src/corelib/concurrent/qtconcurrentexception.cpp
changeset 0 1918ee327afb
child 4 3b1da2848fc7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/corelib/concurrent/qtconcurrentexception.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,228 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qtconcurrentexception.h"
+
+#ifndef QT_NO_QFUTURE
+#ifndef QT_NO_EXCEPTIONS
+
+QT_BEGIN_NAMESPACE
+
+/*! 
+    \class QtConcurrent::Exception
+    \brief The Exception class provides a base class for exceptions that can transferred across threads.
+    \since 4.4
+
+    Qt Concurrent supports throwing and catching exceptions across thread
+    boundaries, provided that the exception inherit from QtConcurrent::Exception
+    and implement two helper functions:
+
+    \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentexception.cpp 0
+
+    QtConcurrent::Exception subclasses must be thrown by value and
+    caught by reference:
+
+    \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentexception.cpp 1
+
+    If you throw an exception that is not a subclass of QtConcurrent::Exception,
+    the Qt Concurrent functions will throw a QtConcurrent::UnhandledException
+    in the receiver thread.
+
+    When using QFuture, transferred exceptions willl be thrown when calling the following functions:
+    \list
+    \o QFuture::waitForFinished()
+    \o QFuture::result()
+    \o QFuture::resultAt()
+    \o QFuture::results()
+    \endlist
+*/
+
+/*!
+    \fn QtConcurrent::Exception::raise() const 
+    In your QtConcurrent::Exception subclass, reimplement raise() like this:
+    
+    \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentexception.cpp 2
+*/
+
+/*!
+    \fn QtConcurrent::Exception::clone() const
+    In your QtConcurrent::Exception subclass, reimplement clone() like this:
+    
+    \snippet doc/src/snippets/code/src_corelib_concurrent_qtconcurrentexception.cpp 3
+*/
+
+/*! 
+    \class QtConcurrent::UnhandledException
+
+    \brief The UnhandledException class represents an unhandled exception in a worker thread.
+    \since 4.4
+
+    If a worker thread throws an exception that is not a subclass of QtConcurrent::Exception,
+    the Qt Concurrent functions will throw a QtConcurrent::UnhandledException
+    on the receiver thread side.
+
+    Inheriting from this class is not supported.
+*/
+
+/*!
+    \fn QtConcurrent::UnhandledException::raise() const
+    \internal
+*/
+
+/*!
+    \fn QtConcurrent::UnhandledException::clone() const
+    \internal
+*/
+
+namespace QtConcurrent
+{
+
+void Exception::raise() const
+{
+    Exception e = *this;
+    throw e;
+}
+
+Exception *Exception::clone() const
+{
+    return new Exception(*this);
+}
+
+void UnhandledException::raise() const
+{
+    UnhandledException e = *this;
+    throw e;
+}
+
+Exception *UnhandledException::clone() const
+{
+    return new UnhandledException(*this);
+}
+
+#ifndef qdoc
+
+namespace internal {
+
+class Base
+{
+public:
+    Base(Exception *exception)
+    : exception(exception), refCount(1), hasThrown(false) { }
+    ~Base() { delete exception; }
+
+    Exception *exception;
+    QAtomicInt refCount;
+    bool hasThrown;
+};
+
+ExceptionHolder::ExceptionHolder(Exception *exception)
+: base(new Base(exception)) {}
+
+ExceptionHolder::ExceptionHolder(const ExceptionHolder &other)
+: base(other.base)
+{
+    base->refCount.ref();
+}
+
+void ExceptionHolder::operator=(const ExceptionHolder &other)
+{
+    if (base == other.base)
+        return;
+
+    if (base->refCount.deref() == false)
+        delete base;
+
+    base = other.base;
+    base->refCount.ref();
+}
+
+ExceptionHolder::~ExceptionHolder()
+{
+    if (base->refCount.deref() == 0)
+        delete base;
+}
+
+Exception *ExceptionHolder::exception() const
+{
+    return base->exception;
+}
+
+void ExceptionStore::setException(const Exception &e)
+{
+    if (hasException() == false)
+        exceptionHolder = ExceptionHolder(e.clone());
+}
+
+bool ExceptionStore::hasException() const
+{
+    return (exceptionHolder.exception() != 0);
+}
+
+ExceptionHolder ExceptionStore::exception()
+{
+    return exceptionHolder;
+}
+
+void ExceptionStore::throwPossibleException()
+{
+    /* On win32-g++, with GCC 3.4.2 std::uncaught_exception() isn't reliable. */
+    if (hasException()
+#ifndef Q_CC_MINGW
+        && std::uncaught_exception() == false
+#endif
+            ) {
+        exceptionHolder.base->hasThrown = true;
+        exceptionHolder.exception()->raise();
+    }
+}
+
+bool ExceptionStore::hasThrown() const { return exceptionHolder.base->hasThrown; }
+
+} // namespace internal
+
+#endif //qdoc
+
+} // namespace QtConcurrent
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_EXCEPTIONS
+#endif // QT_NO_CONCURRENT