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authorTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-07-10 15:24:15 -0500
committerTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-07-10 15:24:15 -0500
commitbd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch)
tree7a520322212d48ebcb9fbe1087e7fca28b76185c /src/tools/qthreadstorage_unix.cpp
downloadqt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz
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+/****************************************************************************
+**
+** ...
+**
+** Copyright (C) 2005-2008 Trolltech ASA. All rights reserved.
+**
+** This file is part of the tools module of the Qt GUI Toolkit.
+**
+** This file may be used under the terms of the GNU General
+** Public License versions 2.0 or 3.0 as published by the Free
+** Software Foundation and appearing in the files LICENSE.GPL2
+** and LICENSE.GPL3 included in the packaging of this file.
+** Alternatively you may (at your option) use any later version
+** of the GNU General Public License if such license has been
+** publicly approved by Trolltech ASA (or its successors, if any)
+** and the KDE Free Qt Foundation.
+**
+** Please review the following information to ensure GNU General
+** Public Licensing requirements will be met:
+** http://trolltech.com/products/qt/licenses/licensing/opensource/.
+** If you are unsure which license is appropriate for your use, please
+** review the following information:
+** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
+** or contact the sales department at sales@trolltech.com.
+**
+** This file may be used under the terms of the Q Public License as
+** defined by Trolltech ASA and appearing in the file LICENSE.QPL
+** included in the packaging of this file. Licensees holding valid Qt
+** Commercial licenses may use this file in accordance with the Qt
+** Commercial License Agreement provided with the Software.
+**
+** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
+** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
+** herein.
+**
+**********************************************************************/
+
+#ifdef QT_THREAD_SUPPORT
+
+#include "qplatformdefs.h"
+
+#include "qthreadstorage.h"
+#include <private/qthreadinstance_p.h>
+
+#include <string.h>
+
+// #define QTHREADSTORAGE_DEBUG
+
+
+// keep this in sync with the implementation in qthreadstorage.cpp
+static const int MAX_THREAD_STORAGE = 257; // 256 maximum + 1 used in QRegExp
+
+static pthread_mutex_t thread_storage_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static bool thread_storage_init = FALSE;
+static struct {
+ bool used;
+ void (*func)( void * );
+} thread_storage_usage[MAX_THREAD_STORAGE];
+
+
+QThreadStorageData::QThreadStorageData( void (*func)( void * ) )
+ : id( 0 )
+{
+ pthread_mutex_lock( &thread_storage_mutex );
+
+ // make sure things are initialized
+ if ( ! thread_storage_init )
+ memset( thread_storage_usage, 0, sizeof( thread_storage_usage ) );
+ thread_storage_init = TRUE;
+
+ for ( ; id < MAX_THREAD_STORAGE; ++id ) {
+ if ( !thread_storage_usage[id].used )
+ break;
+ }
+
+ Q_ASSERT( id >= 0 && id < MAX_THREAD_STORAGE );
+ thread_storage_usage[id].used = TRUE;
+ thread_storage_usage[id].func = func;
+
+#ifdef QTHREADSTORAGE_DEBUG
+ qDebug( "QThreadStorageData: allocated id %d", id );
+#endif // QTHREADSTORAGE_DEBUG
+
+ pthread_mutex_unlock( &thread_storage_mutex );
+}
+
+QThreadStorageData::~QThreadStorageData()
+{
+ pthread_mutex_lock( &thread_storage_mutex );
+ thread_storage_usage[id].used = FALSE;
+ thread_storage_usage[id].func = 0;
+
+#ifdef QTHREADSTORAGE_DEBUG
+ qDebug( "QThreadStorageData: released id %d", id );
+#endif // QTHREADSTORAGE_DEBUG
+
+ pthread_mutex_unlock( &thread_storage_mutex );
+}
+
+void **QThreadStorageData::get() const
+{
+ QThreadInstance *d = QThreadInstance::current();
+ if (!d) {
+ qWarning("QThreadStorage can only be used with threads started with QThread");
+ return 0;
+ }
+ QMutexLocker locker( d->mutex() );
+ return d->thread_storage && d->thread_storage[id] ? &d->thread_storage[id] : 0;
+}
+
+void **QThreadStorageData::set( void *p )
+{
+ QThreadInstance *d = QThreadInstance::current();
+ if (!d) {
+ qWarning("QThreadStorage can only be used with threads started with QThread");
+ return 0;
+ }
+ QMutexLocker locker( d->mutex() );
+ if ( !d->thread_storage ) {
+#ifdef QTHREADSTORAGE_DEBUG
+ qDebug( "QThreadStorageData: allocating storage for thread %lx",
+ (unsigned long) pthread_self() );
+#endif // QTHREADSTORAGE_DEBUG
+
+ d->thread_storage = new void*[MAX_THREAD_STORAGE];
+ memset( d->thread_storage, 0, sizeof( void* ) * MAX_THREAD_STORAGE );
+ }
+
+ // delete any previous data
+ if ( d->thread_storage[id] )
+ thread_storage_usage[id].func( d->thread_storage[id] );
+
+ // store new data
+ d->thread_storage[id] = p;
+ return &d->thread_storage[id];
+}
+
+void QThreadStorageData::finish( void **thread_storage )
+{
+ if ( ! thread_storage ) return; // nothing to do
+
+#ifdef QTHREADSTORAGE_DEBUG
+ qDebug( "QThreadStorageData: destroying storage for thread %lx",
+ (unsigned long) pthread_self() );
+#endif // QTHREADSTORAGE_DEBUG
+
+ for ( int i = 0; i < MAX_THREAD_STORAGE; ++i ) {
+ if ( ! thread_storage[i] ) continue;
+ if ( ! thread_storage_usage[i].used ) {
+#ifdef QT_CHECK_STATE
+ qWarning( "QThreadStorage: thread %lx exited after QThreadStorage destroyed",
+ (unsigned long) pthread_self() );
+#endif // QT_CHECK_STATE
+ continue;
+ }
+
+ thread_storage_usage[i].func( thread_storage[i] );
+ }
+
+ delete [] thread_storage;
+}
+
+
+/*!
+ \class QThreadStorage
+ \brief The QThreadStorage class provides per-thread data storage.
+
+ \threadsafe
+ \ingroup thread
+ \ingroup environment
+
+ QThreadStorage is a template class that provides per-thread data
+ storage.
+
+ \e{Note that due to compiler limitations, QThreadStorage can only
+ store pointers.}
+
+ The setLocalData() function stores a single thread-specific value
+ for the calling thread. The data can be accessed later using the
+ localData() functions. QThreadStorage takes ownership of the
+ data (which must be created on the heap with \e new) and deletes
+ it when the thread exits (either normally or via termination).
+
+ The hasLocalData() function allows the programmer to determine if
+ data has previously been set using the setLocalData() function.
+ This is useful for lazy initializiation.
+
+ For example, the following code uses QThreadStorage to store a
+ single cache for each thread that calls the \e cacheObject() and
+ \e removeFromCache() functions. The cache is automatically
+ deleted when the calling thread exits (either normally or via
+ termination).
+
+ \code
+ QThreadStorage<QCache<SomeClass> *> caches;
+
+ void cacheObject( const QString &key, SomeClass *object )
+ {
+ if ( ! caches.hasLocalData() )
+ caches.setLocalData( new QCache<SomeClass> );
+
+ caches.localData()->insert( key, object );
+ }
+
+ void removeFromCache( const QString &key )
+ {
+ if ( ! caches.hasLocalData() )
+ return; // nothing to do
+
+ caches.localData()->remove( key );
+ }
+ \endcode
+
+ \section1 Caveats
+
+ \list
+
+ \i As noted above, QThreadStorage can only store pointers due to
+ compiler limitations. Support for value-based objects will be
+ added when the majority of compilers are able to support partial
+ template specialization.
+
+ \i The \link ~QThreadStorage() destructor\endlink does \e not
+ delete per-thread data. QThreadStorage only deletes per-thread
+ data when the thread exits or when setLocalData() is called
+ multiple times.
+
+ \i QThreadStorage can only be used with threads started with
+ QThread. It \e cannot be used with threads started with
+ platform-specific APIs.
+
+ \i As a corollary to the above, platform-specific APIs cannot be
+ used to exit or terminate a QThread using QThreadStorage. Doing so
+ will cause all per-thread data to be leaked. See QThread::exit()
+ and QThread::terminate().
+
+ \i QThreadStorage \e can be used to store data for the \e main()
+ thread \e after QApplication has been constructed. QThreadStorage
+ deletes all data set for the \e main() thread when QApplication is
+ destroyed, regardless of whether or not the \e main() thread has
+ actually finished.
+
+ \i The implementation of QThreadStorage limits the total number of
+ QThreadStorage objects to 256. An unlimited number of threads
+ can store per-thread data in each QThreadStorage object.
+
+ \endlist
+*/
+
+/*!
+ \fn QThreadStorage::QThreadStorage()
+
+ Constructs a new per-thread data storage object.
+*/
+
+/*!
+ \fn QThreadStorage::~QThreadStorage()
+
+ Destroys the per-thread data storage object.
+
+ Note: The per-thread data stored is \e not deleted. Any data left
+ in QThreadStorage is leaked. Make sure that all threads using
+ QThreadStorage have exited before deleting the QThreadStorage.
+
+ \sa hasLocalData()
+*/
+
+/*!
+ \fn bool QThreadStorage::hasLocalData() const
+
+ Returns TRUE if the calling thread has non-zero data available;
+ otherwise returns FALSE.
+
+ \sa localData()
+*/
+
+/*!
+ \fn T& QThreadStorage::localData()
+
+ Returns a reference to the data that was set by the calling
+ thread.
+
+ Note: QThreadStorage can only store pointers. This function
+ returns a \e reference to the pointer that was set by the calling
+ thread. The value of this reference is 0 if no data was set by
+ the calling thread,
+
+ \sa hasLocalData()
+*/
+/*
+ ### addition to the above documentation when we start supporting
+ ### partial template specialization, and QThreadStorage can store
+ ### values *and* pointers
+
+ When using QThreadStorage to store values (not pointers), this
+ function stores an object of type \e T (created with its default
+ constructor) and returns a reference to that object.
+*/
+
+/*!
+ \fn const T QThreadStorage::localData() const
+ \overload
+
+ Returns a copy of the data that was set by the calling thread.
+
+ Note: QThreadStorage can only store pointers. This function
+ returns a pointer to the data that was set by the calling thread.
+ If no data was set by the calling thread, this function returns 0.
+
+ \sa hasLocalData()
+*/
+/*
+ ### addition to the above documentation when we start supporting
+ ### partial template specialization, and QThreadStorage can store
+ ### values *and* pointers
+
+ When using QThreadStorage to store values (not pointers), this
+ function returns an object of type \e T (created with its default
+ constructor). Unlike the above function, this object is \e not
+ stored automatically. You will need to call setLocalData() to store
+ the object.
+*/
+
+/*!
+ \fn void QThreadStorage::setLocalData( T data )
+
+ Sets the local data for the calling thread to \a data. It can be
+ accessed later using the localData() functions.
+
+ If \a data is 0, this function deletes the previous data (if
+ any) and returns immediately.
+
+ If \a data is non-zero, QThreadStorage takes ownership of the \a
+ data and deletes it automatically either when the thread exits
+ (either normally or via termination) or when setLocalData() is
+ called again.
+
+ Note: QThreadStorage can only store pointers. The \a data
+ argument must be either a pointer to an object created on the heap
+ (i.e. using \e new) or 0. You should not delete \a data
+ yourself; QThreadStorage takes ownership and will delete the \a
+ data itself.
+
+ \sa localData() hasLocalData()
+*/
+
+#endif // QT_THREAD_SUPPORT