Allow task priority to be specified

nyalldawson · nyalldawson · commit 4dc3dd907762 · 2016-12-05T14:08:11.000+10:00
diff --git a/python/core/qgstaskmanager.sip b/python/core/qgstaskmanager.sip
@@ -311,18 +311,21 @@ class QgsTaskManager : QObject
 
     /** Adds a task to the manager. Ownership of the task is transferred
      * to the manager, and the task manager will be responsible for starting
-     * the task.
+     * the task. The priority argument can be used to control the run queue's
+     * order of execution.
      * @returns unique task ID
      */
-    long addTask( QgsTask* task /Transfer/ );
+    long addTask( QgsTask* task /Transfer/, int priority = 0 );
 
     /**
      * Adds a task to the manager, using a full task definition (including dependancy
      * handling). Ownership of the task is transferred to the manager, and the task
-     * manager will be responsible for starting the task.
+     * manager will be responsible for starting the task. The priority argument can
+     * be used to control the run queue's order of execution.
      * @returns unique task ID
      */
-    long addTask( const TaskDefinition& task /Transfer/ );
+    long addTask( const TaskDefinition& task /Transfer/, int priority = 0 );
+
 
     /** Returns the task with matching ID.
      * @param id task ID
diff --git a/src/core/qgstaskmanager.cpp b/src/core/qgstaskmanager.cpp
@@ -40,7 +40,7 @@ QgsTask::QgsTask( const QString &name, const Flags& flags )
 
 QgsTask::~QgsTask()
 {
-  Q_ASSERT_X( mStatus == Queued || mStatus == Terminated || mStatus == Complete, "delete", QString( "status was %1" ).arg( mStatus ).toLatin1() );
+  Q_ASSERT_X( mStatus != Running, "delete", QString( "status was %1" ).arg( mStatus ).toLatin1() );
 
   QThreadPool::globalInstance()->cancel( this );
 
@@ -333,25 +333,26 @@ QgsTaskManager::~QgsTaskManager()
   delete mLayerDependenciesMutex;
 }
 
-long QgsTaskManager::addTask( QgsTask* task )
+long QgsTaskManager::addTask( QgsTask* task, int priority )
 {
-  return addTaskPrivate( task, QgsTaskList(), false );
+  return addTaskPrivate( task, QgsTaskList(), false, priority );
 }
 
-long QgsTaskManager::addTask( const QgsTaskManager::TaskDefinition& definition )
+long QgsTaskManager::addTask( const QgsTaskManager::TaskDefinition& definition, int priority )
 {
   return addTaskPrivate( definition.task,
                          definition.dependencies,
-                         false );
+                         false,
+                         priority );
 }
 
 
-long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bool isSubTask )
+long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bool isSubTask, int priority )
 {
   long taskId = mNextTaskId++;
 
   mTaskMutex->lockForWrite();
-  mTasks.insert( taskId, task );
+  mTasks.insert( taskId, TaskInfo( task, priority ) );
   mTaskMutex->unlock();
 
   if ( isSubTask )
@@ -387,7 +388,7 @@ long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bo
         break;
     }
     //recursively add sub tasks
-    addTaskPrivate( subTask.task, subTask.dependencies, true );
+    addTaskPrivate( subTask.task, subTask.dependencies, true, priority );
   }
 
   if ( !dependencies.isEmpty() )
@@ -735,7 +736,7 @@ void QgsTaskManager::processQueue()
     QgsTask* task = it.value().task;
     if ( task && task->mStatus == QgsTask::Queued && dependenciesSatisified( it.key() ) && it.value().added.testAndSetRelaxed( 0, 1 ) )
     {
-      QThreadPool::globalInstance()->start( task );
+      QThreadPool::globalInstance()->start( task, it.value().priority );
     }
 
     if ( task && ( task->mStatus != QgsTask::Complete && task->mStatus != QgsTask::Terminated ) )
diff --git a/src/core/qgstaskmanager.h b/src/core/qgstaskmanager.h
@@ -386,18 +386,20 @@ class CORE_EXPORT QgsTaskManager : public QObject
 
     /** Adds a task to the manager. Ownership of the task is transferred
      * to the manager, and the task manager will be responsible for starting
-     * the task.
+     * the task. The priority argument can be used to control the run queue's
+     * order of execution.
      * @returns unique task ID
      */
-    long addTask( QgsTask* task );
+    long addTask( QgsTask* task, int priority = 0 );
 
     /**
      * Adds a task to the manager, using a full task definition (including dependancy
      * handling). Ownership of the task is transferred to the manager, and the task
-     * manager will be responsible for starting the task.
+     * manager will be responsible for starting the task. The priority argument can
+     * be used to control the run queue's order of execution.
      * @returns unique task ID
      */
-    long addTask( const TaskDefinition& task );
+    long addTask( const TaskDefinition& task, int priority = 0 );
 
     /** Returns the task with matching ID.
      * @param id task ID
@@ -498,12 +500,14 @@ class CORE_EXPORT QgsTaskManager : public QObject
 
     struct TaskInfo
     {
-      TaskInfo( QgsTask* task = nullptr )
+      TaskInfo( QgsTask* task = nullptr, int priority = 0 )
           : task( task )
-          , added( false )
+          , added( 0 )
+          , priority( priority )
       {}
       QgsTask* task;
       QAtomicInt added;
+      int priority;
     };
 
     mutable QReadWriteLock* mTaskMutex;
@@ -531,7 +535,8 @@ class CORE_EXPORT QgsTaskManager : public QObject
 
     long addTaskPrivate( QgsTask* task,
                          QgsTaskList dependencies,
-                         bool isSubTask );
+                         bool isSubTask,
+                         int priority );
 
     bool cleanupAndDeleteTask( QgsTask* task );
 

Original file line number	Diff line number	Diff line change
`@@ -40,7 +40,7 @@ QgsTask::QgsTask( const QString &name, const Flags& flags )`
`40`	`40`
`41`	`41`	`QgsTask::~QgsTask()`
`42`	`42`	`{`
`43`		`- Q_ASSERT_X( mStatus == Queued \|\| mStatus == Terminated \|\| mStatus == Complete, "delete", QString( "status was %1" ).arg( mStatus ).toLatin1() );`
	`43`	`+ Q_ASSERT_X( mStatus != Running, "delete", QString( "status was %1" ).arg( mStatus ).toLatin1() );`
`44`	`44`
`45`	`45`	`QThreadPool::globalInstance()->cancel( this );`
`46`	`46`
`@@ -333,25 +333,26 @@ QgsTaskManager::~QgsTaskManager()`
`333`	`333`	`delete mLayerDependenciesMutex;`
`334`	`334`	`}`
`335`	`335`
`336`		`-long QgsTaskManager::addTask( QgsTask* task )`
	`336`	`+long QgsTaskManager::addTask( QgsTask* task, int priority )`
`337`	`337`	`{`
`338`		`- return addTaskPrivate( task, QgsTaskList(), false );`
	`338`	`+ return addTaskPrivate( task, QgsTaskList(), false, priority );`
`339`	`339`	`}`
`340`	`340`
`341`		`-long QgsTaskManager::addTask( const QgsTaskManager::TaskDefinition& definition )`
	`341`	`+long QgsTaskManager::addTask( const QgsTaskManager::TaskDefinition& definition, int priority )`
`342`	`342`	`{`
`343`	`343`	`return addTaskPrivate( definition.task,`
`344`	`344`	`definition.dependencies,`
`345`		`- false );`
	`345`	`+ false,`
	`346`	`+ priority );`
`346`	`347`	`}`
`347`	`348`
`348`	`349`
`349`		`-long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bool isSubTask )`
	`350`	`+long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bool isSubTask, int priority )`
`350`	`351`	`{`
`351`	`352`	`long taskId = mNextTaskId++;`
`352`	`353`
`353`	`354`	`mTaskMutex->lockForWrite();`
`354`		`- mTasks.insert( taskId, task );`
	`355`	`+ mTasks.insert( taskId, TaskInfo( task, priority ) );`
`355`	`356`	`mTaskMutex->unlock();`
`356`	`357`
`357`	`358`	`if ( isSubTask )`
`@@ -387,7 +388,7 @@ long QgsTaskManager::addTaskPrivate( QgsTask* task, QgsTaskList dependencies, bo`
`387`	`388`	`break;`
`388`	`389`	`}`
`389`	`390`	`//recursively add sub tasks`
`390`		`- addTaskPrivate( subTask.task, subTask.dependencies, true );`
	`391`	`+ addTaskPrivate( subTask.task, subTask.dependencies, true, priority );`
`391`	`392`	`}`
`392`	`393`
`393`	`394`	`if ( !dependencies.isEmpty() )`
`@@ -735,7 +736,7 @@ void QgsTaskManager::processQueue()`
`735`	`736`	`QgsTask* task = it.value().task;`
`736`	`737`	`if ( task && task->mStatus == QgsTask::Queued && dependenciesSatisified( it.key() ) && it.value().added.testAndSetRelaxed( 0, 1 ) )`
`737`	`738`	`{`
`738`		`- QThreadPool::globalInstance()->start( task );`
	`739`	`+ QThreadPool::globalInstance()->start( task, it.value().priority );`
`739`	`740`	`}`
`740`	`741`
`741`	`742`	`if ( task && ( task->mStatus != QgsTask::Complete && task->mStatus != QgsTask::Terminated ) )`