Call 'toArray()' with an empty array instead of a pre-sized array

Calls to `Collection.toArray()` is not consistent and in many places and use a pre-sized array parameter. This change makes a consistent use of the `toArray(new T[0])`. The empty array usage is considered faster, safer and cleaner than the sized based array approach.

Signed-off-by: Rabi Panda <[email protected]>

CHANGELOG.md

@@ -43,6 +43,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Relax visibility of the HTTP_CHANNEL_KEY and HTTP_SERVER_CHANNEL_KEY to make it possible for the plugins to access associated Netty4HttpChannel / Netty4HttpServerChannel instance ([#4638](https://github.com/opensearch-project/OpenSearch/pull/4638))
 - Use ReplicationFailedException instead of OpensearchException in ReplicationTarget ([#4725](https://github.com/opensearch-project/OpenSearch/pull/4725))
 - Migrate client transports to Apache HttpClient / Core 5.x ([#4459](https://github.com/opensearch-project/OpenSearch/pull/4459))
+- Call 'toArray()' with an empty array instead of a pre-sized array ([#5277](https://github.com/opensearch-project/OpenSearch/pull/5277))
 
 ### Deprecated
 

buildSrc/src/main/java/org/opensearch/gradle/DistributionDownloadPlugin.java

@@ -174,7 +174,7 @@ private static void addIvyRepo(Project project, String name, String url, String
 
         project.getRepositories().exclusiveContent(exclusiveContentRepository -> {
             exclusiveContentRepository.filter(config -> config.includeGroup(group));
-            exclusiveContentRepository.forRepositories(repos.toArray(new IvyArtifactRepository[repos.size()]));
+            exclusiveContentRepository.forRepositories(repos.toArray(new IvyArtifactRepository[0]));
         });
     }
 

client/rest-high-level/src/main/java/org/opensearch/client/core/CountResponse.java

@@ -233,7 +233,7 @@ static ShardStats fromXContent(XContentParser parser) throws IOException {
                     parser.skipChildren();
                 }
             }
-            return new ShardStats(successfulShards, totalShards, skippedShards, failures.toArray(new ShardSearchFailure[failures.size()]));
+            return new ShardStats(successfulShards, totalShards, skippedShards, failures.toArray(new ShardSearchFailure[0]));
         }
 
         @Override

client/rest-high-level/src/main/java/org/opensearch/client/indices/PutIndexTemplateRequest.java

@@ -435,7 +435,7 @@ public PutIndexTemplateRequest alias(Alias alias) {
 
     @Override
     public String[] indices() {
-        return indexPatterns.toArray(new String[indexPatterns.size()]);
+        return indexPatterns.toArray(new String[0]);
     }
 
     @Override

client/rest-high-level/src/test/java/org/opensearch/client/RestHighLevelClientExtTests.java

@@ -153,7 +153,7 @@ static CustomResponseSection2 fromXContent(XContentParser parser) throws IOExcep
                 values.add(parser.text());
             }
             assertEquals(XContentParser.Token.END_ARRAY, parser.currentToken());
-            CustomResponseSection2 responseSection2 = new CustomResponseSection2(values.toArray(new String[values.size()]));
+            CustomResponseSection2 responseSection2 = new CustomResponseSection2(values.toArray(new String[0]));
             assertEquals(XContentParser.Token.END_OBJECT, parser.nextToken());
             return responseSection2;
         }

distribution/tools/plugin-cli/src/main/java/org/opensearch/plugins/InstallPluginCommand.java

@@ -1028,7 +1028,7 @@ private static void setFileAttributes(final Path path, final Set<PosixFilePermis
 
     @Override
     public void close() throws IOException {
-        IOUtils.rm(pathsToDeleteOnShutdown.toArray(new Path[pathsToDeleteOnShutdown.size()]));
+        IOUtils.rm(pathsToDeleteOnShutdown.toArray(new Path[0]));
     }
 
 }

distribution/tools/plugin-cli/src/main/java/org/opensearch/plugins/RemovePluginCommand.java

@@ -215,7 +215,7 @@ void execute(Terminal terminal, Environment env, String pluginName, boolean purg
         // finally, add the marker file
         pluginPaths.add(removing);
 
-        IOUtils.rm(pluginPaths.toArray(new Path[pluginPaths.size()]));
+        IOUtils.rm(pluginPaths.toArray(new Path[0]));
     }
 
 }

libs/x-content/src/main/java/org/opensearch/common/ParseField.java

@@ -68,12 +68,12 @@ public ParseField(String name, String... deprecatedNames) {
         } else {
             final HashSet<String> set = new HashSet<>();
             Collections.addAll(set, deprecatedNames);
-            this.deprecatedNames = set.toArray(new String[set.size()]);
+            this.deprecatedNames = set.toArray(new String[0]);
         }
         Set<String> allNames = new HashSet<>();
         allNames.add(name);
         Collections.addAll(allNames, this.deprecatedNames);
-        this.allNames = allNames.toArray(new String[allNames.size()]);
+        this.allNames = allNames.toArray(new String[0]);
     }
 
     /**

libs/x-content/src/main/java/org/opensearch/common/xcontent/support/filtering/FilterPath.java

@@ -101,7 +101,7 @@ public static FilterPath[] compile(Set<String> filters) {
                 }
             }
         }
-        return paths.toArray(new FilterPath[paths.size()]);
+        return paths.toArray(new FilterPath[0]);
     }
 
     private static FilterPath parse(final String filter, final String segment) {

libs/x-content/src/main/java/org/opensearch/common/xcontent/support/filtering/FilterPathBasedFilter.java

@@ -95,7 +95,7 @@ private TokenFilter evaluate(String name, FilterPath[] filters) {
             }
 
             if ((nextFilters != null) && (nextFilters.isEmpty() == false)) {
-                return new FilterPathBasedFilter(nextFilters.toArray(new FilterPath[nextFilters.size()]), inclusive);
+                return new FilterPathBasedFilter(nextFilters.toArray(new FilterPath[0]), inclusive);
             }
         }
         return NO_MATCHING;

modules/parent-join/src/internalClusterTest/java/org/opensearch/join/query/ChildQuerySearchIT.java

@@ -310,7 +310,7 @@ public void testHasParentFilter() throws Exception {
             }
             assertThat(parentToChildren.get(previousParentId).add(childId), is(true));
         }
-        indexRandom(true, builders.toArray(new IndexRequestBuilder[builders.size()]));
+        indexRandom(true, builders.toArray(new IndexRequestBuilder[0]));
 
         assertThat(parentToChildren.isEmpty(), equalTo(false));
         for (Map.Entry<String, Set<String>> parentToChildrenEntry : parentToChildren.entrySet()) {

modules/rank-eval/src/main/java/org/opensearch/index/rankeval/TransportRankEvalAction.java

@@ -148,7 +148,7 @@ protected void doExecute(Task task, RankEvalRequest request, ActionListener<Rank
             if (summaryFields.isEmpty()) {
                 evaluationRequest.fetchSource(false);
             } else {
-                evaluationRequest.fetchSource(summaryFields.toArray(new String[summaryFields.size()]), new String[0]);
+                evaluationRequest.fetchSource(summaryFields.toArray(new String[0]), new String[0]);
             }
             SearchRequest searchRequest = new SearchRequest(request.indices(), evaluationRequest);
             searchRequest.indicesOptions(request.indicesOptions());
@@ -158,12 +158,7 @@ protected void doExecute(Task task, RankEvalRequest request, ActionListener<Rank
         assert ratedRequestsInSearch.size() == msearchRequest.requests().size();
         client.multiSearch(
             msearchRequest,
-            new RankEvalActionListener(
-                listener,
-                metric,
-                ratedRequestsInSearch.toArray(new RatedRequest[ratedRequestsInSearch.size()]),
-                errors
-            )
+            new RankEvalActionListener(listener, metric, ratedRequestsInSearch.toArray(new RatedRequest[0]), errors)
         );
     }
 

modules/reindex/src/main/java/org/opensearch/index/reindex/AbstractAsyncBulkByScrollAction.java

@@ -517,7 +517,7 @@ void refreshAndFinish(List<Failure> indexingFailures, List<SearchFailure> search
             return;
         }
         RefreshRequest refresh = new RefreshRequest();
-        refresh.indices(destinationIndices.toArray(new String[destinationIndices.size()]));
+        refresh.indices(destinationIndices.toArray(new String[0]));
         logger.debug("[{}]: refreshing", task.getId());
         client.admin().indices().refresh(refresh, new ActionListener<RefreshResponse>() {
             @Override

modules/reindex/src/test/java/org/opensearch/index/reindex/DeleteByQueryBasicTests.java

@@ -362,7 +362,7 @@ public void testMultipleSources() throws Exception {
         int slices = randomSlices(1, 10);
         int expectedSlices = expectedSliceStatuses(slices, docs.keySet());
 
-        String[] sourceIndexNames = docs.keySet().toArray(new String[docs.size()]);
+        String[] sourceIndexNames = docs.keySet().toArray(new String[0]);
 
         assertThat(
             deleteByQuery().source(sourceIndexNames).filter(QueryBuilders.matchAllQuery()).refresh(true).setSlices(slices).get(),

modules/reindex/src/test/java/org/opensearch/index/reindex/ReindexBasicTests.java

@@ -161,7 +161,7 @@ public void testMultipleSources() throws Exception {
         int slices = randomSlices(1, 10);
         int expectedSlices = expectedSliceStatuses(slices, docs.keySet());
 
-        String[] sourceIndexNames = docs.keySet().toArray(new String[docs.size()]);
+        String[] sourceIndexNames = docs.keySet().toArray(new String[0]);
         ReindexRequestBuilder request = reindex().source(sourceIndexNames).destination("dest").refresh(true).setSlices(slices);
 
         BulkByScrollResponse response = request.get();

modules/reindex/src/test/java/org/opensearch/index/reindex/UpdateByQueryBasicTests.java

@@ -151,7 +151,7 @@ public void testMultipleSources() throws Exception {
         int slices = randomSlices(1, 10);
         int expectedSlices = expectedSliceStatuses(slices, docs.keySet());
 
-        String[] sourceIndexNames = docs.keySet().toArray(new String[docs.size()]);
+        String[] sourceIndexNames = docs.keySet().toArray(new String[0]);
         BulkByScrollResponse response = updateByQuery().source(sourceIndexNames).refresh(true).setSlices(slices).get();
         assertThat(response, matcher().updated(allDocs.size()).slices(hasSize(expectedSlices)));
 

plugins/mapper-annotated-text/src/main/java/org/opensearch/search/fetch/subphase/highlight/AnnotatedPassageFormatter.java

@@ -237,7 +237,7 @@ public AnnotationToken[] getIntersectingAnnotations(int start, int end) {
             // add 1 for the fieldvalue separator character
             fieldValueOffset += fieldValueAnnotations.textMinusMarkup.length() + 1;
         }
-        return intersectingAnnotations.toArray(new AnnotationToken[intersectingAnnotations.size()]);
+        return intersectingAnnotations.toArray(new AnnotationToken[0]);
     }
 
     private void append(StringBuilder dest, String content, int start, int end) {

server/src/internalClusterTest/java/org/opensearch/action/IndicesRequestIT.java

@@ -708,7 +708,7 @@ private String[] randomUniqueIndices() {
         while (uniqueIndices.size() < count) {
             uniqueIndices.add(randomFrom(this.indices));
         }
-        return uniqueIndices.toArray(new String[uniqueIndices.size()]);
+        return uniqueIndices.toArray(new String[0]);
     }
 
     private static void assertAllRequestsHaveBeenConsumed() {

server/src/internalClusterTest/java/org/opensearch/action/admin/indices/get/GetIndexIT.java

@@ -163,7 +163,7 @@ public void testSimpleMixedFeatures() {
         }
         GetIndexResponse response = runWithRandomFeatureMethod(
             client().admin().indices().prepareGetIndex().addIndices("idx"),
-            features.toArray(new Feature[features.size()])
+            features.toArray(new Feature[0])
         );
         String[] indices = response.indices();
         assertThat(indices, notNullValue());
@@ -194,7 +194,7 @@ public void testEmptyMixedFeatures() {
         }
         GetIndexResponse response = runWithRandomFeatureMethod(
             client().admin().indices().prepareGetIndex().addIndices("empty_idx"),
-            features.toArray(new Feature[features.size()])
+            features.toArray(new Feature[0])
         );
         String[] indices = response.indices();
         assertThat(indices, notNullValue());

server/src/internalClusterTest/java/org/opensearch/recovery/RelocationIT.java

@@ -589,7 +589,7 @@ public void testIndexSearchAndRelocateConcurrently() throws Exception {
             logger.info(" --> checking iteration {}", i);
             SearchResponse afterRelocation = client().prepareSearch().setSize(ids.size()).get();
             assertNoFailures(afterRelocation);
-            assertSearchHits(afterRelocation, ids.toArray(new String[ids.size()]));
+            assertSearchHits(afterRelocation, ids.toArray(new String[0]));
         }
         stopped.set(true);
         for (Thread searchThread : searchThreads) {

server/src/internalClusterTest/java/org/opensearch/search/aggregations/bucket/GeoDistanceIT.java

@@ -147,7 +147,7 @@ public void setupSuiteScopeCluster() throws Exception {
                     .setSource(jsonBuilder().startObject().field("value", i * 2).field("location", "52.0945, 5.116").endObject())
             );
         }
-        indexRandom(true, builders.toArray(new IndexRequestBuilder[builders.size()]));
+        indexRandom(true, builders.toArray(new IndexRequestBuilder[0]));
         ensureSearchable();
     }
 

server/src/internalClusterTest/java/org/opensearch/search/aggregations/bucket/LongTermsIT.java

@@ -176,7 +176,7 @@ public void setupSuiteScopeCluster() throws Exception {
 
         getMultiSortDocs(builders);
 
-        indexRandom(true, builders.toArray(new IndexRequestBuilder[builders.size()]));
+        indexRandom(true, builders.toArray(new IndexRequestBuilder[0]));
         ensureSearchable();
     }
 

server/src/internalClusterTest/java/org/opensearch/search/aggregations/pipeline/MaxBucketIT.java

@@ -162,7 +162,7 @@ public void testDocCountTopLevel() throws Exception {
         assertThat(maxBucketValue, notNullValue());
         assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
         assertThat(maxBucketValue.value(), equalTo(maxValue));
-        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
     }
 
     public void testDocCountAsSubAgg() throws Exception {
@@ -214,7 +214,7 @@ public void testDocCountAsSubAgg() throws Exception {
             assertThat(maxBucketValue, notNullValue());
             assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
             assertThat(maxBucketValue.value(), equalTo(maxValue));
-            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
         }
     }
 
@@ -254,7 +254,7 @@ public void testMetricTopLevel() throws Exception {
         assertThat(maxBucketValue, notNullValue());
         assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
         assertThat(maxBucketValue.value(), equalTo(maxValue));
-        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
     }
 
     public void testMetricAsSubAgg() throws Exception {
@@ -313,7 +313,7 @@ public void testMetricAsSubAgg() throws Exception {
             assertThat(maxBucketValue, notNullValue());
             assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
             assertThat(maxBucketValue.value(), equalTo(maxValue));
-            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
         }
     }
 
@@ -362,7 +362,7 @@ public void testMetricAsSubAggOfSingleBucketAgg() throws Exception {
         assertThat(maxBucketValue, notNullValue());
         assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
         assertThat(maxBucketValue.value(), equalTo(maxValue));
-        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+        assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
     }
 
     public void testMetricAsSubAggWithInsertZeros() throws Exception {
@@ -419,7 +419,7 @@ public void testMetricAsSubAggWithInsertZeros() throws Exception {
             assertThat(maxBucketValue, notNullValue());
             assertThat(maxBucketValue.getName(), equalTo("max_bucket"));
             assertThat(maxBucketValue.value(), equalTo(maxValue));
-            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[maxKeys.size()])));
+            assertThat(maxBucketValue.keys(), equalTo(maxKeys.toArray(new String[0])));
         }
     }
 
@@ -500,7 +500,7 @@ public void testNested() throws Exception {
             assertThat(maxBucketValue, notNullValue());
             assertThat(maxBucketValue.getName(), equalTo("max_histo_bucket"));
             assertThat(maxBucketValue.value(), equalTo(maxHistoValue));
-            assertThat(maxBucketValue.keys(), equalTo(maxHistoKeys.toArray(new String[maxHistoKeys.size()])));
+            assertThat(maxBucketValue.keys(), equalTo(maxHistoKeys.toArray(new String[0])));
             if (maxHistoValue > maxTermsValue) {
                 maxTermsValue = maxHistoValue;
                 maxTermsKeys = new ArrayList<>();
@@ -514,7 +514,7 @@ public void testNested() throws Exception {
         assertThat(maxBucketValue, notNullValue());
         assertThat(maxBucketValue.getName(), equalTo("max_terms_bucket"));
         assertThat(maxBucketValue.value(), equalTo(maxTermsValue));
-        assertThat(maxBucketValue.keys(), equalTo(maxTermsKeys.toArray(new String[maxTermsKeys.size()])));
+        assertThat(maxBucketValue.keys(), equalTo(maxTermsKeys.toArray(new String[0])));
     }
 
     /**

server/src/internalClusterTest/java/org/opensearch/search/aggregations/pipeline/MinBucketIT.java

@@ -148,7 +148,7 @@ public void testDocCountTopLevel() throws Exception {
         assertThat(minBucketValue, notNullValue());
         assertThat(minBucketValue.getName(), equalTo("min_bucket"));
         assertThat(minBucketValue.value(), equalTo(minValue));
-        assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[minKeys.size()])));
+        assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[0])));
     }
 
     public void testDocCountAsSubAgg() throws Exception {
@@ -200,7 +200,7 @@ public void testDocCountAsSubAgg() throws Exception {
             assertThat(minBucketValue, notNullValue());
             assertThat(minBucketValue.getName(), equalTo("min_bucket"));
             assertThat(minBucketValue.value(), equalTo(minValue));
-            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[minKeys.size()])));
+            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[0])));
         }
     }
 
@@ -240,7 +240,7 @@ public void testMetricTopLevel() throws Exception {
         assertThat(minBucketValue, notNullValue());
         assertThat(minBucketValue.getName(), equalTo("min_bucket"));
         assertThat(minBucketValue.value(), equalTo(minValue));
-        assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[minKeys.size()])));
+        assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[0])));
     }
 
     public void testMetricAsSubAgg() throws Exception {
@@ -299,7 +299,7 @@ public void testMetricAsSubAgg() throws Exception {
             assertThat(minBucketValue, notNullValue());
             assertThat(minBucketValue.getName(), equalTo("min_bucket"));
             assertThat(minBucketValue.value(), equalTo(minValue));
-            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[minKeys.size()])));
+            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[0])));
         }
     }
 
@@ -357,7 +357,7 @@ public void testMetricAsSubAggWithInsertZeros() throws Exception {
             assertThat(minBucketValue, notNullValue());
             assertThat(minBucketValue.getName(), equalTo("min_bucket"));
             assertThat(minBucketValue.value(), equalTo(minValue));
-            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[minKeys.size()])));
+            assertThat(minBucketValue.keys(), equalTo(minKeys.toArray(new String[0])));
         }
     }
 
@@ -438,7 +438,7 @@ public void testNested() throws Exception {
             assertThat(minBucketValue, notNullValue());
             assertThat(minBucketValue.getName(), equalTo("min_histo_bucket"));
             assertThat(minBucketValue.value(), equalTo(minHistoValue));
-            assertThat(minBucketValue.keys(), equalTo(minHistoKeys.toArray(new String[minHistoKeys.size()])));
+            assertThat(minBucketValue.keys(), equalTo(minHistoKeys.toArray(new String[0])));
             if (minHistoValue < minTermsValue) {
                 minTermsValue = minHistoValue;
                 minTermsKeys = new ArrayList<>();
@@ -452,6 +452,6 @@ public void testNested() throws Exception {
         assertThat(minBucketValue, notNullValue());
         assertThat(minBucketValue.getName(), equalTo("min_terms_bucket"));
         assertThat(minBucketValue.value(), equalTo(minTermsValue));
-        assertThat(minBucketValue.keys(), equalTo(minTermsKeys.toArray(new String[minTermsKeys.size()])));
+        assertThat(minBucketValue.keys(), equalTo(minTermsKeys.toArray(new String[0])));
     }
 }

server/src/internalClusterTest/java/org/opensearch/search/basic/SearchWhileRelocatingIT.java

@@ -85,7 +85,7 @@ private void testSearchAndRelocateConcurrently(final int numberOfReplicas) throw
                     )
             );
         }
-        indexRandom(true, indexBuilders.toArray(new IndexRequestBuilder[indexBuilders.size()]));
+        indexRandom(true, indexBuilders.toArray(new IndexRequestBuilder[0]));
         assertHitCount(client().prepareSearch().get(), (numDocs));
         final int numIters = scaledRandomIntBetween(5, 20);
         for (int i = 0; i < numIters; i++) {