From afd5d1e9344f41a40f882fb204810f8e650813c0 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Wed, 10 Aug 2016 12:28:00 +1000
Subject: [PATCH] Recognise that a cache can be filled using a FilterNone
 request

On behalf of Faunalia, sponsored by ENEL
---
 python/core/qgsvectorlayercache.sip        |  9 ++++
 src/core/qgsvectorlayercache.cpp           |  4 ++
 src/core/qgsvectorlayercache.h             |  9 ++++
 tests/src/core/testqgsvectorlayercache.cpp | 48 ++++++++++++++++++++++
 4 files changed, 70 insertions(+)

diff --git a/python/core/qgsvectorlayercache.sip b/python/core/qgsvectorlayercache.sip
index 99a3fd196b6..3fe37c87f07 100644
--- a/python/core/qgsvectorlayercache.sip
+++ b/python/core/qgsvectorlayercache.sip
@@ -65,9 +65,18 @@ class QgsVectorLayerCache : QObject
      * be used for slow data sources, be aware, that the call to this method might take a long time.
      *
      * @param fullCache   True: enable full caching, False: disable full caching
+     * @see hasFullCache()
      */
     void setFullCache( bool fullCache );
 
+    /** Returns true if the cache is complete, ie it contains all features. This may happen as
+     * a result of a call to setFullCache() or by through a feature request which resulted in
+     * all available features being cached.
+     * @see setFullCache()
+     * @note added in QGIS 3.0
+     */
+    bool hasFullCache() const;
+
     /**
      * @brief
      * Adds a {@link QgsAbstractCacheIndex} to this cache. Cache indices know about features present
diff --git a/src/core/qgsvectorlayercache.cpp b/src/core/qgsvectorlayercache.cpp
index dd8e74ec70b..ffb067a4865 100644
--- a/src/core/qgsvectorlayercache.cpp
+++ b/src/core/qgsvectorlayercache.cpp
@@ -180,6 +180,10 @@ void QgsVectorLayerCache::requestCompleted( const QgsFeatureRequest& featureRequ
     {
       idx->requestCompleted( featureRequest, fids );
     }
+    if ( featureRequest.filterType() == QgsFeatureRequest::FilterNone )
+    {
+      mFullCache = true;
+    }
   }
 }
 
diff --git a/src/core/qgsvectorlayercache.h b/src/core/qgsvectorlayercache.h
index d7c766c63c6..c06127e118d 100644
--- a/src/core/qgsvectorlayercache.h
+++ b/src/core/qgsvectorlayercache.h
@@ -133,9 +133,18 @@ class CORE_EXPORT QgsVectorLayerCache : public QObject
      * be used for slow data sources, be aware, that the call to this method might take a long time.
      *
      * @param fullCache   True: enable full caching, False: disable full caching
+     * @see hasFullCache()
      */
     void setFullCache( bool fullCache );
 
+    /** Returns true if the cache is complete, ie it contains all features. This may happen as
+     * a result of a call to setFullCache() or by through a feature request which resulted in
+     * all available features being cached.
+     * @see setFullCache()
+     * @note added in QGIS 3.0
+     */
+    bool hasFullCache() const { return mFullCache; }
+
     /**
      * @brief
      * Adds a {@link QgsAbstractCacheIndex} to this cache. Cache indices know about features present
diff --git a/tests/src/core/testqgsvectorlayercache.cpp b/tests/src/core/testqgsvectorlayercache.cpp
index 5cd564feb8a..f5d68ed258e 100644
--- a/tests/src/core/testqgsvectorlayercache.cpp
+++ b/tests/src/core/testqgsvectorlayercache.cpp
@@ -52,6 +52,8 @@ class TestVectorLayerCache : public QObject
     void testCacheAttrActions(); // Test attribute add/ attribute delete
     void testFeatureActions();   // Test adding/removing features works
     void testSubsetRequest();
+    void testFullCache();
+    void testFullCacheThroughRequest();
 
     void onCommittedFeaturesAdded( const QString&, const QgsFeatureList& );
 
@@ -219,6 +221,52 @@ void TestVectorLayerCache::testSubsetRequest()
   QVERIFY( a == f.attribute( 3 ) );
 }
 
+void TestVectorLayerCache::testFullCache()
+{
+  // cache is too small to fit all features
+  QgsVectorLayerCache cache( mPointsLayer, 2 );
+  QVERIFY( !cache.hasFullCache() );
+  QVERIFY( cache.cacheSize() < mPointsLayer->featureCount() );
+  // but we set it to full cache
+  cache.setFullCache( true );
+  // so now it should have sufficient size for all features
+  QVERIFY( cache.cacheSize() >= mPointsLayer->featureCount() );
+  QVERIFY( cache.hasFullCache() );
+
+  // double check that everything is indeed in the cache
+  QgsFeatureIterator it = mPointsLayer->getFeatures();
+  QgsFeature f;
+  while ( it.nextFeature( f ) )
+  {
+    QVERIFY( cache.isFidCached( f.id() ) );
+  }
+}
+
+void TestVectorLayerCache::testFullCacheThroughRequest()
+{
+  // make sure cache is sufficient size for all features
+  QgsVectorLayerCache cache( mPointsLayer, mPointsLayer->featureCount() * 2 );
+  QVERIFY( !cache.hasFullCache() );
+
+  // now request all features from cache
+  QgsFeatureIterator it = cache.getFeatures( QgsFeatureRequest() );
+  QgsFeature f;
+  while ( it.nextFeature( f ) )
+  {
+    // suck in all features
+  }
+
+  // cache should now contain all features
+  it = mPointsLayer->getFeatures();
+  while ( it.nextFeature( f ) )
+  {
+    QVERIFY( cache.isFidCached( f.id() ) );
+  }
+
+  // so it should be a full cache!
+  QVERIFY( cache.hasFullCache() );
+}
+
 void TestVectorLayerCache::onCommittedFeaturesAdded( const QString& layerId, const QgsFeatureList& features )
 {
   Q_UNUSED( layerId )