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# Module implementing queues
#
# multiprocessing/queues.py
#
# Copyright (c) 2006-2008, R Oudkerk
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of author nor the names of any contributors may be
#    used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

__all__ = ['Queue', 'SimpleQueue', 'JoinableQueue']

import sys
import os
import threading
import collections
import time
import atexit
import weakref

from Queue import Empty, Full
import _multiprocessing
from multiprocessing import Pipe
from multiprocessing.synchronize import Lock, BoundedSemaphore, Semaphore, Condition
from multiprocessing.util import debug, info, Finalize, register_after_fork
from multiprocessing.forking import assert_spawning

#
# Queue type using a pipe, buffer and thread
#

class Queue(object):

    def __init__(self, maxsize=0):
        if maxsize <= 0:
            maxsize = _multiprocessing.SemLock.SEM_VALUE_MAX
        self._maxsize = maxsize
        self._reader, self._writer = Pipe(duplex=False)
        self._rlock = Lock()
        self._opid = os.getpid()
        if sys.platform == 'win32':
            self._wlock = None
        else:
            self._wlock = Lock()
        self._sem = BoundedSemaphore(maxsize)

        self._after_fork()

        if sys.platform != 'win32':
            register_after_fork(self, Queue._after_fork)

    def __getstate__(self):
        assert_spawning(self)
        return (self._maxsize, self._reader, self._writer,
                self._rlock, self._wlock, self._sem, self._opid)

    def __setstate__(self, state):
        (self._maxsize, self._reader, self._writer,
         self._rlock, self._wlock, self._sem, self._opid) = state
        self._after_fork()

    def _after_fork(self):
        debug('Queue._after_fork()')
        self._notempty = threading.Condition(threading.Lock())
        self._buffer = collections.deque()
        self._thread = None
        self._jointhread = None
        self._joincancelled = False
        self._closed = False
        self._close = None
        self._send = self._writer.send
        self._recv = self._reader.recv
        self._poll = self._reader.poll

    def put(self, obj, block=True, timeout=None):
        assert not self._closed
        if not self._sem.acquire(block, timeout):
            raise Full

        self._notempty.acquire()
        try:
            if self._thread is None:
                self._start_thread()
            self._buffer.append(obj)
            self._notempty.notify()
        finally:
            self._notempty.release()

    def get(self, block=True, timeout=None):
        if block and timeout is None:
            self._rlock.acquire()
            try:
                res = self._recv()
                self._sem.release()