如何保证使用python异步发送tcp数据？

Question

我有一个客户端，连接到服务器并发送列表中的所有消息，每发送一条消息，都会从列表中删除。在

但是当我强制关闭服务器时，客户端仍然继续发送和删除列表中的消息。我想，如果连接断开，客户端停止发送消息，或者不从列表中删除，如果不能保证服务器已经收到消息。在

我检查连接断开后发送超过四条消息时，是否显示错误“套接字.send（）引发异常“。但我不知道如何得到这个错误，我认为这是异步的。不管怎样，如果我得到这个错误，如果列表在连接断开后要发送的消息少于5条，那么这个错误就不会发生。在

附言：我写服务器只是为了我的测试，但服务器我将无法访问。所以，客户端认为需要尽一切努力保证数据的发送。在

非常感谢你。在

在客户端.py在

import asyncio

class Client(asyncio.Protocol):
    TIMEOUT = 1.0
    event_list = []
    for i in range(10):
        event_list.append('msg' + str(i))

    def __init__(self):
        self.client_tcp_timeout = None
        print(self.event_list)

    def connection_made(self, transport):
        print('Connected to Server.')
        self.transport = transport
        self.client_tcp_timeout = loop.call_later(self.TIMEOUT, self.send_from_call_later)

    def data_received(self, data):
        self.data = format(data.decode())
        print('data received: {}'.format(data.decode()))

    def send_from_call_later(self):
        self.msg = self.event_list[0].encode()
        self.transport.write(self.msg)
        print('data sent: {}'.format(self.msg))
        print('Removing data: {}'.format(self.event_list[0]))
        del self.event_list[0]
        print(self.event_list)
        print('-----------------------------------------')
        if len(self.event_list) > 0:
            self.client_tcp_timeout = loop.call_later(self.TIMEOUT, self.send_from_call_later)
        else:
            print('All list was sent to the server.')

    def connection_lost(self, exc):
        print('Connection lost!!!!!!.')

loop = asyncio.get_event_loop()

coro = loop.create_connection(Client, 'localhost', 8000)
client = loop.run_until_complete(coro)

loop.run_forever()

在服务器.py在

^{pr2}$

服务器输出（在收到msg4后强制（CTRL+C）关闭服务器）：

$ python3 server.py
serving on ('127.0.0.1', 8000)
connection from ('127.0.0.1', 56119)
data received: msg0
data received: msg1
data received: msg2
data received: msg3
data received: msg4
^Cexit

客户端输出

$ python3 client.py 
['msg0', 'msg1', 'msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
Connected to Server.
data sent: b'msg0'
Removing data: msg0
['msg1', 'msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg1'
Removing data: msg1
['msg2', 'msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg2'
Removing data: msg2
['msg3', 'msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg3'
Removing data: msg3
['msg4', 'msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg4'
Removing data: msg4
['msg5', 'msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
Connection lost!!!!!!.
data sent: b'msg5'
Removing data: msg5
['msg6', 'msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg6'
Removing data: msg6
['msg7', 'msg8', 'msg9']
-----------------------------------------
data sent: b'msg7'
Removing data: msg7
['msg8', 'msg9']
-----------------------------------------
data sent: b'msg8'
Removing data: msg8
['msg9']
-----------------------------------------
socket.send() raised exception.
data sent: b'msg9'
Removing data: msg9
[]
-----------------------------------------
All list was sent to the server.

Answer 1

对TCP套接字的写入不能保证数据得到接收。它只将数据发送到操作系统内核，然后操作系统内核会尽力将数据发送到另一方。但是，一旦数据被发送到操作系统内核，write调用就会返回成功。如果数据随后被对等操作系统内核接收，它将在TCP级别确认它们。但是，这只意味着数据由内核接收，而不是由应用程序处理。在

如果你想保证消息传递和处理可能的关闭对等，你必须在你的协议中实现某种确认，并且只有在你的对等应用程序成功处理数据后，你从对等应用程序得到明确的确认后才删除数据。在

Answer 2

I would like that if connection is down, client stop to send messages, or don't delete from list if has no guarantee that server has received the message.

所以写一个代码来实现。在服务器指示它已收到消息之前，不要删除该消息。你可以用任何你喜欢的方式来实现它，但是如果它是你想要的行为，你必须对它进行编码。在