112 lines
2.7 KiB
Python
112 lines
2.7 KiB
Python
import errno
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import os
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import re
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import signal
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import sys
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import time
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from contextlib import contextmanager
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from subprocess import PIPE
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from subprocess import Popen
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from py._path.local import LocalPath
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# these signals cause dumb-init to suspend itself
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SUSPEND_SIGNALS = frozenset([
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signal.SIGTSTP,
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signal.SIGTTOU,
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signal.SIGTTIN,
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])
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NORMAL_SIGNALS = frozenset(
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set(range(1, 32)) -
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set([signal.SIGKILL, signal.SIGSTOP, signal.SIGCHLD]) -
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SUSPEND_SIGNALS
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)
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@contextmanager
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def print_signals(args=()):
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"""Start print_signals and yield dumb-init process and print_signals PID."""
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proc = Popen(
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(
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('dumb-init',) +
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tuple(args) +
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(sys.executable, '-m', 'testing.print_signals')
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),
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stdout=PIPE,
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)
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line = proc.stdout.readline()
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m = re.match(b'^ready \(pid: ([0-9]+)\)\n$', line)
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assert m, line
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yield proc, m.group(1).decode('ascii')
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for pid in pid_tree(proc.pid):
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os.kill(pid, signal.SIGKILL)
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def child_pids(pid):
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"""Return a list of direct child PIDs for the given PID."""
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children = set()
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for p in LocalPath('/proc').listdir():
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try:
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stat = open(p.join('stat').strpath).read()
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m = re.match('^\d+ \(.+?\) [a-zA-Z] (\d+) ', stat)
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assert m, stat
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ppid = int(m.group(1))
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if ppid == pid:
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children.add(int(p.basename))
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except IOError:
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# Happens when the process exits after listing it, or between
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# opening stat and reading it.
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pass
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return children
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def pid_tree(pid):
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"""Return a list of all descendant PIDs for the given PID."""
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children = child_pids(pid)
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return set(
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pid
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for child in children
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for pid in pid_tree(child)
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) | children
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def is_alive(pid):
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"""Return whether a process is running with the given PID."""
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return LocalPath('/proc').join(str(pid)).isdir()
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def process_state(pid):
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"""Return a process' state, such as "stopped" or "running"."""
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status = LocalPath('/proc').join(str(pid), 'status').read()
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m = re.search('^State:\s+[A-Z] \(([a-z]+)\)$', status, re.MULTILINE)
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return m.group(1)
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def sleep_until(fn, timeout=1.5):
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"""Sleep until fn succeeds, or we time out."""
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interval = 0.01
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so_far = 0
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while True:
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try:
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fn()
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except:
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if so_far >= timeout:
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raise
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else:
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break
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time.sleep(interval)
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so_far += interval
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def kill_if_alive(pid, signum=signal.SIGKILL):
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"""Kill a process, ignoring "no such process" errors."""
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try:
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os.kill(pid, signum)
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except OSError as ex:
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if ex.errno != errno.ESRCH: # No such process
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raise
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