remaining disjunction scorer full understand

Signed-off-by: bowenlan-amzn <bowenlan23@gmail.com>

server/src/main/java/org/opensearch/search/aggregations/metrics/CardinalityAggregator.java

@@ -125,6 +125,7 @@ private Collector pickCollector(LeafReaderContext ctx) throws IOException {
         if (valuesSource instanceof ValuesSource.Bytes.WithOrdinals) {
             ValuesSource.Bytes.WithOrdinals source = (ValuesSource.Bytes.WithOrdinals) valuesSource;
             final SortedSetDocValues ordinalValues = source.ordinalsValues(ctx);
+            final SortedSetDocValues globalOrdinalValues = source.globalOrdinalsValues(ctx);
             final long maxOrd = ordinalValues.getValueCount();
             if (maxOrd == 0) {
                 emptyCollectorsUsed++;
@@ -179,7 +180,7 @@ public InternalAggregation buildAggregation(long owningBucketOrdinal) {
         if (counts == null || owningBucketOrdinal >= counts.maxOrd() || counts.cardinality(owningBucketOrdinal) == 0) {
             return buildEmptyAggregation();
         }
-        // We need to build a copy because the returned Aggregation needs remain usable after
+        // We need to build a copy because the returned Aggregation needs to remain usable after
         // this Aggregator (and its HLL++ counters) is released.
         AbstractHyperLogLogPlusPlus copy = counts.clone(owningBucketOrdinal, BigArrays.NON_RECYCLING_INSTANCE);
         return new InternalCardinality(name, copy, metadata());
@@ -322,6 +323,9 @@ public void collect(int doc, long bucketOrd) throws IOException {
                     bits.set((int) ord);
                 }
             }
+            // for this owning bucket ord, save the values of current doc as value ordinals bits
+            // visitedOrds (array with index as owning bucket, value as bits)
+            // ordinals is number array, each element representing a text or term, and sorted by the values
         }
 
         @Override
@@ -336,6 +340,7 @@ public void postCollect() throws IOException {
 
                 try (LongArray hashes = bigArrays.newLongArray(maxOrd, false)) {
                     final MurmurHash3.Hash128 hash = new MurmurHash3.Hash128();
+                    // for every ordinal, we want the hash of its value
                     for (long ord = allVisitedOrds.nextSetBit(0); ord < Long.MAX_VALUE; ord = ord + 1 < maxOrd
                         ? allVisitedOrds.nextSetBit(ord + 1)
                         : Long.MAX_VALUE) {
@@ -347,6 +352,7 @@ public void postCollect() throws IOException {
                     for (long bucket = visitedOrds.size() - 1; bucket >= 0; --bucket) {
                         final BitArray bits = visitedOrds.get(bucket);
                         if (bits != null) {
+                            // for every ordinal of this bucket, we collect by using its hash
                             for (long ord = bits.nextSetBit(0); ord < Long.MAX_VALUE; ord = ord + 1 < maxOrd
                                 ? bits.nextSetBit(ord + 1)
                                 : Long.MAX_VALUE) {

server/src/main/java/org/opensearch/search/aggregations/metrics/DisjunctionWithDynamicPruningScorer.java

@@ -31,7 +31,7 @@
  * rest of the search space, so this term's subscorer DISI can be safely removed from list of subscorer to process.
  * <p>
  * 2. {@link #removeAllDISIsOnCurrentDoc()} breaks the invariant of Conjuction DISI i.e. the docIDs of all sub-scorers should be
- * less than or equal to current docID iterator is pointing to. When we remove elements from priority, it results in heapify action, which modifies
+ * less than or equal to current docID iterator is pointing to. When we remove elements from disi priority queue, it results in heapify action, which modifies
  * the top of the priority queye, which represents the current docID for subscorers here. To address this, we are wrapping the
  * iterator with {@link SlowDocIdPropagatorDISI} which keeps the iterator pointing to last docID before {@link #removeAllDISIsOnCurrentDoc()}
  * is called and updates this docID only when next() or advance() is called.
@@ -97,7 +97,6 @@ public DocIdSetIterator iterator() {
 
     private static class SlowDocIdPropagatorDISI extends DocIdSetIterator {
         DocIdSetIterator disi;
-
         Integer curDocId;
 
         SlowDocIdPropagatorDISI(DocIdSetIterator disi, Integer curDocId) {
@@ -147,11 +146,6 @@ public TwoPhaseIterator twoPhaseIterator() {
         return twoPhase;
     }
 
-    @Override
-    public float getMaxScore(int i) throws IOException {
-        return 0;
-    }
-
     private class TwoPhase extends TwoPhaseIterator {
 
         private final float matchCost;
@@ -231,7 +225,6 @@ public float matchCost() {
         }
     }
 
-
     @Override
     public final int docID() {
         return subScorers.top().doc;
@@ -262,4 +255,9 @@ public final Collection<ChildScorable> getChildren() throws IOException {
         }
         return children;
     }
+
+    @Override
+    public float getMaxScore(int i) throws IOException {
+        return 0;
+    }
 }

server/src/main/java/org/opensearch/search/aggregations/metrics/InternalCardinality.java

@@ -117,7 +117,6 @@ public InternalAggregation reduce(List<InternalAggregation> aggregations, Reduce
             return aggregations.get(0);
         } else {
             return new InternalCardinality(name, reduced, getMetadata());
-
         }
     }