Size lists in advance when known

When constructing an array list, if we know the size of the list in
advance (because we are adding objects to it derived from another list),
we should size the array list to the appropriate capacity in advance (to
avoid resizing allocations). This commit does this in various places.

Relates #24439

core/src/main/java/org/elasticsearch/action/admin/cluster/repositories/get/GetRepositoriesResponse.java

@@ -60,7 +60,7 @@ public class GetRepositoriesResponse extends ActionResponse implements Iterable<
     public void readFrom(StreamInput in) throws IOException {
         super.readFrom(in);
         int size = in.readVInt();
-        List<RepositoryMetaData> repositoryListBuilder = new ArrayList<>();
+        List<RepositoryMetaData> repositoryListBuilder = new ArrayList<>(size);
         for (int j = 0; j < size; j++) {
             repositoryListBuilder.add(new RepositoryMetaData(
                     in.readString(),

core/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/get/GetSnapshotsResponse.java

@@ -59,7 +59,7 @@ public class GetSnapshotsResponse extends ActionResponse implements ToXContentOb
     public void readFrom(StreamInput in) throws IOException {
         super.readFrom(in);
         int size = in.readVInt();
-        List<SnapshotInfo> builder = new ArrayList<>();
+        List<SnapshotInfo> builder = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             builder.add(new SnapshotInfo(in));
         }

core/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodes.java

@@ -65,8 +65,8 @@ public class ClusterStatsNodes implements ToXContent {
         this.plugins = new HashSet<>();
 
         Set<InetAddress> seenAddresses = new HashSet<>(nodeResponses.size());
-        List<NodeInfo> nodeInfos = new ArrayList<>();
+        List<NodeInfo> nodeInfos = new ArrayList<>(nodeResponses.size());
-        List<NodeStats> nodeStats = new ArrayList<>();
+        List<NodeStats> nodeStats = new ArrayList<>(nodeResponses.size());
         for (ClusterStatsNodeResponse nodeResponse : nodeResponses) {
             nodeInfos.add(nodeResponse.nodeInfo());
             nodeStats.add(nodeResponse.nodeStats());

core/src/main/java/org/elasticsearch/action/admin/indices/get/GetIndexResponse.java

@@ -114,7 +114,7 @@ public class GetIndexResponse extends ActionResponse {
         for (int i = 0; i < aliasesSize; i++) {
             String key = in.readString();
             int valueSize = in.readVInt();
-            List<AliasMetaData> aliasEntryBuilder = new ArrayList<>();
+            List<AliasMetaData> aliasEntryBuilder = new ArrayList<>(valueSize);
             for (int j = 0; j < valueSize; j++) {
                 aliasEntryBuilder.add(new AliasMetaData(in));
             }

core/src/main/java/org/elasticsearch/action/support/tasks/BaseTasksResponse.java

@@ -81,13 +81,13 @@ public class BaseTasksResponse extends ActionResponse {
     public void readFrom(StreamInput in) throws IOException {
         super.readFrom(in);
         int size = in.readVInt();
-        List<TaskOperationFailure> taskFailures = new ArrayList<>();
+        List<TaskOperationFailure> taskFailures = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             taskFailures.add(new TaskOperationFailure(in));
         }
         size = in.readVInt();
         this.taskFailures = Collections.unmodifiableList(taskFailures);
-        List<FailedNodeException> nodeFailures = new ArrayList<>();
+        List<FailedNodeException> nodeFailures = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             nodeFailures.add(new FailedNodeException(in));
         }

core/src/main/java/org/elasticsearch/cluster/block/ClusterBlock.java

@@ -125,7 +125,7 @@ public class ClusterBlock implements Streamable, ToXContent {
         id = in.readVInt();
         description = in.readString();
         final int len = in.readVInt();
-        ArrayList<ClusterBlockLevel> levels = new ArrayList<>();
+        ArrayList<ClusterBlockLevel> levels = new ArrayList<>(len);
         for (int i = 0; i < len; i++) {
             levels.add(ClusterBlockLevel.fromId(in.readVInt()));
         }

core/src/main/java/org/elasticsearch/common/inject/assistedinject/AssistedConstructor.java

@@ -49,7 +49,7 @@ class AssistedConstructor<T> {
         Annotation[][] annotations = constructor.getParameterAnnotations();
 
         List<Type> typeList = new ArrayList<>();
-        allParameters = new ArrayList<>();
+        allParameters = new ArrayList<>(parameterTypes.size());
 
         // categorize params as @Assisted or @Injected
         for (int i = 0; i < parameterTypes.size(); i++) {

core/src/main/java/org/elasticsearch/index/analysis/CustomAnalyzerProvider.java

@@ -55,8 +55,8 @@ public class CustomAnalyzerProvider extends AbstractIndexAnalyzerProvider<Custom
             throw new IllegalArgumentException("Custom Analyzer [" + name() + "] failed to find tokenizer under name [" + tokenizerName + "]");
         }
 
-        List<CharFilterFactory> charFiltersList = new ArrayList<>();
         String[] charFilterNames = analyzerSettings.getAsArray("char_filter");
+        List<CharFilterFactory> charFiltersList = new ArrayList<>(charFilterNames.length);
         for (String charFilterName : charFilterNames) {
             CharFilterFactory charFilter = charFilters.get(charFilterName);
             if (charFilter == null) {
@@ -65,8 +65,8 @@ public class CustomAnalyzerProvider extends AbstractIndexAnalyzerProvider<Custom
             charFiltersList.add(charFilter);
         }
 
-        List<TokenFilterFactory> tokenFilterList = new ArrayList<>();
         String[] tokenFilterNames = analyzerSettings.getAsArray("filter");
+        List<TokenFilterFactory> tokenFilterList = new ArrayList<>(tokenFilterNames.length);
         for (String tokenFilterName : tokenFilterNames) {
             TokenFilterFactory tokenFilter = tokenFilters.get(tokenFilterName);
             if (tokenFilter == null) {

core/src/main/java/org/elasticsearch/index/analysis/CustomNormalizerProvider.java

@@ -50,8 +50,8 @@ public final class CustomNormalizerProvider extends AbstractIndexAnalyzerProvide
             throw new IllegalArgumentException("Custom normalizer [" + name() + "] cannot configure a tokenizer");
         }
 
-        List<CharFilterFactory> charFiltersList = new ArrayList<>();
         String[] charFilterNames = analyzerSettings.getAsArray("char_filter");
+        List<CharFilterFactory> charFiltersList = new ArrayList<>(charFilterNames.length);
         for (String charFilterName : charFilterNames) {
             CharFilterFactory charFilter = charFilters.get(charFilterName);
             if (charFilter == null) {
@@ -66,8 +66,8 @@ public final class CustomNormalizerProvider extends AbstractIndexAnalyzerProvide
             charFiltersList.add(charFilter);
         }
 
-        List<TokenFilterFactory> tokenFilterList = new ArrayList<>();
         String[] tokenFilterNames = analyzerSettings.getAsArray("filter");
+        List<TokenFilterFactory> tokenFilterList = new ArrayList<>(tokenFilterNames.length);
         for (String tokenFilterName : tokenFilterNames) {
             TokenFilterFactory tokenFilter = tokenFilters.get(tokenFilterName);
             if (tokenFilter == null) {

core/src/main/java/org/elasticsearch/index/mapper/DynamicTemplate.java

@@ -318,7 +318,7 @@ public class DynamicTemplate implements ToXContent {
     }
 
     private List processList(List list, String name, String dynamicType) {
-        List processedList = new ArrayList();
+        List processedList = new ArrayList(list.size());
         for (Object value : list) {
             if (value instanceof Map) {
                 value = processMap((Map<String, Object>) value, name, dynamicType);

core/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java

@@ -250,8 +250,8 @@ public abstract class AbstractQueryBuilder<QB extends AbstractQueryBuilder<QB>>
     }
 
     protected static final List<QueryBuilder> readQueries(StreamInput in) throws IOException {
-        List<QueryBuilder> queries = new ArrayList<>();
         int size = in.readVInt();
+        List<QueryBuilder> queries = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             queries.add(in.readNamedWriteable(QueryBuilder.class));
         }

core/src/main/java/org/elasticsearch/index/query/GeoPolygonQueryBuilder.java

@@ -163,7 +163,7 @@ public class GeoPolygonQueryBuilder extends AbstractQueryBuilder<GeoPolygonQuery
             throw new QueryShardException(context, "field [" + fieldName + "] is not a geo_point field");
         }
 
-        List<GeoPoint> shell = new ArrayList<GeoPoint>();
+        List<GeoPoint> shell = new ArrayList<>(this.shell.size());
         for (GeoPoint geoPoint : this.shell) {
             shell.add(new GeoPoint(geoPoint));
         }

core/src/main/java/org/elasticsearch/index/snapshots/blobstore/BlobStoreIndexShardSnapshots.java

@@ -284,7 +284,7 @@ public class BlobStoreIndexShardSnapshots implements Iterable<SnapshotFiles>, To
             }
         }
 
-        List<SnapshotFiles> snapshots = new ArrayList<>();
+        List<SnapshotFiles> snapshots = new ArrayList<>(snapshotsMap.size());
         for (Map.Entry<String, List<String>> entry : snapshotsMap.entrySet()) {
             List<FileInfo> fileInfosBuilder = new ArrayList<>();
             for (String file : entry.getValue()) {

core/src/main/java/org/elasticsearch/indices/breaker/HierarchyCircuitBreakerService.java

@@ -177,7 +177,7 @@ public class HierarchyCircuitBreakerService extends CircuitBreakerService {
     @Override
     public AllCircuitBreakerStats stats() {
         long parentEstimated = 0;
-        List<CircuitBreakerStats> allStats = new ArrayList<>();
+        List<CircuitBreakerStats> allStats = new ArrayList<>(this.breakers.size());
         // Gather the "estimated" count for the parent breaker by adding the
         // estimations for each individual breaker
         for (CircuitBreaker breaker : this.breakers.values()) {

core/src/main/java/org/elasticsearch/search/aggregations/AggregatorFactories.java

@@ -183,7 +183,7 @@ public class AggregatorFactories {
     }
 
     public List<PipelineAggregator> createPipelineAggregators() throws IOException {
-        List<PipelineAggregator> pipelineAggregators = new ArrayList<>();
+        List<PipelineAggregator> pipelineAggregators = new ArrayList<>(this.pipelineAggregatorFactories.size());
         for (PipelineAggregationBuilder factory : this.pipelineAggregatorFactories) {
             pipelineAggregators.add(factory.create());
         }

core/src/main/java/org/elasticsearch/search/aggregations/BucketCollector.java

@@ -70,7 +70,7 @@ public abstract class BucketCollector implements Collector {
 
                     @Override
                     public LeafBucketCollector getLeafCollector(LeafReaderContext ctx) throws IOException {
-                        List<LeafBucketCollector> leafCollectors = new ArrayList<>();
+                        List<LeafBucketCollector> leafCollectors = new ArrayList<>(collectors.length);
                         for (BucketCollector c : collectors) {
                             leafCollectors.add(c.getLeafCollector(ctx));
                         }

core/src/main/java/org/elasticsearch/search/aggregations/bucket/adjacency/AdjacencyMatrixAggregationBuilder.java

@@ -197,7 +197,7 @@ public class AdjacencyMatrixAggregationBuilder extends AbstractAggregationBuilde
                             + "] index level setting.");
         }
 
-        List<KeyedFilter> rewrittenFilters = new ArrayList<>();
+        List<KeyedFilter> rewrittenFilters = new ArrayList<>(filters.size());
         for (KeyedFilter kf : filters) {
             rewrittenFilters.add(new KeyedFilter(kf.key(), QueryBuilder.rewriteQuery(kf.filter(), context.getQueryShardContext())));
         }

core/src/main/java/org/elasticsearch/search/aggregations/bucket/filters/FiltersAggregationBuilder.java

@@ -169,7 +169,7 @@ public class FiltersAggregationBuilder extends AbstractAggregationBuilder<Filter
     @Override
     protected AggregatorFactory<?> doBuild(SearchContext context, AggregatorFactory<?> parent, Builder subFactoriesBuilder)
             throws IOException {
-        List<KeyedFilter> rewrittenFilters = new ArrayList<>();
+        List<KeyedFilter> rewrittenFilters = new ArrayList<>(filters.size());
         for(KeyedFilter kf : filters) {
             rewrittenFilters.add(new KeyedFilter(kf.key(), QueryBuilder.rewriteQuery(kf.filter(), 
                     context.getQueryShardContext())));

core/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/DoubleTerms.java

@@ -164,7 +164,7 @@ public class DoubleTerms extends InternalMappedTerms<DoubleTerms, DoubleTerms.Bu
         if (promoteToDouble == false) {
             return super.doReduce(aggregations, reduceContext);
         }
-        List<InternalAggregation> newAggs = new ArrayList<>();
+        List<InternalAggregation> newAggs = new ArrayList<>(aggregations.size());
         for (InternalAggregation agg : aggregations) {
             if (agg instanceof LongTerms) {
                 DoubleTerms dTerms = LongTerms.convertLongTermsToDouble((LongTerms) agg, format);

core/src/main/java/org/elasticsearch/search/aggregations/pipeline/cumulativesum/CumulativeSumPipelineAggregator.java

@@ -75,7 +75,7 @@ public class CumulativeSumPipelineAggregator extends PipelineAggregator {
                 InternalMultiBucketAggregation.InternalBucket>) aggregation;
         List<? extends InternalMultiBucketAggregation.InternalBucket> buckets = histo.getBuckets();
         HistogramFactory factory = (HistogramFactory) histo;
-        List<Bucket> newBuckets = new ArrayList<>();
+        List<Bucket> newBuckets = new ArrayList<>(buckets.size());
         double sum = 0;
         for (InternalMultiBucketAggregation.InternalBucket bucket : buckets) {
             Double thisBucketValue = resolveBucketValue(histo, bucket, bucketsPaths()[0], GapPolicy.INSERT_ZEROS);

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ConvertProcessor.java

@@ -153,7 +153,7 @@ public final class ConvertProcessor extends AbstractProcessor {
 
         if (oldValue instanceof List) {
             List<?> list = (List<?>) oldValue;
-            List<Object> newList = new ArrayList<>();
+            List<Object> newList = new ArrayList<>(list.size());
             for (Object value : list) {
                 newList.add(convertType.convert(value));
             }

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateProcessor.java

@@ -54,7 +54,7 @@ public final class DateProcessor extends AbstractProcessor {
         this.field = field;
         this.targetField = targetField;
         this.formats = formats;
-        this.dateParsers = new ArrayList<>();
+        this.dateParsers = new ArrayList<>(this.formats.size());
         for (String format : formats) {
             DateFormat dateFormat = DateFormat.fromString(format);
             dateParsers.add(dateFormat.getFunction(format, timezone, locale));

modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java

@@ -240,7 +240,7 @@ public final class Def {
          }
 
          // convert recipe string to a bitset for convenience (the code below should be refactored...)
-         BitSet lambdaArgs = new BitSet();
+         BitSet lambdaArgs = new BitSet(recipeString.length());
          for (int i = 0; i < recipeString.length(); i++) {
              lambdaArgs.set(recipeString.charAt(i));
          }

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/ELambda.java

@@ -113,7 +113,7 @@ public final class ELambda extends AExpression implements ILambda {
             // we don't know anything: treat as def
             returnType = Definition.DEF_TYPE;
             // don't infer any types, replace any null types with def
-            actualParamTypeStrs = new ArrayList<>();
+            actualParamTypeStrs = new ArrayList<>(paramTypeStrs.size());
             for (String type : paramTypeStrs) {
                 if (type == null) {
                     actualParamTypeStrs.add("def");
@@ -139,7 +139,7 @@ public final class ELambda extends AExpression implements ILambda {
                 returnType = interfaceMethod.rtn;
             }
             // replace any null types with the actual type
-            actualParamTypeStrs = new ArrayList<>();
+            actualParamTypeStrs = new ArrayList<>(paramTypeStrs.size());
             for (int i = 0; i < paramTypeStrs.size(); i++) {
                 String paramType = paramTypeStrs.get(i);
                 if (paramType == null) {
@@ -162,8 +162,8 @@ public final class ELambda extends AExpression implements ILambda {
             }
         }
         // prepend capture list to lambda's arguments
-        List<String> paramTypes = new ArrayList<>();
+        List<String> paramTypes = new ArrayList<>(captures.size() + actualParamTypeStrs.size());
-        List<String> paramNames = new ArrayList<>();
+        List<String> paramNames = new ArrayList<>(captures.size() + paramNameStrs.size());
         for (Variable var : captures) {
             paramTypes.add(var.type.name);
             paramNames.add(var.name);

plugins/discovery-ec2/src/main/java/org/elasticsearch/discovery/ec2/AwsEc2UnicastHostsProvider.java

@@ -125,8 +125,8 @@ class AwsEc2UnicastHostsProvider extends AbstractComponent implements UnicastHos
                 // lets see if we can filter based on groups
                 if (!groups.isEmpty()) {
                     List<GroupIdentifier> instanceSecurityGroups = instance.getSecurityGroups();
-                    ArrayList<String> securityGroupNames = new ArrayList<String>();
+                    List<String> securityGroupNames = new ArrayList<>(instanceSecurityGroups.size());
-                    ArrayList<String> securityGroupIds = new ArrayList<String>();
+                    List<String> securityGroupIds = new ArrayList<>(instanceSecurityGroups.size());
                     for (GroupIdentifier sg : instanceSecurityGroups) {
                         securityGroupNames.add(sg.getGroupName());
                         securityGroupIds.add(sg.getGroupId());

plugins/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageBlobStore.java

@@ -249,7 +249,7 @@ class GoogleCloudStorageBlobStore extends AbstractComponent implements BlobStore
             deleteBlob(blobNames.iterator().next());
             return;
         }
-        final List<Storage.Objects.Delete> deletions = new ArrayList<>();
+        final List<Storage.Objects.Delete> deletions = new ArrayList<>(Math.min(MAX_BATCHING_REQUESTS, blobNames.size()));
         final Iterator<String> blobs = blobNames.iterator();
 
         SocketAccess.doPrivilegedVoidIOException(() -> {

test/framework/src/main/java/org/elasticsearch/bootstrap/BootstrapForTesting.java

@@ -201,7 +201,7 @@ public class BootstrapForTesting {
         codebases.removeAll(excluded);
 
         // parse each policy file, with codebase substitution from the classpath
-        final List<Policy> policies = new ArrayList<>();
+        final List<Policy> policies = new ArrayList<>(pluginPolicies.size());
         for (URL policyFile : pluginPolicies) {
             policies.add(Security.readPolicy(policyFile, codebases));
         }

test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ClientYamlTestExecutionContext.java

@@ -110,7 +110,7 @@ public class ClientYamlTestExecutionContext {
                     ContentType.create(xContentType.mediaTypeWithoutParameters(), StandardCharsets.UTF_8));
         } else {
             XContentType xContentType = getContentType(headers, STREAMING_CONTENT_TYPES);
-            List<BytesRef> bytesRefList = new ArrayList<>();
+            List<BytesRef> bytesRefList = new ArrayList<>(bodies.size());
             int totalBytesLength = 0;
             for (Map<String, Object> body : bodies) {
                 BytesRef bytesRef = bodyAsBytesRef(body, xContentType);