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#!/usr/bin/env python
#
# Copyright 2014-present Facebook. All Rights Reserved.
#
# This program file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program in a file named COPYING; if not, write to the
# Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor,
# Boston, MA 02110-1301 USA
#
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import os
import subprocess
import select
import sys
import time
DEFAULT_TIMEOUT = 10 #sec
# Note: Python 3.0 supports communicate() with a timeout option.
# If we upgrade to this version we will no longer need timed_communicate
class TimeoutError(Exception):
def __init__(self, output, error):
super(TimeoutError, self).__init__('process timed out')
self.output = output
self.error = error
class WaitTimeoutError(Exception):
pass
def kill_process(proc):
proc.terminate()
try:
timed_wait(proc, 0.1)
except WaitTimeoutError:
proc.kill()
try:
timed_wait(proc, 0.1)
except WaitTimeoutError:
# This can happen if the process is stuck waiting inside a system
# call for a long time. There isn't much we can do unless we want
# to keep waiting forever. Just give up. The child process will
# remain around as a zombie until we exit.
pass
def timed_wait(proc, timeout):
# There unfortunately isn't a great way to wait for a process with a
# timeout, other than polling. (Registering for SIGCHLD and sleeping might
# be one option, but that's fragile and not thread-safe.)
poll_interval = 0.1
end_time = time.time() + timeout
while True:
if proc.poll() is not None:
return
time_left = max(end_time - time.time(), 0)
if time_left <= 0:
raise WaitTimeoutError()
time.sleep(min(time_left, poll_interval))
def timed_communicate(proc, timeout=DEFAULT_TIMEOUT):
end_time = time.time() + timeout
p = select.poll()
outfd = proc.stdout.fileno()
errfd = proc.stderr.fileno()
p.register(outfd, select.POLLIN)
p.register(errfd, select.POLLIN)
results = {outfd: [], errfd: []}
remaining_fds = set([outfd, errfd])
bufsize = 4096
while remaining_fds:
time_left = max(end_time - time.time(), 0)
r = p.poll(time_left * 1000) # poll() takes timeout in milliseconds
if not r:
kill_process(proc)
raise TimeoutError(b''.join(results[outfd]),
b''.join(results[errfd]))
for fd, flags in r:
# We didn't put the fds in non-blocking mode, but we know the fd
# has data to read, so os.read() will return immediately.
d = os.read(fd, bufsize)
if d:
results[fd].append(d)
else:
# EOF on this fd, stop listening on it
p.unregister(fd)
remaining_fds.remove(fd)
try:
timed_wait(proc, max(end_time - time.time(), 0))
except WaitTimeoutError:
kill_process(proc)
raise TimeoutError(b''.join(results[outfd]),
b''.join(results[errfd]))
return b''.join(results[outfd]), b''.join(results[errfd])
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