使用 asyncio 的非阻塞 I/O [英] Non-blocking I/O with asyncio

问题描述

我正在尝试使用 Pygame 和 asyncio 编写网络游戏，但我不知道如何避免读取挂起.这是我的客户端代码:

I'm trying to write a networked game with Pygame and asyncio, but I can't work out how to avoid hanging on reads. Here is my code for the client:

@asyncio.coroutine
def handle_client():
    print("Connected!")
    reader, writer = yield from asyncio.open_connection('localhost', 8000)
    while True:
        mouse_up = False
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()                
            elif event.type == pygame.MOUSEBUTTONUP:
                mouse_up = True

        if mouse_up:
            print("Writing")
            writer.write(b"Mouse up")
        print("Waiting to read")
        line = yield from reader.read(2**12)
        print(line.decode())

    writer.close()

这挂在 line = yield from reader.read(2**12) 行上.我以前认为 asyncio 的要点是它是非阻塞的，所以如果没有任何数据要读取，它就会继续执行.我现在明白事实并非如此.

This hangs on the line line = yield from reader.read(2**12). I previously thought that the point of asyncio was that it was non-blocking, and so if there wasn't any data to read it would just continue executing. I see now that this isn't the case.

如何将 asyncio 网络代码与 Pygame 绘图和事件代码集成?

How do I integrate the asyncio networking code with the Pygame drawing and event code?

推荐答案

yield from 的要点是将执行切换到 asyncio 的事件循环 和 以阻止当前协程，直到结果可用.要在不阻塞当前协程的情况下安排任务，您可以使用 asyncio.async().

The point of yield from is to switch the execution to the asyncio's event loop and to block the current coroutine until the result is available. To schedule a task without blocking the current coroutine, you could use asyncio.async().

在不阻塞 pygame 循环的情况下打印读取到的数据:

To print read-so-far data without blocking the pygame loop:

@asyncio.coroutine
def read(reader, callback):
    while True:
        data = yield from reader.read(2**12)
        if not data: # EOF
            break
        callback(data)

@asyncio.coroutine
def echo_client():
    reader, ...
    chunks = []
    asyncio.async(read(reader, chunks.append))
    while True:
        pygame.event.pump() # advance pygame event loop
        ...
        if chunks: # print read-so-far data
            print(b''.join(chunks).decode())
            del chunks[:]
        yield from asyncio.sleep(0.016) # advance asyncio loop

while 循环内不应有阻塞调用.

There should be no blocking calls inside the while loop.

read() 和 sleep() 协程在同一个线程中并发运行(显然你也可以同时运行其他协程).

read() and sleep() coroutines run concurrently in the same thread (obviously you could run other coroutines concurrently too).

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