Add debug collector usage

Signed-off-by: Asim Mahmood <[email protected]>

Author: asimmahmood1

server/src/main/java/org/opensearch/search/aggregations/bucket/histogram/DateHistogramAggregator.java

@@ -115,6 +115,12 @@ class DateHistogramAggregator extends BucketsAggregator implements SizedBucketAg
     private final String fieldName;
     private final boolean fieldIndexSort;
 
+    // Collector usage tracking fields
+    private int noOpCollectorsUsed;
+    private int singleValuedCollectorsUsed;
+    private int multiValuedCollectorsUsed;
+    private int skipListCollectorsUsed;
+
     DateHistogramAggregator(
         String name,
         AggregatorFactories factories,
@@ -215,6 +221,7 @@ protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws
     @Override
     public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
         if (valuesSource == null) {
+            noOpCollectorsUsed++;
             return LeafBucketCollector.NO_OP_COLLECTOR;
         }
 
@@ -228,12 +235,14 @@ public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCol
         if (skipper != null && singleton != null) {
             // TODO: add hard bounds support
             if (hardBounds == null && parent == null) {
+                skipListCollectorsUsed++;
                 return new HistogramSkiplistLeafCollector(singleton, skipper, preparedRounding, bucketOrds, sub, this);
             }
         }
 
         if (singleton != null) {
             // Optimized path for single-valued fields
+            singleValuedCollectorsUsed++;
             return new LeafBucketCollectorBase(sub, values) {
                 @Override
                 public void collect(int doc, long owningBucketOrd) throws IOException {
@@ -246,6 +255,7 @@ public void collect(int doc, long owningBucketOrd) throws IOException {
         }
 
         // Original path for multi-valued fields
+        multiValuedCollectorsUsed++;
         return new LeafBucketCollectorBase(sub, values) {
             @Override
             public void collect(int doc, long owningBucketOrd) throws IOException {
@@ -402,9 +412,13 @@ public void doClose() {
 
     @Override
     public void collectDebugInfo(BiConsumer<String, Object> add) {
+        super.collectDebugInfo(add);
         add.accept("total_buckets", bucketOrds.size());
         filterRewriteOptimizationContext.populateDebugInfo(add);
-        // TODO: add skiplist, single and multi-value usage
+        add.accept("no_op_collectors_used", noOpCollectorsUsed);
+        add.accept("single_valued_collectors_used", singleValuedCollectorsUsed);
+        add.accept("multi_valued_collectors_used", multiValuedCollectorsUsed);
+        add.accept("skip_list_collectors_used", skipListCollectorsUsed);
     }
 
     /**

server/src/test/java/org/opensearch/search/aggregations/bucket/histogram/DateHistogramAggregatorTests.java

@@ -293,7 +293,6 @@ public void testSkiplistWithSingleValueDates() throws IOException {
                     false,
                     fieldType
                 );
-                System.out.println(histogram.getBuckets());
                 assertEquals(3, histogram.getBuckets().size()); // 2015, 2016, 2017 (only type 2 docs)
 
                 assertEquals("2015-01-01T00:00:00.000Z", histogram.getBuckets().get(0).getKeyAsString());