如何使用回调将同步函数转换为python中的异步函数？

Question

我正在使用龙卷风框架和我的所有功能已被写入同步。我将如何使这些异步？

class AuthLoginHandler(BaseHandler): 
    @tornado.web.asynchronous 
    def get(self): 

     self.render("login.html") 

    def post(self): 
     username = self.get_argument("UserName",strip = True) 
     password = self.get_argument("Password",strip = True) 
     user = auth_actions.login(username,password) 
     if not user: 
      self.redirect("/auth/login") 
      return 

     #user = user_actions.get_my_data(self.db,user['_id']) 

     self.set_secure_cookie("userdata", tornado.escape.json_encode(dumps(user.to_mongo()))) 
     self.redirect("/") 


def login(username,password,callback=None): 
    m = hashlib.md5() 
    m.update(password) 
    hashed = m.hexdigest() 
    login = User.objects(UserName=username.lower(),Password=hashed).exclude("Password","Wall","FriendsRequested","Friends","FriendsRequesting") 
    if login.first() is None: 
     login = User.objects(Email=username.lower(),Password=hashed).exclude("Password","Wall","FriendsRequested","Friends","FriendsRequesting") 
     if login.first() is None: 
      return None 
    logger.info(username + " has logged in") 
    if callback != None: 
     return callback(login.first()) 

    return login.first() 

Answer 1

正如安迪提到的那样，你将需要一个单独的线程。以下代码使用tornado-gen的generator - coroutine方法。 另请注意run_asyncdecorator将自己的函数包装在自己的线程中。

import tornado.ioloop 
import tornado.web 
import tornado.gen 
import time 
from threading import Thread 
from functools import wraps 

def run_async(func): 
    @wraps(func) 
    def async_func(*args, **kwargs): 
    func_hl = Thread(target = func, args = args, kwargs = kwargs) 
    func_hl.start() 
    return func_hl 

    return async_func 

@run_async 
def login(username,password,callback=None): 
    m = hashlib.md5() 
    m.update(password) 
    hashed = m.hexdigest() 
    login = User.objects(UserName=username.lower(),Password=hashed).exclude("Password","Wall","FriendsRequested","Friends","FriendsRequesting") 
    if login.first() is None: 
    login = User.objects(Email=username.lower(),Password=hashed).exclude("Password","Wall","FriendsRequested","Friends","FriendsRequesting") 
    if login.first() is None: 
     return None 
    logger.info(username + " has logged in") 
    if callback != None: 
    return callback(login.first()) 
    return login.first() 


class AuthLoginHandler(BaseHandler): 
    @tornado.web.asynchronous 
    def get(self): 
    self.render("login.html") 

    @tornado.web.asynchronous 
    @tornado.gen.coroutine 
    def post(self): 
    username = self.get_argument("UserName",strip = True) 
    password = self.get_argument("Password",strip = True) 
    user = yield tornado.gen.Task(auth_actions.login, username, password) 
    if not user: 
     self.redirect("/auth/login") 
     return 
    self.set_secure_cookie("userdata", tornado.escape.json_encode(dumps(user.to_mongo()))) 
    self.redirect("/") 

Answer 2

如果你打算散列密码，你最好在单独的线程中完成它。这是因为散列需要很长时间才能执行，并会阻塞主线程。

Here is an example of hashing on a separate thread

需要注意的是龙卷风的维护者本达内尔建议使用一个单独的线程来完成密码哈希值：see this google group。