Make Settings Diffable

server/src/main/java/org/elasticsearch/action/admin/cluster/node/info/NodeInfo.java

@@ -183,7 +183,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeBoolean(false);
         } else {
             out.writeBoolean(true);
-            Settings.writeSettingsToStream(settings, out);
+            settings.writeTo(out);
         }
         out.writeOptionalWriteable(getInfo(OsInfo.class));
         out.writeOptionalWriteable(getInfo(ProcessInfo.class));

server/src/main/java/org/elasticsearch/action/admin/cluster/repositories/put/PutRepositoryRequest.java

@@ -22,7 +22,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * Register repository request.
@@ -207,7 +206,7 @@ public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
         out.writeString(name);
         out.writeString(type);
-        writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         out.writeBoolean(verify);
     }
 

server/src/main/java/org/elasticsearch/action/admin/cluster/settings/ClusterGetSettingsAction.java

@@ -92,9 +92,9 @@ public Response(Settings persistentSettings, Settings transientSettings, Setting
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             assert out.getVersion().onOrAfter(Version.V_8_3_0);
-            Settings.writeSettingsToStream(persistentSettings, out);
-            Settings.writeSettingsToStream(transientSettings, out);
-            Settings.writeSettingsToStream(settings, out);
+            persistentSettings.writeTo(out);
+            transientSettings.writeTo(out);
+            settings.writeTo(out);
         }
 
         public Settings persistentSettings() {

server/src/main/java/org/elasticsearch/action/admin/cluster/settings/ClusterUpdateSettingsRequest.java

@@ -25,7 +25,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * Request for an update cluster settings action
@@ -162,8 +161,8 @@ public ClusterUpdateSettingsRequest persistentSettings(Map<String, ?> source) {
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
-        writeSettingsToStream(transientSettings, out);
-        writeSettingsToStream(persistentSettings, out);
+        transientSettings.writeTo(out);
+        persistentSettings.writeTo(out);
     }
 
     @Override

server/src/main/java/org/elasticsearch/action/admin/cluster/settings/ClusterUpdateSettingsResponse.java

@@ -67,8 +67,8 @@ public Settings getPersistentSettings() {
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
-        Settings.writeSettingsToStream(transientSettings, out);
-        Settings.writeSettingsToStream(persistentSettings, out);
+        transientSettings.writeTo(out);
+        persistentSettings.writeTo(out);
     }
 
     @Override

server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/create/CreateSnapshotRequest.java

@@ -33,7 +33,6 @@
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.Strings.EMPTY_ARRAY;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 import static org.elasticsearch.common.xcontent.support.XContentMapValues.nodeBooleanValue;
 
 /**
@@ -115,7 +114,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeStringArray(indices);
         indicesOptions.writeIndicesOptions(out);
         if (out.getVersion().before(SETTINGS_IN_REQUEST_VERSION)) {
-            writeSettingsToStream(Settings.EMPTY, out);
+            Settings.EMPTY.writeTo(out);
         }
         out.writeStringArray(featureStates);
         out.writeBoolean(includeGlobalState);

server/src/main/java/org/elasticsearch/action/admin/cluster/snapshots/restore/RestoreSnapshotRequest.java

@@ -30,7 +30,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 import static org.elasticsearch.common.xcontent.support.XContentMapValues.nodeBooleanValue;
 
 /**
@@ -113,7 +112,7 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getVersion().onOrAfter(VERSION_SUPPORTING_QUIET_PARAMETER)) {
             out.writeBoolean(quiet);
         }
-        writeSettingsToStream(indexSettings, out);
+        indexSettings.writeTo(out);
         out.writeStringArray(ignoreIndexSettings);
         out.writeOptionalString(snapshotUuid);
     }

server/src/main/java/org/elasticsearch/action/admin/indices/create/CreateIndexRequest.java

@@ -43,7 +43,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * A request to create an index. Best created with {@link org.elasticsearch.client.internal.Requests#createIndexRequest(String)}.
@@ -453,7 +452,7 @@ public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
         out.writeString(cause);
         out.writeString(index);
-        writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         if (out.getVersion().before(Version.V_8_0_0)) {
             if ("{}".equals(mappings)) {
                 out.writeVInt(0);

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

@@ -172,8 +172,8 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeStringArray(indices);
         MappingMetadata.writeMappingMetadata(out, mappings);
         out.writeMap(aliases, StreamOutput::writeString, StreamOutput::writeList);
-        out.writeMap(settings, StreamOutput::writeString, (o, v) -> Settings.writeSettingsToStream(v, o));
-        out.writeMap(defaultSettings, StreamOutput::writeString, (o, v) -> Settings.writeSettingsToStream(v, o));
+        out.writeMap(settings, StreamOutput::writeString, (o, v) -> v.writeTo(o));
+        out.writeMap(defaultSettings, StreamOutput::writeString, (o, v) -> v.writeTo(o));
         out.writeMap(dataStreams, StreamOutput::writeString, StreamOutput::writeOptionalString);
     }
 

server/src/main/java/org/elasticsearch/action/admin/indices/settings/get/GetSettingsResponse.java

@@ -90,8 +90,8 @@ public String getSetting(String index, String setting) {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
-        out.writeMap(indexToSettings, StreamOutput::writeString, (o, s) -> Settings.writeSettingsToStream(s, o));
-        out.writeMap(indexToDefaultSettings, StreamOutput::writeString, (o, s) -> Settings.writeSettingsToStream(s, o));
+        out.writeMap(indexToSettings, StreamOutput::writeString, (o, v) -> v.writeTo(o));
+        out.writeMap(indexToDefaultSettings, StreamOutput::writeString, (o, v) -> v.writeTo(o));
     }
 
     private static void parseSettingsField(

server/src/main/java/org/elasticsearch/action/admin/indices/settings/put/UpdateSettingsRequest.java

@@ -31,7 +31,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * Request for an update index settings action
@@ -182,7 +181,7 @@ public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
         out.writeStringArrayNullable(indices);
         indicesOptions.writeIndicesOptions(out);
-        writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         out.writeBoolean(preserveExisting);
         if (out.getVersion().onOrAfter(Version.V_7_12_0)) {
             out.writeString(origin);

server/src/main/java/org/elasticsearch/action/admin/indices/template/put/PutIndexTemplateRequest.java

@@ -43,7 +43,6 @@
 
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * A request to create an index template.
@@ -446,7 +445,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeStringCollection(indexPatterns);
         out.writeInt(order);
         out.writeBoolean(create);
-        writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         if (out.getVersion().before(Version.V_8_0_0)) {
             out.writeVInt(mappings == null ? 0 : 1);
             if (mappings != null) {

server/src/main/java/org/elasticsearch/bootstrap/ServerArgs.java

@@ -82,7 +82,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeBoolean(quiet);
         out.writeOptionalString(pidFile == null ? null : pidFile.toString());
         out.writeSecureString(keystorePassword);
-        Settings.writeSettingsToStream(nodeSettings, out);
+        nodeSettings.writeTo(out);
         out.writeString(configDir.toString());
     }
 }

server/src/main/java/org/elasticsearch/cluster/DiffableUtils.java

@@ -153,7 +153,7 @@ private static <K, T, M extends Map<K, T>> MapDiff<K, T, M> createDiff(
                 inserts++;
             } else if (entry.getValue().equals(previousValue) == false) {
                 if (valueSerializer.supportsDiffableValues()) {
-                    diffs.add(Map.entry(entry.getKey(), valueSerializer.diff(entry.getValue(), previousValue)));
+                    diffs.add(mapEntry(entry.getKey(), valueSerializer.diff(entry.getValue(), previousValue)));
                 } else {
                     upserts.add(entry);
                 }
@@ -307,14 +307,14 @@ private MapDiff(
             for (int i = 0; i < diffsCount; i++) {
                 K key = keySerializer.readKey(in);
                 Diff<T> diff = valueSerializer.readDiff(in, key);
-                diffs.add(Map.entry(key, diff));
+                diffs.add(mapEntry(key, diff));
             }
             int upsertsCount = in.readVInt();
             upserts = upsertsCount == 0 ? List.of() : new ArrayList<>(upsertsCount);
             for (int i = 0; i < upsertsCount; i++) {
                 K key = keySerializer.readKey(in);
                 T newValue = valueSerializer.read(in, key);
-                upserts.add(Map.entry(key, newValue));
+                upserts.add(mapEntry(key, newValue));
             }
             this.builderCtor = builderCtor;
         }
@@ -402,6 +402,25 @@ public void writeTo(StreamOutput out) throws IOException {
         }
     }
 
+    private static <K, T> Map.Entry<K, T> mapEntry(K key, T newValue) {
+        return new Map.Entry<>() {
+            @Override
+            public K getKey() {
+                return key;
+            }
+
+            @Override
+            public T getValue() {
+                return newValue;
+            }
+
+            @Override
+            public T setValue(T value) {
+                throw new UnsupportedOperationException();
+            }
+        };
+    }
+
     /**
      * Provides read and write operations to serialize keys of map
      * @param <K> type of key

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

@@ -188,7 +188,7 @@ public static DesiredNode readFrom(StreamInput in) throws IOException {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
-        Settings.writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         if (out.getVersion().onOrAfter(RANGE_FLOAT_PROCESSORS_SUPPORT_VERSION)) {
             out.writeOptionalFloat(processors);
             out.writeOptionalWriteable(processorsRange);

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

@@ -77,7 +77,6 @@
 import static org.elasticsearch.cluster.node.DiscoveryNodeFilters.OpType.OR;
 import static org.elasticsearch.cluster.node.DiscoveryNodeFilters.validateIpValue;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 import static org.elasticsearch.snapshots.SearchableSnapshotsSettings.SEARCHABLE_SNAPSHOT_PARTIAL_SETTING_KEY;
 
 public class IndexMetadata implements Diffable<IndexMetadata>, ToXContentFragment {
@@ -1313,6 +1312,8 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         return builder;
     }
 
+    private static final Version SETTING_DIFF_VERSION = Version.V_8_4_0;
+
     private static class IndexMetadataDiff implements Diff<IndexMetadata> {
 
         private final String index;
@@ -1323,7 +1324,12 @@ private static class IndexMetadataDiff implements Diff<IndexMetadata> {
         private final long aliasesVersion;
         private final long[] primaryTerms;
         private final State state;
+
+        // used for BwC when this instance was written by an older version node that does not diff settings yet
+        @Nullable
         private final Settings settings;
+        @Nullable
+        private final Diff<Settings> settingsDiff;
         private final Diff<ImmutableOpenMap<String, MappingMetadata>> mappings;
         private final Diff<ImmutableOpenMap<String, AliasMetadata>> aliases;
         private final Diff<ImmutableOpenMap<String, DiffableStringMap>> customData;
@@ -1341,6 +1347,7 @@ private static class IndexMetadataDiff implements Diff<IndexMetadata> {
             routingNumShards = after.routingNumShards;
             state = after.state;
             settings = after.settings;
+            settingsDiff = after.settings.diff(before.settings);
             primaryTerms = after.primaryTerms;
             // TODO: find a nicer way to do BwC here and just work with Diff<MappingMetadata> here and in networking
             mappings = DiffableUtils.diff(
@@ -1386,7 +1393,13 @@ private static class IndexMetadataDiff implements Diff<IndexMetadata> {
                 aliasesVersion = 1;
             }
             state = State.fromId(in.readByte());
-            settings = Settings.readSettingsFromStream(in);
+            if (in.getVersion().onOrAfter(SETTING_DIFF_VERSION)) {
+                settings = null;
+                settingsDiff = Settings.readSettingsDiffFromStream(in);
+            } else {
+                settings = Settings.readSettingsFromStream(in);
+                settingsDiff = null;
+            }
             primaryTerms = in.readVLongArray();
             mappings = DiffableUtils.readImmutableOpenMapDiff(in, DiffableUtils.getStringKeySerializer(), MAPPING_DIFF_VALUE_READER);
             aliases = DiffableUtils.readImmutableOpenMapDiff(in, DiffableUtils.getStringKeySerializer(), ALIAS_METADATA_DIFF_VALUE_READER);
@@ -1420,7 +1433,13 @@ public void writeTo(StreamOutput out) throws IOException {
                 out.writeVLong(aliasesVersion);
             }
             out.writeByte(state.id);
-            Settings.writeSettingsToStream(settings, out);
+            assert settings != null
+                : "settings should always be non-null since this instance is not expected to have been read from another node";
+            if (out.getVersion().onOrAfter(SETTING_DIFF_VERSION)) {
+                settingsDiff.writeTo(out);
+            } else {
+                settings.writeTo(out);
+            }
             out.writeVLongArray(primaryTerms);
             mappings.writeTo(out);
             aliases.writeTo(out);
@@ -1442,7 +1461,11 @@ public IndexMetadata apply(IndexMetadata part) {
             builder.aliasesVersion(aliasesVersion);
             builder.setRoutingNumShards(routingNumShards);
             builder.state(state);
-            builder.settings(settings);
+            if (settingsDiff == null) {
+                builder.settings(settings);
+            } else {
+                builder.settings(settingsDiff.apply(part.settings));
+            }
             builder.primaryTerms(primaryTerms);
             builder.mapping = mappings.apply(
                 ImmutableOpenMap.<String, MappingMetadata>builder(1).fPut(MapperService.SINGLE_MAPPING_NAME, part.mapping).build()
@@ -1530,7 +1553,7 @@ public void writeTo(StreamOutput out, boolean mappingsAsHash) throws IOException
         }
         out.writeInt(routingNumShards);
         out.writeByte(state.id());
-        writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         out.writeVLongArray(primaryTerms);
         // TODO: adjust serialization format to using an optional writable
         if (mapping == null) {

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

@@ -206,7 +206,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(name);
         out.writeInt(order);
         out.writeStringCollection(patterns);
-        Settings.writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         out.writeMap(mappings, StreamOutput::writeString, (o, v) -> v.writeTo(o));
         out.writeCollection(aliases.values());
         out.writeOptionalVInt(version);

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

@@ -81,7 +81,6 @@
 
 import static org.elasticsearch.cluster.metadata.LifecycleExecutionState.ILM_CUSTOM_METADATA_KEY;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
-import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
 /**
  * {@link Metadata} is the part of the {@link ClusterState} which persists across restarts. This persistence is XContent-based, so a
@@ -1228,8 +1227,8 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeBoolean(clusterUUIDCommitted);
             out.writeLong(version);
             coordinationMetadata.writeTo(out);
-            Settings.writeSettingsToStream(transientSettings, out);
-            Settings.writeSettingsToStream(persistentSettings, out);
+            transientSettings.writeTo(out);
+            persistentSettings.writeTo(out);
             if (out.getVersion().onOrAfter(Version.V_7_3_0)) {
                 hashesOfConsistentSettings.writeTo(out);
             }
@@ -1314,8 +1313,8 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(clusterUUID);
         out.writeBoolean(clusterUUIDCommitted);
         coordinationMetadata.writeTo(out);
-        writeSettingsToStream(transientSettings, out);
-        writeSettingsToStream(persistentSettings, out);
+        transientSettings.writeTo(out);
+        persistentSettings.writeTo(out);
         if (out.getVersion().onOrAfter(Version.V_7_3_0)) {
             hashesOfConsistentSettings.writeTo(out);
         }

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

@@ -152,7 +152,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeString(uuid);
         }
         out.writeString(type);
-        Settings.writeSettingsToStream(settings, out);
+        settings.writeTo(out);
         out.writeLong(generation);
         out.writeLong(pendingGeneration);
     }

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

@@ -126,7 +126,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeBoolean(false);
         } else {
             out.writeBoolean(true);
-            Settings.writeSettingsToStream(this.settings, out);
+            this.settings.writeTo(out);
         }
         if (this.mappings == null) {
             out.writeBoolean(false);