这是一种交互方式，简单看下其实现。
一、事件处理类
class EventHandler:
def fileno(self):
'Return the associated file descriptor'
raise NotImplemented('must implement')
def wants_to_receive(self):
'Return True if receiving is allowed'
return False
def handle_receive(self):
'Perform the receive operation'
pass
def wants_to_send(self):
'Return True if sending is requested'
return False
def handle_send(self):
'Send outgoing data'
pass
二、使用
2.1、简单使用
import select
def event_loop(handlers):
while True:
wants_recv = [h for h in handlers if h.wants_to_receive()]
wants_send = [h for h in handlers if h.wants_to_send()]
can_recv, can_send, _ = select.select(wants_recv, wants_send, [])
for h in can_recv:
h.handle_receive()
for h in can_send:
h.handle_send()
2.2、UDP使用
import socket
import time
from chapter11.event_handler import EventHandler
from chapter11.event_use import event_loop
class UDPServer(EventHandler):
def __init__(self, address):
self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.sock.bind(address)
def fileno(self):
return self.sock.fileno()
def wants_to_receive(self):
return True
class UDPTimeServer(UDPServer):
def handle_receive(self):
msg, addr = self.sock.recvfrom(1)
self.sock.sendto(time.ctime().encode('ascii'), addr)
class UDPEchoServer(UDPServer):
def handle_receive(self):
msg, addr = self.sock.recvfrom(8192)
self.sock.sendto(msg, addr)
if __name__ == '__main__':
handlers = [ UDPTimeServer(('',14000)), UDPEchoServer(('',15000)) ]
event_loop(handlers)
from socket import *
s = socket(AF_INET, SOCK_DGRAM)
print(f"sendto: {s.sendto(b'',('localhost',14000))}")
print(f'recv content: {s.recvfrom(128)}')
print(f"sendto: {s.sendto(b'Hello',('localhost',15000))}")
print(f'recv content: {s.recvfrom(128)}')
2.3、TCP使用
import socket
from chapter11.event_handler import EventHandler
from chapter11.event_use import event_loop
class TCPServer(EventHandler):
def __init__(self, address, client_handler, handler_list):
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
self.sock.bind(address)
self.sock.listen(1)
self.client_handler = client_handler
self.handler_list = handler_list
def fileno(self):
return self.sock.fileno()
def wants_to_receive(self):
return True
def handle_receive(self):
client, addr = self.sock.accept()
# Add the client to the event loop's handler list
self.handler_list.append(self.client_handler(client, self.handler_list))
class TCPClient(EventHandler):
def __init__(self, sock, handler_list):
self.sock = sock
self.handler_list = handler_list
self.outgoing = bytearray()
def fileno(self):
return self.sock.fileno()
def close(self):
self.sock.close()
# Remove myself from the event loop's handler list
self.handler_list.remove(self)
def wants_to_send(self):
return True if self.outgoing else False
def handle_send(self):
nsent = self.sock.send(self.outgoing)
self.outgoing = self.outgoing[nsent:]
class TCPEchoClient(TCPClient):
def wants_to_receive(self):
return True
def handle_receive(self):
# data = self.sock.recv(8192)
if not (data := self.sock.recv(8192)):
self.close()
else:
self.outgoing.extend(data)
if __name__ == '__main__':
handlers = []
handlers.append(TCPServer(('',16000), TCPEchoClient, handlers))
event_loop(handlers)
2.4、多线程例子
import os
import socket
from concurrent.futures import ThreadPoolExecutor
from chapter11.event_handler import EventHandler
class ThreadPoolHandler(EventHandler):
def __init__(self, nworkers):
if os.name == 'posix':
self.signal_done_sock, self.done_sock = socket.socketpair()
else:
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(('127.0.0.1', 0))
server.listen(1)
self.signal_done_sock = socket.socket(socket.AF_INET,
socket.SOCK_STREAM)
self.signal_done_sock.connect(server.getsockname())
self.done_sock, _ = server.accept()
server.close()
self.pending = []
self.pool = ThreadPoolExecutor(nworkers)
def fileno(self):
return self.done_sock.fileno()
# Callback that executes when the thread is done
def _complete(self, callback, r):
self.pending.append((callback, r.result()))
self.signal_done_sock.send(b'x')
# Run a function in a thread pool
def run(self, func, args=(), kwargs={},*,callback):
r = self.pool.submit(func, *args, **kwargs)
r.add_done_callback(lambda r: self._complete(callback, r))
def wants_to_receive(self):
return True
# Run callback functions of completed work
def handle_receive(self):
# Invoke all pending callback functions
for callback, result in self.pending:
callback(result)
self.done_sock.recv(1)
self.pending = []
from chapter11.udp_server import UDPServer
from chapter11.thread_pool import ThreadPoolHandler
from chapter11.event_use import event_loop
def fib(n):
if n < 2:
return 1
else:
return fib(n - 1) + fib(n - 2)
class UDPFibServer(UDPServer):
def handle_receive(self):
msg, addr = self.sock.recvfrom(128)
n = int(msg)
pool.run(fib, (n,), callback=lambda r: self.respond(r, addr))
def respond(self, result, addr):
self.sock.sendto(str(result).encode('ascii'), addr)
if __name__ == '__main__':
pool = ThreadPoolHandler(16)
handlers = [ pool, UDPFibServer(('',16000))]
event_loop(handlers)
from socket import *
sock = socket(AF_INET, SOCK_DGRAM)
for x in range(40):
sock.sendto(str(x).encode('ascii'), ('localhost', 16000))
resp = sock.recvfrom(8192)
print(resp[0])
