88 lines
2.2 KiB
Python
88 lines
2.2 KiB
Python
"""Example writing to and reading from a subprocess at the same time using
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tasks."""
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import asyncio
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import os
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from asyncio.subprocess import PIPE
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@asyncio.coroutine
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def send_input(writer, input):
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try:
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for line in input:
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print('sending', len(line), 'bytes')
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writer.write(line)
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d = writer.drain()
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if d:
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print('pause writing')
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yield from d
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print('resume writing')
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writer.close()
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except BrokenPipeError:
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print('stdin: broken pipe error')
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except ConnectionResetError:
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print('stdin: connection reset error')
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@asyncio.coroutine
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def log_errors(reader):
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while True:
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line = yield from reader.readline()
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if not line:
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break
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print('ERROR', repr(line))
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@asyncio.coroutine
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def read_stdout(stdout):
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while True:
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line = yield from stdout.readline()
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print('received', repr(line))
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if not line:
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break
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@asyncio.coroutine
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def start(cmd, input=None, **kwds):
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kwds['stdout'] = PIPE
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kwds['stderr'] = PIPE
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if input is None and 'stdin' not in kwds:
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kwds['stdin'] = None
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else:
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kwds['stdin'] = PIPE
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proc = yield from asyncio.create_subprocess_shell(cmd, **kwds)
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tasks = []
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if input is not None:
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tasks.append(send_input(proc.stdin, input))
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else:
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print('No stdin')
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if proc.stderr is not None:
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tasks.append(log_errors(proc.stderr))
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else:
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print('No stderr')
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if proc.stdout is not None:
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tasks.append(read_stdout(proc.stdout))
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else:
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print('No stdout')
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if tasks:
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# feed stdin while consuming stdout to avoid hang
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# when stdin pipe is full
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yield from asyncio.wait(tasks)
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exitcode = yield from proc.wait()
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print("exit code: %s" % exitcode)
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def main():
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if os.name == 'nt':
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loop = asyncio.ProactorEventLoop()
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asyncio.set_event_loop(loop)
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else:
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loop = asyncio.get_event_loop()
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loop.run_until_complete(start(
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'sleep 2; wc', input=[b'foo bar baz\n'*300 for i in range(100)]))
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loop.close()
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if __name__ == '__main__':
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main()
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