QgsCacheIndexFeatureId can also handle non-FilterFid requests

in certain circumstances

On behalf of Faunalia, sponsored by ENEL

python/core/qgscacheindexfeatureid.sip

@@ -6,42 +6,8 @@ class QgsCacheIndexFeatureId : QgsAbstractCacheIndex
   public:
     QgsCacheIndexFeatureId( QgsVectorLayerCache* );
 
-    /**
-     * Is called, whenever a feature is removed from the cache. You should update your indexes, so
-     * they become invalid in case this feature was required to successfuly answer a request.
-     */
     virtual void flushFeature( const QgsFeatureId fid );
-
-    /**
-     * Sometimes, the whole cache changes its state and its easier to just withdraw everything.
-     * In this case, this method is issued. Be sure to clear all cache information in here.
-     */
     virtual void flush();
-
-    /**
-     * @brief
-     * Implement this method to update the the indices, in case you need information contained by the request
-     * to properly index. (E.g. spatial index)
-     * Does nothing by default
-     *
-     * @param featureRequest  The feature request that was answered
-     * @param fids            The feature ids that have been returned
-     */
     virtual void requestCompleted( const QgsFeatureRequest& featureRequest, const QgsFeatureIds& fids );
-
-    /**
-     * Is called, when a feature request is issued on a cached layer.
-     * If this cache index is able to completely answer the feature request, it will return true
-     * and write the list of feature ids of cached features to cachedFeatures. If it is not able
-     * it will return false and the cachedFeatures state is undefined.
-     *
-     * @param featureIterator  A reference to a {@link QgsFeatureIterator}. A valid featureIterator will
-     *                         be assigned in case this index is able to answer the request and the return
-     *                         value is true.
-     * @param featureRequest   The feature request, for which this index is queried.
-     *
-     * @return   True, if this index holds the information to answer the request.
-     *
-     */
     virtual bool getCacheIterator( QgsFeatureIterator& featureIterator, const QgsFeatureRequest& featureRequest );
 };

python/core/qgsvectorlayercache.sip

@@ -123,8 +123,15 @@ class QgsVectorLayerCache : QObject
      * Check if a certain feature id is cached.
      * @param  fid The feature id to look for
      * @return True if this id is in the cache
+     * @see cachedFeatureIds()
      */
-    bool isFidCached( const QgsFeatureId fid );
+    bool isFidCached( const QgsFeatureId fid ) const;
+
+    /** Returns the set of feature IDs for features which are cached.
+     * @note added in QGIS 3.0
+     * @see isFidCached()
+     */
+    QgsFeatureIds cachedFeatureIds() const;
 
     /**
      * Gets the feature at the given feature id. Considers the changed, added, deleted and permanent features

src/core/qgscacheindex.h

@@ -58,8 +58,8 @@ class CORE_EXPORT QgsAbstractCacheIndex
     /**
      * Is called, when a feature request is issued on a cached layer.
      * If this cache index is able to completely answer the feature request, it will return true
-     * and write the list of feature ids of cached features to cachedFeatures. If it is not able
-     * it will return false and the cachedFeatures state is undefined.
+     * and set the iterator to a valid iterator over the cached features. If it is not able
+     * it will return false.
      *
      * @param featureIterator  A reference to a {@link QgsFeatureIterator}. A valid featureIterator will
      *                         be assigned in case this index is able to answer the request and the return

src/core/qgscacheindexfeatureid.cpp

@@ -42,12 +42,36 @@ void QgsCacheIndexFeatureId::requestCompleted( const QgsFeatureRequest& featureR
 
 bool QgsCacheIndexFeatureId::getCacheIterator( QgsFeatureIterator &featureIterator, const QgsFeatureRequest &featureRequest )
 {
-  if ( featureRequest.filterType() == QgsFeatureRequest::FilterFid )
+  switch ( featureRequest.filterType() )
   {
-    if ( C->isFidCached( featureRequest.filterFid() ) )
+    case QgsFeatureRequest::FilterFid:
     {
-      featureIterator = QgsFeatureIterator( new QgsCachedFeatureIterator( C, featureRequest ) );
-      return true;
+      if ( C->isFidCached( featureRequest.filterFid() ) )
+      {
+        featureIterator = QgsFeatureIterator( new QgsCachedFeatureIterator( C, featureRequest ) );
+        return true;
+      }
+      break;
+    }
+    case QgsFeatureRequest::FilterFids:
+    {
+      if ( C->cachedFeatureIds().contains( featureRequest.filterFids() ) )
+      {
+        featureIterator = QgsFeatureIterator( new QgsCachedFeatureIterator( C, featureRequest ) );
+        return true;
+      }
+      break;
+    }
+    case QgsFeatureRequest::FilterNone:
+    case QgsFeatureRequest::FilterRect:
+    case QgsFeatureRequest::FilterExpression:
+    {
+      if ( C->hasFullCache() )
+      {
+        featureIterator = QgsFeatureIterator( new QgsCachedFeatureIterator( C, featureRequest ) );
+        return true;
+      }
+      break;
     }
   }
 

src/core/qgscacheindexfeatureid.h

@@ -28,43 +28,9 @@ class CORE_EXPORT QgsCacheIndexFeatureId : public QgsAbstractCacheIndex
   public:
     QgsCacheIndexFeatureId( QgsVectorLayerCache* );
 
-    /**
-     * Is called, whenever a feature is removed from the cache. You should update your indexes, so
-     * they become invalid in case this feature was required to successfuly answer a request.
-     */
     virtual void flushFeature( const QgsFeatureId fid ) override;
-
-    /**
-     * Sometimes, the whole cache changes its state and its easier to just withdraw everything.
-     * In this case, this method is issued. Be sure to clear all cache information in here.
-     */
     virtual void flush() override;
-
-    /**
-     * @brief
-     * Implement this method to update the the indices, in case you need information contained by the request
-     * to properly index. (E.g. spatial index)
-     * Does nothing by default
-     *
-     * @param featureRequest  The feature request that was answered
-     * @param fids            The feature ids that have been returned
-     */
     virtual void requestCompleted( const QgsFeatureRequest& featureRequest, const QgsFeatureIds& fids ) override;
-
-    /**
-     * Is called, when a feature request is issued on a cached layer.
-     * If this cache index is able to completely answer the feature request, it will return true
-     * and write the list of feature ids of cached features to cachedFeatures. If it is not able
-     * it will return false and the cachedFeatures state is undefined.
-     *
-     * @param featureIterator  A reference to a {@link QgsFeatureIterator}. A valid featureIterator will
-     *                         be assigned in case this index is able to answer the request and the return
-     *                         value is true.
-     * @param featureRequest   The feature request, for which this index is queried.
-     *
-     * @return   True, if this index holds the information to answer the request.
-     *
-     */
     virtual bool getCacheIterator( QgsFeatureIterator& featureIterator, const QgsFeatureRequest& featureRequest ) override;
 
   private:

src/core/qgsvectorlayercache.cpp

@@ -364,7 +364,7 @@ QgsFeatureIterator QgsVectorLayerCache::getFeatures( const QgsFeatureRequest &fe
   return it;
 }
 
-bool QgsVectorLayerCache::isFidCached( const QgsFeatureId fid )
+bool QgsVectorLayerCache::isFidCached( const QgsFeatureId fid ) const
 {
   return mCache.contains( fid );
 }

src/core/qgsvectorlayercache.h

@@ -205,8 +205,15 @@ class CORE_EXPORT QgsVectorLayerCache : public QObject
      * Check if a certain feature id is cached.
      * @param  fid The feature id to look for
      * @return True if this id is in the cache
+     * @see cachedFeatureIds()
      */
-    bool isFidCached( const QgsFeatureId fid );
+    bool isFidCached( const QgsFeatureId fid ) const;
+
+    /** Returns the set of feature IDs for features which are cached.
+     * @note added in QGIS 3.0
+     * @see isFidCached()
+     */
+    QgsFeatureIds cachedFeatureIds() const { return mCache.keys().toSet(); }
 
     /**
      * Gets the feature at the given feature id. Considers the changed, added, deleted and permanent features

tests/src/core/testqgsvectorlayercache.cpp

@@ -289,6 +289,7 @@ void TestVectorLayerCache::testCanUseCacheForRequest()
   // get just the first feature into the cache
   it = cache.getFeatures( QgsFeatureRequest().setFilterFid( id1 ) );
   while ( it.nextFeature( f ) ) { }
+  QCOMPARE( cache.cachedFeatureIds(), QgsFeatureIds() << id1 );
   QVERIFY( cache.canUseCacheForRequest( QgsFeatureRequest().setFilterFid( id1 ), it ) );
   //verify that the returned iterator was correct
   QVERIFY( it.nextFeature( f ) );
@@ -302,6 +303,7 @@ void TestVectorLayerCache::testCanUseCacheForRequest()
   // get feature 2 into cache
   it = cache.getFeatures( QgsFeatureRequest().setFilterFid( id2 ) );
   while ( it.nextFeature( f ) ) { }
+  QCOMPARE( cache.cachedFeatureIds(), QgsFeatureIds() << id1 << id2 );
   QVERIFY( cache.canUseCacheForRequest( QgsFeatureRequest().setFilterFid( id1 ), it ) );
   QVERIFY( it.nextFeature( f ) );
   QCOMPARE( f.id(), id1 );