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Task/Priority-queue/Python/priority-queue-2.py

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+>>> import queue
+>>> help(queue.PriorityQueue)
+Help on class PriorityQueue in module queue:
+
+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).
+ |
+ |  Method resolution order:
+ |      PriorityQueue
+ |      Queue
+ |      builtins.object
+ |
+ |  Methods inherited from Queue:
+ |
+ |  __init__(self, maxsize=0)
+ |
+ |  empty(self)
+ |      Return True if the queue is empty, False otherwise (not reliable!).
+ |
+ |      This method is likely to be removed at some point.  Use qsize() == 0
+ |      as a direct substitute, but be aware that either approach risks a race
+ |      condition where a queue can grow before the result of empty() or
+ |      qsize() can be used.
+ |
+ |      To create code that needs to wait for all queued tasks to be
+ |      completed, the preferred technique is to use the join() method.
+ |
+ |  full(self)
+ |      Return True if the queue is full, False otherwise (not reliable!).
+ |
+ |      This method is likely to be removed at some point.  Use qsize() >= n
+ |      as a direct substitute, but be aware that either approach risks a race
+ |      condition where a queue can shrink before the result of full() or
+ |      qsize() can be used.
+ |
+ |  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).
+ |
+ |  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.
+ |
+ |  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.
+ |
+ |  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).
+ |
+ |  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.
+ |
+ |  qsize(self)
+ |      Return the approximate size of the queue (not reliable!).
+ |
+ |  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.
+ |
+ |  ----------------------------------------------------------------------
+ |  Data descriptors inherited from Queue:
+ |
+ |  __dict__
+ |      dictionary for instance variables (if defined)
+ |
+ |  __weakref__
+ |      list of weak references to the object (if defined)
+
+>>>