Revert "Bratseth/allocation free hit field traversal"

15 files changed, 166 insertions, 151 deletions

diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
index 4310124037e..298bd839393 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
@@ -19,7 +19,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import java.util.function.BiConsumer;
 
 /**
  * A regular hit from a Vespa backend
@@ -218,13 +217,7 @@ public class FastHit extends Hit {
         return getSummaryValue(name);
     }
 
-    @Override
-    public void forEachField(BiConsumer<String, Object> consumer) {
-        super.forEachField(consumer);
-        for (SummaryData summaryData : summaries)
-            summaryData.forEachField(consumer);
-    }
-
+    /** Returns the fields of this as a read-only map. This is more costly than fieldIterator() */
     @Override
     public Map<String, Object> fields() {
         Map<String, Object> fields = new HashMap<>();
@@ -235,23 +228,14 @@ public class FastHit extends Hit {
         return fields;
     }
 
+    /** Returns a modifiable iterator over the fields of this */
     @Override
     public Iterator<Map.Entry<String, Object>> fieldIterator() {
         return new FieldIterator(this, super.fieldIterator());
     }
 
-    /**
-     * Returns the keys of the fields of this hit as a modifiable view.
-     * This follows the rules of key sets returned from maps: Key removals are reflected
-     * in the map, add and addAll is not supported.
-     */
-    @Override
-    public Set<String> fieldKeys() {
-        return new FieldSet(this);
-    }
-
     /** Returns a modifiable iterator over the field names of this */
-    private Iterator<String> fieldNameIterator() {
+    Iterator<String> fieldNameIterator() {
         return new FieldNameIterator(this, super.fieldKeys().iterator());
     }
 
@@ -284,6 +268,16 @@ public class FastHit extends Hit {
         return removedValue;
     }
 
+    /**
+     * Returns the keys of the fields of this hit as a modifiable view.
+     * This follows the rules of key sets returned from maps: Key removals are reflected
+     * in the map, add and addAll is not supported.
+     */
+    @Override
+    public Set<String> fieldKeys() {
+        return new FieldSet(this);
+    }
+
     private Set<String> mapFieldKeys() {
         return super.fieldKeys();
     }
@@ -526,36 +520,25 @@ public class FastHit extends Hit {
             return fieldType.convert(fieldValue);
         }
 
-        void forEachField(BiConsumer<String, Object> consumer) {
-            data.traverse((ObjectTraverser)(name, value) -> {
-                if ( ! shadowed(name) && ! removed(name))
-                    consumer.accept(name, value);
-            });
-        }
-
-        Iterator<Map.Entry<String, Object>> fieldIterator() {
-            return new SummaryDataFieldIterator(this, type, data.fields().iterator());
-        }
-
-        Iterator<String> fieldNameIterator() {
-            return new SummaryDataFieldNameIterator(this, data.fields().iterator());
+        /** Decodes the given summary into the field map in the parent */
+        private void decodeInto(FastHit hit) {
+            hit.reserve(type.getFieldCount());
+            for (DocsumField field : type.getFields()) {
+                String fieldName = field.getName();
+                Inspector f = data.field(fieldName);
+                if (field.getEmulConfig().forceFillEmptyFields() || f.valid()) {
+                    if (hit.getField(fieldName) == null)
+                        hit.setField(fieldName, field.convert(f));
+                }
+            }
         }
 
-        /**
-         * Returns whether this field is present in the map properties
-         * or an earlier (lower index) summary in this hit
-         */
-        private boolean shadowed(String name) {
-            if (hit.hasField(name)) return true;
-            for (int i = 0; i < index; i++) {
-                if (hit.summaries.get(i).type.fieldNames().contains(name))
-                    return true;
-            }
-            return false;
+        private Iterator<Map.Entry<String, Object>> fieldIterator() {
+            return new SummaryDataFieldIterator(hit, type, data.fields().iterator(), index);
         }
 
-        private boolean removed(String fieldName) {
-            return hit.removedFields != null && hit.removedFields.contains(fieldName);
+        private Iterator<String> fieldNameIterator() {
+            return new SummaryDataFieldNameIterator(hit, data.fields().iterator(), index);
         }
 
         /**
@@ -564,15 +547,19 @@ public class FastHit extends Hit {
          */
         private static abstract class SummaryDataIterator<VALUE> implements Iterator<VALUE> {
 
-            private final SummaryData summaryData;
+            private final FastHit hit;
             private final Iterator<Map.Entry<String, Inspector>> fieldIterator;
+            private final int index;
 
             /** The next value or null if none, eagerly read because we need to skip removed and overwritten values */
             private VALUE next;
 
-            SummaryDataIterator(SummaryData summaryData, Iterator<Map.Entry<String, Inspector>> fieldIterator) {
-                this.summaryData = summaryData;
+            SummaryDataIterator(FastHit hit,
+                                Iterator<Map.Entry<String, Inspector>> fieldIterator,
+                                int index) {
+                this.hit = hit;
                 this.fieldIterator = fieldIterator;
+                this.index = index;
             }
 
             @Override
@@ -596,23 +583,40 @@ public class FastHit extends Hit {
                     Map.Entry<String, Inspector> nextEntry = fieldIterator.next();
                     String fieldName = nextEntry.getKey();
                     next = toValue(nextEntry);
-                    if ( next != null && ! summaryData.shadowed(fieldName) && ! summaryData.removed(fieldName))
+                    if ( next != null &&
+                         ! hit.hasField(fieldName) &&
+                         ! isRemoved(fieldName) &&
+                         ! isAlreadyReturned(fieldName))
                         return;
                 }
                 next = null;
             }
 
+            private boolean isRemoved(String fieldName) {
+                return hit.removedFields != null && hit.removedFields.contains(fieldName);
+            }
+
+            private boolean isAlreadyReturned(String fieldName) {
+                for (int i = 0; i < index; i++) {
+                    if (hit.summaries.get(i).type.fieldNames().contains(fieldName))
+                        return true;
+                }
+                return false;
+            }
+
         }
 
+
         /** Iterator over the fields in a SummaryData instance. Read only. */
         private static class SummaryDataFieldIterator extends SummaryDataIterator<Map.Entry<String, Object>> {
 
             private final DocsumDefinition type;
 
-            SummaryDataFieldIterator(SummaryData summaryData,
+            SummaryDataFieldIterator(FastHit hit,
                                      DocsumDefinition type,
-                                     Iterator<Map.Entry<String, Inspector>> fieldIterator) {
-                super(summaryData, fieldIterator);
+                                     Iterator<Map.Entry<String, Inspector>> fieldIterator,
+                                     int index) {
+                super(hit, fieldIterator, index);
                 this.type = type;
                 advanceNext();
             }
@@ -650,9 +654,10 @@ public class FastHit extends Hit {
         /** Iterator over the field names in a SummaryData instance. Read only. */
         private static class SummaryDataFieldNameIterator extends SummaryDataIterator<String> {
 
-            SummaryDataFieldNameIterator(SummaryData summaryData,
-                                         Iterator<Map.Entry<String, Inspector>> fieldIterator) {
-                super(summaryData, fieldIterator);
+            SummaryDataFieldNameIterator(FastHit hit,
+                                         Iterator<Map.Entry<String, Inspector>> fieldIterator,
+                                         int index) {
+                super(hit, fieldIterator, index);
                 advanceNext();
             }
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/searcher/DocumentSourceSearcher.java b/container-search/src/main/java/com/yahoo/prelude/searcher/DocumentSourceSearcher.java
index 415ebd7871c..164ff9a993b 100644
--- a/container-search/src/main/java/com/yahoo/prelude/searcher/DocumentSourceSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/searcher/DocumentSourceSearcher.java
@@ -74,7 +74,7 @@ public class DocumentSourceSearcher extends Searcher {
             removePropertiesNotStartingByA(attributeHit);
             attributeHit.setFillable();
             attributeHit.setRelevance(fullHit.getRelevance());
-            for (Object propertyKeyObject : fullHit.fields().keySet()) {
+            for (Object propertyKeyObject : (Set) fullHit.fields().keySet()) {
                 String propertyKey=propertyKeyObject.toString();
                 if (propertyKey.startsWith("attribute"))
                     attributeHit.setField(propertyKey, fullHit.getField(propertyKey));
diff --git a/container-search/src/main/java/com/yahoo/prelude/searcher/JuniperSearcher.java b/container-search/src/main/java/com/yahoo/prelude/searcher/JuniperSearcher.java
index ca87c0c1d46..9e1808bb08e 100644
--- a/container-search/src/main/java/com/yahoo/prelude/searcher/JuniperSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/searcher/JuniperSearcher.java
@@ -107,12 +107,6 @@ public class JuniperSearcher extends Searcher {
             if (searchDefinitionField == null) continue;
             String searchDefinitionName = searchDefinitionField.toString();
 
-            // TODO: Switch to iterate over indexes in the outer loop:
-            //for (Index index : indexFacts.getIndexes(searchDefinitionName())) {
-            //    if (index.getDynamicSummary() || index.getHighlightSummary()) {
-            //        insertTags(hit.buildHitField(index.getName(), true, true), bolding, index.getDynamicSummary());
-            //    }
-            //}
             for (String fieldName : hit.fields().keySet()) {
                 Index index = indexFacts.getIndex(fieldName, searchDefinitionName);
                 if (index.getDynamicSummary() || index.getHighlightSummary())
diff --git a/container-search/src/main/java/com/yahoo/prelude/searcher/QuotingSearcher.java b/container-search/src/main/java/com/yahoo/prelude/searcher/QuotingSearcher.java
index d4cad7f1246..7ff5b1b1a0e 100644
--- a/container-search/src/main/java/com/yahoo/prelude/searcher/QuotingSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/searcher/QuotingSearcher.java
@@ -20,7 +20,7 @@ import com.yahoo.search.searchchain.Execution;
  *
  * May be extended to do quoting template sensitive.
  *
- * @author Steinar Knutsen
+ * @author  <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
  */
 public class QuotingSearcher extends Searcher {
 
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/result/HitRenderer.java b/container-search/src/main/java/com/yahoo/search/grouping/result/HitRenderer.java
index 37906c8012f..259b219b181 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/result/HitRenderer.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/result/HitRenderer.java
@@ -13,7 +13,7 @@ import java.util.Map;
 /**
  * This is a helper class for rendering grouping results.
  *
- * @author Simon Thoresen
+ * @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen</a>
  */
 public abstract class HitRenderer {
 
@@ -50,7 +50,9 @@ public abstract class HitRenderer {
             if (hit instanceof RootGroup) {
                 renderContinuation(Continuation.THIS_PAGE, ((RootGroup)hit).continuation(), writer);
             }
-            hit.forEachField((name, value) -> writer.openTag(TAG_OUTPUT).attribute(ATR_LABEL, name).content(value, false).closeTag());
+            for (String label : hit.fieldKeys()) {
+                writer.openTag(TAG_OUTPUT).attribute(ATR_LABEL, label).content(hit.getField(label), false).closeTag();
+            }
         } else if (hit instanceof HitList) {
             writer.openTag(TAG_HIT_LIST).attribute(ATR_LABEL, ((HitList)hit).getLabel());
             renderContinuations(((HitList)hit).continuations(), writer);
diff --git a/container-search/src/main/java/com/yahoo/search/pagetemplates/engine/Organizer.java b/container-search/src/main/java/com/yahoo/search/pagetemplates/engine/Organizer.java
index 3e6e82a5584..97a5bdd72ca 100644
--- a/container-search/src/main/java/com/yahoo/search/pagetemplates/engine/Organizer.java
+++ b/container-search/src/main/java/com/yahoo/search/pagetemplates/engine/Organizer.java
@@ -37,7 +37,11 @@ public class Organizer {
         sectionGroup.setQuery(result.hits().getQuery());
         if (errors!=null && errors instanceof DefaultErrorHit)
             sectionGroup.add((DefaultErrorHit)errors);
-        result.hits().forEachField((name, value) -> sectionGroup.setField(name, value));
+        for (Iterator<Map.Entry<String, Object>> it = result.hits().fieldIterator(); it.hasNext(); ) {
+            Map.Entry<String, Object> field = it.next();
+            sectionGroup.setField(field.getKey(), field.getValue());
+        }
+
         result.setHits(sectionGroup);
     }
 
diff --git a/container-search/src/main/java/com/yahoo/search/querytransform/NGramSearcher.java b/container-search/src/main/java/com/yahoo/search/querytransform/NGramSearcher.java
index 2768a546cd0..c64927072e2 100644
--- a/container-search/src/main/java/com/yahoo/search/querytransform/NGramSearcher.java
+++ b/container-search/src/main/java/com/yahoo/search/querytransform/NGramSearcher.java
@@ -160,7 +160,7 @@ public class NGramSearcher extends Searcher {
             if (hit.isMeta()) continue;
             Object sddocname = hit.getField(Hit.SDDOCNAME_FIELD);
             if (sddocname == null) return;
-            for (String fieldName : hit.fieldKeys()) { // TODO: Iterate over indexes instead
+            for (String fieldName : hit.fieldKeys()) {
                 Index index = session.getIndex(fieldName, sddocname.toString());
                 if (index.isNGram() && (index.getHighlightSummary() || index.getDynamicSummary())) {
                     hit.setField(fieldName, recombineNGramsField(hit.getField(fieldName), index.getGramSize()));
diff --git a/container-search/src/main/java/com/yahoo/search/rendering/DefaultRenderer.java b/container-search/src/main/java/com/yahoo/search/rendering/DefaultRenderer.java
index 2d69a262f15..bae1185d6a9 100644
--- a/container-search/src/main/java/com/yahoo/search/rendering/DefaultRenderer.java
+++ b/container-search/src/main/java/com/yahoo/search/rendering/DefaultRenderer.java
@@ -185,19 +185,28 @@ public final class DefaultRenderer extends AsynchronousSectionedRenderer<Result>
 
     private void renderHitFields(XMLWriter writer, Hit hit) {
         renderSyntheticRelevanceField(writer, hit);
-        hit.forEachField((name, value) -> renderField(writer, name, value));
+        for (Iterator<Map.Entry<String, Object>> it = hit.fieldIterator(); it.hasNext(); ) {
+            renderField(writer, hit, it);
+        }
+    }
+
+    private void renderField(XMLWriter writer, Hit hit, Iterator<Map.Entry<String, Object>> it) {
+        renderGenericField(writer, hit, it.next());
     }
 
-    private void renderField(XMLWriter writer, String name, Object value) {
-        if (name.startsWith("$")) return;
+    private void renderGenericField(XMLWriter writer, Hit hit, Map.Entry<String, Object> entry) {
+        String fieldName = entry.getKey();
+
+        // skip depending on hit type
+        if (fieldName.startsWith("$")) return; // Don't render fields that start with $ // TODO: Move to should render
 
-        writeOpenFieldElement(writer, name);
-        renderFieldContent(writer, value);
+        writeOpenFieldElement(writer, fieldName);
+        renderFieldContent(writer, hit, fieldName);
         writeCloseFieldElement(writer);
     }
 
-    private void renderFieldContent(XMLWriter writer, Object value) {
-        writer.escapedContent(asXML(value), false);
+    private void renderFieldContent(XMLWriter writer, Hit hit, String fieldName) {
+        writer.escapedContent(asXML(hit.getField(fieldName)), false);
     }
 
     private String asXML(Object value) {
diff --git a/container-search/src/main/java/com/yahoo/search/rendering/JsonRenderer.java b/container-search/src/main/java/com/yahoo/search/rendering/JsonRenderer.java
index 6c7018317c3..34b02b1bee8 100644
--- a/container-search/src/main/java/com/yahoo/search/rendering/JsonRenderer.java
+++ b/container-search/src/main/java/com/yahoo/search/rendering/JsonRenderer.java
@@ -14,7 +14,7 @@ import com.yahoo.document.datatypes.FieldValue;
 import com.yahoo.document.datatypes.StringFieldValue;
 import com.yahoo.document.datatypes.TensorFieldValue;
 import com.yahoo.document.json.JsonWriter;
-import com.yahoo.lang.MutableBoolean;
+import com.yahoo.prelude.fastsearch.FastHit;
 import com.yahoo.processing.Response;
 import com.yahoo.processing.execution.Execution.Trace;
 import com.yahoo.processing.rendering.AsynchronousSectionedRenderer;
@@ -49,7 +49,6 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.io.StringWriter;
-import java.io.UncheckedIOException;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.nio.charset.StandardCharsets;
@@ -473,14 +472,14 @@ public class JsonRenderer extends AsynchronousSectionedRenderer<Result> {
         return ! (hit instanceof DefaultErrorHit);
     }
 
-    private void fieldsStart(MutableBoolean hasFieldsField) throws IOException {
-        if (hasFieldsField.get()) return;
+    private boolean fieldsStart(boolean hasFieldsField) throws IOException {
+        if (hasFieldsField) return true;
         generator.writeObjectFieldStart(FIELDS);
-        hasFieldsField.set(true);
+        return true;
     }
 
-    private void fieldsEnd(MutableBoolean hasFieldsField) throws IOException {
-        if ( ! hasFieldsField.get()) return;
+    private void fieldsEnd(boolean hasFieldsField) throws IOException {
+        if (!hasFieldsField) return;
         generator.writeEndObject();
     }
 
@@ -509,37 +508,39 @@ public class JsonRenderer extends AsynchronousSectionedRenderer<Result> {
     }
 
     private void renderAllFields(Hit hit) throws IOException {
-        MutableBoolean hasFieldsField = new MutableBoolean(false);
-        renderTotalHitCount(hit, hasFieldsField);
-        renderStandardFields(hit, hasFieldsField);
+        boolean hasFieldsField = false;
+
+        hasFieldsField |= renderTotalHitCount(hit, hasFieldsField);
+        hasFieldsField |= renderStandardFields(hit, hasFieldsField);
         fieldsEnd(hasFieldsField);
     }
 
-    private void renderStandardFields(Hit hit, MutableBoolean hasFieldsField) {
-        hit.forEachField((name, value) -> {
-            try {
-                if (shouldRender(name, value)) {
-                    fieldsStart(hasFieldsField);
-                    renderField(name, value);
-                }
-            }
-            catch (IOException e) {
-                throw new UncheckedIOException(e);
-            }
-        });
+    private boolean renderStandardFields(Hit hit, boolean initialHasFieldsField) throws IOException {
+        boolean hasFieldsField = initialHasFieldsField;
+        for (String fieldName : hit.fieldKeys()) {
+            if (!shouldRender(fieldName, hit)) continue;
+
+            // We can't look at the size of fieldKeys() and know whether we need
+            // the fields object, as all fields may be hidden.
+            hasFieldsField |= fieldsStart(hasFieldsField);
+            renderField(fieldName, hit);
+        }
+        return hasFieldsField;
     }
 
-    private boolean shouldRender(String name, Object value) {
+    private boolean shouldRender(String fieldName, Hit hit) {
         if (debugRendering) return true;
 
-        if (name.startsWith(VESPA_HIDDEN_FIELD_PREFIX)) return false;
+        if (fieldName.startsWith(VESPA_HIDDEN_FIELD_PREFIX)) return false;
 
-        if (value instanceof CharSequence && ((CharSequence) value).length() == 0) return false;
+        Object field = hit.getField(fieldName);
+
+        if (field instanceof CharSequence && ((CharSequence) field).length() == 0) return false;
 
         // StringFieldValue cannot hold a null, so checking length directly is OK:
-        if (value instanceof StringFieldValue && ((StringFieldValue) value).getString().isEmpty()) return false;
+        if (field instanceof StringFieldValue && ((StringFieldValue) field).getString().isEmpty()) return false;
 
-        if (value instanceof NanNumber) return false;
+        if (field instanceof NanNumber) return false;
 
         return true;
     }
@@ -606,16 +607,17 @@ public class JsonRenderer extends AsynchronousSectionedRenderer<Result> {
         return (id instanceof RawBucketId ? Arrays.toString(((RawBucketId) id).getTo()) : id.getTo()).toString();
     }
 
-    private void renderTotalHitCount(Hit hit, MutableBoolean hasFieldsField) throws IOException {
-        if ( ! (getRecursionLevel() == 1 && hit instanceof HitGroup)) return;
+    private boolean renderTotalHitCount(Hit hit, boolean hasFieldsField) throws IOException {
+        if ( ! (getRecursionLevel() == 1 && hit instanceof HitGroup)) return false;
 
         fieldsStart(hasFieldsField);
         generator.writeNumberField(TOTAL_COUNT, getResult().getTotalHitCount());
+        return true;
     }
 
-    private void renderField(String name, Object value) throws IOException {
-        generator.writeFieldName(name);
-        renderFieldContents(value);
+    private void renderField(String fieldName, Hit hit) throws IOException {
+        generator.writeFieldName(fieldName);
+        renderFieldContents(hit.getField(fieldName));
     }
 
     private void renderFieldContents(Object field) throws IOException {
diff --git a/container-search/src/main/java/com/yahoo/search/rendering/SyncDefaultRenderer.java b/container-search/src/main/java/com/yahoo/search/rendering/SyncDefaultRenderer.java
index 08599540cb1..dc72061e224 100644
--- a/container-search/src/main/java/com/yahoo/search/rendering/SyncDefaultRenderer.java
+++ b/container-search/src/main/java/com/yahoo/search/rendering/SyncDefaultRenderer.java
@@ -271,19 +271,25 @@ public final class SyncDefaultRenderer extends Renderer {
 
     private void renderHitFields(XMLWriter writer, Hit hit) {
         renderSyntheticRelevanceField(writer, hit);
-        hit.forEachField((name, value) -> renderField(writer, name, value));
+        for (Iterator<Map.Entry<String, Object>> it = hit.fieldIterator(); it.hasNext(); ) {
+            renderField(writer, hit, it);
+        }
     }
 
-    private void renderField(XMLWriter writer, String name, Object value) {
-        if (name.startsWith("$")) return;
+    private void renderField(XMLWriter writer, Hit hit, Iterator<Map.Entry<String, Object>> it) {
+        Map.Entry<String, Object> entry = it.next();
+        String fieldName = entry.getKey();
+
+        if ( ! shouldRenderField(hit, fieldName)) return;
+        if (fieldName.startsWith("$")) return; // Don't render fields that start with $ // TODO: Move to should render
 
-        writeOpenFieldElement(writer, name);
-        renderFieldContent(writer, value);
+        writeOpenFieldElement(writer, fieldName);
+        renderFieldContent(writer, hit, fieldName);
         writeCloseFieldElement(writer);
     }
 
-    private void renderFieldContent(XMLWriter writer, Object value) {
-        writer.escapedContent(asXML(value), false);
+    private void renderFieldContent(XMLWriter writer, Hit hit, String fieldName) {
+        writer.escapedContent(asXML(hit.getField(fieldName)), false);
     }
 
     private String asXML(Object value) {
@@ -298,10 +304,10 @@ public final class SyncDefaultRenderer extends Renderer {
     }
 
     private void renderSyntheticRelevanceField(XMLWriter writer, Hit hit) {
-        String relevancyFieldName = "relevancy";
-        Relevance relevance = hit.getRelevance();
+        final String relevancyFieldName = "relevancy";
+        final Relevance relevance = hit.getRelevance();
 
-        if (relevance != null) {
+        if (shouldRenderField(hit, relevancyFieldName) && relevance != null) {
             renderSimpleField(writer, relevancyFieldName, relevance);
         }
     }
@@ -326,6 +332,11 @@ public final class SyncDefaultRenderer extends Renderer {
         writer.closeStartTag();
     }
 
+    private boolean shouldRenderField(Hit hit, String relevancyFieldName) {
+        // skip depending on hit type
+        return true;
+    }
+
     private void renderHitAttributes(XMLWriter writer, Hit hit) {
         writer.attribute(TYPE, hit.types().stream().collect(Collectors.joining(" ")));
         if (hit.getRelevance() != null) {
diff --git a/container-search/src/main/java/com/yahoo/search/result/Hit.java b/container-search/src/main/java/com/yahoo/search/result/Hit.java
index f68916c8a68..15c148b7db7 100644
--- a/container-search/src/main/java/com/yahoo/search/result/Hit.java
+++ b/container-search/src/main/java/com/yahoo/search/result/Hit.java
@@ -21,7 +21,6 @@ import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import java.util.function.BiConsumer;
 import java.util.stream.Collectors;
 
 /**
@@ -402,30 +401,10 @@ public class Hit extends ListenableFreezableClass implements Data, Comparable<Hi
     /** Returns the name of the source creating this hit */
     public String getSource() { return source; }
 
-    /**
-     * Receive a callback on the given object for each field in this hit.
-     * This is the most resource efficient way of traversing all the fields of a hit.
-     */
-    public void forEachField(BiConsumer<String, Object> consumer) {
-        if (fields == null) return;
-        fields.forEach(consumer);
-    }
-
     /** Returns the fields of this as a read-only map. This is more costly than fieldIterator() */
+    // TODO Should it be deprecated ?
     public Map<String, Object> fields() { return getUnmodifiableFieldMap(); }
 
-    /** Returns a modifiable iterator over the fields of this */
-    public Iterator<Map.Entry<String, Object>> fieldIterator() { return getFieldMap().entrySet().iterator(); }
-
-    /**
-     * Returns the keys of the fields of this hit as a modifiable view.
-     * This follows the rules of key sets returned from maps: Key removals are reflected
-     * in the map, add and addAll is not supported.
-     */
-    public Set<String> fieldKeys() {
-        return getFieldMap().keySet();
-    }
-
     /** Allocate room for the given number of fields to avoid resizing. */
     public void reserve(int minSize) {
         getFieldMap(minSize);
@@ -440,6 +419,9 @@ public class Hit extends ListenableFreezableClass implements Data, Comparable<Hi
         return getFieldMap().put(key, value);
     }
 
+    /** Returns a modifiable iterator over the fields of this */
+    public Iterator<Map.Entry<String, Object>> fieldIterator() { return getFieldMap().entrySet().iterator(); }
+
     /** Returns a field value or null if not present */
     public Object getField(String value) { return fields != null ? fields.get(value) : null; }
 
@@ -457,6 +439,15 @@ public class Hit extends ListenableFreezableClass implements Data, Comparable<Hi
         return getFieldMap().remove(field);
     }
 
+    /**
+     * Returns the keys of the fields of this hit as a modifiable view.
+     * This follows the rules of key sets returned from maps: Key removals are reflected
+     * in the map, add and addAll is not supported.
+     */
+    public Set<String> fieldKeys() {
+        return getFieldMap().keySet();
+    }
+
     protected boolean hasField(String name) {
         return fields != null && fields.containsKey(name);
     }
diff --git a/container-search/src/main/java/com/yahoo/search/yql/FieldFilter.java b/container-search/src/main/java/com/yahoo/search/yql/FieldFilter.java
index 14dce2f6342..75c2865d0a5 100644
--- a/container-search/src/main/java/com/yahoo/search/yql/FieldFilter.java
+++ b/container-search/src/main/java/com/yahoo/search/yql/FieldFilter.java
@@ -52,7 +52,12 @@ public class FieldFilter extends Searcher {
         for (Iterator<Hit> i = result.hits().unorderedDeepIterator(); i.hasNext();) {
             Hit h = i.next();
             if (h.isMeta()) continue;
-            h.fieldKeys().retainAll(requestedFields);
+            for (Iterator<Entry<String, Object>> fields = h.fieldIterator(); fields.hasNext();) {
+                Entry<String, Object> field = fields.next();
+                if ( ! requestedFields.contains(field.getKey()))
+                    fields.remove();
+            }
+
         }
     }
 
diff --git a/container-search/src/test/java/com/yahoo/prelude/fastsearch/SlimeSummaryTestCase.java b/container-search/src/test/java/com/yahoo/prelude/fastsearch/SlimeSummaryTestCase.java
index 1b74a6c5b29..83871b559b4 100644
--- a/container-search/src/test/java/com/yahoo/prelude/fastsearch/SlimeSummaryTestCase.java
+++ b/container-search/src/test/java/com/yahoo/prelude/fastsearch/SlimeSummaryTestCase.java
@@ -31,7 +31,6 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
 
 public class SlimeSummaryTestCase {
 
@@ -287,14 +286,6 @@ public class SlimeSummaryTestCase {
             assertEquals(field.getValue(), expected.get(field.getKey()));
         }
         assertEquals(expected.size(), fieldIteratorFieldCount);
-        // field traverser
-        Map<String, Object> traversed = new HashMap<>();
-        hit.forEachField((name, value) -> {
-            if (traversed.containsKey(name))
-                fail("Multiple callbacks for " + name);
-            traversed.put(name, value);
-        });
-        assertEquals(expected, traversed);
     }
 
     private byte[] emptySummary() {
diff --git a/container-search/src/test/java/com/yahoo/search/rendering/JsonRendererTestCase.java b/container-search/src/test/java/com/yahoo/search/rendering/JsonRendererTestCase.java
index 4a0075c0cf1..defabc7463b 100644
--- a/container-search/src/test/java/com/yahoo/search/rendering/JsonRendererTestCase.java
+++ b/container-search/src/test/java/com/yahoo/search/rendering/JsonRendererTestCase.java
@@ -1069,6 +1069,7 @@ public class JsonRendererTestCase {
         r.getElapsedTime().add(t);
         renderer.setTimeSource(() -> 8L);
         String summary = render(r);
+        System.out.println(summary);
         assertEqualJson(expected, summary);
     }
 
diff --git a/container-search/src/test/java/com/yahoo/search/yql/FieldFilterTestCase.java b/container-search/src/test/java/com/yahoo/search/yql/FieldFilterTestCase.java
index 50313b630ea..f5097aec6e1 100644
--- a/container-search/src/test/java/com/yahoo/search/yql/FieldFilterTestCase.java
+++ b/container-search/src/test/java/com/yahoo/search/yql/FieldFilterTestCase.java
@@ -20,10 +20,9 @@ import com.yahoo.search.searchchain.testutil.DocumentSourceSearcher;
 /**
  * Smoketest that we remove fields in a sane manner.
  *
- * @author Steinar Knutsen
+ * @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
  */
 public class FieldFilterTestCase {
-
     private static final String FIELD_C = "c";
     private static final String FIELD_B = "b";
     private static final String FIELD_A = "a";
@@ -42,7 +41,8 @@ public class FieldFilterTestCase {
         DocumentSourceSearcher mockBackend = new DocumentSourceSearcher();
         mockBackend.addResult(query, result);
 
-        searchChain = new Chain<Searcher>(new FieldFilter(), mockBackend);
+        searchChain = new Chain<Searcher>(new FieldFilter(),
+                mockBackend);
         context = Execution.Context.createContextStub(null);
         execution = new Execution(searchChain, context);