cpython-lru_cache-weakref: Lib/Queue.py annotate

annotate Lib/Queue.py @ 27022:e2c88c451c19 legacy-trunk

Replaced imp.set_frozenmodules() cruft with proper zipimport support. This work uncovered the zipimport bug in 2.3a1 -- wish I'd had time to do this before the release :-(.

author	Just van Rossum <just@letterror.com>
date	Thu, 02 Jan 2003 13:13:01 +0000
parents	95510f0a0624
children	58132c813d7b

rev	line source
11691 e34991022571 Mass patch by Ka-Ping Yee: Guido van Rossum <guido@python.org> parents: 11267 diff changeset	1 """A multi-producer, multi-consumer queue."""
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	2
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	3 from time import time as _time, sleep as _sleep
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	4
15902 eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	5 class Empty(Exception):
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	6 "Exception raised by Queue.get(block=0)/get_nowait()."
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	7 pass
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	8
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	9 class Full(Exception):
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	10 "Exception raised by Queue.put(block=0)/put_nowait()."
eef321b6e41c Variant of Skip's patch 103246 (Remove unneeded string exception compat from Queue). Tim Peters <tim.peters@gmail.com> parents: 13050 diff changeset	11 pass
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	12
f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	13 class Queue:
11267 2b26e48a85a6 Make the maxsize constructor argument default to 0 (an unlimited queue size). Guido van Rossum <guido@python.org> parents: 10120 diff changeset	14 def __init__(self, maxsize=0):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	15 """Initialize a queue object with a given maximum size.
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	16
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	17 If maxsize is <= 0, the queue size is infinite.
fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	18 """
26892 95510f0a0624 Use the dummy_thread module in Queue.py and tempfile.py. Guido van Rossum <guido@python.org> parents: 25796 diff changeset	19 try:
95510f0a0624 Use the dummy_thread module in Queue.py and tempfile.py. Guido van Rossum <guido@python.org> parents: 25796 diff changeset	20 import thread
95510f0a0624 Use the dummy_thread module in Queue.py and tempfile.py. Guido van Rossum <guido@python.org> parents: 25796 diff changeset	21 except ImportError:
95510f0a0624 Use the dummy_thread module in Queue.py and tempfile.py. Guido van Rossum <guido@python.org> parents: 25796 diff changeset	22 import dummy_thread as thread
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	23 self._init(maxsize)
fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	24 self.mutex = thread.allocate_lock()
fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	25 self.esema = thread.allocate_lock()
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	26 self.esema.acquire()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	27 self.fsema = thread.allocate_lock()
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	28
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	29 def qsize(self):
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	30 """Return the approximate size of the queue (not reliable!)."""
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	31 self.mutex.acquire()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	32 n = self._qsize()
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	33 self.mutex.release()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	34 return n
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	35
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	36 def empty(self):
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	37 """Return True if the queue is empty, False otherwise (not reliable!)."""
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	38 self.mutex.acquire()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	39 n = self._empty()
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	40 self.mutex.release()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	41 return n
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	42
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	43 def full(self):
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	44 """Return True if the queue is full, False otherwise (not reliable!)."""
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	45 self.mutex.acquire()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	46 n = self._full()
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	47 self.mutex.release()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	48 return n
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	49
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	50 def put(self, item, block=True, timeout=None):
7926 e29d435ab142 Clarify that put blocks when the queue is full. Add some blank Guido van Rossum <guido@python.org> parents: 7755 diff changeset	51 """Put an item into the queue.
e29d435ab142 Clarify that put blocks when the queue is full. Add some blank Guido van Rossum <guido@python.org> parents: 7755 diff changeset	52
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	53 If optional args 'block' is true and 'timeout' is None (the default),
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	54 block if necessary until a free slot is available. If 'timeout' is
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	55 a positive number, it blocks at most 'timeout' seconds and raises
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	56 the Full exception if no free slot was available within that time.
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	57 Otherwise ('block' is false), put an item on the queue if a free slot
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	58 is immediately available, else raise the Full exception ('timeout'
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	59 is ignored in that case).
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	60 """
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	61 if block:
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	62 if timeout is None:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	63 # blocking, w/o timeout, i.e. forever
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	64 self.fsema.acquire()
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	65 elif timeout >= 0:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	66 # waiting max. 'timeout' seconds.
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	67 # this code snipped is from threading.py: _Event.wait():
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	68 # Balancing act: We can't afford a pure busy loop, so we
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	69 # have to sleep; but if we sleep the whole timeout time,
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	70 # we'll be unresponsive. The scheme here sleeps very
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	71 # little at first, longer as time goes on, but never longer
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	72 # than 20 times per second (or the timeout time remaining).
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	73 delay = 0.0005 # 500 us -> initial delay of 1 ms
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	74 endtime = _time() + timeout
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	75 while True:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	76 if self.fsema.acquire(0):
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	77 break
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	78 remaining = endtime - _time()
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	79 if remaining <= 0: #time is over and no slot was free
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	80 raise Full
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	81 delay = min(delay * 2, remaining, .05)
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	82 _sleep(delay) #reduce CPU usage by using a sleep
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	83 else:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	84 raise ValueError("'timeout' must be a positive number")
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	85 elif not self.fsema.acquire(0):
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	86 raise Full
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	87 self.mutex.acquire()
23160 c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	88 release_fsema = True
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	89 try:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	90 was_empty = self._empty()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	91 self._put(item)
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	92 # If we fail before here, the empty state has
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	93 # not changed, so we can skip the release of esema
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	94 if was_empty:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	95 self.esema.release()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	96 # If we fail before here, the queue can not be full, so
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	97 # release_full_sema remains True
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	98 release_fsema = not self._full()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	99 finally:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	100 # Catching system level exceptions here (RecursionDepth,
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	101 # OutOfMemory, etc) - so do as little as possible in terms
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	102 # of Python calls.
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	103 if release_fsema:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	104 self.fsema.release()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	105 self.mutex.release()
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	106
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	107 def put_nowait(self, item):
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	108 """Put an item into the queue without blocking.
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	109
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	110 Only enqueue the item if a free slot is immediately available.
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	111 Otherwise raise the Full exception.
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	112 """
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	113 return self.put(item, False)
7926 e29d435ab142 Clarify that put blocks when the queue is full. Add some blank Guido van Rossum <guido@python.org> parents: 7755 diff changeset	114
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	115 def get(self, block=True, timeout=None):
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	116 """Remove and return an item from the queue.
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	117
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	118 If optional args 'block' is true and 'timeout' is None (the default),
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	119 block if necessary until an item is available. If 'timeout' is
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	120 a positive number, it blocks at most 'timeout' seconds and raises
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	121 the Empty exception if no item was available within that time.
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	122 Otherwise ('block' is false), return an item if one is immediately
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	123 available, else raise the Empty exception ('timeout' is ignored
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	124 in that case).
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	125 """
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	126 if block:
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	127 if timeout is None:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	128 # blocking, w/o timeout, i.e. forever
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	129 self.esema.acquire()
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	130 elif timeout >= 0:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	131 # waiting max. 'timeout' seconds.
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	132 # this code snipped is from threading.py: _Event.wait():
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	133 # Balancing act: We can't afford a pure busy loop, so we
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	134 # have to sleep; but if we sleep the whole timeout time,
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	135 # we'll be unresponsive. The scheme here sleeps very
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	136 # little at first, longer as time goes on, but never longer
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	137 # than 20 times per second (or the timeout time remaining).
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	138 delay = 0.0005 # 500 us -> initial delay of 1 ms
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	139 endtime = _time() + timeout
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	140 while 1:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	141 if self.esema.acquire(0):
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	142 break
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	143 remaining = endtime - _time()
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	144 if remaining <= 0: #time is over and no element arrived
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	145 raise Empty
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	146 delay = min(delay * 2, remaining, .05)
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	147 _sleep(delay) #reduce CPU usage by using a sleep
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	148 else:
3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	149 raise ValueError("'timeout' must be a positive number")
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	150 elif not self.esema.acquire(0):
5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	151 raise Empty
8197 3a55b4c5e3c7 Replace all calls to acquire_lock() and release_lock() with acquire() Guido van Rossum <guido@python.org> parents: 7926 diff changeset	152 self.mutex.acquire()
23160 c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	153 release_esema = True
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	154 try:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	155 was_full = self._full()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	156 item = self._get()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	157 # If we fail before here, the full state has
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	158 # not changed, so we can skip the release of fsema
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	159 if was_full:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	160 self.fsema.release()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	161 # Failure means empty state also unchanged - release_esema
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	162 # remains True.
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	163 release_esema = not self._empty()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	164 finally:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	165 if release_esema:
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	166 self.esema.release()
c548e726b3bc Fix bug 544473 - "Queue module can deadlock". Mark Hammond <mhammond@skippinet.com.au> parents: 16657 diff changeset	167 self.mutex.release()
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	168 return item
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	169
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	170 def get_nowait(self):
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	171 """Remove and return an item from the queue without blocking.
7926 e29d435ab142 Clarify that put blocks when the queue is full. Add some blank Guido van Rossum <guido@python.org> parents: 7755 diff changeset	172
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	173 Only get an item if one is immediately available. Otherwise
10120 5b15642e7bdf Tim Peters: Guido van Rossum <guido@python.org> parents: 8197 diff changeset	174 raise the Empty exception.
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	175 """
25796 3eafbde56b21 Patch #572628: Optional timeouts for put and get. Martin v. Löwis <martin@v.loewis.de> parents: 24058 diff changeset	176 return self.get(False)
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	177
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	178 # Override these methods to implement other queue organizations
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	179 # (e.g. stack or priority queue).
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	180 # These will only be called with appropriate locks held
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	181
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	182 # Initialize the queue representation
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	183 def _init(self, maxsize):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	184 self.maxsize = maxsize
fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	185 self.queue = []
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	186
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	187 def _qsize(self):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	188 return len(self.queue)
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	189
13050 a195962e389c typos fixed by Rob Hooft Jeremy Hylton <jeremy@alum.mit.edu> parents: 11691 diff changeset	190 # Check whether the queue is empty
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	191 def _empty(self):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	192 return not self.queue
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	193
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	194 # Check whether the queue is full
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	195 def _full(self):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	196 return self.maxsize > 0 and len(self.queue) == self.maxsize
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	197
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	198 # Put a new item in the queue
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	199 def _put(self, item):
7755 fb4b4d069cc7 Mass check-in after untabifying all files that need it. Guido van Rossum <guido@python.org> parents: 6612 diff changeset	200 self.queue.append(item)
995 f025eef93130 New module implementing a multi-everything queue. Guido van Rossum <guido@python.org> parents: diff changeset	201
6612 4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	202 # Get an item from the queue
4b2d8dc92db4 (Queue.Empty): When class based exceptions are in force, derive this Barry Warsaw <barry@python.org> parents: 1463 diff changeset	203 def _get(self):
24058 37ffce2d9c3c Code modernization. Replace v=s[i]; del s[i] with single lookup v=s.pop(i) Raymond Hettinger <python@rcn.com> parents: 23160 diff changeset	204 return self.queue.pop(0)

Mercurial > cpython-lru_cache-weakref

annotate Lib/Queue.py @ 27022:e2c88c451c19 legacy-trunk