使用Popen模拟glib.spawn_async ...

Question

函数glib.spawn_async允许您挂钩在stdout，stderr上调用事件的三个​​回调，以及进程完成时。

如何使用subprocess与线程或asyncio模仿相同的功能？

我更感兴趣的功能，而不是线程/ asynio但包含两个答案将获得赏金。

这里是一个玩具程序，它显示了我想做的事：

import glib 
import logging 
import os 
import gtk 


class MySpawn(object): 
    def __init__(self): 
     self._logger = logging.getLogger(self.__class__.__name__) 

    def execute(self, cmd, on_done, on_stdout, on_stderr): 
     self.pid, self.idin, self.idout, self.iderr = \ 
      glib.spawn_async(cmd, 
          flags=glib.SPAWN_DO_NOT_REAP_CHILD, 
          standard_output=True, 
          standard_error=True) 
     fout = os.fdopen(self.idout, "r") 
     ferr = os.fdopen(self.iderr, "r") 
     glib.child_watch_add(self.pid, on_done) 
     glib.io_add_watch(fout, glib.IO_IN, on_stdout) 
     glib.io_add_watch(ferr, glib.IO_IN, on_stderr) 
     return self.pid 


if __name__ == '__main__': 
    logging.basicConfig(format='%(thread)d %(levelname)s: %(message)s', 
         level=logging.DEBUG) 
    cmd = '/usr/bin/git ls-remote https://github.com/DiffSK/configobj'.split() 

    def on_done(pid, retval, *args): 
     logging.info("That's all folks!…") 

    def on_stdout(fobj, cond): 
     """This blocks which is fine for this toy example…""" 
     for line in fobj.readlines(): 
      logging.info(line.strip()) 
     return True 

    def on_stderr(fobj, cond): 
     """This blocks which is fine for this toy example…""" 
     for line in fobj.readlines(): 
      logging.error(line.strip()) 
     return True 

    runner = MySpawn() 
    runner.execute(cmd, on_done, on_stdout, on_stderr) 
    try: 
     gtk.main() 
    except KeyboardInterrupt: 
     print('') 

我要补充的是，由于readlines()挡住，上面会缓冲所有的输出，并立刻发送。如果这不是您想要的，那么您必须使用readline()，并确保在命令结束时读完您之前未读过的所有行。

Answer 1

ASYNCIO有subprocess_exec，就没有必要使用子模块都：

import asyncio 

class Handler(asyncio.SubprocessProtocol): 
    def pipe_data_received(self, fd, data): 
     # fd == 1 for stdout, and 2 for stderr 
     print("Data from /bin/ls on fd %d: %s" % (fd, data.decode())) 

    def pipe_connection_lost(self, fd, exc): 
     print("Connection lost to /bin/ls") 

    def process_exited(self): 
     print("/bin/ls is finished.") 

loop = asyncio.get_event_loop() 
coro = loop.subprocess_exec(Handler, "/bin/ls", "/") 

loop.run_until_complete(coro) 
loop.close() 

随着子和线程，这是很简单。你可以只产卵每管螺纹，一到wait()的过程：

import subprocess 
import threading 

class PopenWrapper(object): 
    def __init__(self, args): 
     self.process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.DEVNULL) 

     self.stdout_reader_thread = threading.Thread(target=self._reader, args=(self.process.stdout,)) 
     self.stderr_reader_thread = threading.Thread(target=self._reader, args=(self.process.stderr,)) 
     self.exit_watcher = threading.Thread(target=self._exit_watcher) 

     self.stdout_reader_thread.start() 
     self.stderr_reader_thread.start() 
     self.exit_watcher.start() 

    def _reader(self, fileobj): 
     for line in fileobj: 
      self.on_data(fileobj, line) 

    def _exit_watcher(self): 
     self.process.wait() 
     self.stdout_reader_thread.join() 
     self.stderr_reader_thread.join() 
     self.on_exit() 

    def on_data(self, fd, data): 
     return NotImplementedError 

    def on_exit(self): 
     return NotImplementedError 

    def join(self): 
     self.process.wait() 

class LsWrapper(PopenWrapper): 
    def on_data(self, fd, data): 
     print("Received on fd %r: %s" % (fd, data)) 

    def on_exit(self): 
     print("Process exited.") 


LsWrapper(["/bin/ls", "/"]).join() 

但是，记住，油嘴不不使用线程来执行asynchroneously您的回调。它使用事件循环，就像asyncio一样。这个想法是，程序的核心是一个等待事件发生的循环，然后同步执行相关的回调。就你而言，这就是“数据可用于读取其中一个管道”，并且“子进程已退出”。一般来说，它也有类似“X11服务器报告的鼠标移动”，“存在传入的网络流量”等。您可以通过编写自己的事件循环来模拟glib的行为。在两个管道上使用select module。如果选择报告管道可读，但read不返回任何数据，则可能退出该过程 - 在这种情况下，调用子进程对象上的poll()方法来检查它是否完成，并在出现回调（如果有）或错误否则回拨。