[英]Python - connecting sockets, client/server agnostic
我希望2個進程在給定端口上進行通信,而沒有一個進程具有定義的客戶端或服務器角色。 這兩個進程都可能單獨運行。 可以隨時以任何順序停止並重新啟動。 當它們都在運行時,它們需要進行通信(當僅一個正在運行時,通信將被丟棄)。
我想要非阻塞套接字和Windows / Linux支持。
這是一個相當粗糙的類,實際上在某種程度上有效,這可能會讓您入門。
這里的主要技巧是根本不用去理會listen
:它們是純對等連接,完全由<local-addr,remote-addr>對指定。
請注意,套接字處於非阻塞模式。 我捕獲了recv
異常,但也可能有一個send
異常(另外,在發送給失效的對等節點時,您會遇到管道破裂錯誤等)。 您還需要處理EOF-from-terminated-peer(當recv
返回''
而不是EAGAIN
失敗時)。
import errno
import os
import select
import socket
class Peer(object):
def __init__(self, local_addr, peer_addr):
self._local_addr = local_addr
self._peer_addr = peer_addr
self._renew()
self.reopen()
def _renew(self):
self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._sock.bind(self._local_addr)
self._sock.setblocking(False)
self._sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._state = 'bound'
def is_open(self):
return self._state == 'open'
def is_opening(self):
return self._state == 'opening'
def reopen(self):
if self._state == 'open':
raise ValueError('already open')
if self._state == 'opening':
raise ValueError('open in progress')
print 'try connect to:', self._peer_addr
error = self._sock.connect_ex(self._peer_addr)
print 'result:', error
if error == 0:
self._state = 'open'
print 'connected immediately'
elif error in (errno.EINPROGRESS, errno.EINTR):
self._state = 'opening'
print 'connection in progress'
else:
raise socket.error(error, os.strerror(error))
def _check_open(self):
if self._state != 'opening':
raise ValueError('improper call to _check_open')
print 'check connect to:', self._peer_addr
_, wfds, _ = select.select([], [self._sock], [])
if len(wfds) == 0:
# connection still in progress
return
# we have a result: fail or succeed, either way a result
try:
peer = self._sock.getpeername()
except socket.error as err:
print 'caught err:', err
if err.errno == errno.ENOTCONN:
print 'connection failed, no peer available'
self.close()
return
raise
print 'got a peer:', peer
self._state = 'open'
print 'connection finished'
def close(self):
if self._state in ('open', 'opening'):
self._sock.close()
self._renew()
# self.reopen() - or leave to caller
def send_if_connected(self, data):
# to do: add check for send to dead peer, and if so, _renew etc
if self._state == 'bound':
self.reopen()
if self._state == 'opening':
self._check_open()
if self._state == 'open':
self._sock.send(data)
def recv_if_connected(self):
# to do: add check for send to dead peer, and if so, _renew etc
if self._state == 'bound':
self.reopen()
if self._state == 'opening':
self._check_open()
if self._state == 'open':
try:
return self._sock.recv(1024)
except socket.error as err:
# still connected but no data avail
if err.errno == errno.EAGAIN:
return ''
raise
else:
return None
if __name__ == '__main__':
import argparse
import time
parser = argparse.ArgumentParser(description='test Peer()')
parser.add_argument('-l', '--localhost', default='')
parser.add_argument('-p', '--port', type=int, default=9001)
parser.add_argument('-R', '--remote-host', default='')
parser.add_argument('-r', '--remote-port', type=int, default=9002)
args = parser.parse_args()
x = Peer((args.localhost, args.port), (args.remote_host, args.remote_port))
for i in range(1, 10):
print 'attempt to send %d' % i
x.send_if_connected('send %d' % i)
got = x.recv_if_connected()
if got is not None:
print 'got: "%s"' % got
time.sleep(1)
例如: $ python peerish.py -p 9001 -r 9002 & python peerish.py -p 9002 -r 9001 &
。
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