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