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author | 2014-12-16 00:00:17 +0100 | |
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committer | 2014-12-16 00:00:17 +0100 | |
commit | f195588254e4f1516ec024973ebba3660622c3fa (patch) | |
tree | 28f573850a9b34dc20a5b91b998599dcab77274e | |
parent | roverlay/util/common: doc typo (diff) | |
download | R_overlay-f195588254e4f1516ec024973ebba3660622c3fa.tar.gz R_overlay-f195588254e4f1516ec024973ebba3660622c3fa.tar.bz2 R_overlay-f195588254e4f1516ec024973ebba3660622c3fa.zip |
add subprocess helper module
-rw-r--r-- | roverlay/tools/subproc.py | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/roverlay/tools/subproc.py b/roverlay/tools/subproc.py new file mode 100644 index 0000000..a62601f --- /dev/null +++ b/roverlay/tools/subproc.py @@ -0,0 +1,157 @@ +# R overlay -- tools, subprocess helpers +# -*- coding: utf-8 -*- +# Copyright (C) 2014 André Erdmann <dywi@mailerd.de> +# Distributed under the terms of the GNU General Public License; +# either version 2 of the License, or (at your option) any later version. + +import os +import subprocess +import sys + +__all__ = [ + 'get_subproc_devnull', + 'subproc_send_term', 'subproc_send_kill', + 'stop_subprocess', 'gracefully_stop_subprocess', + 'create_subprocess', 'run_subprocess' +] + +# python >= 3.3 has ProcessLookupError, use more generic exception otherwise +if sys.hexversion >= 0x3030000: + _ProcessLookupError = ProcessLookupError +else: + _ProcessLookupError = OSError + +# python >= 3.3: +if hasattr ( subprocess, 'DEVNULL' ): + def get_subproc_devnull(mode=None): + """Returns a devnull object suitable + for passing it as stdin/stdout/stderr to subprocess.Popen(). + + Python 3.3 and later variant: uses subprocess.DEVNULL + + arguments: + * mode -- ignored + """ + return subprocess.DEVNULL +else: + def get_subproc_devnull(mode='a+'): + """Returns a devnull object suitable + for passing it as stdin/stdout/stderr to subprocess.Popen(). + + Python 3.2 and earlier variant: opens os.devnull + + arguments: + * mode -- mode for open(). Defaults to read/append + """ + return open ( os.devnull, mode ) +# -- + +def _proc_catch_lookup_err ( func ): + def wrapped ( proc ): + try: + func ( proc ) + except _ProcessLookupError: + return False + return True + + return wrapped + +@_proc_catch_lookup_err +def subproc_send_term ( proc ): + proc.terminate() + +@_proc_catch_lookup_err +def subproc_send_kill ( proc ): + proc.kill() + + +def stop_subprocess ( proc, kill_timeout_cs=10 ): + """Terminates or kills a subprocess created by subprocess.Popen(). + + Sends SIGTERM first and sends SIGKILL if the process is still alive after + the given timeout. + + Returns: None + + arguments: + * proc -- subprocess + * kill_timeout_cs -- max time to wait after terminate() before sending a + kill signal (in centiseconds). Should be an int. + Defaults to 10 (= 1s). + """ + if not subproc_send_term ( proc ): + return + + try: + for k in range ( kill_timeout_cs ): + if proc.poll() is not None: + return + time.sleep ( 0.1 ) + except: + subproc_send_kill ( proc ) + else: + subproc_send_kill ( proc ) +# --- end of stop_subprocess (...) --- + +def gracefully_stop_subprocess ( proc, **kill_kwargs ): + try: + if subproc_send_term ( proc ): + proc.communicate() + except: + stop_subprocess ( proc, **kwargs ) + raise + +def create_subprocess ( cmdv, **kwargs ): + """subprocess.Popen() wrapper that redirects stdin/stdout/stderr to + devnull or to a pipe if set to False/True. + + Returns: subprocess + + arguments: + * cmdv -- + * **kwargs -- + """ + devnull_obj = None + + for key in { 'stdin', 'stdout', 'stderr' }: + if key not in kwargs: + pass + elif kwargs [key] is True: + kwargs [key] = subprocess.PIPE + + elif kwargs [key] is False: + if devnull_obj is None: + devnull_obj = get_subproc_devnull() + assert devnull_obj is not None + + kwargs [key] = devnull_obj + # else don't care + # -- + + return subprocess.Popen ( cmdv, **kwargs ) +# --- end of create_subprocess (...) --- + +def run_subprocess ( cmdv, kill_timeout_cs=10, **kwargs ): + """Calls create_subprocess() and waits for the process to exit. + Catches exceptions and terminates/kills the process in that case + + Returns: 2-tuple ( subprocess, output ) + + arguments: + * cmdv -- + * kill_timeout_cs -- time to wait after SIGTERM before sending SIGKILL + (in centiseconds), see stop_subprocess() for details + Defaults to 10. + * **kwargs -- + """ + proc = None + try: + proc = create_subprocess ( cmdv, **kwargs ) + output = proc.communicate() + except: + if proc is not None: + stop_subprocess ( proc, kill_timeout_cs=kill_timeout_cs ) + raise + + return ( proc, output ) +# --- end of run_subprocess (...) --- |