Simplify QgsTask::waitForFinished, hopefully fix bugs

Author: nyalldawson

python/core/auto_generated/qgstaskmanager.sip.in

@@ -178,7 +178,7 @@ be canceled if any of these layers are about to be removed.
 .. seealso:: :py:func:`setDependentLayers`
 %End
 
-    bool waitForFinished( unsigned long timeout = 30000 );
+    bool waitForFinished( int timeout = 30000 );
 %Docstring
 Blocks the current thread until the task finishes or a maximum of ``timeout`` milliseconds.
 If ``timeout`` is ``0`` the thread will be blocked forever.

src/core/qgstaskmanager.cpp

@@ -144,7 +144,7 @@ QList<QgsMapLayer *> QgsTask::dependentLayers() const
   return _qgis_listQPointerToRaw( mDependentLayers );
 }
 
-bool QgsTask::waitForFinished( unsigned long timeout )
+bool QgsTask::waitForFinished( int timeout )
 {
   bool rv = true;
   if ( mOverallStatus == Complete || mOverallStatus == Terminated )
@@ -154,8 +154,16 @@ bool QgsTask::waitForFinished( unsigned long timeout )
   else
   {
     if ( timeout == 0 )
-      timeout = ULONG_MAX;
-    rv = mTaskFinished.wait( &mNotFinishedMutex, timeout );
+      timeout = std::numeric_limits< int >::max();
+    if ( mNotFinishedMutex.tryLock( timeout ) )
+    {
+      mNotFinishedMutex.unlock();
+      rv = true;
+    }
+    else
+    {
+      rv = false;
+    }
   }
   return rv;
 }
@@ -253,9 +261,7 @@ void QgsTask::processSubTasksForCompletion()
     setProgress( 100.0 );
     emit statusChanged( Complete );
     emit taskCompleted();
-    mTaskFinished.wakeAll();
     mNotFinishedMutex.unlock();
-    mTaskFinished.wakeAll();
   }
   else if ( mStatus == Complete )
   {
@@ -282,9 +288,7 @@ void QgsTask::processSubTasksForTermination()
 
     emit statusChanged( Terminated );
     emit taskTerminated();
-    mTaskFinished.wakeAll();
     mNotFinishedMutex.unlock();
-    mTaskFinished.wakeAll();
   }
   else if ( mStatus == Terminated && !subTasksTerminated )
   {

src/core/qgstaskmanager.h

@@ -204,7 +204,7 @@ class CORE_EXPORT QgsTask : public QObject
      *
      * The result will be false if the wait timed out and true in any other case.
      */
-    bool waitForFinished( unsigned long timeout = 30000 );
+    bool waitForFinished( int timeout = 30000 );
 
   signals:
 
@@ -312,8 +312,6 @@ class CORE_EXPORT QgsTask : public QObject
     bool mShouldTerminate = false;
     int mStartCount = 0;
 
-    QWaitCondition mTaskFinished;
-
     struct SubTask
     {
       SubTask( QgsTask *task, const QgsTaskList &dependencies, SubTaskDependency dependency )