Merge pull request #30101 from qgis/backport-30039-to-release-3_4

[Backport release-3_4] [WFS provider] Avoid dangling download progress dialog
qgis · Jun 5, 2019 · 393983f · 393983f
2 parents 0deda6c + 66d05b8
commit 393983f
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/src/providers/wfs/qgswfsfeatureiterator.cpp b/src/providers/wfs/qgswfsfeatureiterator.cpp
@@ -165,6 +165,12 @@ void QgsWFSFeatureDownloader::createProgressDialog()
 {
   Q_ASSERT( qApp->thread() == QThread::currentThread() );
 
+  // Make sure that the creation is done in an atomic way, so that the
+  // starting thread (running QgsWFSFeatureDownloader::run()) can be sure that
+  // this function has either run completely, or not at all (mStop == true),
+  // when it wants to destroy mProgressDialog
+  QMutexLocker locker( &mMutexCreateProgressDialog );
+
   if ( mStop )
     return;
   Q_ASSERT( !mProgressDialog );
@@ -833,7 +839,10 @@ void QgsWFSFeatureDownloader::run( bool serializeFeatures, int maxFeatures )
     }
   }
 
-  mStop = true;
+  {
+    QMutexLocker locker( &mMutexCreateProgressDialog );
+    mStop = true;
+  }
 
   if ( serializeFeatures )
     mShared->endOfDownload( success, mTotalDownloadedFeatureCount, truncatedResponse, interrupted, mErrorMessage );
@@ -856,6 +865,7 @@ void QgsWFSFeatureDownloader::run( bool serializeFeatures, int maxFeatures )
     mTimer->deleteLater();
     mTimer = nullptr;
   }
+
   // explicitly abort here so that mReply is destroyed within the right thread
   // otherwise will deadlock because deleteLayer() will not have a valid thread to post
   abort();

diff --git a/src/providers/wfs/qgswfsfeatureiterator.h b/src/providers/wfs/qgswfsfeatureiterator.h
@@ -158,6 +158,7 @@ class QgsWFSFeatureDownloader: public QgsWfsRequest
     QTimer *mTimer = nullptr;
     QgsWFSFeatureHitsAsyncRequest mFeatureHitsAsyncRequest;
     qint64 mTotalDownloadedFeatureCount;
+    QMutex mMutexCreateProgressDialog;
 };
 
 //! Downloader thread