[GEOS-8181] KML reflector attempts to query all records in table

src/kml/src/main/java/org/geoserver/kml/sequence/FeatureSequenceFactory.java

@@ -7,6 +7,7 @@
 
 import java.util.EmptyStackException;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.geoserver.kml.KmlEncodingContext;
 import org.geoserver.kml.decorator.KmlDecoratorFactory.KmlDecorator;
@@ -18,6 +19,7 @@
 import org.geotools.filter.function.EnvFunction;
 import org.geotools.map.FeatureLayer;
 import org.geotools.map.Layer;
+import org.geotools.styling.AbstractStyleVisitor;
 import org.geotools.styling.Style;
 import org.geotools.styling.Symbolizer;
 import org.opengis.feature.simple.SimpleFeature;
@@ -44,6 +46,8 @@ public class FeatureSequenceFactory implements SequenceFactory<Feature> {
     private Style simplified;
 
     private KmlEncodingContext context;
+
+    private boolean hasActiveRules;
 
     public FeatureSequenceFactory(KmlEncodingContext context, FeatureLayer layer) {
         this.context = context;
@@ -59,10 +63,22 @@ public FeatureSequenceFactory(KmlEncodingContext context, FeatureLayer layer) {
 
         // prepare the style for this layer
         simplified = getSimplifiedStyle(mapContent, layer);
+
+        AtomicBoolean rulesFound = new AtomicBoolean(false);
+        if(simplified != null) {
+            simplified.accept(new AbstractStyleVisitor() {
+                public void visit(org.geotools.styling.Rule rule) {
+                    rulesFound.set(true);
+                    // no need to scan inside rules
+                }
+            });
+        }
+        this.hasActiveRules = rulesFound.get();
     }
 
     private Style getSimplifiedStyle(WMSMapContent mc, Layer layer) {
-        ScaleStyleVisitor visitor = new ScaleStyleVisitor(mc.getScaleDenominator(), 
+        final double scaleDenominator = mc.getScaleDenominator();
+        ScaleStyleVisitor visitor = new ScaleStyleVisitor(scaleDenominator, 
                 (SimpleFeatureType) layer.getFeatureSource().getSchema());
         try {
             layer.getStyle().accept(visitor);
@@ -74,7 +90,7 @@ private Style getSimplifiedStyle(WMSMapContent mc, Layer layer) {
 
     @Override
     public Sequence<Feature> newSequence() {
-        return new FeatureGenerator(simplified != null ? context.openIterator(features) : null);
+        return new FeatureGenerator(hasActiveRules ? context.openIterator(features) : null);
     }
 
     public class FeatureGenerator implements Sequence<Feature> {

src/kml/src/test/java/org/geoserver/kml/sequence/FeatureSequenceFactoryTest.java

@@ -0,0 +1,53 @@
+/* (c) 2017 Open Source Geospatial Foundation - all rights reserved
+ * This code is licensed under the GPL 2.0 license, available at the root
+ * application directory.
+ */
+package org.geoserver.kml.sequence;
+
+import static org.easymock.EasyMock.*;
+import static org.junit.Assert.*;
+
+import org.geoserver.kml.KmlEncodingContext;
+import org.geoserver.wms.WMSMapContent;
+import org.geotools.data.simple.SimpleFeatureCollection;
+import org.geotools.feature.DefaultFeatureCollection;
+import org.geotools.map.FeatureLayer;
+import org.geotools.styling.Style;
+import org.geotools.styling.StyleBuilder;
+import org.junit.Test;
+
+import de.micromata.opengis.kml.v_2_2_0.Feature;
+import junit.framework.AssertionFailedError;
+
+public class FeatureSequenceFactoryTest {
+
+    @Test
+    public void testNoScanOnEmptyStyle() {
+        // a style with scale dependency
+        StyleBuilder sb = new StyleBuilder();
+        Style style = sb.createStyle(sb.createPolygonSymbolizer());
+        style.featureTypeStyles().get(0).rules().get(0).setMaxScaleDenominator(1000);
+
+        // the layer
+        final DefaultFeatureCollection fc = new DefaultFeatureCollection();
+        FeatureLayer layer = new FeatureLayer(fc, style);
+
+        // a max context with a scale outside the rule range
+        WMSMapContent mc = createNiceMock(WMSMapContent.class);
+        expect(mc.getScaleDenominator()).andReturn(2000d).anyTimes();
+        replay(mc);
+
+        // and the context wiring everything toghether
+        KmlEncodingContext context = createNiceMock(KmlEncodingContext.class);
+        expect(context.openIterator(anyObject(SimpleFeatureCollection.class)))
+                .andThrow(new AssertionFailedError("Should not have called openIterator")).anyTimes();
+        expect(context.getCurrentFeatureCollection()).andReturn(fc).anyTimes();
+        expect(context.getMapContent()).andReturn(mc).anyTimes();
+        replay(context);
+
+        // check no features have been read
+        FeatureSequenceFactory sf = new FeatureSequenceFactory(context, layer);
+        Sequence<Feature> sequence = sf.newSequence();
+        assertNull(sequence.next());
+    }
+}