Use QScopedValueRollback more as a reentrancy guard

It is documented for the use, but we were rarely using it.

Change-Id: I812b9e6c8fbf204aba43ce2b79eca308ca75de88
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/animation/qabstractanimation.cpp

@@ -152,6 +152,7 @@
 #include <QtCore/qthreadstorage.h>
 #include <QtCore/qcoreevent.h>
 #include <QtCore/qpointer.h>
+#include <QtCore/qscopedvaluerollback.h>
 
 #define DEFAULT_TIMER_INTERVAL 16
 #define PAUSE_TIMER_COARSE_THRESHOLD 2000
@@ -315,14 +316,13 @@ void QUnifiedTimer::updateAnimationTimers(qint64 currentTick)
     //* it might happen in some cases that the delta is negative because the animation driver
     //  advances faster than time.elapsed()
     if (delta > 0) {
-        insideTick = true;
+        QScopedValueRollback<bool> guard(insideTick, true);
         if (profilerCallback)
             profilerCallback(delta);
         for (currentAnimationIdx = 0; currentAnimationIdx < animationTimers.count(); ++currentAnimationIdx) {
             QAbstractAnimationTimer *animation = animationTimers.at(currentAnimationIdx);
             animation->updateAnimationsTime(delta);
         }
-        insideTick = false;
         currentAnimationIdx = 0;
     }
 }
@@ -361,10 +361,11 @@ void QUnifiedTimer::localRestart()
 
 void QUnifiedTimer::restart()
 {
-    insideRestart = true;
+    {
+        QScopedValueRollback<bool> guard(insideRestart, true);
         for (int i = 0; i < animationTimers.count(); ++i)
             animationTimers.at(i)->restartAnimationTimer();
-    insideRestart = false;
+    }
 
     localRestart();
 }
@@ -599,14 +600,13 @@ void QAnimationTimer::updateAnimationsTime(qint64 delta)
     //it might happen in some cases that the time doesn't change because events are delayed
     //when the CPU load is high
     if (delta) {
-        insideTick = true;
+        QScopedValueRollback<bool> guard(insideTick, true);
         for (currentAnimationIdx = 0; currentAnimationIdx < animations.count(); ++currentAnimationIdx) {
             QAbstractAnimation *animation = animations.at(currentAnimationIdx);
             int elapsed = QAbstractAnimationPrivate::get(animation)->totalCurrentTime
                           + (animation->direction() == QAbstractAnimation::Forward ? delta : -delta);
             animation->setCurrentTime(elapsed);
         }
-        insideTick = false;
         currentAnimationIdx = 0;
     }
 }

src/corelib/io/qprocess.cpp

@@ -42,6 +42,7 @@
 
 #include <qdebug.h>
 #include <qdir.h>
+#include <qscopedvaluerollback.h>
 #if defined(Q_OS_WIN)
 #include <qtimer.h>
 #endif
@@ -1062,9 +1063,8 @@ bool QProcessPrivate::tryReadFromChannel(Channel *channel)
     if (currentReadChannel == channelIdx) {
         didRead = true;
         if (!emittedReadyRead) {
-            emittedReadyRead = true;
+            QScopedValueRollback<bool> guard(emittedReadyRead, true);
             emit q->readyRead();
-            emittedReadyRead = false;
         }
     }
     emit q->channelReadyRead(int(channelIdx));

src/corelib/io/qwindowspipereader.cpp

@@ -40,6 +40,7 @@
 #include "qwindowspipereader_p.h"
 #include "qiodevice_p.h"
 #include <qelapsedtimer.h>
+#include <qscopedvaluerollback.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -301,9 +302,8 @@ void QWindowsPipeReader::emitPendingReadyRead()
 {
     if (readyReadPending) {
         readyReadPending = false;
-        inReadyRead = true;
+        QScopedValueRollback<bool> guard(inReadyRead, true);
         emit readyRead();
-        inReadyRead = false;
     }
 }
 

src/corelib/io/qwindowspipewriter.cpp

@@ -39,6 +39,7 @@
 
 #include "qwindowspipewriter_p.h"
 #include "qiodevice_p.h"
+#include <qscopedvaluerollback.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -111,9 +112,8 @@ void QWindowsPipeWriter::emitPendingBytesWrittenValue()
 
         emit canWrite();
         if (!inBytesWritten) {
-            inBytesWritten = true;
+            QScopedValueRollback<bool> guard(inBytesWritten, true);
             emit bytesWritten(bytes);
-            inBytesWritten = false;
         }
     }
 }

src/gui/painting/qoutlinemapper.cpp

@@ -42,6 +42,7 @@
 #include "qbezier_p.h"
 #include "qmath.h"
 #include "qpainterpath_p.h"
+#include "qscopedvaluerollback.h"
 
 #include <stdlib.h>
 
@@ -354,7 +355,7 @@ void QOutlineMapper::clipElements(const QPointF *elements,
     // instead of going through convenience functionallity, but since
     // this part of code hardly every used, it shouldn't matter.
 
-    m_in_clip_elements = true;
+    QScopedValueRollback<bool> in_clip_elements(m_in_clip_elements, true);
 
     QPainterPath path;
 
@@ -397,8 +398,6 @@ void QOutlineMapper::clipElements(const QPointF *elements,
         convertPath(clippedPath);
         m_transform = oldTransform;
     }
-
-    m_in_clip_elements = false;
 }
 
 QT_END_NAMESPACE

src/gui/text/qsyntaxhighlighter.cpp

@@ -45,6 +45,7 @@
 #include <private/qtextdocument_p.h>
 #include <qtextlayout.h>
 #include <qpointer.h>
+#include <qscopedvaluerollback.h>
 #include <qtextobject.h>
 #include <qtextcursor.h>
 #include <qdebug.h>
@@ -68,14 +69,14 @@ public:
     void reformatBlocks(int from, int charsRemoved, int charsAdded);
     void reformatBlock(const QTextBlock &block);
 
-    inline void rehighlight(QTextCursor &cursor, QTextCursor::MoveOperation operation) {
+    inline void rehighlight(QTextCursor &cursor, QTextCursor::MoveOperation operation)
-        inReformatBlocks = true;
+    {
+        QScopedValueRollback<bool> bg(inReformatBlocks, true);
         cursor.beginEditBlock();
         int from = cursor.position();
         cursor.movePosition(operation);
         reformatBlocks(from, 0, cursor.position() - from);
         cursor.endEditBlock();
-        inReformatBlocks = false;
     }
 
     inline void _q_delayedRehighlight() {

src/gui/text/qtextdocument_p.cpp

@@ -40,6 +40,7 @@
 #include <private/qtools_p.h>
 #include <qdebug.h>
 
+#include <qscopedvaluerollback.h>
 #include "qtextdocument_p.h"
 #include "qtextdocument.h"
 #include <qtextformat.h>
@@ -274,9 +275,10 @@ void QTextDocumentPrivate::clear()
         rtFrame = 0;
         init();
         cursors = oldCursors;
-        inContentsChange = true;
+        {
+            QScopedValueRollback<bool> bg(inContentsChange, true);
             emit q->contentsChange(0, len, 0);
-        inContentsChange = false;
+        }
         if (lout)
             lout->documentChanged(0, len, 0);
     } QT_CATCH(...) {
@@ -309,9 +311,10 @@ void QTextDocumentPrivate::setLayout(QAbstractTextDocumentLayout *layout)
             it->free();
 
     emit q->documentLayoutChanged();
-    inContentsChange = true;
+    {
+        QScopedValueRollback<bool> bg(inContentsChange, true);
         emit q->contentsChange(0, 0, length());
-    inContentsChange = false;
+    }
     if (lout)
         lout->documentChanged(0, 0, length());
 }
@@ -1213,9 +1216,8 @@ void QTextDocumentPrivate::finishEdit()
 
     if (lout && docChangeFrom >= 0) {
         if (!inContentsChange) {
-            inContentsChange = true;
+            QScopedValueRollback<bool> bg(inContentsChange, true);
             emit q->contentsChange(docChangeFrom, docChangeOldLength, docChangeLength);
-            inContentsChange = false;
         }
         lout->documentChanged(docChangeFrom, docChangeOldLength, docChangeLength);
     }

src/gui/text/qtextdocument_p.h

@@ -339,6 +339,7 @@ private:
     int lastBlockCount;
 
 public:
+    bool inContentsChange;
     QTextOption defaultTextOption;
     Qt::CursorMoveStyle defaultCursorMoveStyle;
 #ifndef QT_NO_CSSPARSER
@@ -346,7 +347,6 @@ public:
 #endif
     int maximumBlockCount;
     uint needsEnsureMaximumBlockCount : 1;
-    uint inContentsChange : 1;
     uint blockCursorAdjustment : 1;
     QSizeF pageSize;
     QString title;