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m-kuhnm-kuhn
authoredSep 5, 2018
Merge pull request #7792 from m-kuhn/threadsafefeaturesource
Add threadsafe method to get featuresource from layer
·
ltr-3_40final-3_4_0
2 parents 969c7c5 + 86f4293 commit f875bb7

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‎src/core/qgsvectorlayerutils.cpp

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@@ -498,6 +498,37 @@ QgsFeature QgsVectorLayerUtils::duplicateFeature( QgsVectorLayer *layer, const Q
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return newFeature;
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}
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std::unique_ptr<QgsVectorLayerFeatureSource> QgsVectorLayerUtils::getFeatureSource( QPointer<QgsVectorLayer> layer )
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{
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std::unique_ptr<QgsVectorLayerFeatureSource> featureSource;
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auto getFeatureSource = [ layer, &featureSource ]
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{
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#if QT_VERSION >= QT_VERSION_CHECK( 5, 10, 0 )
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Q_ASSERT( QThread::currentThread() == qApp->thread() );
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#endif
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QgsVectorLayer *lyr = layer.data();
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if ( lyr )
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{
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featureSource.reset( new QgsVectorLayerFeatureSource( lyr ) );
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}
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};
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#if QT_VERSION >= QT_VERSION_CHECK( 5, 10, 0 )
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// Make sure we only deal with the vector layer on the main thread where it lives.
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// Anything else risks a crash.
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if ( QThread::currentThread() == qApp->thread() )
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getFeatureSource();
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else
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QMetaObject::invokeMethod( qApp, getFeatureSource, Qt::BlockingQueuedConnection );
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#else
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getFeatureSource();
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#endif
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return featureSource;
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}
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QList<QgsVectorLayer *> QgsVectorLayerUtils::QgsDuplicateFeatureContext::layers() const
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{
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QList<QgsVectorLayer *> layers;

‎src/core/qgsvectorlayerutils.h

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@@ -19,6 +19,7 @@
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#include "qgis_core.h"
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#include "qgsvectorlayer.h"
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#include "qgsgeometry.h"
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#include "qgsvectorlayerfeatureiterator.h"
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/**
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* \ingroup core
@@ -155,6 +156,18 @@ class CORE_EXPORT QgsVectorLayerUtils
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*/
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static QgsFeature duplicateFeature( QgsVectorLayer *layer, const QgsFeature &feature, QgsProject *project, int depth, QgsDuplicateFeatureContext &duplicateFeatureContext SIP_OUT );
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/**
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* Gets the feature source from a QgsVectorLayer pointer.
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* This method is thread-safe but will block the main thread for execution. Executing it from the main
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* thread is safe too.
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* This should be used in scenarios, where a ``QWeakPointer<QgsVectorLayer>`` is kept in a thread
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* and features should be fetched from this layer. Using the layer directly is not safe to do.
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* The result will be ``nullptr`` if the layer has been deleted.
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*
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* \note Requires Qt >= 5.10 to make use of the thread-safe implementation
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* \since QGIS 3.4
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*/
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static std::unique_ptr<QgsVectorLayerFeatureSource> getFeatureSource( QPointer<QgsVectorLayer> layer ) SIP_SKIP;
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};
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‎tests/src/core/CMakeLists.txt

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@@ -192,6 +192,7 @@ SET(TESTS
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testqgsvectorlayercache.cpp
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testqgsvectorlayerjoinbuffer.cpp
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testqgsvectorlayer.cpp
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testqgsvectorlayerutils.cpp
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testziplayer.cpp
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testqgsmeshlayer.cpp
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testqgsmeshlayerrenderer.cpp

‎tests/src/core/testqgsvectorlayerutils.cpp

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/***************************************************************************
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test_template.cpp
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--------------------------------------
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Date : Sun Sep 16 12:22:23 AKDT 2007
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Copyright : (C) 2007 by Gary E. Sherman
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Email : sherman at mrcc dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#include "qgstest.h"
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#include "qgsvectorlayerutils.h"
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/**
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* \ingroup UnitTests
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* This is a unit test for the vector layer class.
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*/
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class TestQgsVectorLayerUtils : public QObject
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{
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Q_OBJECT
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public:
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TestQgsVectorLayerUtils() = default;
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private slots:
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void initTestCase(); // will be called before the first testfunction is executed.
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void cleanupTestCase(); // will be called after the last testfunction was executed.
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void init() {} // will be called before each testfunction is executed.
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void cleanup() {} // will be called after every testfunction.
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void testGetFeatureSource();
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};
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void TestQgsVectorLayerUtils::initTestCase()
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{
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QgsApplication::init();
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QgsApplication::initQgis();
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QgsApplication::showSettings();
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}
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void TestQgsVectorLayerUtils::cleanupTestCase()
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{
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QgsApplication::exitQgis();
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}
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class FeatureFetcher : public QThread
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{
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Q_OBJECT
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public:
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FeatureFetcher( QPointer<QgsVectorLayer> layer )
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: mLayer( layer )
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{
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}
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void run() override
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{
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QgsFeature feat;
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auto fs = QgsVectorLayerUtils::getFeatureSource( mLayer );
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if ( fs )
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fs->getFeatures().nextFeature( feat );
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emit resultReady( feat.attribute( QStringLiteral( "col1" ) ) );
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}
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signals:
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void resultReady( const QVariant &attribute );
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private:
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QPointer<QgsVectorLayer> mLayer;
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};
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void TestQgsVectorLayerUtils::testGetFeatureSource()
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{
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std::unique_ptr<QgsVectorLayer> vl = qgis::make_unique<QgsVectorLayer>( QStringLiteral( "Point?field=col1:integer" ), QStringLiteral( "vl" ), QStringLiteral( "memory" ) );
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vl->startEditing();
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QgsFeature f1( vl->fields(), 1 );
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f1.setAttribute( QStringLiteral( "col1" ), 10 );
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vl->addFeature( f1 );
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QPointer<QgsVectorLayer> vlPtr( vl.get() );
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QgsFeature feat;
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QgsVectorLayerUtils::getFeatureSource( vlPtr )->getFeatures().nextFeature( feat );
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QCOMPARE( feat.attribute( QStringLiteral( "col1" ) ).toInt(), 10 );
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FeatureFetcher *thread = new FeatureFetcher( vlPtr );
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bool finished = false;
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QVariant result;
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auto onResultReady = [&finished, &result]( const QVariant & res )
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{
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finished = true;
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result = res;
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};
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connect( thread, &FeatureFetcher::resultReady, this, onResultReady );
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connect( thread, &QThread::finished, thread, &QThread::deleteLater );
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thread->start();
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while ( !finished )
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QCoreApplication::processEvents();
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QCOMPARE( result.toInt(), 10 );
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thread->quit();
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FeatureFetcher *thread2 = new FeatureFetcher( vlPtr );
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finished = false;
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result = QVariant();
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connect( thread2, &FeatureFetcher::resultReady, this, onResultReady );
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connect( thread2, &QThread::finished, thread, &QThread::deleteLater );
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vl.reset();
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thread2->start();
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while ( !finished )
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QCoreApplication::processEvents();
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QVERIFY( result.isNull() );
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thread2->quit();
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}
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QGSTEST_MAIN( TestQgsVectorLayerUtils )
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#include "testqgsvectorlayerutils.moc"

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