89 lines
2.8 KiB
TeX
89 lines
2.8 KiB
TeX
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\section{Standard module \sectcode{Queue}}
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\stmodindex{Queue}
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\label{module-Queue}
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% ==== 2. ====
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% Give a short overview of what the module does.
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% If it is platform specific, mention this.
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% Mention other important restrictions or general operating principles.
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% For example:
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The \code{Queue} module implements a multi-producer, multi-consumer
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FIFO queue. It is especially useful in threads programming when
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information must be exchanged safely between multiple threads. The
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\code{Queue} class in this module implements all the required locking
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semantics. It depends on the availability of thread support in
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Python.
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The \code{Queue} module defines the following exception:
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\renewcommand{\indexsubitem}{(in module Queue)}
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\begin{excdesc}{Empty}
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Exception raised when non-blocking get (e.g. \code{get_nowait()}) is
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called on a Queue object which is empty, or for which the emptyiness
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cannot be determined (i.e. because the appropriate locks cannot be
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acquired).
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\end{excdesc}
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\subsection{Queue Objects}
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Class \code{Queue} implements queue objects and has the methods
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described below. This class can be derived from in order to implement
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other queue organizations (e.g. stack) but the inheritable interface
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is not described here. See the source code for details. The public
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interface methods are:
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\renewcommand{\indexsubitem}{(__init__ method)}
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\begin{funcdesc}{__init__}{maxsize}
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Constructor for the class. \var{maxsize} is an integer that sets the
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upperbound limit on the number of items that can be placed in the
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queue. Insertion will block once this size has been reached, until
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queue items are consumed. If \var{maxsize} is less than or equal to
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zero, the queue size is infinite.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(qsize method)}
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\begin{funcdesc}{qsize}{}
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Returns the approximate size of the queue. Because of multithreading
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semantics, this number is not reliable.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(empty method)}
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\begin{funcdesc}{empty}{}
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Returns 1 if the queue is empty, 0 otherwise. Because of
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multithreading semantics, this is not reliable.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(full method)}
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\begin{funcdesc}{full}{}
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Returns 1 if the queue is full, 0 otherwise. Because of
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multithreading semantics, this is not reliable.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(put method)}
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\begin{funcdesc}{put}{item}
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Puts \var{item} into the queue.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(get method)}
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\begin{funcdesc}{get}{}
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Gets and returns an item from the queue, blocking if necessary until
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one is available.
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\end{funcdesc}
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\renewcommand{\indexsubitem}{(get_nowait method)}
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\begin{funcdesc}{get_nowait}{}
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Gets and returns an item from the queue if one is immediately
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available. Raises an \code{Empty} exception if the queue is empty or
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if the queue's emptiness cannot be determined.
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\end{funcdesc}
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