Make some Mappers Singletons (#77067)

Just some obvious singletons we can use to save a little memory/cache that I found during other experiments.
elastic · Aug 31, 2021 · 37516da · 37516da
1 parent 9e9a6d5
commit 37516da
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Showing 13 changed files with 58 additions and 30 deletions.
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/DocCountFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/DocCountFieldMapper.java
@@ -22,7 +22,9 @@ public class DocCountFieldMapper extends MetadataFieldMapper {
     public static final String NAME = "_doc_count";
     public static final String CONTENT_TYPE = "_doc_count";
 
-    public static final TypeParser PARSER = new FixedTypeParser(c -> new DocCountFieldMapper());
+    private static final DocCountFieldMapper INSTANCE = new DocCountFieldMapper();
+
+    public static final TypeParser PARSER = new FixedTypeParser(c -> INSTANCE);
 
     public static final class DocCountFieldType extends MappedFieldType {
 

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/FieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/FieldMapper.java
@@ -385,8 +385,10 @@ public final Map<String, NamedAnalyzer> indexAnalyzers() {
 
     public static class MultiFields implements Iterable<FieldMapper>, ToXContent {
 
+        private static final MultiFields EMPTY = new MultiFields(Collections.emptyMap());
+
         public static MultiFields empty() {
-            return new MultiFields(Collections.emptyMap());
+            return EMPTY;
         }
 
         public static class Builder {

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/FieldNamesFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/FieldNamesFieldMapper.java
@@ -93,21 +93,28 @@ public FieldNamesFieldMapper build() {
                         "field_names_enabled_parameter", ENABLED_DEPRECATION_MESSAGE);
                 }
             }
-            FieldNamesFieldType fieldNamesFieldType = new FieldNamesFieldType(enabled.getValue().value());
-            return new FieldNamesFieldMapper(enabled.getValue(), indexVersionCreated, fieldNamesFieldType);
+            return new FieldNamesFieldMapper(enabled.getValue(), indexVersionCreated);
         }
     }
 
     public static final TypeParser PARSER = new ConfigurableTypeParser(
-        c -> new FieldNamesFieldMapper(Defaults.ENABLED, c.indexVersionCreated(), new FieldNamesFieldType(Defaults.ENABLED.value())),
+        c -> new FieldNamesFieldMapper(Defaults.ENABLED, c.indexVersionCreated()),
         c -> new Builder(c.indexVersionCreated())
     );
 
     public static final class FieldNamesFieldType extends TermBasedFieldType {
 
+        private static final FieldNamesFieldType ENABLED = new FieldNamesFieldType(true);
+
+        private static final FieldNamesFieldType DISABLED = new FieldNamesFieldType(false);
+
         private final boolean enabled;
 
-        public FieldNamesFieldType(boolean enabled) {
+        public static FieldNamesFieldType get(boolean enabled) {
+            return enabled ? ENABLED : DISABLED;
+        }
+
+        private FieldNamesFieldType(boolean enabled) {
             super(Defaults.NAME, true, false, false, TextSearchInfo.SIMPLE_MATCH_ONLY, Collections.emptyMap());
             this.enabled = enabled;
         }
@@ -145,8 +152,8 @@ public Query termQuery(Object value, SearchExecutionContext context) {
     private final Explicit<Boolean> enabled;
     private final Version indexVersionCreated;
 
-    private FieldNamesFieldMapper(Explicit<Boolean> enabled, Version indexVersionCreated, FieldNamesFieldType mappedFieldType) {
-        super(mappedFieldType);
+    private FieldNamesFieldMapper(Explicit<Boolean> enabled, Version indexVersionCreated) {
+        super(FieldNamesFieldType.get(enabled.value()));
         this.enabled = enabled;
         this.indexVersionCreated = indexVersionCreated;
     }

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/IgnoredFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/IgnoredFieldMapper.java
@@ -40,7 +40,9 @@ public static class Defaults {
         }
     }
 
-    public static final TypeParser PARSER = new FixedTypeParser(c -> new IgnoredFieldMapper());
+    private static final IgnoredFieldMapper INSTANCE = new IgnoredFieldMapper();
+
+    public static final TypeParser PARSER = new FixedTypeParser(c -> INSTANCE);
 
     public static final class IgnoredFieldType extends StringFieldType {
 

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/IndexFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/IndexFieldMapper.java
@@ -26,7 +26,9 @@ public class IndexFieldMapper extends MetadataFieldMapper {
 
     public static final String CONTENT_TYPE = "_index";
 
-    public static final TypeParser PARSER = new FixedTypeParser(c -> new IndexFieldMapper());
+    private static final IndexFieldMapper INSTANCE = new IndexFieldMapper();
+
+    public static final TypeParser PARSER = new FixedTypeParser(c -> INSTANCE);
 
     static final class IndexFieldType extends ConstantFieldType {
 

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/KeywordFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/KeywordFieldMapper.java
@@ -452,8 +452,8 @@ public boolean isDimension() {
 
     private final IndexAnalyzers indexAnalyzers;
 
-    protected KeywordFieldMapper(String simpleName, FieldType fieldType, KeywordFieldType mappedFieldType,
-                                 MultiFields multiFields, CopyTo copyTo, Builder builder) {
+    private KeywordFieldMapper(String simpleName, FieldType fieldType, KeywordFieldType mappedFieldType,
+                               MultiFields multiFields, CopyTo copyTo, Builder builder) {
         super(simpleName, mappedFieldType, mappedFieldType.normalizer, multiFields, copyTo,
             builder.script.get() != null, builder.onScriptError.getValue());
         assert fieldType.indexOptions().compareTo(IndexOptions.DOCS_AND_FREQS) <= 0;

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/NestedPathFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/NestedPathFieldMapper.java
@@ -23,8 +23,12 @@
 public class NestedPathFieldMapper extends MetadataFieldMapper {
 
     public static final String NAME_PRE_V8 = "_type";
+
     public static final String NAME = "_nested_path";
 
+    private static final NestedPathFieldMapper INSTANCE = new NestedPathFieldMapper(NAME);
+    private static final NestedPathFieldMapper INSTANCE_PRE_V8 = new NestedPathFieldMapper(NAME_PRE_V8);
+
     public static String name(Version version) {
         if (version.before(Version.V_8_0_0)) {
             return NAME_PRE_V8;
@@ -53,12 +57,13 @@ public static class Defaults {
         }
     }
 
-    public static final TypeParser PARSER = new FixedTypeParser(c -> new NestedPathFieldMapper(c.indexVersionCreated()));
+    public static final TypeParser PARSER =
+        new FixedTypeParser(c -> c.indexVersionCreated().before(Version.V_8_0_0) ? INSTANCE_PRE_V8 : INSTANCE);
 
     public static final class NestedPathFieldType extends StringFieldType {
 
-        private NestedPathFieldType(Version version) {
-            super(NestedPathFieldMapper.name(version), true, false, false, TextSearchInfo.SIMPLE_MATCH_ONLY, Collections.emptyMap());
+        private NestedPathFieldType(String name) {
+            super(name, true, false, false, TextSearchInfo.SIMPLE_MATCH_ONLY, Collections.emptyMap());
         }
 
         @Override
@@ -77,8 +82,8 @@ public ValueFetcher valueFetcher(SearchExecutionContext context, String format)
         }
     }
 
-    private NestedPathFieldMapper(Version version) {
-        super(new NestedPathFieldType(version));
+    private NestedPathFieldMapper(String name) {
+        super(new NestedPathFieldType(name));
     }
 
     @Override

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/RoutingFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/RoutingFieldMapper.java
@@ -60,12 +60,12 @@ protected List<Parameter<?>> getParameters() {
 
         @Override
         public RoutingFieldMapper build() {
-            return new RoutingFieldMapper(required.getValue());
+            return RoutingFieldMapper.get(required.getValue());
         }
     }
 
     public static final TypeParser PARSER = new ConfigurableTypeParser(
-        c -> new RoutingFieldMapper(Defaults.REQUIRED),
+        c -> RoutingFieldMapper.get(Defaults.REQUIRED),
         c -> new Builder()
     );
 
@@ -90,6 +90,13 @@ public ValueFetcher valueFetcher(SearchExecutionContext context, String format)
 
     private final boolean required;
 
+    private static final RoutingFieldMapper REQUIRED = new RoutingFieldMapper(true);
+    private static final RoutingFieldMapper NOT_REQUIRED = new RoutingFieldMapper(false);
+
+    public static RoutingFieldMapper get(boolean required) {
+        return required ? REQUIRED : NOT_REQUIRED;
+    }
+
     private RoutingFieldMapper(boolean required) {
         super(RoutingFieldType.INSTANCE, Lucene.KEYWORD_ANALYZER);
         this.required = required;

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/SeqNoFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/SeqNoFieldMapper.java
@@ -178,7 +178,7 @@ public IndexFieldData.Builder fielddataBuilder(String fullyQualifiedIndexName, S
         }
     }
 
-    public SeqNoFieldMapper() {
+    private SeqNoFieldMapper() {
         super(SeqNoFieldType.INSTANCE);
     }
 

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/SourceFieldMapper.java
@@ -43,6 +43,8 @@ public class SourceFieldMapper extends MetadataFieldMapper {
     public static final String CONTENT_TYPE = "_source";
     private final Function<Map<String, ?>, Map<String, Object>> filter;
 
+    private static final SourceFieldMapper DEFAULT = new SourceFieldMapper(Defaults.ENABLED, Strings.EMPTY_ARRAY, Strings.EMPTY_ARRAY);
+
     public static class Defaults {
         public static final String NAME = SourceFieldMapper.NAME;
         public static final boolean ENABLED = true;
@@ -80,13 +82,16 @@ protected List<Parameter<?>> getParameters() {
 
         @Override
         public SourceFieldMapper build() {
+            if (enabled.getValue() == Defaults.ENABLED && includes.getValue().isEmpty() && excludes.getValue().isEmpty()) {
+                return DEFAULT;
+            }
             return new SourceFieldMapper(enabled.getValue(),
                 includes.getValue().toArray(String[]::new),
                 excludes.getValue().toArray(String[]::new));
         }
     }
 
-    public static final TypeParser PARSER = new ConfigurableTypeParser(c -> new SourceFieldMapper(), c -> new Builder());
+    public static final TypeParser PARSER = new ConfigurableTypeParser(c -> DEFAULT, c -> new Builder());
 
     static final class SourceFieldType extends MappedFieldType {
 
@@ -122,10 +127,6 @@ public Query termQuery(Object value, SearchExecutionContext context) {
     private final String[] includes;
     private final String[] excludes;
 
-    private SourceFieldMapper() {
-        this(Defaults.ENABLED, Strings.EMPTY_ARRAY, Strings.EMPTY_ARRAY);
-    }
-
     private SourceFieldMapper(boolean enabled, String[] includes, String[] excludes) {
         super(new SourceFieldType(enabled));
         this.enabled = enabled;

diff --git a/server/src/test/java/org/elasticsearch/index/mapper/FieldNamesFieldTypeTests.java b/server/src/test/java/org/elasticsearch/index/mapper/FieldNamesFieldTypeTests.java
@@ -27,7 +27,7 @@
 public class FieldNamesFieldTypeTests extends ESTestCase {
 
     public void testTermQuery() {
-        FieldNamesFieldMapper.FieldNamesFieldType fieldNamesFieldType = new FieldNamesFieldMapper.FieldNamesFieldType(true);
+        FieldNamesFieldMapper.FieldNamesFieldType fieldNamesFieldType = FieldNamesFieldMapper.FieldNamesFieldType.get(true);
         KeywordFieldMapper.KeywordFieldType fieldType = new KeywordFieldMapper.KeywordFieldType("field_name");
 
         Settings settings = settings(Version.CURRENT).build();
@@ -42,7 +42,7 @@ public void testTermQuery() {
         assertEquals(new TermQuery(new Term(FieldNamesFieldMapper.CONTENT_TYPE, "field_name")), termQuery);
         assertWarnings("terms query on the _field_names field is deprecated and will be removed, use exists query instead");
 
-        FieldNamesFieldMapper.FieldNamesFieldType unsearchable = new FieldNamesFieldMapper.FieldNamesFieldType(false);
+        FieldNamesFieldMapper.FieldNamesFieldType unsearchable = FieldNamesFieldMapper.FieldNamesFieldType.get(false);
         IllegalStateException e = expectThrows(IllegalStateException.class, () -> unsearchable.termQuery("field_name", null));
         assertEquals("Cannot run [exists] queries if the [_field_names] field is disabled", e.getMessage());
     }

diff --git a/...test/java/org/elasticsearch/search/aggregations/bucket/filter/FiltersAggregatorTests.java b/...test/java/org/elasticsearch/search/aggregations/bucket/filter/FiltersAggregatorTests.java
@@ -1101,7 +1101,7 @@ private void docValuesFieldExistsTestCase(
     ) throws IOException {
         AggregationBuilder builder = new FiltersAggregationBuilder("test", new KeyedFilter("q1", exists));
         // Exists queries convert to MatchNone if this isn't defined
-        FieldNamesFieldMapper.FieldNamesFieldType fnft = new FieldNamesFieldMapper.FieldNamesFieldType(true);
+        FieldNamesFieldMapper.FieldNamesFieldType fnft = FieldNamesFieldMapper.FieldNamesFieldType.get(true);
         debugTestCase(builder, new MatchAllDocsQuery(), iw -> {
             for (int i = 0; i < 10; i++) {
                 iw.addDocument(buildDocWithField.apply(i));
@@ -1127,7 +1127,7 @@ private void docValuesFieldExistsNoDataTestCase(MappedFieldType fieldType) throw
             }
         };
         // Exists queries convert to MatchNone if this isn't defined
-        FieldNamesFieldMapper.FieldNamesFieldType fnft = new FieldNamesFieldMapper.FieldNamesFieldType(true);
+        FieldNamesFieldMapper.FieldNamesFieldType fnft = FieldNamesFieldMapper.FieldNamesFieldType.get(true);
         withAggregator(builder, new MatchAllDocsQuery(), buildIndex, (searcher, aggregator) -> {
             assertThat(aggregator, instanceOf(FilterByFilterAggregator.class));
 

diff --git a/.../org/elasticsearch/search/aggregations/bucket/histogram/DateHistogramAggregatorTests.java b/.../org/elasticsearch/search/aggregations/bucket/histogram/DateHistogramAggregatorTests.java
@@ -844,7 +844,7 @@ public void testOneBucketOptimized() throws IOException {
         };
         DateFieldMapper.DateFieldType ft = new DateFieldMapper.DateFieldType("f");
         // Exists queries convert to MatchNone if this isn't defined
-        FieldNamesFieldMapper.FieldNamesFieldType fnft = new FieldNamesFieldMapper.FieldNamesFieldType(true);
+        FieldNamesFieldMapper.FieldNamesFieldType fnft = FieldNamesFieldMapper.FieldNamesFieldType.get(true);
         debugTestCase(
             builder,
             new MatchAllDocsQuery(),