
return HttpResponse(future.value)
def req(request):
print('请求到来')
obj = Future(callback=callback)
request_list.append(obj)
yield obj
def stop(request):
obj = request_list[0]
obj.set_result('done')
del request_list[0]
return HttpResponse('stop')
routes = [
(r'/req/', req),
(r'/stop/', stop),
]
app = Snow(routes)
app.run(port=8012)
由于我们在最外层循环了一个{conn:future}的字典，所以需要手动去对stop视图函数发送请求，由它进行set_result，如果是自动的方法，就是将这个conn添加到select中，由select进行监听并set_result，
达到程序自动返回的效果。