diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/mutex.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/mutex.rst Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,68 @@ + +:mod:`mutex` --- Mutual exclusion support +========================================= + +.. module:: mutex + :synopsis: Lock and queue for mutual exclusion. + :deprecated: + +.. deprecated:: + The :mod:`mutex` module has been removed in Python 3.0. + +.. sectionauthor:: Moshe Zadka + + +The :mod:`mutex` module defines a class that allows mutual-exclusion via +acquiring and releasing locks. It does not require (or imply) +:mod:`threading` or multi-tasking, though it could be useful for those +purposes. + +The :mod:`mutex` module defines the following class: + + +.. class:: mutex() + + Create a new (unlocked) mutex. + + A mutex has two pieces of state --- a "locked" bit and a queue. When the mutex + is not locked, the queue is empty. Otherwise, the queue contains zero or more + ``(function, argument)`` pairs representing functions (or methods) waiting to + acquire the lock. When the mutex is unlocked while the queue is not empty, the + first queue entry is removed and its ``function(argument)`` pair called, + implying it now has the lock. + + Of course, no multi-threading is implied -- hence the funny interface for + :meth:`lock`, where a function is called once the lock is acquired. + + +.. _mutex-objects: + +Mutex Objects +------------- + +:class:`mutex` objects have following methods: + + +.. method:: mutex.test() + + Check whether the mutex is locked. + + +.. method:: mutex.testandset() + + "Atomic" test-and-set, grab the lock if it is not set, and return ``True``, + otherwise, return ``False``. + + +.. method:: mutex.lock(function, argument) + + Execute ``function(argument)``, unless the mutex is locked. In the case it is + locked, place the function and argument on the queue. See :meth:`unlock` for + explanation of when ``function(argument)`` is executed in that case. + + +.. method:: mutex.unlock() + + Unlock the mutex if queue is empty, otherwise execute the first element in the + queue. +