author | kergoth <kergoth> | 2002-11-01 00:10:42 (UTC) |
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committer | kergoth <kergoth> | 2002-11-01 00:10:42 (UTC) |
commit | 5042e3cf0d3514552769e441f5aad590c8eaf967 (patch) (side-by-side diff) | |
tree | 4a5ea45f3519d981a172ab5275bf38c6fa778dec /qmake/tools/qmutexpool.cpp | |
parent | 108c1c753e74e989cc13923086996791428c9af4 (diff) | |
download | opie-5042e3cf0d3514552769e441f5aad590c8eaf967.zip opie-5042e3cf0d3514552769e441f5aad590c8eaf967.tar.gz opie-5042e3cf0d3514552769e441f5aad590c8eaf967.tar.bz2 |
Adding qmake in preperation for new build system
-rw-r--r-- | qmake/tools/qmutexpool.cpp | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/qmake/tools/qmutexpool.cpp b/qmake/tools/qmutexpool.cpp new file mode 100644 index 0000000..9ed2829 --- a/dev/null +++ b/qmake/tools/qmutexpool.cpp @@ -0,0 +1,130 @@ +#include "qmutexpool_p.h" + +#ifdef QT_THREAD_SUPPORT + +#include <qthread.h> +#include <stdio.h> + +QMutexPool *qt_global_mutexpool = 0; + +// this is an internal class used only for inititalizing the global mutexpool +class QGlobalMutexPoolInitializer +{ +public: + inline QGlobalMutexPoolInitializer() + { + /* + Purify will report a leak here. However, this mutex pool must be alive + until *everything* in Qt has been destructed. Unfortunately there is + no way to guarantee this, so we never destroy this mutex pool. + */ + qt_global_mutexpool = new QMutexPool( TRUE ); + } +}; +QGlobalMutexPoolInitializer qt_global_mutexpool_initializer; + +/*! + \class QMutexPool qmutexpool_p.h + \brief The QMutexPool class provides a pool of QMutex objects. + + \internal + + \ingroup thread + + QMutexPool is a convenience class that provides access to a fixed + number of QMutex objects. + + Typical use of a QMutexPool is in situations where it is not + possible or feasible to use one QMutex for every protected object. + The mutex pool will return a mutex based on the address of the + object that needs protection. + + For example, consider this simple class: + + \code + class Number { + public: + Number( double n ) : num ( n ) { } + + void setNumber( double n ) { num = n; } + double number() const { return num; } + + private: + double num; + }; + \endcode + + Adding a QMutex member to the Number class does not make sense, + because it is so small. However, in order to ensure that access to + each Number is protected, you need to use a mutex. In this case, a + QMutexPool would be ideal. + + Code to calculate the square of a number would then look something + like this: + + \code + void calcSquare( Number *num ) + { + QMutexLocker locker( mutexpool.get( num ) ); + num.setNumber( num.number() * num.number() ); + } + \endcode + + This function will safely calculate the square of a number, since + it uses a mutex from a QMutexPool. The mutex is locked and + unlocked automatically by the QMutexLocker class. See the + QMutexLocker documentation for more details. +*/ + +/*! + Constructs a QMutexPool, reserving space for \a size QMutexes. If + \a recursive is TRUE, all QMutexes in the pool will be recursive + mutexes; otherwise they will all be non-recursive (the default). + + The QMutexes are created when needed, and deleted when the + QMutexPool is destructed. +*/ +QMutexPool::QMutexPool( bool recursive, int size ) + : mutex( FALSE ), mutexes( size ), recurs( recursive ) +{ + mutexes.fill( 0 ); +} + +/*! + Destructs a QMutexPool. All QMutexes that were created by the pool + are deleted. +*/ +QMutexPool::~QMutexPool() +{ + QMutexLocker locker( &mutex ); + QMutex **d = mutexes.data(); + for ( int index = 0; (uint) index < mutexes.size(); index++ ) { + delete d[index]; + d[index] = 0; + } +} + +/*! + Returns a QMutex from the pool. QMutexPool uses the value \a + address to determine which mutex is retured from the pool. +*/ +QMutex *QMutexPool::get( void *address ) +{ + QMutex **d = mutexes.data(); + int index = (int)( (ulong) address % mutexes.size() ); + + if ( ! d[index] ) { + // mutex not created, create one + + QMutexLocker locker( &mutex ); + // we need to check once again that the mutex hasn't been created, since + // 2 threads could be trying to create a mutex as the same index... + if ( ! d[index] ) { + d[index] = new QMutex( recurs ); + } + } + + return d[index]; +} + +#endif |