Python的消息队列包SnakeMQ使用初探

一、关于snakemq的官方介绍
SnakeMQ的GitHub项目页：https://github.com/dsiroky/snakemq
1.纯python实现，跨平台

2.自动重连接

3.可靠发送--可配置的消息方式与消息超时方式

4.持久化/临时 两种队列

5.支持异步 -- poll()

6.symmetrical -- 单个TCP连接可用于双工通讯

7.多数据库支持 -- SQLite、MongoDB……

8.brokerless - 类似ZeroMQ的实现原理

9.扩展模块：RPC, bandwidth throttling

以上都是官话，需要自己验证，动手封装了一下，感觉萌萌哒。

二、几个主要问题说明

1.支持自动重连，不需要自己动手写心跳逻辑，你只需要关注发送和接收就行

2.支持数据持久化，如果开始持久化，在重连之后会自动发送数据。

3.数据的接收，snakemq通过提供回调实现，你只需要写个接收方法添加到回调列表里去。

4.数据的发送，在此发送的都是bytes类型（二进制），因此需要转换。我在程序中测试的都是文本字符串，使用str.encode(‘utf-8')转换成bytes，接收时再转换回来。

5.术语解释，Connector：类似于socket的TcpClient，Lisenter：类似于socket的TcpServer，每个connector或者listener都一个一个ident标识，发送和接收数据时就知道是谁的数据了。

6.使用sqlite持久化时，需要修改源码，sqlite3.connect(filename,check_same_thread = False)，用于解决多线程访问sqlite的问题。（会不会死锁？）

7.启动持久化时，如果重新连上，则会自动发送，保证可靠。

8.为了封装的需要，数据接收以后，我通过callback方式传送出去。

三、代码

说明代码中使用了自定义的日志模块

from common import nxlogger

import snakemqlogger as logger

可替换成logging的。

回调类（callbacks.py）：

# -*- coding:utf-8 -*-

'''synchronized callback'''

class Callback(object):

  def __init__(self):

    self.callbacks = []

  def add(self, func):

    self.callbacks.append(func)

  def remove(self, func):

    self.callbacks.remove(func)

  def __call__(self, *args, **kwargs):

    for callback in self.callbacks:

      callback(*args, **kwargs)

Connector类（snakemqConnector.py）：

# -*- coding:utf-8 -*-

import threading

import snakemq

import snakemq.link

import snakemq.packeter

import snakemq.messaging

import snakemq.message

from snakemq.storage.sqlite import SqliteQueuesStorage

from snakemq.message import FLAG_PERSISTENT

from common.callbacks import Callback

from common import nxlogger

import snakemqlogger as logger

class SnakemqConnector(threading.Thread):

     def __init__(self, snakemqident = None, remoteIp = "localhost", remotePort = 9090, persistent = False):

         super(SnakemqConnector,self).__init__()

         self.messaging = None

         self.link = None

         self.snakemqident = snakemqident

         self.pktr = None

         self.remoteIp = remoteIp

         self.remotePort = remotePort

         self.persistent = persistent

         self.on_recv = Callback()

         self._initConnector()

     def run(self):

         logger.info("connector start...")

         if self.link != None:

              self.link.loop()

         logger.info("connector end...")

     def terminate(self):

         logger.info("connetor terminating...")

         if self.link != None:

              self.link.stop()

              self.link.cleanup()

         logger.info("connetor terminated")

     def on_recv_message(self, conn, ident, message):

         try:

              self.on_recv(ident, message.data.decode('utf-8'))#dispatch received data

         except Exception as e:

              logger.error("connector recv:{0}".format(e))

              print(e)

     '''send message to dest host named destIdent'''

     def sendMsg(self, destIdent, byteseq):

         msg = None

         if self.persistent:

              msg = snakemq.message.Message(byteseq, ttl=60, flags=FLAG_PERSISTENT)

         else:

              msg = snakemq.message.Message(byteseq, ttl=60)

         if self.messaging == None:

              logger.error("connector:messaging is not initialized, send message failed")

              return

         self.messaging.send_message(destIdent, msg)

     '''

     '''

     def _initConnector(self):

         try:

              self.link = snakemq.link.Link()

              self.link.add_connector((self.remoteIp, self.remotePort))

              self.pktr = snakemq.packeter.Packeter(self.link)

              if self.persistent:

                  storage = SqliteQueuesStorage("SnakemqStorage.db")

                  self.messaging = snakemq.messaging.Messaging(self.snakemqident, "", self.pktr, storage)

              else:

                  self.messaging = snakemq.messaging.Messaging(self.snakemqident, "", self.pktr)

              self.messaging.on_message_recv.add(self.on_recv_message)

         except Exception as e:

              logger.error("connector:{0}".format(e))

         finally:

              logger.info("connector[{0}] loop ended...".format(self.snakemqident))

Listener类（snakemqListener.py）：

# -*- coding:utf-8 -*-

import threading

import snakemq

import snakemq.link

import snakemq.packeter

import snakemq.messaging

import snakemq.message

from common import nxlogger

import snakemqlogger as logger

from common.callbacks import Callback

class SnakemqListener(threading.Thread):

     def __init__(self, snakemqident = None, ip = "localhost", port = 9090, persistent = False):

         super(SnakemqListener,self).__init__()

         self.messaging = None

         self.link = None

         self.pktr = None

         self.snakemqident = snakemqident

         self.ip = ip;

         self.port = port

         self.connectors = {}

         self.on_recv = Callback()

         self.persistent = persistent

         self._initlistener()

     '''

     thread run

     '''

     def run(self):

         logger.info("listener start...")

         if self.link != None:

              self.link.loop()

         logger.info("listener end...")

     '''

     terminate snakemq listener thread

     '''

     def terminate(self):

         logger.info("listener terminating...")

         if self.link != None:

              self.link.stop()

              self.link.cleanup()

         logger.info("listener terminated")

     '''

     receive message from host named ident

     '''

     def on_recv_message(self, conn, ident, message):

         try:

              self.on_recv(ident, message.data.decode('utf-8'))#dispatch received data

              self.sendMsg('bob','hello,{0}'.format(ident).encode('utf-8'))

         except Exception as e:

              logger.error("listener recv:{0}".format(e))

              print(e)

     def on_drop_message(self, ident, message):

         print("message dropped", ident, message)

         logger.debug("listener:message dropped,ident:{0},message:{1}".format(ident, message))

     '''client connect'''

     def on_connect(self, ident):

         logger.debug("listener:{0} connected".format(ident))

         self.connectors[ident] = ident

         self.sendMsg(ident, "hello".encode('utf-8'))

     '''client disconnect'''

     def on_disconnect(self, ident):

         logger.debug("listener:{0} disconnected".format(ident))

         if ident in self.connectors:

              self.connectors.pop(ident)

     '''

     listen start loop

     '''

     def _initlistener(self):

         try:

              self.link = snakemq.link.Link()

              self.link.add_listener((self.ip, self.port))

              self.pktr = snakemq.packeter.Packeter(self.link)

              self.pktr.on_connect.add(self.on_connect)

              self.pktr.on_disconnect.add(self.on_disconnect)

              if self.persistent:

                  storage = SqliteQueuesStorage("SnakemqStorage.db")

                  self.messaging = snakemq.messaging.Messaging(self.snakemqident, "", self.pktr, storage)

              else:

                  self.messaging = snakemq.messaging.Messaging(self.snakemqident, "", self.pktr)

              self.messaging.on_message_recv.add(self.on_recv_message)

              self.messaging.on_message_drop.add(self.on_drop_message)

         except Exception as e:

              logger.error("listener:{0}".format(e))

         finally:

              logger.info("listener:loop ended...")

     '''send message to dest host named destIdent'''

     def sendMsg(self, destIdent, byteseq):

         msg = None

         if self.persistent:

              msg = snakemq.message.Message(byteseq, ttl=60, flags=FLAG_PERSISTENT)

         else:

              msg = snakemq.message.Message(byteseq, ttl=60)

         if self.messaging == None:

              logger.error("listener:messaging is not initialized, send message failed")

              return

         self.messaging.send_message(destIdent, msg)

测试代码connector（testSnakeConnector.py）：

读取本地一个1M的文件，然后发送给listener，然后listener发回一个hello的信息。

from netComm.snakemq import snakemqConnector

import time

import sys

import os

def received(ident, data):

     print(data)

if __name__ == "__main__":

     bob = snakemqConnector.SnakemqConnector('bob',"10.16.5.45",4002,True)

     bob.on_recv.add(received)

     bob.start()

     try:

         with open("testfile.txt",encoding='utf-8') as f:

              txt = f.read()

              for i in range(100):

                  bob.sendMsg("niess",txt.encode('utf-8'))

                  time.sleep(0.1)

     except Exception as e:

         print(e)

     time.sleep(5)

     bob.terminate()   

测试代码listener（testSnakeListener.py）：

from netComm.snakemq import snakemqListener

import time

def received(ident, data):

     filename = "log/recFile{0}.txt".format(time.strftime('%S',time.localtime()))

     file = open(filename,'w')

     file.writelines(data)

     file.close()

if __name__ == "__main__":

     niess = snakemqListener.SnakemqListener("niess","10.16.5.45",4002)

     niess.on_recv.add(received)

     niess.start()

     print("niess start...")

     time.sleep(60)

     niess.terminate()  

     print("niess end...")