Some obvious speedups to parsing alias filters (#127240)

It's in the title, saving some allocations and weird indirection in obvious spots.

Author: original-brownbear

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

@@ -374,11 +374,14 @@ protected static Collection<ResolvedExpression> resolveExpressionsToResources(Co
                 return List.of();
             }
         } else {
-            Predicate<String> isMatchAll = (((Predicate<String>) Metadata.ALL::equals)).or(Regex::isMatchAllPattern);
             if (expressions == null
                 || expressions.length == 0
                 || expressions.length == 1
-                    && (SelectorResolver.selectorsValidatedAndMatchesPredicate(expressions[0], context, isMatchAll))) {
+                    && (SelectorResolver.selectorsValidatedAndMatchesPredicate(
+                        expressions[0],
+                        context,
+                        s -> Metadata.ALL.equals(s) || Regex.isMatchAllPattern(s)
+                    ))) {
                 IndexComponentSelector selector;
                 if (expressions != null && expressions.length == 1) {
                     selector = SelectorResolver.parseMatchAllToSelector(context, expressions[0]);

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

@@ -1023,6 +1023,12 @@ public IndicesQueryCache getIndicesQueryCache() {
         return indicesQueryCache;
     }
 
+    private QueryBuilder parseFilter(BytesReference bytes) throws IOException {
+        try (XContentParser parser = XContentHelper.createParser(parserConfig, bytes)) {
+            return parseTopLevelQuery(parser);
+        }
+    }
+
     static class OldShardsStats implements IndexEventListener {
 
         final SearchStats searchStats = new SearchStats();
@@ -1743,13 +1749,6 @@ interface IndexDeletionAllowedPredicate {
     public AliasFilter buildAliasFilter(ProjectState project, String index, Set<ResolvedExpression> 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<BytesReference, QueryBuilder, IOException> filterParser = bytes -> {
-            try (
-                XContentParser parser = XContentHelper.createParserNotCompressed(parserConfig, bytes, XContentHelper.xContentType(bytes))
-            ) {
-                return parseTopLevelQuery(parser);
-            }
-        };
 
         final ProjectMetadata metadata = project.metadata();
         String[] aliases = indexNameExpressionResolver.filteringAliases(metadata, index, resolvedExpressions);
@@ -1759,43 +1758,36 @@ public AliasFilter buildAliasFilter(ProjectState project, String index, Set<Reso
 
         IndexAbstraction ia = metadata.getIndicesLookup().get(index);
         DataStream dataStream = ia.getParentDataStream();
+        final QueryBuilder filter;
         if (dataStream != null) {
+            var dsAliases = metadata.dataStreamAliases();
             String dataStreamName = dataStream.getName();
-            List<QueryBuilder> filters = Arrays.stream(aliases)
-                .map(name -> metadata.dataStreamAliases().get(name))
-                .filter(dataStreamAlias -> dataStreamAlias.getFilter(dataStreamName) != null)
-                .map(dataStreamAlias -> {
-                    try {
-                        return filterParser.apply(dataStreamAlias.getFilter(dataStreamName).uncompressed());
-                    } catch (IOException e) {
-                        throw new UncheckedIOException(e);
-                    }
-                })
-                .toList();
+            List<QueryBuilder> filters = Arrays.stream(aliases).map(key -> {
+                var f = dsAliases.get(key).getFilter(dataStreamName);
+                if (f == null) {
+                    return null;
+                }
+                try {
+                    return parseFilter(f.compressedReference());
+                } catch (IOException e) {
+                    throw new UncheckedIOException(e);
+                }
+            }).filter(Objects::nonNull).toList();
             if (filters.isEmpty()) {
-                return AliasFilter.of(null, aliases);
+                filter = null;
+            } else if (filters.size() == 1) {
+                filter = filters.getFirst();
             } else {
-                if (filters.size() == 1) {
-                    return AliasFilter.of(filters.get(0), aliases);
-                } else {
-                    BoolQueryBuilder bool = new BoolQueryBuilder();
-                    for (QueryBuilder filter : filters) {
-                        bool.should(filter);
-                    }
-                    return AliasFilter.of(bool, aliases);
+                BoolQueryBuilder bool = new BoolQueryBuilder();
+                for (QueryBuilder f : filters) {
+                    bool.should(f);
                 }
+                filter = bool;
             }
         } else {
-            IndexMetadata indexMetadata = metadata.index(index);
-            return AliasFilter.of(ShardSearchRequest.parseAliasFilter(filterParser, indexMetadata, aliases), aliases);
+            filter = ShardSearchRequest.parseAliasFilter(this::parseFilter, metadata.index(index), aliases);
         }
-    }
-
-    /**
-     * Returns a new {@link QueryRewriteContext} with the given {@code now} provider
-     */
-    public QueryRewriteContext getRewriteContext(LongSupplier nowInMillis, ResolvedIndices resolvedIndices, PointInTimeBuilder pit) {
-        return getRewriteContext(nowInMillis, resolvedIndices, pit, false);
+        return AliasFilter.of(filter, aliases);
     }
 
     /**

server/src/main/java/org/elasticsearch/search/internal/ShardSearchRequest.java

@@ -58,7 +58,6 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
-import java.util.function.Function;
 
 import static java.util.Collections.emptyMap;
 import static org.elasticsearch.search.internal.SearchContext.TRACK_TOTAL_HITS_DISABLED;
@@ -630,23 +629,13 @@ public static QueryBuilder parseAliasFilter(
         }
         Index index = metadata.getIndex();
         Map<String, AliasMetadata> aliases = metadata.getAliases();
-        Function<AliasMetadata, QueryBuilder> parserFunction = (alias) -> {
-            if (alias.filter() == null) {
-                return null;
-            }
-            try {
-                return filterParser.apply(alias.filter().uncompressed());
-            } catch (IOException ex) {
-                throw new AliasFilterParsingException(index, alias.getAlias(), "Invalid alias filter", ex);
-            }
-        };
         if (aliasNames.length == 1) {
             AliasMetadata alias = aliases.get(aliasNames[0]);
             if (alias == null) {
                 // This shouldn't happen unless alias disappeared after filteringAliases was called.
                 throw new InvalidAliasNameException(index, aliasNames[0], "Unknown alias name was passed to alias Filter");
             }
-            return parserFunction.apply(alias);
+            return parseAliasFilter(filterParser, alias, index);
         } else {
             // we need to bench here a bit, to see maybe it makes sense to use OrFilter
             BoolQueryBuilder combined = new BoolQueryBuilder();
@@ -656,7 +645,7 @@ public static QueryBuilder parseAliasFilter(
                     // This shouldn't happen unless alias disappeared after filteringAliases was called.
                     throw new InvalidAliasNameException(index, aliasNames[0], "Unknown alias name was passed to alias Filter");
                 }
-                QueryBuilder parsedFilter = parserFunction.apply(alias);
+                QueryBuilder parsedFilter = parseAliasFilter(filterParser, alias, index);
                 if (parsedFilter != null) {
                     combined.should(parsedFilter);
                 } else {
@@ -668,6 +657,21 @@ public static QueryBuilder parseAliasFilter(
         }
     }
 
+    private static QueryBuilder parseAliasFilter(
+        CheckedFunction<BytesReference, QueryBuilder, IOException> filterParser,
+        AliasMetadata alias,
+        Index index
+    ) {
+        if (alias.filter() == null) {
+            return null;
+        }
+        try {
+            return filterParser.apply(alias.filter().compressedReference());
+        } catch (IOException ex) {
+            throw new AliasFilterParsingException(index, alias.getAlias(), "Invalid alias filter", ex);
+        }
+    }
+
     public final Map<String, Object> getRuntimeMappings() {
         return source == null ? emptyMap() : source.runtimeMappings();
     }

server/src/test/java/org/elasticsearch/search/internal/ShardSearchRequestTests.java

@@ -19,6 +19,7 @@
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.compress.CompressedXContent;
+import org.elasticsearch.common.compress.CompressorFactory;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.settings.Settings;
@@ -210,7 +211,7 @@ private IndexMetadata add(IndexMetadata indexMetadata, String alias, @Nullable C
     public QueryBuilder aliasFilter(IndexMetadata indexMetadata, String... aliasNames) {
         return ShardSearchRequest.parseAliasFilter(bytes -> {
             try (
-                InputStream inputStream = bytes.streamInput();
+                InputStream inputStream = CompressorFactory.COMPRESSOR.uncompress(bytes).streamInput();
                 XContentParser parser = XContentFactory.xContentType(inputStream)
                     .xContent()
                     .createParser(xContentRegistry(), DeprecationHandler.THROW_UNSUPPORTED_OPERATION, inputStream)