Fix thread synchronization issues in Symbian QFileSystemWatcher

In Symbian the QSymbianFileSystemWatcherEngine thread now stays running
as long as the instance is alive to avoid repeatedly stopping and
restarting the thread as watched paths are removed and added.

Also fixed issue of misreporting adding failure in cases where both
adds and removes were done in quick succession.

Task-number: QTBUG-10091
Reviewed-by: Shane Kearns

2 files changed, 24 insertions, 45 deletions

diff --git a/src/corelib/io/qfilesystemwatcher_symbian.cpp b/src/corelib/io/qfilesystemwatcher_symbian.cpp
index 69daae7..6136742 100644
--- a/src/corelib/io/qfilesystemwatcher_symbian.cpp
+++ b/src/corelib/io/qfilesystemwatcher_symbian.cpp
@@ -106,7 +106,7 @@ void QNotifyChangeEvent::DoCancel()
 }
 
 QSymbianFileSystemWatcherEngine::QSymbianFileSystemWatcherEngine() :
-        errorCode(KErrNone), watcherStarted(false)
+        watcherStarted(false)
 {
     moveToThread(this);
 }
@@ -122,11 +122,7 @@ QStringList QSymbianFileSystemWatcherEngine::addPaths(const QStringList &paths,
     QMutexLocker locker(&mutex);
     QStringList p = paths;
 
-    if (!startWatcher()) {
-        qWarning("Could not start QSymbianFileSystemWatcherEngine thread");
-
-        return p;
-    }
+    startWatcher();
 
     QMutableListIterator<QString> it(p);
     while (it.hasNext()) {
@@ -150,18 +146,17 @@ QStringList QSymbianFileSystemWatcherEngine::addPaths(const QStringList &paths,
             filePath += QChar(L'/');
         }
 
-        currentEvent = NULL;
+        currentAddEvent = NULL;
         QMetaObject::invokeMethod(this,
                                   "addNativeListener",
                                   Qt::QueuedConnection,
                                   Q_ARG(QString, filePath));
 
         syncCondition.wait(&mutex);
+        if (currentAddEvent) {
+            currentAddEvent->isDir = isDir;
 
-        if (currentEvent) {
-            currentEvent->isDir = isDir;
-
-            activeObjectToPath.insert(currentEvent, path);
+            activeObjectToPath.insert(currentAddEvent, path);
             it.remove();
 
             if (isDir)
@@ -185,10 +180,10 @@ QStringList QSymbianFileSystemWatcherEngine::removePaths(const QStringList &path
     while (it.hasNext()) {
         QString path = it.next();
 
-        currentEvent = activeObjectToPath.key(path);
-        if (!currentEvent)
+        currentRemoveEvent = activeObjectToPath.key(path);
+        if (!currentRemoveEvent)
             continue;
-        activeObjectToPath.remove(currentEvent);
+        activeObjectToPath.remove(currentRemoveEvent);
 
         QMetaObject::invokeMethod(this,
                                   "removeNativeListener",
@@ -202,9 +197,6 @@ QStringList QSymbianFileSystemWatcherEngine::removePaths(const QStringList &path
         directories->removeAll(path);
     }
 
-    if (activeObjectToPath.size() == 0)
-        stop();
-
     return p;
 }
 
@@ -228,44 +220,31 @@ void QSymbianFileSystemWatcherEngine::stop()
 }
 
 // This method must be called inside mutex
-bool QSymbianFileSystemWatcherEngine::startWatcher()
+void QSymbianFileSystemWatcherEngine::startWatcher()
 {
-    bool retval = true;
-
     if (!watcherStarted) {
         setStackSize(0x5000);
         start();
         syncCondition.wait(&mutex);
-
-        if (errorCode != KErrNone) {
-            retval = false;
-        } else {
-            watcherStarted = true;
-        }
+        watcherStarted = true;
     }
-    return retval;
 }
 
 
 void QSymbianFileSystemWatcherEngine::run()
 {
-    // Initialize file session
-
     mutex.lock();
     syncCondition.wakeOne();
     mutex.unlock();
 
-    if (errorCode == KErrNone) {
-        exec();
+    exec();
 
-        foreach(QNotifyChangeEvent *e, activeObjectToPath.keys()) {
-            e->Cancel();
-            delete e;
-        }
-
-        activeObjectToPath.clear();
-        watcherStarted = false;
+    foreach(QNotifyChangeEvent *e, activeObjectToPath.keys()) {
+        e->Cancel();
+        delete e;
     }
+
+    activeObjectToPath.clear();
 }
 
 void QSymbianFileSystemWatcherEngine::addNativeListener(const QString &directoryPath)
@@ -273,16 +252,16 @@ void QSymbianFileSystemWatcherEngine::addNativeListener(const QString &directory
     QMutexLocker locker(&mutex);
     QString nativeDir(QDir::toNativeSeparators(directoryPath));
     TPtrC ptr(qt_QString2TPtrC(nativeDir));
-    currentEvent = new QNotifyChangeEvent(qt_s60GetRFs(), ptr, this, directoryPath.endsWith(QChar(L'/'), Qt::CaseSensitive));
+    currentAddEvent = new QNotifyChangeEvent(qt_s60GetRFs(), ptr, this, directoryPath.endsWith(QChar(L'/'), Qt::CaseSensitive));
     syncCondition.wakeOne();
 }
 
 void QSymbianFileSystemWatcherEngine::removeNativeListener()
 {
     QMutexLocker locker(&mutex);
-    currentEvent->Cancel();
-    delete currentEvent;
-    currentEvent = NULL;
+    currentRemoveEvent->Cancel();
+    delete currentRemoveEvent;
+    currentRemoveEvent = NULL;
     syncCondition.wakeOne();
 }
 
diff --git a/src/corelib/io/qfilesystemwatcher_symbian_p.h b/src/corelib/io/qfilesystemwatcher_symbian_p.h
index 7e3f045..e687a4a 100644
--- a/src/corelib/io/qfilesystemwatcher_symbian_p.h
+++ b/src/corelib/io/qfilesystemwatcher_symbian_p.h
@@ -113,14 +113,14 @@ private:
     friend class QNotifyChangeEvent;
     void emitPathChanged(QNotifyChangeEvent *e);
 
-    bool startWatcher();
+    void startWatcher();
 
     QHash<QNotifyChangeEvent*, QString> activeObjectToPath;
     QMutex mutex;
     QWaitCondition syncCondition;
-    int errorCode;
     bool watcherStarted;
-    QNotifyChangeEvent *currentEvent;
+    QNotifyChangeEvent *currentAddEvent;
+    QNotifyChangeEvent *currentRemoveEvent;
 };
 
 #endif // QT_NO_FILESYSTEMWATCHER