Unify precomputation of aggregations behind a common API

server/src/main/java/org/opensearch/search/aggregations/AggregatorBase.java

@@ -32,6 +32,7 @@
 package org.opensearch.search.aggregations;
 
 import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.search.CollectionTerminatedException;
 import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.search.ScoreMode;
 import org.opensearch.core.common.breaker.CircuitBreaker;
@@ -200,6 +201,9 @@ public Map<String, Object> metadata() {
 
     @Override
     public final LeafBucketCollector getLeafCollector(LeafReaderContext ctx) throws IOException {
+        if (tryPrecomputeAggregationForLeaf(ctx)) {
+            throw new CollectionTerminatedException();
+        }
         preGetSubLeafCollectors(ctx);
         final LeafBucketCollector sub = collectableSubAggregators.getLeafCollector(ctx);
         return getLeafCollector(ctx, sub);
@@ -216,6 +220,10 @@ protected void preGetSubLeafCollectors(LeafReaderContext ctx) throws IOException
      */
     protected void doPreCollection() throws IOException {}
 
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+        return false;
+    }
+
     @Override
     public final void preCollection() throws IOException {
         List<BucketCollector> collectors = Arrays.asList(subAggregators);
@@ -251,8 +259,8 @@ public Aggregator[] subAggregators() {
     public Aggregator subAggregator(String aggName) {
         if (subAggregatorbyName == null) {
             subAggregatorbyName = new HashMap<>(subAggregators.length);
-            for (int i = 0; i < subAggregators.length; i++) {
-                subAggregatorbyName.put(subAggregators[i].name(), subAggregators[i]);
+            for (Aggregator subAggregator : subAggregators) {
+                subAggregatorbyName.put(subAggregator.name(), subAggregator);
             }
         }
         return subAggregatorbyName.get(aggName);

server/src/main/java/org/opensearch/search/aggregations/bucket/composite/CompositeAggregator.java

@@ -564,10 +564,13 @@ private void processLeafFromQuery(LeafReaderContext ctx, Sort indexSortPrefix) t
     }
 
     @Override
-    protected LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
-        boolean optimized = filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, segmentMatchAll(context, ctx));
-        if (optimized) throw new CollectionTerminatedException();
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+        finishLeaf(); // May need to wrap up previous leaf if it could not be precomputed
+        return filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, segmentMatchAll(context, ctx));
+    }
 
+    @Override
+    protected LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
         finishLeaf();
 
         boolean fillDocIdSet = deferredCollectors != NO_OP_COLLECTOR;

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

@@ -33,7 +33,6 @@
 
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.SortedNumericDocValues;
-import org.apache.lucene.search.CollectionTerminatedException;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.search.ScoreMode;
 import org.apache.lucene.util.CollectionUtil;
@@ -187,22 +186,23 @@ public ScoreMode scoreMode() {
     }
 
     @Override
-    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
-        if (valuesSource == null) {
-            return LeafBucketCollector.NO_OP_COLLECTOR;
-        }
-
-        boolean optimized = filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, segmentMatchAll(context, ctx));
-        if (optimized) throw new CollectionTerminatedException();
-
-        SortedNumericDocValues values = valuesSource.longValues(ctx);
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
         CompositeIndexFieldInfo supportedStarTree = getSupportedStarTree(this.context.getQueryShardContext());
         if (supportedStarTree != null) {
             if (preComputeWithStarTree(ctx, supportedStarTree) == true) {
-                throw new CollectionTerminatedException();
+                return true;
             }
         }
+        return filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, segmentMatchAll(context, ctx));
+    }
 
+    @Override
+    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
+        if (valuesSource == null) {
+            return LeafBucketCollector.NO_OP_COLLECTOR;
+        }
+
+        SortedNumericDocValues values = valuesSource.longValues(ctx);
         return new LeafBucketCollectorBase(sub, values) {
             @Override
             public void collect(int doc, long owningBucketOrd) throws IOException {

server/src/main/java/org/opensearch/search/aggregations/bucket/range/RangeAggregator.java

@@ -32,7 +32,6 @@
 package org.opensearch.search.aggregations.bucket.range;
 
 import org.apache.lucene.index.LeafReaderContext;
-import org.apache.lucene.search.CollectionTerminatedException;
 import org.apache.lucene.search.ScoreMode;
 import org.opensearch.core.ParseField;
 import org.opensearch.core.common.io.stream.StreamInput;
@@ -310,10 +309,15 @@ public ScoreMode scoreMode() {
     }
 
     @Override
-    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
-        if (segmentMatchAll(context, ctx) && filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, false)) {
-            throw new CollectionTerminatedException();
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+        if (segmentMatchAll(context, ctx)) {
+            return filterRewriteOptimizationContext.tryOptimize(ctx, this::incrementBucketDocCount, false);
         }
+        return false;
+    }
+
+    @Override
+    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
 
         final SortedNumericDoubleValues values = valuesSource.doubleValues(ctx);
         return new LeafBucketCollectorBase(sub, values) {

server/src/main/java/org/opensearch/search/aggregations/bucket/terms/GlobalOrdinalsStringTermsAggregator.java

@@ -40,7 +40,6 @@
 import org.apache.lucene.index.SortedSetDocValues;
 import org.apache.lucene.index.Terms;
 import org.apache.lucene.index.TermsEnum;
-import org.apache.lucene.search.CollectionTerminatedException;
 import org.apache.lucene.search.Weight;
 import org.apache.lucene.util.ArrayUtil;
 import org.apache.lucene.util.BytesRef;
@@ -165,35 +164,32 @@ public void setWeight(Weight weight) {
      @return A LeafBucketCollector implementation with collection termination, since collection is complete
      @throws IOException If an I/O error occurs during reading
      */
-    LeafBucketCollector termDocFreqCollector(
-        LeafReaderContext ctx,
-        SortedSetDocValues globalOrds,
-        BiConsumer<Long, Integer> ordCountConsumer
-    ) throws IOException {
+    boolean tryCollectFromTermFrequencies(LeafReaderContext ctx, SortedSetDocValues globalOrds, BiConsumer<Long, Integer> ordCountConsumer)
+        throws IOException {
         if (weight == null) {
             // Weight not assigned - cannot use this optimization
-            return null;
+            return false;
         } else {
             if (weight.count(ctx) == 0) {
                 // No documents matches top level query on this segment, we can skip the segment entirely
-                return LeafBucketCollector.NO_OP_COLLECTOR;
+                return true;
             } else if (weight.count(ctx) != ctx.reader().maxDoc()) {
                 // weight.count(ctx) == ctx.reader().maxDoc() implies there are no deleted documents and
                 // top-level query matches all docs in the segment
-                return null;
+                return false;
             }
         }
 
         Terms segmentTerms = ctx.reader().terms(this.fieldName);
         if (segmentTerms == null) {
             // Field is not indexed.
-            return null;
+            return false;
         }
 
         NumericDocValues docCountValues = DocValues.getNumeric(ctx.reader(), DocCountFieldMapper.NAME);
         if (docCountValues.nextDoc() != NO_MORE_DOCS) {
             // This segment has at least one document with the _doc_count field.
-            return null;
+            return false;
         }
 
         TermsEnum indexTermsEnum = segmentTerms.iterator();
@@ -217,31 +213,28 @@ LeafBucketCollector termDocFreqCollector(
                 ordinalTerm = globalOrdinalTermsEnum.next();
             }
         }
-        return new LeafBucketCollector() {
-            @Override
-            public void collect(int doc, long owningBucketOrd) throws IOException {
-                throw new CollectionTerminatedException();
-            }
-        };
+        return true;
     }
 
     @Override
-    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
         SortedSetDocValues globalOrds = valuesSource.globalOrdinalsValues(ctx);
-        collectionStrategy.globalOrdsReady(globalOrds);
-
         if (collectionStrategy instanceof DenseGlobalOrds
             && this.resultStrategy instanceof StandardTermsResults
-            && sub == LeafBucketCollector.NO_OP_COLLECTOR) {
-            LeafBucketCollector termDocFreqCollector = termDocFreqCollector(
+            && subAggregators.length == 0) {
+            return tryCollectFromTermFrequencies(
                 ctx,
                 globalOrds,
                 (ord, docCount) -> incrementBucketDocCount(collectionStrategy.globalOrdToBucketOrd(0, ord), docCount)
             );
-            if (termDocFreqCollector != null) {
-                return termDocFreqCollector;
-            }
         }
+        return false;
+    }
+
+    @Override
+    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
+        SortedSetDocValues globalOrds = valuesSource.globalOrdinalsValues(ctx);
+        collectionStrategy.globalOrdsReady(globalOrds);
 
         SortedDocValues singleValues = DocValues.unwrapSingleton(globalOrds);
         if (singleValues != null) {
@@ -436,6 +429,24 @@ static class LowCardinality extends GlobalOrdinalsStringTermsAggregator {
             this.segmentDocCounts = context.bigArrays().newLongArray(1, true);
         }
 
+        @Override
+        protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+            if (subAggregators.length == 0) {
+                if (mapping != null) {
+                    mapSegmentCountsToGlobalCounts(mapping);
+                }
+                final SortedSetDocValues segmentOrds = valuesSource.ordinalsValues(ctx);
+                segmentDocCounts = context.bigArrays().grow(segmentDocCounts, 1 + segmentOrds.getValueCount());
+                mapping = valuesSource.globalOrdinalsMapping(ctx);
+                return tryCollectFromTermFrequencies(
+                    ctx,
+                    segmentOrds,
+                    (ord, docCount) -> incrementBucketDocCount(mapping.applyAsLong(ord), docCount)
+                );
+            }
+            return false;
+        }
+
         @Override
         public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
             if (mapping != null) {
@@ -446,17 +457,6 @@ public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, LeafBucketCol
             assert sub == LeafBucketCollector.NO_OP_COLLECTOR;
             mapping = valuesSource.globalOrdinalsMapping(ctx);
 
-            if (this.resultStrategy instanceof StandardTermsResults) {
-                LeafBucketCollector termDocFreqCollector = this.termDocFreqCollector(
-                    ctx,
-                    segmentOrds,
-                    (ord, docCount) -> incrementBucketDocCount(mapping.applyAsLong(ord), docCount)
-                );
-                if (termDocFreqCollector != null) {
-                    return termDocFreqCollector;
-                }
-            }
-
             final SortedDocValues singleValues = DocValues.unwrapSingleton(segmentOrds);
             if (singleValues != null) {
                 segmentsWithSingleValuedOrds++;

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

@@ -104,6 +104,21 @@ public ScoreMode scoreMode() {
         return valuesSource != null && valuesSource.needsScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
     }
 
+    @Override
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+        CompositeIndexFieldInfo supportedStarTree = getSupportedStarTree(this.context.getQueryShardContext());
+        if (supportedStarTree != null) {
+            if (parent != null && subAggregators.length == 0) {
+                // If this a child aggregator, then the parent will trigger star-tree pre-computation.
+                // Returning NO_OP_COLLECTOR explicitly because the getLeafCollector() are invoked starting from innermost aggregators
+                return true;
+            }
+            precomputeLeafUsingStarTree(ctx, supportedStarTree);
+            return true;
+        }
+        return false;
+    }
+
     @Override
     public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
         if (valuesSource == null) {
@@ -130,20 +145,6 @@ public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBuc
             }
         }
 
-        CompositeIndexFieldInfo supportedStarTree = getSupportedStarTree(this.context.getQueryShardContext());
-        if (supportedStarTree != null) {
-            if (parent != null && subAggregators.length == 0) {
-                // If this a child aggregator, then the parent will trigger star-tree pre-computation.
-                // Returning NO_OP_COLLECTOR explicitly because the getLeafCollector() are invoked starting from innermost aggregators
-                return LeafBucketCollector.NO_OP_COLLECTOR;
-            }
-            getStarTreeCollector(ctx, sub, supportedStarTree);
-        }
-        return getDefaultLeafCollector(ctx, sub);
-    }
-
-    private LeafBucketCollector getDefaultLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
-
         final BigArrays bigArrays = context.bigArrays();
         final SortedNumericDoubleValues allValues = valuesSource.doubleValues(ctx);
         final NumericDoubleValues values = MultiValueMode.MAX.select(allValues);
@@ -167,9 +168,9 @@ public void collect(int doc, long bucket) throws IOException {
         };
     }
 
-    public void getStarTreeCollector(LeafReaderContext ctx, LeafBucketCollector sub, CompositeIndexFieldInfo starTree) throws IOException {
+    private void precomputeLeafUsingStarTree(LeafReaderContext ctx, CompositeIndexFieldInfo starTree) throws IOException {
         AtomicReference<Double> max = new AtomicReference<>(maxes.get(0));
-        StarTreeQueryHelper.getStarTreeLeafCollector(context, valuesSource, ctx, sub, starTree, MetricStat.MAX.getTypeName(), value -> {
+        StarTreeQueryHelper.precomputeLeafUsingStarTree(context, valuesSource, ctx, starTree, MetricStat.MAX.getTypeName(), value -> {
             max.set(Math.max(max.get(), (NumericUtils.sortableLongToDouble(value))));
         }, () -> maxes.set(0, max.get()));
     }

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

@@ -104,6 +104,22 @@ public ScoreMode scoreMode() {
         return valuesSource != null && valuesSource.needsScores() ? ScoreMode.COMPLETE : ScoreMode.COMPLETE_NO_SCORES;
     }
 
+    @Override
+    protected boolean tryPrecomputeAggregationForLeaf(LeafReaderContext ctx) throws IOException {
+        CompositeIndexFieldInfo supportedStarTree = getSupportedStarTree(this.context.getQueryShardContext());
+        if (supportedStarTree != null) {
+            if (parent != null && subAggregators.length == 0) {
+                // If this a child aggregator, then the parent will trigger star-tree pre-computation.
+                // Returning NO_OP_COLLECTOR explicitly because the getLeafCollector() are invoked starting from innermost aggregators
+                return true;
+            }
+            precomputeLeafUsingStarTree(ctx, supportedStarTree);
+            return true;
+        }
+
+        return false;
+    }
+
     @Override
     public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBucketCollector sub) throws IOException {
         if (valuesSource == null) {
@@ -129,19 +145,6 @@ public LeafBucketCollector getLeafCollector(LeafReaderContext ctx, final LeafBuc
             }
         }
 
-        CompositeIndexFieldInfo supportedStarTree = getSupportedStarTree(this.context.getQueryShardContext());
-        if (supportedStarTree != null) {
-            if (parent != null && subAggregators.length == 0) {
-                // If this a child aggregator, then the parent will trigger star-tree pre-computation.
-                // Returning NO_OP_COLLECTOR explicitly because the getLeafCollector() are invoked starting from innermost aggregators
-                return LeafBucketCollector.NO_OP_COLLECTOR;
-            }
-            getStarTreeCollector(ctx, sub, supportedStarTree);
-        }
-        return getDefaultLeafCollector(ctx, sub);
-    }
-
-    private LeafBucketCollector getDefaultLeafCollector(LeafReaderContext ctx, LeafBucketCollector sub) throws IOException {
         final BigArrays bigArrays = context.bigArrays();
         final SortedNumericDoubleValues allValues = valuesSource.doubleValues(ctx);
         final NumericDoubleValues values = MultiValueMode.MIN.select(allValues);
@@ -164,9 +167,9 @@ public void collect(int doc, long bucket) throws IOException {
         };
     }
 
-    public void getStarTreeCollector(LeafReaderContext ctx, LeafBucketCollector sub, CompositeIndexFieldInfo starTree) throws IOException {
+    private void precomputeLeafUsingStarTree(LeafReaderContext ctx, CompositeIndexFieldInfo starTree) throws IOException {
         AtomicReference<Double> min = new AtomicReference<>(mins.get(0));
-        StarTreeQueryHelper.getStarTreeLeafCollector(context, valuesSource, ctx, sub, starTree, MetricStat.MIN.getTypeName(), value -> {
+        StarTreeQueryHelper.precomputeLeafUsingStarTree(context, valuesSource, ctx, starTree, MetricStat.MIN.getTypeName(), value -> {
             min.set(Math.min(min.get(), (NumericUtils.sortableLongToDouble(value))));
         }, () -> mins.set(0, min.get()));
     }