Adds cluster setting to allow caching requests with size>0 in request cache

server/src/internalClusterTest/java/org/opensearch/indices/IndicesRequestCacheIT.java

@@ -43,6 +43,7 @@
 import org.opensearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.opensearch.action.admin.cluster.node.stats.NodeStats;
 import org.opensearch.action.admin.cluster.node.stats.NodesStatsResponse;
+import org.opensearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
 import org.opensearch.action.admin.indices.alias.Alias;
 import org.opensearch.action.admin.indices.cache.clear.ClearIndicesCacheRequest;
 import org.opensearch.action.admin.indices.forcemerge.ForceMergeResponse;
@@ -89,6 +90,7 @@
 import static org.opensearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_REPLICAS;
 import static org.opensearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_SHARDS;
 import static org.opensearch.cluster.routing.allocation.decider.EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING;
+import static org.opensearch.indices.IndicesRequestCache.ALLOW_SIZE_NONZERO_SETTING;
 import static org.opensearch.search.SearchService.CLUSTER_CONCURRENT_SEGMENT_SEARCH_SETTING;
 import static org.opensearch.search.aggregations.AggregationBuilders.dateHistogram;
 import static org.opensearch.search.aggregations.AggregationBuilders.dateRange;
@@ -579,6 +581,20 @@ public void testCanCache() throws Exception {
         OpenSearchAssertions.assertAllSuccessful(r4);
         assertThat(r4.getHits().getTotalHits().value, equalTo(7L));
         assertCacheState(client, index, 0, 4);
+
+        // If size > 0 we should cache if this is enabled via cluster setting
+        ClusterUpdateSettingsRequest updateSettingsRequest = new ClusterUpdateSettingsRequest();
+        updateSettingsRequest.persistentSettings(Settings.builder().put(ALLOW_SIZE_NONZERO_SETTING.getKey(), true));
+        assertAcked(client().admin().cluster().updateSettings(updateSettingsRequest).actionGet());
+
+        final SearchResponse r7 = client.prepareSearch(index)
+            .setSearchType(SearchType.QUERY_THEN_FETCH)
+            .setSize(1)
+            .setQuery(QueryBuilders.rangeQuery("s").gte("2016-03-22").lte("2016-03-26"))
+            .get();
+        OpenSearchAssertions.assertAllSuccessful(r7);
+        assertThat(r7.getHits().getTotalHits().value, equalTo(5L));
+        assertCacheState(client, index, 0, 6);
     }
 
     public void testCacheWithFilteredAlias() throws InterruptedException {

server/src/main/java/org/opensearch/common/settings/ClusterSettings.java

@@ -518,6 +518,7 @@ public void apply(Settings value, Settings current, Settings previous) {
                 IndicesRequestCache.INDICES_CACHE_QUERY_EXPIRE,
                 IndicesRequestCache.INDICES_REQUEST_CACHE_CLEANUP_INTERVAL_SETTING,
                 IndicesRequestCache.INDICES_REQUEST_CACHE_STALENESS_THRESHOLD_SETTING,
+                IndicesRequestCache.ALLOW_SIZE_NONZERO_SETTING,
                 HunspellService.HUNSPELL_LAZY_LOAD,
                 HunspellService.HUNSPELL_IGNORE_CASE,
                 HunspellService.HUNSPELL_DICTIONARY_OPTIONS,

server/src/main/java/org/opensearch/indices/IndicesRequestCache.java

@@ -147,6 +147,16 @@ public final class IndicesRequestCache implements RemovalListener<ICacheKey<Indi
         Property.NodeScope
     );
 
+    /**
+     * If enabled, allows caching size > 0 queries.
+     */
+    public static final Setting<Boolean> ALLOW_SIZE_NONZERO_SETTING = Setting.boolSetting(
+        "indices.requests.cache.allow_size_nonzero",
+        false,
+        Property.NodeScope,
+        Property.Dynamic
+    );
+
     private final static long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(Key.class);
 
     private final ConcurrentMap<CleanupKey, Boolean> registeredClosedListeners = ConcurrentCollections.newConcurrentMap();

server/src/main/java/org/opensearch/indices/IndicesService.java

@@ -205,6 +205,7 @@
 import static org.opensearch.index.IndexService.IndexCreationContext.CREATE_INDEX;
 import static org.opensearch.index.IndexService.IndexCreationContext.METADATA_VERIFICATION;
 import static org.opensearch.index.query.AbstractQueryBuilder.parseInnerQueryBuilder;
+import static org.opensearch.indices.IndicesRequestCache.ALLOW_SIZE_NONZERO_SETTING;
 import static org.opensearch.node.remotestore.RemoteStoreNodeAttribute.isRemoteDataAttributePresent;
 import static org.opensearch.search.SearchService.ALLOW_EXPENSIVE_QUERIES;
 
@@ -360,6 +361,7 @@ public class IndicesService extends AbstractLifecycleComponent
     private final FileCache fileCache;
     private final CompositeIndexSettings compositeIndexSettings;
     private final Consumer<IndexShard> replicator;
+    private boolean canCacheSizeNonzeroRequests;
 
     @Override
     protected void doStart() {
@@ -507,6 +509,8 @@ protected void closeInternal() {
         this.compositeIndexSettings = compositeIndexSettings;
         this.fileCache = fileCache;
         this.replicator = replicator;
+        this.canCacheSizeNonzeroRequests = ALLOW_SIZE_NONZERO_SETTING.get(clusterService.getSettings());
+        clusterService.getClusterSettings().addSettingsUpdateConsumer(ALLOW_SIZE_NONZERO_SETTING, this::setCanCacheSizeNonzeroRequests);
     }
 
     public IndicesService(
@@ -1748,9 +1752,10 @@ public boolean canCache(ShardSearchRequest request, SearchContext context) {
         if (request.requestCache() == null) {
             if (settings.getValue(IndicesRequestCache.INDEX_CACHE_REQUEST_ENABLED_SETTING) == false) {
                 return false;
-            } else if (context.size() != 0) {
+            } else if (context.size() != 0 && !canCacheSizeNonzeroRequests) {
                 // If no request cache query parameter and shard request cache
                 // is enabled in settings don't cache for requests with size > 0
+                // unless this is enabled via cluster setting
                 return false;
             }
         } else if (request.requestCache() == false) {
@@ -2118,4 +2123,9 @@ public RemoteStoreSettings getRemoteStoreSettings() {
     public CompositeIndexSettings getCompositeIndexSettings() {
         return this.compositeIndexSettings;
     }
+
+    // Package-private for testing
+    void setCanCacheSizeNonzeroRequests(Boolean canCacheSizeNonzeroRequests) {
+        this.canCacheSizeNonzeroRequests = canCacheSizeNonzeroRequests;
+    }
 }

server/src/test/java/org/opensearch/indices/IndicesServiceTests.java

@@ -641,25 +641,68 @@ public void testDirectoryReaderWithoutDelegatingCacheHelperNotCacheable() throws
         ShardSearchRequest request = mock(ShardSearchRequest.class);
         when(request.requestCache()).thenReturn(true);
 
-        TestSearchContext context = new TestSearchContext(indexService.getBigArrays(), indexService) {
-            @Override
-            public SearchType searchType() {
-                return SearchType.QUERY_THEN_FETCH;
-            }
-        };
+        TestSearchContext context = getTestContext(indexService, 0);
+        IndexReader.CacheHelper notDelegatingCacheHelper = mock(IndexReader.CacheHelper.class);
+        DelegatingCacheHelper delegatingCacheHelper = mock(DelegatingCacheHelper.class);
+        for (boolean useDelegatingCacheHelper : new boolean[] { true, false }) {
+            IndexReader.CacheHelper cacheHelper = useDelegatingCacheHelper ? delegatingCacheHelper : notDelegatingCacheHelper;
+            setupMocksForCanCache(context, cacheHelper);
+            assertEquals(useDelegatingCacheHelper, indicesService.canCache(request, context));
+        }
+    }
+
+    public void testCanCacheSizeNonzero() {
+        // Size == 0 requests should always be cacheable (if they pass the other checks).
+        // Size > 0 requests should only be cacheable if ALLOW_SIZE_NONZERO_SETTING is true.
+
+        final IndexService indexService = createIndex("test");
+        ShardSearchRequest request = mock(ShardSearchRequest.class);
+        when(request.requestCache()).thenReturn(null);
+
+        TestSearchContext sizeZeroContext = getTestContext(indexService, 0);
+        TestSearchContext sizeNonzeroContext = getTestContext(indexService, 10);
+
+        // Test for an IndicesService with the default setting value of false
+        IndicesService indicesService = getIndicesService();
+        DelegatingCacheHelper cacheHelper = mock(DelegatingCacheHelper.class);
+        Map<TestSearchContext, Boolean> expectedResultMap = Map.of(sizeZeroContext, true, sizeNonzeroContext, false);
 
+        for (Map.Entry<TestSearchContext, Boolean> entry : expectedResultMap.entrySet()) {
+            TestSearchContext context = entry.getKey();
+            setupMocksForCanCache(context, cacheHelper);
+            assertEquals(entry.getValue(), indicesService.canCache(request, context));
+        }
+        // Simulate the cluster setting update by manually calling setCanCacheSizeNonzeroRequests
+        indicesService.setCanCacheSizeNonzeroRequests(true);
+        expectedResultMap = Map.of(sizeZeroContext, true, sizeNonzeroContext, true);
+
+        for (Map.Entry<TestSearchContext, Boolean> entry : expectedResultMap.entrySet()) {
+            TestSearchContext context = entry.getKey();
+            setupMocksForCanCache(context, cacheHelper);
+            assertEquals(entry.getValue(), indicesService.canCache(request, context));
+        }
+    }
+
+    private void setupMocksForCanCache(TestSearchContext context, IndexReader.CacheHelper cacheHelper) {
         ContextIndexSearcher searcher = mock(ContextIndexSearcher.class);
         context.setSearcher(searcher);
         DirectoryReader reader = mock(DirectoryReader.class);
         when(searcher.getDirectoryReader()).thenReturn(reader);
         when(searcher.getIndexReader()).thenReturn(reader);
-        IndexReader.CacheHelper notDelegatingCacheHelper = mock(IndexReader.CacheHelper.class);
-        DelegatingCacheHelper delegatingCacheHelper = mock(DelegatingCacheHelper.class);
+        when(reader.getReaderCacheHelper()).thenReturn(cacheHelper);
+    }
 
-        for (boolean useDelegatingCacheHelper : new boolean[] { true, false }) {
-            IndexReader.CacheHelper cacheHelper = useDelegatingCacheHelper ? delegatingCacheHelper : notDelegatingCacheHelper;
-            when(reader.getReaderCacheHelper()).thenReturn(cacheHelper);
-            assertEquals(useDelegatingCacheHelper, indicesService.canCache(request, context));
-        }
+    private TestSearchContext getTestContext(IndexService indexService, int size) {
+        return new TestSearchContext(indexService.getBigArrays(), indexService) {
+            @Override
+            public SearchType searchType() {
+                return SearchType.QUERY_THEN_FETCH;
+            }
+
+            @Override
+            public int size() {
+                return size;
+            }
+        };
     }
 }