Fix alias resolution runtime complexity.

rest-api-spec/src/main/resources/rest-api-spec/test/search_shards/10_basic.yml

@@ -64,10 +64,9 @@
   - length: { shards: 1 }
   - match: { shards.0.0.index: test_index }
   - match: { indices.test_index.aliases: [test_alias_filter_1, test_alias_filter_2]}
-  - match: { indices.test_index.filter.bool.should.0.term.field.value: value1 }
+  - length: { indices.test_index.filter.bool.should: 2 }
   - lte: { indices.test_index.filter.bool.should.0.term.field.boost: 1.0 }
   - gte: { indices.test_index.filter.bool.should.0.term.field.boost: 1.0 }
-  - match: { indices.test_index.filter.bool.should.1.term.field.value: value2}
   - lte: { indices.test_index.filter.bool.should.1.term.field.boost: 1.0 }
   - gte: { indices.test_index.filter.bool.should.1.term.field.boost: 1.0 }
   - match: { indices.test_index.filter.bool.adjust_pure_negative: true}

server/src/main/java/org/elasticsearch/action/admin/cluster/shards/TransportClusterSearchShardsAction.java

@@ -88,10 +88,11 @@ protected void masterOperation(final ClusterSearchShardsRequest request, final C
         String[] concreteIndices = indexNameExpressionResolver.concreteIndexNames(clusterState, request);
         Map<String, Set<String>> routingMap = indexNameExpressionResolver.resolveSearchRouting(state, request.routing(), request.indices());
         Map<String, AliasFilter> indicesAndFilters = new HashMap<>();
+        Set<String> indicesAndAliases = indexNameExpressionResolver.resolveExpressions(clusterState, request.indices());
         for (String index : concreteIndices) {
-            final AliasFilter aliasFilter = indicesService.buildAliasFilter(clusterState, index, request.indices());
+            final AliasFilter aliasFilter = indicesService.buildAliasFilter(clusterState, index, indicesAndAliases);
             final String[] aliases = indexNameExpressionResolver.indexAliases(clusterState, index, aliasMetadata -> true, true,
-                request.indices());
+                indicesAndAliases);
             indicesAndFilters.put(index, new AliasFilter(aliasFilter.getQueryBuilder(), aliases));
         }
 

server/src/main/java/org/elasticsearch/action/admin/indices/validate/query/TransportValidateQueryAction.java

@@ -115,8 +115,9 @@ protected void doExecute(Task task, ValidateQueryRequest request, ActionListener
 
     @Override
     protected ShardValidateQueryRequest newShardRequest(int numShards, ShardRouting shard, ValidateQueryRequest request) {
-        final AliasFilter aliasFilter = searchService.buildAliasFilter(clusterService.state(), shard.getIndexName(),
-            request.indices());
+        final ClusterState clusterState = clusterService.state();
+        final Set<String> indicesAndAliases = indexNameExpressionResolver.resolveExpressions(clusterState, request.indices());
+        final AliasFilter aliasFilter = searchService.buildAliasFilter(clusterState, shard.getIndexName(), indicesAndAliases);
         return new ShardValidateQueryRequest(shard.shardId(), aliasFilter, request);
     }
 

server/src/main/java/org/elasticsearch/action/explain/TransportExplainAction.java

@@ -52,6 +52,7 @@
 import org.elasticsearch.transport.TransportService;
 
 import java.io.IOException;
+import java.util.Set;
 
 /**
  * Explain transport action. Computes the explain on the targeted shard.
@@ -83,8 +84,8 @@ protected boolean resolveIndex(ExplainRequest request) {
 
     @Override
     protected void resolveRequest(ClusterState state, InternalRequest request) {
-        final AliasFilter aliasFilter = searchService.buildAliasFilter(state, request.concreteIndex(),
-            request.request().index());
+        final Set<String> indicesAndAliases = indexNameExpressionResolver.resolveExpressions(state, request.request().index());
+        final AliasFilter aliasFilter = searchService.buildAliasFilter(state, request.concreteIndex(), indicesAndAliases);
         request.request().filteringAlias(aliasFilter);
         // Fail fast on the node that received the request.
         if (request.request().routing() == null && state.getMetaData().routingRequired(request.concreteIndex())) {

server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java

@@ -116,9 +116,10 @@ public TransportSearchAction(ThreadPool threadPool, TransportService transportSe
     private Map<String, AliasFilter> buildPerIndexAliasFilter(SearchRequest request, ClusterState clusterState,
                                                               Index[] concreteIndices, Map<String, AliasFilter> remoteAliasMap) {
         final Map<String, AliasFilter> aliasFilterMap = new HashMap<>();
+        final Set<String> indicesAndAliases = indexNameExpressionResolver.resolveExpressions(clusterState, request.indices());
         for (Index index : concreteIndices) {
             clusterState.blocks().indexBlockedRaiseException(ClusterBlockLevel.READ, index.getName());
-            AliasFilter aliasFilter = searchService.buildAliasFilter(clusterState, index.getName(), request.indices());
+            AliasFilter aliasFilter = searchService.buildAliasFilter(clusterState, index.getName(), indicesAndAliases);
             assert aliasFilter != null;
             aliasFilterMap.put(index.getUUID(), aliasFilter);
         }

server/src/main/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolver.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.time.DateFormatter;
@@ -42,15 +43,19 @@
 import java.time.ZoneOffset;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.SortedMap;
+import java.util.Spliterators;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
 
 import static java.util.Collections.unmodifiableList;
 
@@ -322,71 +327,88 @@ public String resolveDateMathExpression(String dateExpression) {
         return dateMathExpressionResolver.resolveExpression(dateExpression, new Context(null, null));
     }
 
+    /**
+     * Resolve an array of expressions to the set of indices and aliases that these expressions match.
+     */
+    public Set<String> resolveExpressions(ClusterState state, String... expressions) {
+        Context context = new Context(state, IndicesOptions.lenientExpandOpen(), true, false);
+        List<String> resolvedExpressions = Arrays.asList(expressions);
+        for (ExpressionResolver expressionResolver : expressionResolvers) {
+            resolvedExpressions = expressionResolver.resolve(context, resolvedExpressions);
+        }
+        return Collections.unmodifiableSet(new HashSet<>(resolvedExpressions));
+    }
+
     /**
      * Iterates through the list of indices and selects the effective list of filtering aliases for the
      * given index.
      * <p>Only aliases with filters are returned. If the indices list contains a non-filtering reference to
      * the index itself - null is returned. Returns {@code null} if no filtering is required.
+     * <b>NOTE</b>: The provided expressions must have been resolved already via {@link #resolveExpressions}.
      */
-    public String[] filteringAliases(ClusterState state, String index, String... expressions) {
-        return indexAliases(state, index, AliasMetaData::filteringRequired, false, expressions);
+    public String[] filteringAliases(ClusterState state, String index, Set<String> resolvedExpressions) {
+        return indexAliases(state, index, AliasMetaData::filteringRequired, false, resolvedExpressions);
+    }
+
+    /**
+     * Whether to generate the candidate set from index aliases, or from the set of resolved expressions.
+     * @param indexAliasesSize        the number of aliases of the index
+     * @param resolvedExpressionsSize the number of resolved expressions
+     */
+    // pkg-private for testing
+    boolean iterateIndexAliases(int indexAliasesSize, int resolvedExpressionsSize) {
+        return indexAliasesSize <= resolvedExpressionsSize;
     }
 
     /**
      * Iterates through the list of indices and selects the effective list of required aliases for the given index.
      * <p>Only aliases where the given predicate tests successfully are returned. If the indices list contains a non-required reference to
      * the index itself - null is returned. Returns {@code null} if no filtering is required.
+     * <p><b>NOTE</b>: the provided expressions must have been resolved already via {@link #resolveExpressions}.
      */
     public String[] indexAliases(ClusterState state, String index, Predicate<AliasMetaData> requiredAlias, boolean skipIdentity,
-                                 String... expressions) {
-        // expand the aliases wildcard
-        List<String> resolvedExpressions = expressions != null ? Arrays.asList(expressions) : Collections.emptyList();
-        Context context = new Context(state, IndicesOptions.lenientExpandOpen(), true, false);
-        for (ExpressionResolver expressionResolver : expressionResolvers) {
-            resolvedExpressions = expressionResolver.resolve(context, resolvedExpressions);
-        }
-
+            Set<String> resolvedExpressions) {
         if (isAllIndices(resolvedExpressions)) {
             return null;
         }
+
         final IndexMetaData indexMetaData = state.metaData().getIndices().get(index);
         if (indexMetaData == null) {
             // Shouldn't happen
             throw new IndexNotFoundException(index);
         }
-        // optimize for the most common single index/alias scenario
-        if (resolvedExpressions.size() == 1) {
-            String alias = resolvedExpressions.get(0);
 
-            AliasMetaData aliasMetaData = indexMetaData.getAliases().get(alias);
-            if (aliasMetaData == null || requiredAlias.test(aliasMetaData) == false) {
-                return null;
-            }
-            return new String[]{alias};
+        if (skipIdentity == false && resolvedExpressions.contains(index)) {
+            return null;
+        }
+
+        final ImmutableOpenMap<String, AliasMetaData> indexAliases = indexMetaData.getAliases();
+        final AliasMetaData[] aliasCandidates;
+        if (iterateIndexAliases(indexAliases.size(), resolvedExpressions.size())) {
+            // faster to iterate indexAliases
+            aliasCandidates = StreamSupport.stream(Spliterators.spliteratorUnknownSize(indexAliases.values().iterator(), 0), false)
+                    .map(cursor -> cursor.value)
+                    .filter(aliasMetaData -> resolvedExpressions.contains(aliasMetaData.alias()))
+                    .toArray(AliasMetaData[]::new);
+        } else {
+            // faster to iterate resolvedExpressions
+            aliasCandidates = resolvedExpressions.stream()
+                    .map(indexAliases::get)
+                    .filter(Objects::nonNull)
+                    .toArray(AliasMetaData[]::new);
         }
+
         List<String> aliases = null;
-        for (String alias : resolvedExpressions) {
-            if (alias.equals(index)) {
-                if (skipIdentity) {
-                    continue;
-                } else {
-                    return null;
-                }
-            }
-            AliasMetaData aliasMetaData = indexMetaData.getAliases().get(alias);
-            // Check that this is an alias for the current index
-            // Otherwise - skip it
-            if (aliasMetaData != null) {
-                if (requiredAlias.test(aliasMetaData)) {
-                    // If required - add it to the list of aliases
-                    if (aliases == null) {
-                        aliases = new ArrayList<>();
-                    }
-                    aliases.add(alias);
-                } else {
-                    // If not, we have a non required alias for this index - no further checking needed
-                    return null;
+        for (AliasMetaData aliasMetaData : aliasCandidates) {
+            if (requiredAlias.test(aliasMetaData)) {
+                // If required - add it to the list of aliases
+                if (aliases == null) {
+                    aliases = new ArrayList<>();
                 }
+                aliases.add(aliasMetaData.alias());
+            } else {
+                // If not, we have a non required alias for this index - no further checking needed
+                return null;
             }
         }
         if (aliases == null) {
@@ -513,7 +535,7 @@ public Map<String, Set<String>> resolveSearchRoutingAllIndices(MetaData metaData
      * @param aliasesOrIndices the array containing index names
      * @return true if the provided array maps to all indices, false otherwise
      */
-    public static boolean isAllIndices(List<String> aliasesOrIndices) {
+    public static boolean isAllIndices(Collection<String> aliasesOrIndices) {
         return aliasesOrIndices == null || aliasesOrIndices.isEmpty() || isExplicitAllPattern(aliasesOrIndices);
     }
 
@@ -524,8 +546,8 @@ public static boolean isAllIndices(List<String> aliasesOrIndices) {
      * @param aliasesOrIndices the array containing index names
      * @return true if the provided array explicitly maps to all indices, false otherwise
      */
-    static boolean isExplicitAllPattern(List<String> aliasesOrIndices) {
-        return aliasesOrIndices != null && aliasesOrIndices.size() == 1 && MetaData.ALL.equals(aliasesOrIndices.get(0));
+    static boolean isExplicitAllPattern(Collection<String> aliasesOrIndices) {
+        return aliasesOrIndices != null && aliasesOrIndices.size() == 1 && MetaData.ALL.equals(aliasesOrIndices.iterator().next());
     }
 
     /**
@@ -598,7 +620,7 @@ public long getStartTime() {
         /**
          * This is used to prevent resolving aliases to concrete indices but this also means
          * that we might return aliases that point to a closed index. This is currently only used
-         * by {@link #filteringAliases(ClusterState, String, String...)} since it's the only one that needs aliases
+         * by {@link #filteringAliases(ClusterState, String, Set)} since it's the only one that needs aliases
          */
         boolean isPreserveAliases() {
             return preserveAliases;
@@ -642,6 +664,8 @@ public List<String> resolve(Context context, List<String> expressions) {
                 return resolveEmptyOrTrivialWildcard(options, metaData);
             }
 
+            // TODO: Fix API to work with sets rather than lists since we need to convert to sets
+            // internally anyway.
             Set<String> result = innerResolve(context, expressions, options, metaData);
 
             if (result == null) {

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

@@ -1379,7 +1379,7 @@ interface IndexDeletionAllowedPredicate {
         (Index index, IndexSettings indexSettings) -> canDeleteIndexContents(index, indexSettings);
     private final IndexDeletionAllowedPredicate ALWAYS_TRUE = (Index index, IndexSettings indexSettings) -> true;
 
-    public AliasFilter buildAliasFilter(ClusterState state, String index, String... expressions) {
+    public AliasFilter buildAliasFilter(ClusterState state, String index, Set<String> resolvedExpressions) {
         /* Being static, parseAliasFilter doesn't have access to whatever guts it needs to parse a query. Instead of passing in a bunch
          * of dependencies we pass in a function that can perform the parsing. */
         CheckedFunction<byte[], QueryBuilder, IOException> filterParser = bytes -> {
@@ -1388,8 +1388,8 @@ public AliasFilter buildAliasFilter(ClusterState state, String index, String...
                 return parseInnerQueryBuilder(parser);
             }
         };
-        String[] aliases = indexNameExpressionResolver.filteringAliases(state, index, expressions);
         IndexMetaData indexMetaData = state.metaData().index(index);
+        String[] aliases = indexNameExpressionResolver.filteringAliases(state, index, resolvedExpressions);
         return new AliasFilter(ShardSearchRequest.parseAliasFilter(filterParser, indexMetaData, aliases), aliases);
     }
 

server/src/main/java/org/elasticsearch/search/SearchService.java

@@ -109,6 +109,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -1004,8 +1005,8 @@ public void run() {
         }
     }
 
-    public AliasFilter buildAliasFilter(ClusterState state, String index, String... expressions) {
-        return indicesService.buildAliasFilter(state, index, expressions);
+    public AliasFilter buildAliasFilter(ClusterState state, String index, Set<String> resolvedExpressions) {
+        return indicesService.buildAliasFilter(state, index, resolvedExpressions);
     }
 
     /**

server/src/test/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolverAliasIterationTests.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.cluster.metadata;
+
+public class IndexNameExpressionResolverAliasIterationTests extends IndexNameExpressionResolverTests {
+
+    protected IndexNameExpressionResolver getIndexNameExpressionResolver() {
+        return new IndexNameExpressionResolver() {
+            @Override
+            boolean iterateIndexAliases(int indexAliasesSize, int resolvedExpressionsSize) {
+                return true;
+            }
+        };
+    }
+
+}

server/src/test/java/org/elasticsearch/cluster/metadata/IndexNameExpressionResolverExpressionsIterationTests.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.cluster.metadata;
+
+public class IndexNameExpressionResolverExpressionsIterationTests extends IndexNameExpressionResolverTests {
+
+    protected IndexNameExpressionResolver getIndexNameExpressionResolver() {
+        return new IndexNameExpressionResolver() {
+            @Override
+            boolean iterateIndexAliases(int indexAliasesSize, int resolvedExpressionsSize) {
+                return false;
+            }
+        };
+    }
+
+}