基于pythonrpc的简单文件共享

本文记录了一个使用rpc进行简单文件共享的程序，仅用于p2p原理学习，关于这段代码中的异常处理等部分还有很多值得学习的地方。
server.py

# -*- coding=utf-8 -*-

from xmlrpclib import ServerProxy, Fault
from SimpleXMLRPCServer import SimpleXMLRPCServer
from SocketServer import ThreadingMixIn
import os
import sys

UNHANDLED = 100 # faultCode
MAX_LENGTH = 12

# 多线程声明,增强并发能力

class ThreadXMLRPCServer(ThreadingMixIn, SimpleXMLRPCServer):pass

# 异常类定义：

class UnhandledQuery(Fault):
    """
    查找异常
    """
    def __init__(self, message='Not right query.'):
        Fault.__init__(self, UNHANDLED, message)

class MyNode:
    def __init__(self, url):
        self.url = url
        self.know = set() # 创建集合
        pass

    def _start(self):
        server = ThreadXMLRPCServer(("localhost", 8088), allow_none=True)
        server.register_instance(self)
        server.serve_forever()

    def query(self, query, queue=[]):
        """
        通过异常捕捉，判断本节点是否有该文件，如果找到则返回，找不到则查找其他已知节点 
        """
        try:
            print 'search local file'
            return self._getfile(query)
        except UnhandledQuery:
            queue.append(self.url)
            if len(history) >= MAX_LENGTH:
                raise # 抛出异常
            print 'Search other servers.'
            return self._broadcast(query, queue)

    def _getfile(self, query, queue=[]):
        """
        查找文件
        """
        dir = os.getcwd()
        filename = join(dir, query)
        if not os.path.isfile(filename):
            raise UnhandledQuery # 抛出异常
        return open(filename).read()

    def _broadcast(self, query, history):
        """
        内部时使用，用于将查询广播到其他已知节点
        """
        for other in self.know.copy():
            try:
                # 根据url创建远程节点的proxy，使用xml_rpc进行远程调用
                print 'search ----', other
                server = ServerProxy(other)
                print 'start query', other
                return server.query(query, history)
            except Fault, f:
                if f.faultCode == UNHANDLED:
                    pass
                else:
                    self.know.remove(other)
            except:
                # 说明该server已经不可用
                self.know.remove(other)
        # 如果在所有节点中没有找到，就返回异常
        raise UnhandledQuery

    def hello(self, other):
        """
        认识其他节点
        """
        self.know.add(other)
        return 0

    def fetch(self, query):
        """
        用于从节点下载数据
        """
        print 'server fetch'       
        result = self.query(query)
        print 'get----'
        # 把查询到的数据写到本地
        f = open(join(os.getcwd(), query), 'w')
        f.write(result)
        f.close()
        return 0

if __name__ == '__main__':
    url = sys.argv[1]
    node = MyNode(url)
    node._start()
    print "Server Node Start."

client.py

# -*- coding=utf-8 -*-

from xmlrpclib import ServerProxy, Fault
from string import lowercase
from server import MyNode, UNHANDLED
from threading import Thread
from time import sleep
import sys

HEAD_START = 0.1 # second

class Client1():

    def __init__(self, url, urlfile):
        """
        启动服务器       
        """
        print 'in'
        n = MyNode(url)
        t = Thread(target=n._start)
        t.setDaemon(1)
        t.start()
        # 等待服务器启动
        sleep(HEAD_START)
        self.server = ServerProxy(url)
        self.server.hello(url)
        for line in open(urlfile):
            line = line.strip()


    def do_fetch(self, arg):
        "调用服务器的fetch方法"
        try:
            print 'do_fetch'
            self.server.fetch(arg)
        except Fault, f:
            print f
            if f.faultCode != UNHANDLED:
                raise
            print 'Could not find the file ', arg


def main():
    url, urlfile = sys.argv[1:]
    print url, urlfile
    print '---------'
    client = Client1(url, urlfile)

if __name__ == '__main__':
    main()