Turn NumericValues into functional interface (elastic#135068)

Author: martijnvg

server/src/main/java/org/elasticsearch/index/codec/tsdb/es819/ES819TSDBDocValuesProducer.java

@@ -1232,8 +1232,9 @@ private static void readTermDict(IndexInput meta, TermsDictEntry entry) throws I
         entry.termsIndexAddressesLength = meta.readLong();
     }
 
-    private abstract static class NumericValues {
-        abstract long advance(long index) throws IOException;
+    @FunctionalInterface
+    private interface NumericValues {
+        long advance(long index) throws IOException;
     }
 
     static final class SortedOrdinalReader {
@@ -1603,30 +1604,26 @@ private NumericValues getValues(NumericEntry entry, final long maxOrd) throws IO
 
         final IndexInput valuesData = data.slice("values", entry.valuesOffset, entry.valuesLength);
         final int bitsPerOrd = maxOrd >= 0 ? PackedInts.bitsRequired(maxOrd - 1) : -1;
-        return new NumericValues() {
 
-            private final TSDBDocValuesEncoder decoder = new TSDBDocValuesEncoder(ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SIZE);
-            private long currentBlockIndex = -1;
-            private final long[] currentBlock = new long[ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SIZE];
-
-            @Override
-            long advance(long index) throws IOException {
-                final long blockIndex = index >>> ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SHIFT;
-                final int blockInIndex = (int) (index & ES819TSDBDocValuesFormat.NUMERIC_BLOCK_MASK);
-                if (blockIndex != currentBlockIndex) {
-                    // no need to seek if the loading block is the next block
-                    if (currentBlockIndex + 1 != blockIndex) {
-                        valuesData.seek(indexReader.get(blockIndex));
-                    }
-                    currentBlockIndex = blockIndex;
-                    if (bitsPerOrd == -1) {
-                        decoder.decode(valuesData, currentBlock);
-                    } else {
-                        decoder.decodeOrdinals(valuesData, currentBlock, bitsPerOrd);
-                    }
+        final long[] currentBlockIndex = { -1 };
+        final long[] currentBlock = new long[ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SIZE];
+        final TSDBDocValuesEncoder decoder = new TSDBDocValuesEncoder(ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SIZE);
+        return index -> {
+            final long blockIndex = index >>> ES819TSDBDocValuesFormat.NUMERIC_BLOCK_SHIFT;
+            final int blockInIndex = (int) (index & ES819TSDBDocValuesFormat.NUMERIC_BLOCK_MASK);
+            if (blockIndex != currentBlockIndex[0]) {
+                // no need to seek if the loading block is the next block
+                if (currentBlockIndex[0] + 1 != blockIndex) {
+                    valuesData.seek(indexReader.get(blockIndex));
+                }
+                currentBlockIndex[0] = blockIndex;
+                if (bitsPerOrd == -1) {
+                    decoder.decode(valuesData, currentBlock);
+                } else {
+                    decoder.decodeOrdinals(valuesData, currentBlock, bitsPerOrd);
                 }
-                return currentBlock[blockInIndex];
             }
+            return currentBlock[blockInIndex];
         };
     }