Merge branch 'master' of scm.dev.nokia.troll.no:qt/oslo-staging-1 into master-integration

* 'master' of scm.dev.nokia.troll.no:qt/oslo-staging-1: (39 commits)
  Whitespace change
  Fix for coding conventions.
  Fix resource leak in QCLuceneStandardAnalyzer::QCLuceneStandardAnalyzer.
  Fix resource leak in QCLuceneStopAnalyzer::QCLuceneStopAnalyzer.
  Assistant: Get rid of bogus warning.
  add missing license header
  Add inter-process binary shader cache for MeeGo
  Track average wait times under our maximum spin time threshold
  Store and track spin times in nanosecond resolution
  Optimize adaptive spinning mutex code
  Improve QMutex contention performance on Linux
  Improve QMutex contention performance on Mac OS X
  Disable spinning under lock contention on single CPU machines
  Remove unnecessary testAndSetAcquire from QMutex::lockInternal()
  Move contender count maintenance to QMutexPrivate
  test contention when using 2 mutexes
  Ensure that every thread does contend in the contention tests
  Add baseline test data to measure test overhead
  Test contention performance for long (10ms) critical sections
  Add a benchmark for contended and uncontended QMutex performance
  ...

20 files changed, 382 insertions, 158 deletions

diff --git a/src/corelib/io/qdatastream.cpp b/src/corelib/io/qdatastream.cpp
index 58f0190..73ce490 100644
--- a/src/corelib/io/qdatastream.cpp
+++ b/src/corelib/io/qdatastream.cpp
@@ -223,6 +223,7 @@ QT_BEGIN_NAMESPACE
     \value ReadPastEnd      The data stream has read past the end of the
                             data in the underlying device.
     \value ReadCorruptData  The data stream has read corrupt data.
+    \value WriteFailed      The data stream cannot write to the underlying device.
 */
 
 /*****************************************************************************
@@ -243,6 +244,11 @@ QT_BEGIN_NAMESPACE
     }
 #endif
 
+#define CHECK_STREAM_WRITE_PRECOND(retVal) \
+    CHECK_STREAM_PRECOND(retVal) \
+    if (q_status != Ok) \
+        return retVal;
+
 enum {
     DefaultStreamVersion = QDataStream::Qt_4_6
 };
@@ -495,6 +501,9 @@ void QDataStream::resetStatus()
 /*!
     Sets the status of the data stream to the \a status given.
 
+    Subsequent calls to setStatus() are ignored until resetStatus()
+    is called.
+
     \sa Status status() resetStatus()
 */
 void QDataStream::setStatus(Status status)
@@ -992,8 +1001,9 @@ int QDataStream::readRawData(char *s, int len)
 
 QDataStream &QDataStream::operator<<(qint8 i)
 {
-    CHECK_STREAM_PRECOND(*this)
-    dev->putChar(i);
+    CHECK_STREAM_WRITE_PRECOND(*this)
+    if (!dev->putChar(i))
+        q_status = WriteFailed;
     return *this;
 }
 
@@ -1015,11 +1025,12 @@ QDataStream &QDataStream::operator<<(qint8 i)
 
 QDataStream &QDataStream::operator<<(qint16 i)
 {
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
     if (!noswap) {
         i = qbswap(i);
     }
-    dev->write((char *)&i, sizeof(qint16));
+    if (dev->write((char *)&i, sizeof(qint16)) != sizeof(qint16))
+        q_status = WriteFailed;
     return *this;
 }
 
@@ -1032,11 +1043,12 @@ QDataStream &QDataStream::operator<<(qint16 i)
 
 QDataStream &QDataStream::operator<<(qint32 i)
 {
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
     if (!noswap) {
         i = qbswap(i);
     }
-    dev->write((char *)&i, sizeof(qint32));
+    if (dev->write((char *)&i, sizeof(qint32)) != sizeof(qint32))
+        q_status = WriteFailed;
     return *this;
 }
 
@@ -1057,7 +1069,7 @@ QDataStream &QDataStream::operator<<(qint32 i)
 
 QDataStream &QDataStream::operator<<(qint64 i)
 {
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
     if (version() < 6) {
         quint32 i1 = i & 0xffffffff;
         quint32 i2 = i >> 32;
@@ -1066,7 +1078,8 @@ QDataStream &QDataStream::operator<<(qint64 i)
         if (!noswap) {
             i = qbswap(i);
         }
-        dev->write((char *)&i, sizeof(qint64));
+        if (dev->write((char *)&i, sizeof(qint64)) != sizeof(qint64))
+            q_status = WriteFailed;
     }
     return *this;
 }
@@ -1086,8 +1099,9 @@ QDataStream &QDataStream::operator<<(qint64 i)
 
 QDataStream &QDataStream::operator<<(bool i)
 {
-    CHECK_STREAM_PRECOND(*this)
-    dev->putChar(qint8(i));
+    CHECK_STREAM_WRITE_PRECOND(*this)
+    if (!dev->putChar(qint8(i)))
+        q_status = WriteFailed;
     return *this;
 }
 
@@ -1108,7 +1122,7 @@ QDataStream &QDataStream::operator<<(float f)
         return *this;
     }
 
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
     float g = f;                                // fixes float-on-stack problem
     if (!noswap) {
         union {
@@ -1119,7 +1133,8 @@ QDataStream &QDataStream::operator<<(float f)
         x.val2 = qbswap(x.val2);
         g = x.val1;
     }
-    dev->write((char *)&g, sizeof(float));
+    if (dev->write((char *)&g, sizeof(float)) != sizeof(float))
+        q_status = WriteFailed;
     return *this;
 }
 
@@ -1141,10 +1156,11 @@ QDataStream &QDataStream::operator<<(double f)
         return *this;
     }
 
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
 #ifndef Q_DOUBLE_FORMAT
     if (noswap) {
-        dev->write((char *)&f, sizeof(double));
+        if (dev->write((char *)&f, sizeof(double)) != sizeof(double))
+            q_status = WriteFailed;
     } else {
         union {
             double val1;
@@ -1152,7 +1168,8 @@ QDataStream &QDataStream::operator<<(double f)
         } x;
         x.val1 = f;
         x.val2 = qbswap(x.val2);
-        dev->write((char *)&x.val2, sizeof(double));
+        if (dev->write((char *)&x.val2, sizeof(double)) != sizeof(double))
+            q_status = WriteFailed;
     }
 #else
     union {
@@ -1181,7 +1198,8 @@ QDataStream &QDataStream::operator<<(double f)
         b[Q_DF(1)] = *p++;
         b[Q_DF(0)] = *p;
     }
-    dev->write(b, 8);
+    if (dev->write(b, 8) != 8)
+        q_status = WriteFailed;
 #endif
     return *this;
 }
@@ -1221,7 +1239,7 @@ QDataStream &QDataStream::operator<<(const char *s)
 
 QDataStream &QDataStream::writeBytes(const char *s, uint len)
 {
-    CHECK_STREAM_PRECOND(*this)
+    CHECK_STREAM_WRITE_PRECOND(*this)
     *this << (quint32)len;                        // write length specifier
     if (len)
         writeRawData(s, len);
@@ -1239,8 +1257,11 @@ QDataStream &QDataStream::writeBytes(const char *s, uint len)
 
 int QDataStream::writeRawData(const char *s, int len)
 {
-    CHECK_STREAM_PRECOND(-1)
-    return dev->write(s, len);
+    CHECK_STREAM_WRITE_PRECOND(-1)
+    int ret = dev->write(s, len);
+    if (ret != len)
+        q_status = WriteFailed;
+    return ret;
 }
 
 /*!
diff --git a/src/corelib/io/qdatastream.h b/src/corelib/io/qdatastream.h
index 774c4bc..05248ac 100644
--- a/src/corelib/io/qdatastream.h
+++ b/src/corelib/io/qdatastream.h
@@ -101,7 +101,8 @@ public:
     enum Status {
         Ok,
         ReadPastEnd,
-	ReadCorruptData
+        ReadCorruptData,
+        WriteFailed
     };
 
     enum FloatingPointPrecision {
diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 216c382..e52d132 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -169,17 +169,27 @@ private:
 
 Q_GLOBAL_STATIC(QMutex, processManagerGlobalMutex)
 
-static QProcessManager *processManager() {
+static QProcessManager *processManagerInstance = 0;
+
+static QProcessManager *processManager()
+{
     // The constructor of QProcessManager should be called only once
     // so we cannot use Q_GLOBAL_STATIC directly for QProcessManager
     QMutex *mutex = processManagerGlobalMutex();
     QMutexLocker locker(mutex);
-    static QProcessManager processManager;
-    return &processManager;
+
+    if (!processManagerInstance)
+        QProcessPrivate::initializeProcessManager();
+
+    Q_ASSERT(processManagerInstance);
+    return processManagerInstance;
 }
 
 QProcessManager::QProcessManager()
 {
+    // can only be called from main thread
+    Q_ASSERT(!qApp || qApp->thread() == QThread::currentThread());
+
 #if defined (QPROCESS_DEBUG)
     qDebug() << "QProcessManager::QProcessManager()";
 #endif
@@ -198,6 +208,8 @@ QProcessManager::QProcessManager()
     ::sigaction(SIGCHLD, &action, &oldAction);
     if (oldAction.sa_handler != qt_sa_sigchld_handler)
 	qt_sa_old_sigchld_handler = oldAction.sa_handler;
+
+    processManagerInstance = this;
 }
 
 QProcessManager::~QProcessManager()
@@ -226,6 +238,8 @@ QProcessManager::~QProcessManager()
     if (oldAction.sa_handler != qt_sa_sigchld_handler) {
         ::sigaction(SIGCHLD, &oldAction, 0);
     }
+
+    processManagerInstance = 0;
 }
 
 void QProcessManager::run()
@@ -1289,7 +1303,15 @@ bool QProcessPrivate::startDetached(const QString &program, const QStringList &a
 
 void QProcessPrivate::initializeProcessManager()
 {
-    (void) processManager();
+    if (qApp && qApp->thread() != QThread::currentThread()) {
+        // The process manager must be initialized in the main thread
+        // Note: The call below will re-enter this function, but in the right thread,
+        // so the else statement below will be executed.
+        QMetaObject::invokeMethod(qApp, "_q_initializeProcessManager", Qt::BlockingQueuedConnection);
+    } else {
+        static QProcessManager processManager;
+        Q_UNUSED(processManager);
+    }
 }
 
 QT_END_NAMESPACE
diff --git a/src/corelib/io/qtextstream.cpp b/src/corelib/io/qtextstream.cpp
index 6091ec0..3bdbf32 100644
--- a/src/corelib/io/qtextstream.cpp
+++ b/src/corelib/io/qtextstream.cpp
@@ -224,6 +224,7 @@ static const int QTEXTSTREAM_BUFFERSIZE = 16384;
     \value ReadPastEnd      The text stream has read past the end of the
                             data in the underlying device.
     \value ReadCorruptData  The text stream has read corrupt data.
+    \value WriteFailed      The text stream cannot write to the underlying device.
 
     \sa status()
 */
@@ -396,19 +397,19 @@ public:
         npsInvalidPrefix
     };
 
-    inline bool write(const QString &data);
     inline bool getChar(QChar *ch);
     inline void ungetChar(const QChar &ch);
     NumberParsingStatus getNumber(qulonglong *l);
     bool getReal(double *f);
 
-    bool putNumber(qulonglong number, bool negative);
-    inline bool putString(const QString &ch, bool number = false);
+    inline void write(const QString &data);
+    inline void putString(const QString &ch, bool number = false);
+    void putNumber(qulonglong number, bool negative);
 
     // buffers
     bool fillReadBuffer(qint64 maxBytes = -1);
     void resetReadBuffer();
-    bool flushWriteBuffer();
+    void flushWriteBuffer();
     QString writeBuffer;
     QString readBuffer;
     int readBufferOffset;
@@ -642,14 +643,20 @@ void QTextStreamPrivate::resetReadBuffer()
 
 /*! \internal
 */
-bool QTextStreamPrivate::flushWriteBuffer()
+void QTextStreamPrivate::flushWriteBuffer()
 {
     // no buffer next to the QString itself; this function should only
     // be called internally, for devices.
     if (string || !device)
-        return false;
+        return;
+
+    // Stream went bye-bye already. Appending further data may succeed again,
+    // but would create a corrupted stream anyway.
+    if (status != QTextStream::Ok)
+        return;
+
     if (writeBuffer.isEmpty())
-        return true;
+        return;
 
 #if defined (Q_OS_WIN)
     // handle text translation and bypass the Text flag in the device.
@@ -681,8 +688,10 @@ bool QTextStreamPrivate::flushWriteBuffer()
     qDebug("QTextStreamPrivate::flushWriteBuffer(), device->write(\"%s\") == %d",
            qt_prettyDebug(data.constData(), qMin(data.size(),32), data.size()).constData(), int(bytesWritten));
 #endif
-    if (bytesWritten <= 0)
-        return false;
+    if (bytesWritten <= 0) {
+        status = QTextStream::WriteFailed;
+        return;
+    }
 
 #if defined (Q_OS_WIN)
     // replace the text flag
@@ -693,7 +702,7 @@ bool QTextStreamPrivate::flushWriteBuffer()
     // flush the file
 #ifndef QT_NO_QOBJECT
     QFile *file = qobject_cast<QFile *>(device);
-    bool flushed = file && file->flush();
+    bool flushed = !file || file->flush();
 #else
     bool flushed = true;
 #endif
@@ -702,7 +711,8 @@ bool QTextStreamPrivate::flushWriteBuffer()
     qDebug("QTextStreamPrivate::flushWriteBuffer() wrote %d bytes",
            int(bytesWritten));
 #endif
-    return flushed && bytesWritten == qint64(data.size());
+    if (!flushed || bytesWritten != qint64(data.size()))
+        status = QTextStream::WriteFailed;
 }
 
 QString QTextStreamPrivate::read(int maxlen)
@@ -908,7 +918,7 @@ inline void QTextStreamPrivate::restoreToSavedConverterState()
 
 /*! \internal
 */
-inline bool QTextStreamPrivate::write(const QString &data)
+inline void QTextStreamPrivate::write(const QString &data)
 {
     if (string) {
         // ### What about seek()??
@@ -916,9 +926,8 @@ inline bool QTextStreamPrivate::write(const QString &data)
     } else {
         writeBuffer += data;
         if (writeBuffer.size() > QTEXTSTREAM_BUFFERSIZE)
-            return flushWriteBuffer();
+            flushWriteBuffer();
     }
-    return true;
 }
 
 /*! \internal
@@ -959,7 +968,7 @@ inline void QTextStreamPrivate::ungetChar(const QChar &ch)
 
 /*! \internal
 */
-inline bool QTextStreamPrivate::putString(const QString &s, bool number)
+inline void QTextStreamPrivate::putString(const QString &s, bool number)
 {
     QString tmp = s;
 
@@ -993,7 +1002,7 @@ inline bool QTextStreamPrivate::putString(const QString &s, bool number)
            qt_prettyDebug(a.constData(), a.size(), qMax(16, a.size())).constData(),
            qt_prettyDebug(b.constData(), b.size(), qMax(16, b.size())).constData());
 #endif
-    return write(tmp);
+    write(tmp);
 }
 
 /*!
@@ -1593,6 +1602,9 @@ void QTextStream::resetStatus()
 
     Sets the status of the text stream to the \a status given.
 
+    Subsequent calls to setStatus() are ignored until resetStatus()
+    is called.
+
     \sa Status status() resetStatus()
 */
 void QTextStream::setStatus(Status status)
@@ -2267,7 +2279,7 @@ QTextStream &QTextStream::operator>>(char *c)
 
 /*! \internal
  */
-bool QTextStreamPrivate::putNumber(qulonglong number, bool negative)
+void QTextStreamPrivate::putNumber(qulonglong number, bool negative)
 {
     QString result;
 
@@ -2307,7 +2319,7 @@ bool QTextStreamPrivate::putNumber(qulonglong number, bool negative)
             result.prepend(QLatin1Char('0'));
         }
     }
-    return putString(result, true);
+    putString(result, true);
 }
 
 /*!
diff --git a/src/corelib/io/qtextstream.h b/src/corelib/io/qtextstream.h
index d82da59..c635691 100644
--- a/src/corelib/io/qtextstream.h
+++ b/src/corelib/io/qtextstream.h
@@ -89,7 +89,8 @@ public:
     enum Status {
         Ok,
         ReadPastEnd,
-        ReadCorruptData
+        ReadCorruptData,
+        WriteFailed
     };
     enum NumberFlag {
         ShowBase = 0x1,
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 0f95ee0..799433b 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -336,6 +336,16 @@ void QCoreApplicationPrivate::createEventDispatcher()
 #endif
 }
 
+void QCoreApplicationPrivate::_q_initializeProcessManager()
+{
+#ifndef QT_NO_PROCESS
+#  ifdef Q_OS_UNIX
+    QProcessPrivate::initializeProcessManager();
+#  endif
+#endif
+}
+
+
 QThread *QCoreApplicationPrivate::theMainThread = 0;
 QThread *QCoreApplicationPrivate::mainThread()
 {
@@ -600,12 +610,6 @@ void QCoreApplication::init()
     }
 #endif
 
-#if defined(Q_OS_UNIX) && !(defined(QT_NO_PROCESS))
-    // Make sure the process manager thread object is created in the main
-    // thread.
-    QProcessPrivate::initializeProcessManager();
-#endif
-
 #ifdef QT_EVAL
     extern void qt_core_eval_init(uint);
     qt_core_eval_init(d->application_type);
@@ -2666,3 +2670,5 @@ int QCoreApplication::loopLevel()
 */
 
 QT_END_NAMESPACE
+
+#include "moc_qcoreapplication.cpp"
diff --git a/src/corelib/kernel/qcoreapplication.h b/src/corelib/kernel/qcoreapplication.h
index f1c7c26..17e784e 100644
--- a/src/corelib/kernel/qcoreapplication.h
+++ b/src/corelib/kernel/qcoreapplication.h
@@ -205,6 +205,7 @@ protected:
     QCoreApplication(QCoreApplicationPrivate &p);
 
 private:
+    Q_PRIVATE_SLOT(d_func(), void _q_initializeProcessManager())
     static bool sendSpontaneousEvent(QObject *receiver, QEvent *event);
     bool notifyInternal(QObject *receiver, QEvent *event);
 
diff --git a/src/corelib/kernel/qcoreapplication_p.h b/src/corelib/kernel/qcoreapplication_p.h
index 2355c37..aafa821 100644
--- a/src/corelib/kernel/qcoreapplication_p.h
+++ b/src/corelib/kernel/qcoreapplication_p.h
@@ -82,6 +82,8 @@ public:
     bool sendThroughObjectEventFilters(QObject *, QEvent *);
     bool notify_helper(QObject *, QEvent *);
 
+    void _q_initializeProcessManager();
+
     virtual QString appName() const;
     virtual void createEventDispatcher();
     static void removePostedEvent(QEvent *);
diff --git a/src/corelib/thread/qmutex.cpp b/src/corelib/thread/qmutex.cpp
index b85a22d..1009f7b 100644
--- a/src/corelib/thread/qmutex.cpp
+++ b/src/corelib/thread/qmutex.cpp
@@ -45,6 +45,7 @@
 
 #ifndef QT_NO_THREAD
 #include "qatomic.h"
+#include "qelapsedtimer.h"
 #include "qthread.h"
 #include "qmutex_p.h"
 
@@ -157,15 +158,12 @@ void QMutex::lock()
             return;
         }
 
-        bool isLocked = d->contenders.fetchAndAddAcquire(1) == 0;
+        bool isLocked = d->contenders.testAndSetAcquire(0, 1);
         if (!isLocked) {
             // didn't get the lock, wait for it
             isLocked = d->wait();
             Q_ASSERT_X(isLocked, "QMutex::lock",
                        "Internal error, infinite wait has timed out.");
-
-            // don't need to wait for the lock anymore
-            d->contenders.deref();
         }
 
         d->owner = self;
@@ -174,8 +172,7 @@ void QMutex::lock()
         return;
     }
 
-
-    bool isLocked = d->contenders == 0 && d->contenders.testAndSetAcquire(0, 1);
+    bool isLocked = d->contenders.testAndSetAcquire(0, 1);
     if (!isLocked) {
         lockInternal();
     }
@@ -211,7 +208,7 @@ bool QMutex::tryLock()
             return true;
         }
 
-        bool isLocked = d->contenders == 0 && d->contenders.testAndSetAcquire(0, 1);
+        bool isLocked = d->contenders.testAndSetAcquire(0, 1);
         if (!isLocked) {
             // some other thread has the mutex locked, or we tried to
             // recursively lock an non-recursive mutex
@@ -224,13 +221,7 @@ bool QMutex::tryLock()
         return isLocked;
     }
 
-    bool isLocked = d->contenders == 0 && d->contenders.testAndSetAcquire(0, 1);
-    if (!isLocked) {
-        // some other thread has the mutex locked, or we tried to
-        // recursively lock an non-recursive mutex
-        return isLocked;
-    }
-    return isLocked;
+    return d->contenders.testAndSetAcquire(0, 1);
 }
 
 /*! \overload
@@ -269,13 +260,10 @@ bool QMutex::tryLock(int timeout)
             return true;
         }
 
-        bool isLocked = d->contenders.fetchAndAddAcquire(1) == 0;
+        bool isLocked = d->contenders.testAndSetAcquire(0, 1);
         if (!isLocked) {
             // didn't get the lock, wait for it
             isLocked = d->wait(timeout);
-
-            // don't need to wait for the lock anymore
-            d->contenders.deref();
             if (!isLocked)
                 return false;
         }
@@ -286,17 +274,9 @@ bool QMutex::tryLock(int timeout)
         return true;
     }
 
-    bool isLocked = d->contenders.fetchAndAddAcquire(1) == 0;
-    if (!isLocked) {
-        // didn't get the lock, wait for it
-        isLocked = d->wait(timeout);
-
-        // don't need to wait for the lock anymore
-        d->contenders.deref();
-        if (!isLocked)
-            return false;
-    }
-    return true;
+    return (d->contenders.testAndSetAcquire(0, 1)
+            // didn't get the lock, wait for it
+            || d->wait(timeout));
 }
 
 
@@ -310,7 +290,6 @@ bool QMutex::tryLock(int timeout)
 void QMutex::unlock()
 {
     QMutexPrivate *d = static_cast<QMutexPrivate *>(this->d);
-
     if (d->recursive) {
         if (!--d->count) {
             d->owner = 0;
@@ -451,37 +430,57 @@ void QMutex::unlock()
 void QMutex::lockInternal()
 {
     QMutexPrivate *d = static_cast<QMutexPrivate *>(this->d);
-    int spinCount = 0;
-    int lastSpinCount = d->lastSpinCount;
 
-    enum { AdditionalSpins = 20, SpinCountPenalizationDivisor = 4 };
-    const int maximumSpinCount = lastSpinCount + AdditionalSpins;
+    if (QThread::idealThreadCount() == 1) {
+        // don't spin on single cpu machines
+        bool isLocked = d->wait();
+        Q_ASSERT_X(isLocked, "QMutex::lock",
+                   "Internal error, infinite wait has timed out.");
+        Q_UNUSED(isLocked);
+        return;
+    }
 
+    QElapsedTimer elapsedTimer;
+    elapsedTimer.start();
     do {
-        if (spinCount++ > maximumSpinCount) {
-            // puts("spinning useless, sleeping");
-            bool isLocked = d->contenders.fetchAndAddAcquire(1) == 0;
-            if (!isLocked) {
-
-                // didn't get the lock, wait for it
-                isLocked = d->wait();
-                Q_ASSERT_X(isLocked, "QMutex::lock",
-                            "Internal error, infinite wait has timed out.");
-
-                // don't need to wait for the lock anymore
-                d->contenders.deref();
+        qint64 spinTime = elapsedTimer.nsecsElapsed();
+        if (spinTime > d->maximumSpinTime) {
+            // didn't get the lock, wait for it, since we're not going to gain anything by spinning more
+            elapsedTimer.start();
+            bool isLocked = d->wait();
+            Q_ASSERT_X(isLocked, "QMutex::lock",
+                       "Internal error, infinite wait has timed out.");
+            Q_UNUSED(isLocked);
+
+            qint64 maximumSpinTime = d->maximumSpinTime;
+            qint64 averageWaitTime = d->averageWaitTime;
+            qint64 actualWaitTime = elapsedTimer.nsecsElapsed();
+            if (actualWaitTime < (QMutexPrivate::MaximumSpinTimeThreshold * 3 / 2)) {
+                // measure the wait times
+                averageWaitTime = d->averageWaitTime = qMin((averageWaitTime + actualWaitTime) / 2, qint64(QMutexPrivate::MaximumSpinTimeThreshold));
             }
-            // decrease the lastSpinCount since we didn't actually get the lock by spinning
-            spinCount = -d->lastSpinCount / SpinCountPenalizationDivisor;
-            break;
+
+            // adjust the spin count when spinning does not benefit contention performance
+            if ((spinTime + actualWaitTime) - qint64(QMutexPrivate::MaximumSpinTimeThreshold) >= qint64(QMutexPrivate::MaximumSpinTimeThreshold)) {
+                // long waits, stop spinning
+                d->maximumSpinTime = 0;
+            } else {
+                // allow spinning if wait times decrease, but never spin more than the average wait time (otherwise we may perform worse)
+                d->maximumSpinTime = qBound(qint64(averageWaitTime * 3 / 2), maximumSpinTime / 2, qint64(QMutexPrivate::MaximumSpinTimeThreshold));
+            }
+            return;
         }
+        // be a good citizen... yielding lets something else run if there is something to run, but may also relieve memory pressure if not
+        QThread::yieldCurrentThread();
     } while (d->contenders != 0 || !d->contenders.testAndSetAcquire(0, 1));
 
-    // adjust the last spin lock count
-    lastSpinCount = d->lastSpinCount;
-    d->lastSpinCount = spinCount >= 0
-                        ? qMax(lastSpinCount, spinCount)
-                        : lastSpinCount + spinCount;
+    // spinning is working, do not change the spin time (unless we are using much less time than allowed to spin)
+    qint64 maximumSpinTime = d->maximumSpinTime;
+    qint64 spinTime = elapsedTimer.nsecsElapsed();
+    if (spinTime < maximumSpinTime / 2) {
+        // we are using much less time than we need, adjust the limit
+        d->maximumSpinTime = qBound(qint64(d->averageWaitTime * 3 / 2), maximumSpinTime / 2, qint64(QMutexPrivate::MaximumSpinTimeThreshold));
+    }
 }
 
 /*!
diff --git a/src/corelib/thread/qmutex_p.h b/src/corelib/thread/qmutex_p.h
index 6126423..9d40bea 100644
--- a/src/corelib/thread/qmutex_p.h
+++ b/src/corelib/thread/qmutex_p.h
@@ -58,6 +58,10 @@
 #include <QtCore/qnamespace.h>
 #include <QtCore/qmutex.h>
 
+#if defined(Q_OS_MAC)
+# include <mach/semaphore.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 class QMutexPrivate : public QMutexData {
@@ -65,15 +69,19 @@ public:
     QMutexPrivate(QMutex::RecursionMode mode);
     ~QMutexPrivate();
 
-    ulong self();
     bool wait(int timeout = -1);
     void wakeUp();
 
-    volatile int lastSpinCount;
+    // 1ms = 1000000ns
+    enum { MaximumSpinTimeThreshold = 1000000 };
+    volatile qint64 maximumSpinTime;
+    volatile qint64 averageWaitTime;
     Qt::HANDLE owner;
     uint count;
 
-#if defined(Q_OS_UNIX)
+#if defined(Q_OS_MAC)
+    semaphore_t mach_semaphore;
+#elif defined(Q_OS_UNIX) && !defined(Q_OS_LINUX)
     volatile bool wakeup;
     pthread_mutex_t mutex;
     pthread_cond_t cond;
diff --git a/src/corelib/thread/qmutex_unix.cpp b/src/corelib/thread/qmutex_unix.cpp
index 7e7ef22..0e09ea0 100644
--- a/src/corelib/thread/qmutex_unix.cpp
+++ b/src/corelib/thread/qmutex_unix.cpp
@@ -53,30 +53,116 @@
 #undef wakeup
 #endif
 
+#if defined(Q_OS_MAC)
+# include <mach/mach.h>
+# include <mach/task.h>
+#elif defined(Q_OS_LINUX)
+# include <linux/futex.h>
+# include <sys/syscall.h>
+# include <unistd.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
+#if !defined(Q_OS_MAC) && !defined(Q_OS_LINUX)
 static void report_error(int code, const char *where, const char *what)
 {
     if (code != 0)
         qWarning("%s: %s failure: %s", where, what, qPrintable(qt_error_string(code)));
 }
+#endif
 
 
 QMutexPrivate::QMutexPrivate(QMutex::RecursionMode mode)
-    : QMutexData(mode), lastSpinCount(0), owner(0), count(0), wakeup(false)
+    : QMutexData(mode), maximumSpinTime(MaximumSpinTimeThreshold), averageWaitTime(0), owner(0), count(0)
 {
+#if defined(Q_OS_MAC)
+    kern_return_t r = semaphore_create(mach_task_self(), &mach_semaphore, SYNC_POLICY_FIFO, 0);
+    if (r != KERN_SUCCESS)
+        qWarning("QMutex: failed to create semaphore, error %d", r);
+#elif !defined(Q_OS_LINUX)
+    wakeup = false;
     report_error(pthread_mutex_init(&mutex, NULL), "QMutex", "mutex init");
     report_error(pthread_cond_init(&cond, NULL), "QMutex", "cv init");
+#endif
 }
 
 QMutexPrivate::~QMutexPrivate()
 {
+#if defined(Q_OS_MAC)
+    kern_return_t r = semaphore_destroy(mach_task_self(), mach_semaphore);
+    if (r != KERN_SUCCESS)
+        qWarning("QMutex: failed to destroy semaphore, error %d", r);
+#elif !defined(Q_OS_LINUX)
     report_error(pthread_cond_destroy(&cond), "QMutex", "cv destroy");
     report_error(pthread_mutex_destroy(&mutex), "QMutex", "mutex destroy");
+#endif
+}
+
+#if defined(Q_OS_MAC)
+
+bool QMutexPrivate::wait(int timeout)
+{
+    if (contenders.fetchAndAddAcquire(1) == 0) {
+        // lock acquired without waiting
+        return true;
+    }
+    bool returnValue;
+    if (timeout < 0) {
+        returnValue = semaphore_wait(mach_semaphore) == KERN_SUCCESS;
+    } else {
+        mach_timespec_t ts;
+        ts.tv_nsec = ((timeout % 1000) * 1000) * 1000;
+        ts.tv_sec = (timeout / 1000);
+        kern_return_t r = semaphore_timedwait(mach_semaphore, ts);
+        returnValue = r == KERN_SUCCESS;
+    }
+    contenders.deref();
+    return returnValue;
+}
+
+void QMutexPrivate::wakeUp()
+{
+    semaphore_signal(mach_semaphore);
+}
+
+#elif defined(Q_OS_LINUX)
+
+static inline int _q_futex(volatile int *addr, int op, int val, const struct timespec *timeout, int *addr2, int val2)
+{
+    return syscall(SYS_futex, addr, op, val, timeout, addr2, val2);
 }
 
 bool QMutexPrivate::wait(int timeout)
 {
+    while (contenders.fetchAndStoreAcquire(2) > 0) {
+        struct timespec ts, *pts = 0;
+        if (timeout >= 0) {
+            ts.tv_nsec = ((timeout % 1000) * 1000) * 1000;
+            ts.tv_sec = (timeout / 1000);
+            pts = &ts;
+        }
+        int r = _q_futex(&contenders._q_value, FUTEX_WAIT, 2, pts, 0, 0);
+        if (r != 0 && errno == ETIMEDOUT)
+            return false;
+    }
+    return true;
+}
+
+void QMutexPrivate::wakeUp()
+{
+    (void) contenders.fetchAndStoreRelease(0);
+    (void) _q_futex(&contenders._q_value, FUTEX_WAKE, 1, 0, 0, 0);
+}
+
+#else // !Q_OS_MAC && !Q_OS_LINUX
+
+bool QMutexPrivate::wait(int timeout)
+{
+    if (contenders.fetchAndAddAcquire(1) == 0) {
+        // lock acquired without waiting
+        return true;
+    }
     report_error(pthread_mutex_lock(&mutex), "QMutex::lock", "mutex lock");
     int errorCode = 0;
     while (!wakeup) {
@@ -101,6 +187,7 @@ bool QMutexPrivate::wait(int timeout)
     }
     wakeup = false;
     report_error(pthread_mutex_unlock(&mutex), "QMutex::lock", "mutex unlock");
+    contenders.deref();
     return errorCode == 0;
 }
 
@@ -112,6 +199,8 @@ void QMutexPrivate::wakeUp()
     report_error(pthread_mutex_unlock(&mutex), "QMutex::unlock", "mutex unlock");
 }
 
+#endif // !Q_OS_MAC && !Q_OS_LINUX
+
 QT_END_NAMESPACE
 
 #endif // QT_NO_THREAD
diff --git a/src/corelib/thread/qmutex_win.cpp b/src/corelib/thread/qmutex_win.cpp
index a810000..a759caa 100644
--- a/src/corelib/thread/qmutex_win.cpp
+++ b/src/corelib/thread/qmutex_win.cpp
@@ -48,7 +48,7 @@
 QT_BEGIN_NAMESPACE
 
 QMutexPrivate::QMutexPrivate(QMutex::RecursionMode mode)
-    : QMutexData(mode), lastSpinCount(0), owner(0), count(0)
+    : QMutexData(mode), maximumSpinTime(MaximumSpinTimeThreshold), averageWaitTime(0), owner(0), count(0)
 {
     event = CreateEvent(0, FALSE, FALSE, 0);
     if (!event)
@@ -60,7 +60,13 @@ QMutexPrivate::~QMutexPrivate()
 
 bool QMutexPrivate::wait(int timeout)
 {
-    return WaitForSingleObject(event, timeout < 0 ? INFINITE : timeout) ==  WAIT_OBJECT_0;
+    if (contenders.fetchAndAddAcquire(1) == 0) {
+        // lock acquired without waiting
+        return true;
+    }
+    bool returnValue = (WaitForSingleObject(event, timeout < 0 ? INFINITE : timeout) ==  WAIT_OBJECT_0);
+    contenders.deref();
+    return returnValue;
 }
 
 void QMutexPrivate::wakeUp()
diff --git a/src/corelib/tools/qelapsedtimer.h b/src/corelib/tools/qelapsedtimer.h
index b996f6a..4118389 100644
--- a/src/corelib/tools/qelapsedtimer.h
+++ b/src/corelib/tools/qelapsedtimer.h
@@ -68,6 +68,7 @@ public:
     void invalidate();
     bool isValid() const;
 
+    qint64 nsecsElapsed() const;
     qint64 elapsed() const;
     bool hasExpired(qint64 timeout) const;
 
diff --git a/src/corelib/tools/qelapsedtimer_generic.cpp b/src/corelib/tools/qelapsedtimer_generic.cpp
index 85986e6..740f496 100644
--- a/src/corelib/tools/qelapsedtimer_generic.cpp
+++ b/src/corelib/tools/qelapsedtimer_generic.cpp
@@ -103,6 +103,22 @@ qint64 QElapsedTimer::restart()
     return t1 - old;
 }
 
+/*! \since 4.8
+
+    Returns the number of nanoseconds since this QElapsedTimer was last
+    started. Calling this function in a QElapsedTimer that was invalidated
+    will result in undefined results.
+
+    On platforms that do not provide nanosecond resolution, the value returned
+    will be the best estimate available.
+
+    \sa start(), restart(), hasExpired(), invalidate()
+*/
+qint64 QElapsedTimer::nsecsElapsed() const
+{
+    return elapsed() * 1000000;
+}
+
 /*!
     Returns the number of milliseconds since this QElapsedTimer was last
     started. Calling this function in a QElapsedTimer that was invalidated
diff --git a/src/corelib/tools/qelapsedtimer_mac.cpp b/src/corelib/tools/qelapsedtimer_mac.cpp
index 8fceb49..e51f8b3 100644
--- a/src/corelib/tools/qelapsedtimer_mac.cpp
+++ b/src/corelib/tools/qelapsedtimer_mac.cpp
@@ -97,6 +97,12 @@ qint64 QElapsedTimer::restart()
     return absoluteToMSecs(t1 - old);
 }
 
+qint64 QElapsedTimer::nsecsElapsed() const
+{
+    uint64_t cpu_time = mach_absolute_time();
+    return absoluteToNSecs(cpu_time - t1);
+}
+
 qint64 QElapsedTimer::elapsed() const
 {
     uint64_t cpu_time = mach_absolute_time();
diff --git a/src/corelib/tools/qelapsedtimer_symbian.cpp b/src/corelib/tools/qelapsedtimer_symbian.cpp
index 038b102..7cd5f1e 100644
--- a/src/corelib/tools/qelapsedtimer_symbian.cpp
+++ b/src/corelib/tools/qelapsedtimer_symbian.cpp
@@ -64,11 +64,6 @@ static quint64 getMicrosecondFromTick()
     return nanokernel_tick_period * (val | (quint64(highdword) << 32));
 }
 
-static quint64 getMillisecondFromTick()
-{
-    return getMicrosecondFromTick() / 1000;
-}
-
 timeval qt_gettime()
 {
     timeval tv;
@@ -91,36 +86,41 @@ bool QElapsedTimer::isMonotonic()
 
 void QElapsedTimer::start()
 {
-    t1 = getMillisecondFromTick();
+    t1 = getMicrosecondFromTick();
     t2 = 0;
 }
 
 qint64 QElapsedTimer::restart()
 {
     qint64 oldt1 = t1;
-    t1 = getMillisecondFromTick();
+    t1 = getMicrosecondFromTick();
     t2 = 0;
     return t1 - oldt1;
 }
 
+qint64 QElapsedTimer::nsecsElapsed() const
+{
+    return (getMicrosecondFromTick() - t1) * 1000;
+}
+
 qint64 QElapsedTimer::elapsed() const
 {
-    return getMillisecondFromTick() - t1;
+    return (getMicrosecondFromTick() - t1) / 1000;
 }
 
 qint64 QElapsedTimer::msecsSinceReference() const
 {
-    return t1;
+    return t1 / 1000;
 }
 
 qint64 QElapsedTimer::msecsTo(const QElapsedTimer &other) const
 {
-    return other.t1 - t1;
+    return (other.t1 - t1) / 1000;
 }
 
 qint64 QElapsedTimer::secsTo(const QElapsedTimer &other) const
 {
-    return msecsTo(other) / 1000;
+    return msecsTo(other) / 1000000;
 }
 
 bool operator<(const QElapsedTimer &v1, const QElapsedTimer &v2)
diff --git a/src/corelib/tools/qelapsedtimer_unix.cpp b/src/corelib/tools/qelapsedtimer_unix.cpp
index 633fa00..7407e1b 100644
--- a/src/corelib/tools/qelapsedtimer_unix.cpp
+++ b/src/corelib/tools/qelapsedtimer_unix.cpp
@@ -167,6 +167,17 @@ qint64 QElapsedTimer::restart()
     return elapsedAndRestart(t1, t2, &t1, &t2);
 }
 
+qint64 QElapsedTimer::nsecsElapsed() const
+{
+    qint64 sec, frac;
+    do_gettime(&sec, &frac);
+    sec = sec - t1;
+    frac = frac - t2;
+    if (!monotonicClockAvailable)
+        frac *= 1000;
+    return sec * Q_INT64_C(1000000000) + frac;
+}
+
 qint64 QElapsedTimer::elapsed() const
 {
     qint64 sec, frac;
diff --git a/src/corelib/tools/qelapsedtimer_win.cpp b/src/corelib/tools/qelapsedtimer_win.cpp
index c77acaa..3f4acc1 100644
--- a/src/corelib/tools/qelapsedtimer_win.cpp
+++ b/src/corelib/tools/qelapsedtimer_win.cpp
@@ -79,14 +79,14 @@ static void resolveLibs()
     done = true;
 }
 
-static inline qint64 ticksToMilliseconds(qint64 ticks)
+static inline qint64 ticksToNanoseconds(qint64 ticks)
 {
     if (counterFrequency > 0) {
         // QueryPerformanceCounter uses an arbitrary frequency
-        return ticks * 1000 / counterFrequency;
+        return ticks * 1000000000 / counterFrequency;
     } else {
         // GetTickCount(64) return milliseconds
-        return ticks;
+        return ticks * 1000000;
     }
 }
 
@@ -144,24 +144,30 @@ qint64 QElapsedTimer::restart()
     qint64 oldt1 = t1;
     t1 = getTickCount();
     t2 = 0;
-    return ticksToMilliseconds(t1 - oldt1);
+    return ticksToNanoseconds(t1 - oldt1) / 1000000;
+}
+
+qint64 QElapsedTimer::nsecsElapsed() const
+{
+    qint64 elapsed = getTickCount() - t1;
+    return ticksToNanoseconds(elapsed);
 }
 
 qint64 QElapsedTimer::elapsed() const
 {
     qint64 elapsed = getTickCount() - t1;
-    return ticksToMilliseconds(elapsed);
+    return ticksToNanoseconds(elapsed) / 1000000;
 }
 
 qint64 QElapsedTimer::msecsSinceReference() const
 {
-    return ticksToMilliseconds(t1);
+    return ticksToNanoseconds(t1) / 1000000;
 }
 
 qint64 QElapsedTimer::msecsTo(const QElapsedTimer &other) const
 {
     qint64 difference = other.t1 - t1;
-    return ticksToMilliseconds(difference);
+    return ticksToNanoseconds(difference) / 1000000;
 }
 
 qint64 QElapsedTimer::secsTo(const QElapsedTimer &other) const
diff --git a/src/corelib/xml/qxmlstream.cpp b/src/corelib/xml/qxmlstream.cpp
index 91c3a19..64a9857 100644
--- a/src/corelib/xml/qxmlstream.cpp
+++ b/src/corelib/xml/qxmlstream.cpp
@@ -2941,6 +2941,9 @@ QStringRef QXmlStreamReader::documentEncoding() const
   By default, QXmlStreamWriter encodes XML in UTF-8. Different
   encodings can be enforced using setCodec().
 
+  If an error occurs while writing to the underlying device, hasError()
+  starts returning true and subsequent writes are ignored.
+
   The \l{QXmlStream Bookmarks Example} illustrates how to use a
   stream writer to write an XML bookmark file (XBEL) that
   was previously read in by a QXmlStreamReader.
@@ -2965,7 +2968,8 @@ public:
     void write(const QStringRef &);
     void write(const QString &);
     void writeEscaped(const QString &, bool escapeWhitespace = false);
-    void write(const char *s);
+    void write(const char *s, int len);
+    template <int N> void write(const char (&s)[N]) { write(s, N - 1); }
     bool finishStartElement(bool contents = true);
     void writeStartElement(const QString &namespaceUri, const QString &name);
     QIODevice *device;
@@ -2975,6 +2979,7 @@ public:
     uint inEmptyElement :1;
     uint lastWasStartElement :1;
     uint wroteSomething :1;
+    uint hasError :1;
     uint autoFormatting :1;
     QByteArray autoFormattingIndent;
     NamespaceDeclaration emptyNamespace;
@@ -3007,6 +3012,7 @@ QXmlStreamWriterPrivate::QXmlStreamWriterPrivate(QXmlStreamWriter *q)
 #endif
     inStartElement = inEmptyElement = false;
     wroteSomething = false;
+    hasError = false;
     lastWasStartElement = false;
     lastNamespaceDeclaration = 1;
     autoFormatting = false;
@@ -3016,11 +3022,15 @@ QXmlStreamWriterPrivate::QXmlStreamWriterPrivate(QXmlStreamWriter *q)
 void QXmlStreamWriterPrivate::write(const QStringRef &s)
 {
     if (device) {
+        if (hasError)
+            return;
 #ifdef QT_NO_TEXTCODEC
-        device->write(s.toString().toLatin1(), s.size());
+        QByteArray bytes = s.toLatin1();
 #else
-        device->write(encoder->fromUnicode(s.constData(), s.size()));
+        QByteArray bytes = encoder->fromUnicode(s.constData(), s.size());
 #endif
+        if (device->write(bytes) != bytes.size())
+            hasError = true;
     }
     else if (stringDevice)
         s.appendTo(stringDevice);
@@ -3031,11 +3041,15 @@ void QXmlStreamWriterPrivate::write(const QStringRef &s)
 void QXmlStreamWriterPrivate::write(const QString &s)
 {
     if (device) {
+        if (hasError)
+            return;
 #ifdef QT_NO_TEXTCODEC
-        device->write(s.toLatin1(), s.size());
+        QByteArray bytes = s.toLatin1();
 #else
-        device->write(encoder->fromUnicode(s));
+        QByteArray bytes = encoder->fromUnicode(s);
 #endif
+        if (device->write(bytes) != bytes.size())
+            hasError = true;
     }
     else if (stringDevice)
         stringDevice->append(s);
@@ -3070,31 +3084,19 @@ void QXmlStreamWriterPrivate::writeEscaped(const QString &s, bool escapeWhitespa
             escaped += QChar(c);
         }
     }
-    if (device) {
-#ifdef QT_NO_TEXTCODEC
-        device->write(escaped.toLatin1(), escaped.size());
-#else
-        device->write(encoder->fromUnicode(escaped));
-#endif
-    }
-    else if (stringDevice)
-        stringDevice->append(escaped);
-    else
-        qWarning("QXmlStreamWriter: No device");
+    write(escaped);
 }
 
-
-void QXmlStreamWriterPrivate::write(const char *s)
+// ASCII only!
+void QXmlStreamWriterPrivate::write(const char *s, int len)
 {
     if (device) {
-#ifndef QT_NO_TEXTCODEC
-        if (codec->mibEnum() != 106)
-            device->write(encoder->fromUnicode(QLatin1String(s)));
-        else
-#endif
-            device->write(s, strlen(s));
+        if (hasError)
+            return;
+        if (device->write(s, len) != len)
+            hasError = true;
     } else if (stringDevice) {
-        stringDevice->append(QLatin1String(s));
+        stringDevice->append(QString::fromLatin1(s, len));
     } else
         qWarning("QXmlStreamWriter: No device");
 }
@@ -3172,7 +3174,7 @@ void QXmlStreamWriterPrivate::indent(int level)
 {
     write("\n");
     for (int i = level; i > 0; --i)
-        write(autoFormattingIndent.constData());
+        write(autoFormattingIndent.constData(), autoFormattingIndent.length());
 }
 
 
@@ -3373,6 +3375,17 @@ int QXmlStreamWriter::autoFormattingIndent() const
     return d->autoFormattingIndent.count(' ') - d->autoFormattingIndent.count('\t');
 }
 
+/*!
+    Returns \c true if the stream failed to write to the underlying device.
+
+    The error status is never reset. Writes happening after the error
+    occurred are ignored, even if the error condition is cleared.
+ */
+bool QXmlStreamWriter::hasError() const
+{
+    Q_D(const QXmlStreamWriter);
+    return d->hasError;
+}
 
 /*!
   \overload
@@ -3759,7 +3772,7 @@ void QXmlStreamWriter::writeStartDocument(const QString &version)
 #ifdef QT_NO_TEXTCODEC
         d->write("iso-8859-1");
 #else
-        d->write(d->codec->name().constData());
+        d->write(d->codec->name().constData(), d->codec->name().length());
 #endif
     }
     d->write("\"?>");
@@ -3782,12 +3795,13 @@ void QXmlStreamWriter::writeStartDocument(const QString &version, bool standalon
 #ifdef QT_NO_TEXTCODEC
         d->write("iso-8859-1");
 #else
-        d->write(d->codec->name().constData());
+        d->write(d->codec->name().constData(), d->codec->name().length());
 #endif
     }
-    d->write("\" standalone=\"");
-    d->write(standalone ? "yes" : "no");
-    d->write("\"?>");
+    if (standalone)
+        d->write("\" standalone=\"yes\"?>");
+    else
+        d->write("\" standalone=\"no\"?>");
 }
 
 
diff --git a/src/corelib/xml/qxmlstream.h b/src/corelib/xml/qxmlstream.h
index d7143bd..244d3d4 100644
--- a/src/corelib/xml/qxmlstream.h
+++ b/src/corelib/xml/qxmlstream.h
@@ -474,6 +474,8 @@ public:
     void writeCurrentToken(const QXmlStreamReader &reader);
 #endif
 
+    bool hasError() const;
+
 private:
     Q_DISABLE_COPY(QXmlStreamWriter)
     Q_DECLARE_PRIVATE(QXmlStreamWriter)