126 lines
3.8 KiB
Python
126 lines
3.8 KiB
Python
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# Copyright 2013 The Chromium Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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"""Thread and ThreadGroup that reraise exceptions on the main thread."""
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import logging
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import sys
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import threading
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import time
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import traceback
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import watchdog_timer
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class TimeoutError(Exception):
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"""Module-specific timeout exception."""
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pass
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class ReraiserThread(threading.Thread):
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"""Thread class that can reraise exceptions."""
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def __init__(self, func, args=[], kwargs={}, name=None):
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"""Initialize thread.
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Args:
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func: callable to call on a new thread.
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args: list of positional arguments for callable, defaults to empty.
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kwargs: dictionary of keyword arguments for callable, defaults to empty.
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name: thread name, defaults to Thread-N.
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"""
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super(ReraiserThread, self).__init__(name=name)
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self.daemon = True
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self._func = func
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self._args = args
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self._kwargs = kwargs
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self._exc_info = None
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def ReraiseIfException(self):
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"""Reraise exception if an exception was raised in the thread."""
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if self._exc_info:
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raise self._exc_info[0], self._exc_info[1], self._exc_info[2]
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#override
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def run(self):
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"""Overrides Thread.run() to add support for reraising exceptions."""
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try:
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self._func(*self._args, **self._kwargs)
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except:
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self._exc_info = sys.exc_info()
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raise
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class ReraiserThreadGroup(object):
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"""A group of ReraiserThread objects."""
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def __init__(self, threads=[]):
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"""Initialize thread group.
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Args:
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threads: a list of ReraiserThread objects; defaults to empty.
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"""
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self._threads = threads
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def Add(self, thread):
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"""Add a thread to the group.
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Args:
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thread: a ReraiserThread object.
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"""
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self._threads.append(thread)
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def StartAll(self):
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"""Start all threads."""
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for thread in self._threads:
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thread.start()
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def _JoinAll(self, watcher=watchdog_timer.WatchdogTimer(None)):
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"""Join all threads without stack dumps.
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Reraises exceptions raised by the child threads and supports breaking
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immediately on exceptions raised on the main thread.
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Args:
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watcher: Watchdog object providing timeout, by default waits forever.
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"""
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alive_threads = self._threads[:]
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while alive_threads:
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for thread in alive_threads[:]:
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if watcher.IsTimedOut():
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raise TimeoutError('Timed out waiting for %d of %d threads.' %
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(len(alive_threads), len(self._threads)))
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# Allow the main thread to periodically check for interrupts.
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thread.join(0.1)
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if not thread.isAlive():
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alive_threads.remove(thread)
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# All threads are allowed to complete before reraising exceptions.
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for thread in self._threads:
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thread.ReraiseIfException()
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def JoinAll(self, watcher=watchdog_timer.WatchdogTimer(None)):
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"""Join all threads.
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Reraises exceptions raised by the child threads and supports breaking
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immediately on exceptions raised on the main thread. Unfinished threads'
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stacks will be logged on watchdog timeout.
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Args:
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watcher: Watchdog object providing timeout, by default waits forever.
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"""
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try:
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self._JoinAll(watcher)
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except TimeoutError:
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for thread in (t for t in self._threads if t.isAlive()):
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stack = sys._current_frames()[thread.ident]
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logging.critical('*' * 80)
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logging.critical('Stack dump for timed out thread \'%s\'', thread.name)
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logging.critical('*' * 80)
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for filename, lineno, name, line in traceback.extract_stack(stack):
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logging.critical('File: "%s", line %d, in %s', filename, lineno, name)
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if line:
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logging.critical(' %s', line.strip())
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logging.critical('*' * 80)
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raise
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