diff options
Diffstat (limited to 'Lib/Queue.py')
| -rw-r--r-- | Lib/Queue.py | 248 |
1 files changed, 6 insertions, 242 deletions
diff --git a/Lib/Queue.py b/Lib/Queue.py index 7b0b328..e358a04 100644 --- a/Lib/Queue.py +++ b/Lib/Queue.py @@ -1,244 +1,8 @@ -"""A multi-producer, multi-consumer queue.""" +import sys +from warnings import warnpy3k -from time import time as _time -from collections import deque -import heapq +warnpy3k("the Queue module has been renamed " + "to 'queue' in Python 3.0", stacklevel=2) -__all__ = ['Empty', 'Full', 'Queue', 'PriorityQueue', 'LifoQueue'] - -class Empty(Exception): - "Exception raised by Queue.get(block=0)/get_nowait()." - pass - -class Full(Exception): - "Exception raised by Queue.put(block=0)/put_nowait()." - pass - -class Queue: - """Create a queue object with a given maximum size. - - If maxsize is <= 0, the queue size is infinite. - """ - def __init__(self, maxsize=0): - try: - import threading - except ImportError: - import dummy_threading as threading - self.maxsize = maxsize - self._init(maxsize) - # mutex must be held whenever the queue is mutating. All methods - # that acquire mutex must release it before returning. mutex - # is shared between the three conditions, so acquiring and - # releasing the conditions also acquires and releases mutex. - self.mutex = threading.Lock() - # Notify not_empty whenever an item is added to the queue; a - # thread waiting to get is notified then. - self.not_empty = threading.Condition(self.mutex) - # Notify not_full whenever an item is removed from the queue; - # a thread waiting to put is notified then. - self.not_full = threading.Condition(self.mutex) - # Notify all_tasks_done whenever the number of unfinished tasks - # drops to zero; thread waiting to join() is notified to resume - self.all_tasks_done = threading.Condition(self.mutex) - self.unfinished_tasks = 0 - - def task_done(self): - """Indicate that a formerly enqueued task is complete. - - Used by Queue consumer threads. For each get() used to fetch a task, - a subsequent call to task_done() tells the queue that the processing - on the task is complete. - - If a join() is currently blocking, it will resume when all items - have been processed (meaning that a task_done() call was received - for every item that had been put() into the queue). - - Raises a ValueError if called more times than there were items - placed in the queue. - """ - self.all_tasks_done.acquire() - try: - unfinished = self.unfinished_tasks - 1 - if unfinished <= 0: - if unfinished < 0: - raise ValueError('task_done() called too many times') - self.all_tasks_done.notifyAll() - self.unfinished_tasks = unfinished - finally: - self.all_tasks_done.release() - - def join(self): - """Blocks until all items in the Queue have been gotten and processed. - - The count of unfinished tasks goes up whenever an item is added to the - queue. The count goes down whenever a consumer thread calls task_done() - to indicate the item was retrieved and all work on it is complete. - - When the count of unfinished tasks drops to zero, join() unblocks. - """ - self.all_tasks_done.acquire() - try: - while self.unfinished_tasks: - self.all_tasks_done.wait() - finally: - self.all_tasks_done.release() - - def qsize(self): - """Return the approximate size of the queue (not reliable!).""" - self.mutex.acquire() - n = self._qsize() - self.mutex.release() - return n - - def empty(self): - """Return True if the queue is empty, False otherwise (not reliable!).""" - self.mutex.acquire() - n = not self._qsize() - self.mutex.release() - return n - - def full(self): - """Return True if the queue is full, False otherwise (not reliable!).""" - self.mutex.acquire() - n = 0 < self.maxsize == self._qsize() - self.mutex.release() - return n - - def put(self, item, block=True, timeout=None): - """Put an item into the queue. - - If optional args 'block' is true and 'timeout' is None (the default), - block if necessary until a free slot is available. If 'timeout' is - a positive number, it blocks at most 'timeout' seconds and raises - the Full exception if no free slot was available within that time. - Otherwise ('block' is false), put an item on the queue if a free slot - is immediately available, else raise the Full exception ('timeout' - is ignored in that case). - """ - self.not_full.acquire() - try: - if self.maxsize > 0: - if not block: - if self._qsize() == self.maxsize: - raise Full - elif timeout is None: - while self._qsize() == self.maxsize: - self.not_full.wait() - elif timeout < 0: - raise ValueError("'timeout' must be a positive number") - else: - endtime = _time() + timeout - while self._qsize() == self.maxsize: - remaining = endtime - _time() - if remaining <= 0.0: - raise Full - self.not_full.wait(remaining) - self._put(item) - self.unfinished_tasks += 1 - self.not_empty.notify() - finally: - self.not_full.release() - - def put_nowait(self, item): - """Put an item into the queue without blocking. - - Only enqueue the item if a free slot is immediately available. - Otherwise raise the Full exception. - """ - return self.put(item, False) - - def get(self, block=True, timeout=None): - """Remove and return an item from the queue. - - If optional args 'block' is true and 'timeout' is None (the default), - block if necessary until an item is available. If 'timeout' is - a positive number, it blocks at most 'timeout' seconds and raises - the Empty exception if no item was available within that time. - Otherwise ('block' is false), return an item if one is immediately - available, else raise the Empty exception ('timeout' is ignored - in that case). - """ - self.not_empty.acquire() - try: - if not block: - if not self._qsize(): - raise Empty - elif timeout is None: - while not self._qsize(): - self.not_empty.wait() - elif timeout < 0: - raise ValueError("'timeout' must be a positive number") - else: - endtime = _time() + timeout - while not self._qsize(): - remaining = endtime - _time() - if remaining <= 0.0: - raise Empty - self.not_empty.wait(remaining) - item = self._get() - self.not_full.notify() - return item - finally: - self.not_empty.release() - - def get_nowait(self): - """Remove and return an item from the queue without blocking. - - Only get an item if one is immediately available. Otherwise - raise the Empty exception. - """ - return self.get(False) - - # Override these methods to implement other queue organizations - # (e.g. stack or priority queue). - # These will only be called with appropriate locks held - - # Initialize the queue representation - def _init(self, maxsize): - self.queue = deque() - - def _qsize(self, len=len): - return len(self.queue) - - # Put a new item in the queue - def _put(self, item): - self.queue.append(item) - - # Get an item from the queue - def _get(self): - return self.queue.popleft() - - -class PriorityQueue(Queue): - '''Variant of Queue that retrieves open entries in priority order (lowest first). - - Entries are typically tuples of the form: (priority number, data). - ''' - - def _init(self, maxsize): - self.queue = [] - - def _qsize(self, len=len): - return len(self.queue) - - def _put(self, item, heappush=heapq.heappush): - heappush(self.queue, item) - - def _get(self, heappop=heapq.heappop): - return heappop(self.queue) - - -class LifoQueue(Queue): - '''Variant of Queue that retrieves most recently added entries first.''' - - def _init(self, maxsize): - self.queue = [] - - def _qsize(self, len=len): - return len(self.queue) - - def _put(self, item): - self.queue.append(item) - - def _get(self): - return self.queue.pop() +import queue +sys.modules[__name__] = queue |