Enforce optimal IndexedInts iteration

benchmarks/src/main/java/io/druid/benchmark/CompressedVSizeColumnarMultiIntsBenchmark.java

@@ -152,7 +152,7 @@ public void uncompressed(Blackhole blackhole)
   {
     for (int i = filter.nextSetBit(0); i >= 0; i = filter.nextSetBit(i + 1)) {
       IndexedInts row = uncompressed.get(i);
-      for (int j = 0; j < row.size(); j++) {
+      for (int j = 0, rowSize = row.size(); j < rowSize; j++) {
         blackhole.consume(row.get(j));
       }
     }
@@ -165,7 +165,7 @@ public void compressed(Blackhole blackhole)
   {
     for (int i = filter.nextSetBit(0); i >= 0; i = filter.nextSetBit(i + 1)) {
       IndexedInts row = compressed.get(i);
-      for (int j = 0; j < row.size(); j++) {
+      for (int j = 0, rowSize = row.size(); j < rowSize; j++) {
         blackhole.consume(row.get(j));
       }
     }

extensions-contrib/distinctcount/src/main/java/io/druid/query/aggregation/distinctcount/DistinctCountAggregator.java

@@ -43,7 +43,7 @@ public DistinctCountAggregator(
   public void aggregate()
   {
     IndexedInts row = selector.getRow();
-    for (int i = 0; i < row.size(); i++) {
+    for (int i = 0, rowSize = row.size(); i < rowSize; i++) {
       int index = row.get(i);
       mutableBitmap.add(index);
     }

extensions-contrib/distinctcount/src/main/java/io/druid/query/aggregation/distinctcount/DistinctCountBufferAggregator.java

@@ -53,7 +53,7 @@ public void aggregate(ByteBuffer buf, int position)
   {
     MutableBitmap mutableBitmap = getMutableBitmap(position);
     IndexedInts row = selector.getRow();
-    for (int i = 0; i < row.size(); i++) {
+    for (int i = 0, rowSize = row.size(); i < rowSize; i++) {
       int index = row.get(i);
       mutableBitmap.add(index);
     }

processing/src/main/java/io/druid/query/aggregation/cardinality/types/StringCardinalityAggregatorColumnSelectorStrategy.java

@@ -62,7 +62,7 @@ public void hashRow(DimensionSelector dimSelector, Hasher hasher)
   public void hashValues(DimensionSelector dimSelector, HyperLogLogCollector collector)
   {
     IndexedInts row = dimSelector.getRow();
-    for (int i = 0; i < row.size(); i++) {
+    for (int i = 0, rowSize = row.size(); i < rowSize; i++) {
       int index = row.get(i);
       final String value = dimSelector.lookupName(index);
       collector.add(CardinalityAggregator.hashFn.hashUnencodedChars(nullToSpecial(value)).asBytes());

processing/src/main/java/io/druid/query/groupby/GroupByQueryEngine.java

@@ -190,12 +190,13 @@ private List<ByteBuffer> updateValues(
 
         final DimensionSelector dimSelector = dims.get(0);
         final IndexedInts row = dimSelector.getRow();
-        if (row == null || row.size() == 0) {
+        final int rowSize = row.size();
+        if (rowSize == 0) {
           ByteBuffer newKey = key.duplicate();
           newKey.putInt(MISSING_VALUE);
           unaggregatedBuffers = updateValues(newKey, dims.subList(1, dims.size()));
         } else {
-          for (int i = 0; i < row.size(); i++) {
+          for (int i = 0; i < rowSize; i++) {
             ByteBuffer newKey = key.duplicate();
             int dimValue = row.get(i);
             newKey.putInt(dimValue);

processing/src/main/java/io/druid/query/groupby/epinephelinae/GroupByQueryEngineV2.java

@@ -639,12 +639,13 @@ private void aggregateMultiValueDims(IntGrouper grouper)
       }
 
       while (!cursor.isDone()) {
-        if (multiValues.size() == 0) {
+        int multiValuesSize = multiValues.size();
+        if (multiValuesSize == 0) {
           if (!grouper.aggregate(GroupByColumnSelectorStrategy.GROUP_BY_MISSING_VALUE).isOk()) {
             return;
           }
         } else {
-          for (; nextValIndex < multiValues.size(); nextValIndex++) {
+          for (; nextValIndex < multiValuesSize; nextValIndex++) {
             if (!grouper.aggregate(multiValues.get(nextValIndex)).isOk()) {
               return;
             }

processing/src/main/java/io/druid/query/groupby/epinephelinae/column/DictionaryBuildingStringGroupByColumnSelectorStrategy.java

@@ -75,7 +75,7 @@ public void initColumnValues(ColumnValueSelector selector, int columnIndex, Obje
     }
     int rowSize = row.size();
     newRow.ensureSize(rowSize);
-    for (int i = 0; i < row.size(); i++) {
+    for (int i = 0; i < rowSize; i++) {
       final String value = dimSelector.lookupName(row.get(i));
       final int dictId = reverseDictionary.getInt(value);
       if (dictId < 0) {

processing/src/main/java/io/druid/query/metadata/SegmentAnalyzer.java

@@ -276,9 +276,9 @@ public Long accumulate(Long accumulated, Cursor cursor)
               }
               long current = accumulated;
               while (!cursor.isDone()) {
-                final IndexedInts vals = selector.getRow();
-                for (int i = 0; i < vals.size(); ++i) {
-                  final String dimVal = selector.lookupName(vals.get(i));
+                final IndexedInts row = selector.getRow();
+                for (int i = 0, rowSize = row.size(); i < rowSize; ++i) {
+                  final String dimVal = selector.lookupName(row.get(i));
                   if (dimVal != null && !dimVal.isEmpty()) {
                     current += StringUtils.estimatedBinaryLengthAsUTF8(dimVal);
                   }

processing/src/main/java/io/druid/query/search/SearchQueryRunner.java

@@ -127,9 +127,9 @@ public void updateSearchResultSet(
     )
     {
       if (selector != null && !isNilSelector(selector)) {
-        final IndexedInts vals = selector.getRow();
-        for (int i = 0; i < vals.size(); ++i) {
-          final String dimVal = selector.lookupName(vals.get(i));
+        final IndexedInts row = selector.getRow();
+        for (int i = 0, rowSize = row.size(); i < rowSize; ++i) {
+          final String dimVal = selector.lookupName(row.get(i));
           if (searchQuerySpec.accept(dimVal)) {
             set.addTo(new SearchHit(outputName, Strings.nullToEmpty(dimVal)), 1);
             if (set.size() >= limit) {

processing/src/main/java/io/druid/query/select/SelectQueryEngine.java

@@ -111,21 +111,19 @@ public static class StringSelectColumnSelectorStrategy implements SelectColumnSe
     @Override
     public void addRowValuesToSelectResult(String outputName, DimensionSelector selector, Map<String, Object> resultMap)
     {
-      if (selector == null) {
+      final IndexedInts row = selector.getRow();
+      int rowSize = row.size();
+      if (rowSize == 0) {
         resultMap.put(outputName, null);
+      } else if (rowSize == 1) {
+        final String dimVal = selector.lookupName(row.get(0));
+        resultMap.put(outputName, dimVal);
       } else {
-        final IndexedInts vals = selector.getRow();
-
-        if (vals.size() == 1) {
-          final String dimVal = selector.lookupName(vals.get(0));
-          resultMap.put(outputName, dimVal);
-        } else {
-          List<String> dimVals = new ArrayList<>(vals.size());
-          for (int i = 0; i < vals.size(); ++i) {
-            dimVals.add(selector.lookupName(vals.get(i)));
-          }
-          resultMap.put(outputName, dimVals);
+        List<String> dimVals = new ArrayList<>(rowSize);
+        for (int i = 0; i < rowSize; ++i) {
+          dimVals.add(selector.lookupName(row.get(i)));
         }
+        resultMap.put(outputName, dimVals);
       }
     }
   }
@@ -300,7 +298,9 @@ public static Map<String, Object> singleEvent(
     theEvent.put(timestampKey, DateTimes.utc(timestampColumnSelector.getLong()));
 
     for (ColumnSelectorPlus<SelectColumnSelectorStrategy> selectorPlus : selectorPlusList) {
-      selectorPlus.getColumnSelectorStrategy().addRowValuesToSelectResult(selectorPlus.getOutputName(), selectorPlus.getSelector(), theEvent);
+      selectorPlus
+          .getColumnSelectorStrategy()
+          .addRowValuesToSelectResult(selectorPlus.getOutputName(), selectorPlus.getSelector(), theEvent);
     }
 
     for (Map.Entry<String, BaseObjectColumnValueSelector<?>> metSelector : metSelectors.entrySet()) {

processing/src/main/java/io/druid/query/topn/types/StringTopNColumnSelectorStrategy.java

@@ -132,7 +132,7 @@ private long dimExtractionScanAndAggregateWithCardinalityKnown(
     long processedRows = 0;
     while (!cursor.isDone()) {
       final IndexedInts dimValues = selector.getRow();
-      for (int i = 0; i < dimValues.size(); ++i) {
+      for (int i = 0, size = dimValues.size(); i < size; ++i) {
         final int dimIndex = dimValues.get(i);
         Aggregator[] theAggregators = rowSelector[dimIndex];
         if (theAggregators == null) {
@@ -165,7 +165,7 @@ private long dimExtractionScanAndAggregateWithCardinalityUnknown(
     long processedRows = 0;
     while (!cursor.isDone()) {
       final IndexedInts dimValues = selector.getRow();
-      for (int i = 0; i < dimValues.size(); ++i) {
+      for (int i = 0, size = dimValues.size(); i < size; ++i) {
         final int dimIndex = dimValues.get(i);
         final String key = selector.lookupName(dimIndex);
 

processing/src/main/java/io/druid/segment/DimensionSelector.java

@@ -167,16 +167,17 @@ default boolean isNull()
   default Object defaultGetObject()
   {
     IndexedInts row = getRow();
-    if (row.size() == 0) {
+    int rowSize = row.size();
+    if (rowSize == 0) {
       return null;
-    }
-    if (row.size() == 1) {
+    } else if (rowSize == 1) {
       return lookupName(row.get(0));
+    } else {
+      final String[] strings = new String[rowSize];
+      for (int i = 0; i < rowSize; i++) {
+        strings[i] = lookupName(row.get(i));
+      }
+      return strings;
     }
-    final String[] strings = new String[row.size()];
-    for (int i = 0; i < row.size(); i++) {
-      strings[i] = lookupName(row.get(i));
-    }
-    return strings;
   }
 }

processing/src/main/java/io/druid/segment/data/CompressedVSizeColumnarMultiIntsSupplier.java

@@ -109,7 +109,7 @@ public static CompressedVSizeColumnarMultiIntsSupplier fromIterable(
     while (objects.hasNext()) {
       IndexedInts next = objects.next();
       offsetList.add(offset);
-      for (int i = 0; i < next.size(); i++) {
+      for (int i = 0, size = next.size(); i < size; i++) {
         values.add(next.get(i));
       }
       offset += next.size();

processing/src/main/java/io/druid/segment/data/V3CompressedVSizeColumnarMultiIntsSupplier.java

@@ -91,7 +91,7 @@ public static V3CompressedVSizeColumnarMultiIntsSupplier fromIterable(
     while (objects.hasNext()) {
       IndexedInts next = objects.next();
       offsetList.add(offset);
-      for (int i = 0; i < next.size(); i++) {
+      for (int i = 0, size = next.size(); i < size; i++) {
         values.add(next.get(i));
       }
       offset += next.size();

processing/src/test/java/io/druid/segment/data/CompressedColumnarIntsSupplierTest.java

@@ -205,7 +205,7 @@ public void run()
 
         try {
           for (int i = 0; i < numRuns; ++i) {
-            for (int j = 0; j < columnarInts.size(); ++j) {
+            for (int j = 0, size = columnarInts.size(); j < size; ++j) {
               final long val = vals[j];
               final long indexedVal = columnarInts.get(j);
               if (Longs.compare(val, indexedVal) != 0) {
@@ -285,7 +285,7 @@ private void assertIndexMatchesVals()
 
     // sequential access
     int[] indices = new int[vals.length];
-    for (int i = 0; i < columnarInts.size(); ++i) {
+    for (int i = 0, size = columnarInts.size(); i < size; ++i) {
       Assert.assertEquals(vals[i], columnarInts.get(i), 0.0);
       indices[i] = i;
     }

processing/src/test/java/io/druid/segment/data/CompressedVSizeColumnarIntsSupplierTest.java

@@ -282,7 +282,7 @@ public void run()
 
         try {
           for (int i = 0; i < numRuns; ++i) {
-            for (int j = 0; j < columnarInts.size(); ++j) {
+            for (int j = 0, size = columnarInts.size(); j < size; ++j) {
               final long val = vals[j];
               final long indexedVal = columnarInts.get(j);
               if (Longs.compare(val, indexedVal) != 0) {
@@ -362,7 +362,7 @@ private void assertIndexMatchesVals()
 
     // sequential access of every element
     int[] indices = new int[vals.length];
-    for (int i = 0; i < columnarInts.size(); ++i) {
+    for (int i = 0, size = columnarInts.size(); i < size; ++i) {
       final int expected = vals[i];
       final int actual = columnarInts.get(i);
       Assert.assertEquals(expected, actual);

processing/src/test/java/io/druid/segment/data/CompressedVSizeColumnarMultiIntsSupplierTest.java

@@ -107,7 +107,7 @@ public void testIterators()
       final IndexedInts vSizeIndexedInts = iterator.next();
 
       Assert.assertEquals(ints.length, vSizeIndexedInts.size());
-      for (int i = 0; i < vSizeIndexedInts.size(); i++) {
+      for (int i = 0, size = vSizeIndexedInts.size(); i < size; i++) {
         Assert.assertEquals(ints[i], vSizeIndexedInts.get(i));
       }
       row++;

processing/src/test/java/io/druid/segment/data/V3CompressedVSizeColumnarMultiIntsSerializerTest.java

@@ -155,7 +155,7 @@ private void checkSerializedSizeAndData(int offsetChunkFactor, int valueChunkFac
         for (int i = 0; i < vals.size(); ++i) {
           IndexedInts subVals = columnarMultiInts.get(i);
           assertEquals(subVals.size(), vals.get(i).length);
-          for (int j = 0; j < subVals.size(); ++j) {
+          for (int j = 0, size = subVals.size(); j < size; ++j) {
             assertEquals(subVals.get(j), vals.get(i)[j]);
           }
         }
@@ -278,7 +278,7 @@ private void checkV2SerializedSizeAndData(int offsetChunkFactor, int valueChunkF
       for (int i = 0; i < vals.size(); ++i) {
         IndexedInts subVals = columnarMultiInts.get(i);
         assertEquals(subVals.size(), vals.get(i).length);
-        for (int j = 0; j < subVals.size(); ++j) {
+        for (int j = 0, size = subVals.size(); j < size; ++j) {
           assertEquals(subVals.get(j), vals.get(i)[j]);
         }
       }

server/src/main/java/io/druid/segment/realtime/firehose/IngestSegmentFirehose.java

@@ -21,7 +21,6 @@
 
 import com.google.common.base.Function;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import io.druid.data.input.Firehose;
 import io.druid.data.input.InputRow;
@@ -49,6 +48,7 @@
 
 import javax.annotation.Nullable;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -139,12 +139,13 @@ public InputRow next()
                                           final DimensionSelector selector = dimSelector.getValue();
                                           final IndexedInts vals = selector.getRow();
 
-                                          if (vals.size() == 1) {
+                                          int valsSize = vals.size();
+                                          if (valsSize == 1) {
                                             final String dimVal = selector.lookupName(vals.get(0));
                                             theEvent.put(dim, dimVal);
-                                          } else {
-                                            List<String> dimVals = Lists.newArrayList();
-                                            for (int i = 0; i < vals.size(); ++i) {
+                                          } else if (valsSize > 1) {
+                                            List<String> dimVals = new ArrayList<>(valsSize);
+                                            for (int i = 0; i < valsSize; ++i) {
                                               dimVals.add(selector.lookupName(vals.get(i)));
                                             }
                                             theEvent.put(dim, dimVals);