Introduce index settings version (#34429)

This commit introduces settings version to index metadata. This value is
monotonically increasing and is updated on settings updates. This will
be useful in cross-cluster replication so that we can request settings
updates from the leader only when there is a settings update.

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

@@ -284,7 +284,10 @@ public String toString() {
         final String TAB = "   ";
         for (IndexMetaData indexMetaData : metaData) {
             sb.append(TAB).append(indexMetaData.getIndex());
-            sb.append(": v[").append(indexMetaData.getVersion()).append("], mv[").append(indexMetaData.getMappingVersion()).append("]\n");
+            sb.append(": v[").append(indexMetaData.getVersion())
+                    .append("], mv[").append(indexMetaData.getMappingVersion())
+                    .append("], sv[").append(indexMetaData.getSettingsVersion())
+                    .append("]\n");
             for (int shard = 0; shard < indexMetaData.getNumberOfShards(); shard++) {
                 sb.append(TAB).append(TAB).append(shard).append(": ");
                 sb.append("p_term [").append(indexMetaData.primaryTerm(shard)).append("], ");

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

@@ -243,6 +243,7 @@ public Iterator<Setting<Integer>> settings() {
     public static final String KEY_IN_SYNC_ALLOCATIONS = "in_sync_allocations";
     static final String KEY_VERSION = "version";
     static final String KEY_MAPPING_VERSION = "mapping_version";
+    static final String KEY_SETTINGS_VERSION = "settings_version";
     static final String KEY_ROUTING_NUM_SHARDS = "routing_num_shards";
     static final String KEY_SETTINGS = "settings";
     static final String KEY_STATE = "state";
@@ -264,6 +265,8 @@ public Iterator<Setting<Integer>> settings() {
 
     private final long mappingVersion;
 
+    private final long settingsVersion;
+
     private final long[] primaryTerms;
 
     private final State state;
@@ -291,7 +294,7 @@ public Iterator<Setting<Integer>> settings() {
     private final ActiveShardCount waitForActiveShards;
     private final ImmutableOpenMap<String, RolloverInfo> rolloverInfos;
 
-    private IndexMetaData(Index index, long version, long mappingVersion, long[] primaryTerms, State state, int numberOfShards, int numberOfReplicas, Settings settings,
+    private IndexMetaData(Index index, long version, long mappingVersion, long settingsVersion, long[] primaryTerms, State state, int numberOfShards, int numberOfReplicas, Settings settings,
                           ImmutableOpenMap<String, MappingMetaData> mappings, ImmutableOpenMap<String, AliasMetaData> aliases,
                           ImmutableOpenMap<String, DiffableStringMap> customData, ImmutableOpenIntMap<Set<String>> inSyncAllocationIds,
                           DiscoveryNodeFilters requireFilters, DiscoveryNodeFilters initialRecoveryFilters, DiscoveryNodeFilters includeFilters, DiscoveryNodeFilters excludeFilters,
@@ -302,6 +305,8 @@ private IndexMetaData(Index index, long version, long mappingVersion, long[] pri
         this.version = version;
         assert mappingVersion >= 0 : mappingVersion;
         this.mappingVersion = mappingVersion;
+        assert settingsVersion >= 0 : settingsVersion;
+        this.settingsVersion = settingsVersion;
         this.primaryTerms = primaryTerms;
         assert primaryTerms.length == numberOfShards;
         this.state = state;
@@ -355,6 +360,10 @@ public long getMappingVersion() {
         return mappingVersion;
     }
 
+    public long getSettingsVersion() {
+        return settingsVersion;
+    }
+
     /**
      * The term of the current selected primary. This is a non-negative number incremented when
      * a primary shard is assigned after a full cluster restart or a replica shard is promoted to a primary.
@@ -596,6 +605,7 @@ private static class IndexMetaDataDiff implements Diff<IndexMetaData> {
         private final int routingNumShards;
         private final long version;
         private final long mappingVersion;
+        private final long settingsVersion;
         private final long[] primaryTerms;
         private final State state;
         private final Settings settings;
@@ -609,6 +619,7 @@ private static class IndexMetaDataDiff implements Diff<IndexMetaData> {
             index = after.index.getName();
             version = after.version;
             mappingVersion = after.mappingVersion;
+            settingsVersion = after.settingsVersion;
             routingNumShards = after.routingNumShards;
             state = after.state;
             settings = after.settings;
@@ -630,6 +641,11 @@ private static class IndexMetaDataDiff implements Diff<IndexMetaData> {
             } else {
                 mappingVersion = 1;
             }
+            if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+                settingsVersion = in.readVLong();
+            } else {
+                settingsVersion = 1;
+            }
             state = State.fromId(in.readByte());
             settings = Settings.readSettingsFromStream(in);
             primaryTerms = in.readVLongArray();
@@ -658,6 +674,9 @@ public void writeTo(StreamOutput out) throws IOException {
             if (out.getVersion().onOrAfter(Version.V_6_5_0)) {
                 out.writeVLong(mappingVersion);
             }
+            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+                out.writeVLong(settingsVersion);
+            }
             out.writeByte(state.id);
             Settings.writeSettingsToStream(settings, out);
             out.writeVLongArray(primaryTerms);
@@ -675,6 +694,7 @@ public IndexMetaData apply(IndexMetaData part) {
             Builder builder = builder(index);
             builder.version(version);
             builder.mappingVersion(mappingVersion);
+            builder.settingsVersion(settingsVersion);
             builder.setRoutingNumShards(routingNumShards);
             builder.state(state);
             builder.settings(settings);
@@ -696,6 +716,11 @@ public static IndexMetaData readFrom(StreamInput in) throws IOException {
         } else {
             builder.mappingVersion(1);
         }
+        if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            builder.settingsVersion(in.readVLong());
+        } else {
+            builder.settingsVersion(1);
+        }
         builder.setRoutingNumShards(in.readInt());
         builder.state(State.fromId(in.readByte()));
         builder.settings(readSettingsFromStream(in));
@@ -745,6 +770,9 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getVersion().onOrAfter(Version.V_6_5_0)) {
             out.writeVLong(mappingVersion);
         }
+        if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            out.writeVLong(settingsVersion);
+        }
         out.writeInt(routingNumShards);
         out.writeByte(state.id());
         writeSettingsToStream(settings, out);
@@ -793,6 +821,7 @@ public static class Builder {
         private State state = State.OPEN;
         private long version = 1;
         private long mappingVersion = 1;
+        private long settingsVersion = 1;
         private long[] primaryTerms = null;
         private Settings settings = Settings.Builder.EMPTY_SETTINGS;
         private final ImmutableOpenMap.Builder<String, MappingMetaData> mappings;
@@ -816,6 +845,7 @@ public Builder(IndexMetaData indexMetaData) {
             this.state = indexMetaData.state;
             this.version = indexMetaData.version;
             this.mappingVersion = indexMetaData.mappingVersion;
+            this.settingsVersion = indexMetaData.settingsVersion;
             this.settings = indexMetaData.getSettings();
             this.primaryTerms = indexMetaData.primaryTerms.clone();
             this.mappings = ImmutableOpenMap.builder(indexMetaData.mappings);
@@ -990,11 +1020,20 @@ public long mappingVersion() {
             return mappingVersion;
         }
 
+        public long settingsVersion() {
+            return settingsVersion;
+        }
+
         public Builder mappingVersion(final long mappingVersion) {
             this.mappingVersion = mappingVersion;
             return this;
         }
 
+        public Builder settingsVersion(final long settingsVersion) {
+            this.settingsVersion = settingsVersion;
+            return this;
+        }
+
         /**
          * returns the primary term for the given shard.
          * See {@link IndexMetaData#primaryTerm(int)} for more information.
@@ -1122,7 +1161,7 @@ public IndexMetaData build() {
 
             final String uuid = settings.get(SETTING_INDEX_UUID, INDEX_UUID_NA_VALUE);
 
-            return new IndexMetaData(new Index(index, uuid), version, mappingVersion, primaryTerms, state, numberOfShards, numberOfReplicas, tmpSettings, mappings.build(),
+            return new IndexMetaData(new Index(index, uuid), version, mappingVersion, settingsVersion, primaryTerms, state, numberOfShards, numberOfReplicas, tmpSettings, mappings.build(),
                 tmpAliases.build(), customMetaData.build(), filledInSyncAllocationIds.build(), requireFilters, initialRecoveryFilters, includeFilters, excludeFilters,
                 indexCreatedVersion, indexUpgradedVersion, getRoutingNumShards(), routingPartitionSize, waitForActiveShards, rolloverInfos.build());
         }
@@ -1132,6 +1171,7 @@ public static void toXContent(IndexMetaData indexMetaData, XContentBuilder build
 
             builder.field(KEY_VERSION, indexMetaData.getVersion());
             builder.field(KEY_MAPPING_VERSION, indexMetaData.getMappingVersion());
+            builder.field(KEY_SETTINGS_VERSION, indexMetaData.getSettingsVersion());
             builder.field(KEY_ROUTING_NUM_SHARDS, indexMetaData.getRoutingNumShards());
             builder.field(KEY_STATE, indexMetaData.getState().toString().toLowerCase(Locale.ENGLISH));
 
@@ -1205,6 +1245,7 @@ public static IndexMetaData fromXContent(XContentParser parser) throws IOExcepti
                 throw new IllegalArgumentException("expected object but got a " + token);
             }
             boolean mappingVersion = false;
+            boolean settingsVersion = false;
             while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                 if (token == XContentParser.Token.FIELD_NAME) {
                     currentFieldName = parser.currentName();
@@ -1299,6 +1340,9 @@ public static IndexMetaData fromXContent(XContentParser parser) throws IOExcepti
                     } else if (KEY_MAPPING_VERSION.equals(currentFieldName)) {
                         mappingVersion = true;
                         builder.mappingVersion(parser.longValue());
+                    } else if (KEY_SETTINGS_VERSION.equals(currentFieldName)) {
+                        settingsVersion = true;
+                        builder.settingsVersion(parser.longValue());
                     } else if (KEY_ROUTING_NUM_SHARDS.equals(currentFieldName)) {
                         builder.setRoutingNumShards(parser.intValue());
                     } else {
@@ -1311,6 +1355,9 @@ public static IndexMetaData fromXContent(XContentParser parser) throws IOExcepti
             if (Assertions.ENABLED && Version.indexCreated(builder.settings).onOrAfter(Version.V_6_5_0)) {
                 assert mappingVersion : "mapping version should be present for indices created on or after 6.5.0";
             }
+            if (Assertions.ENABLED && Version.indexCreated(builder.settings).onOrAfter(Version.V_7_0_0_alpha1)) {
+                assert settingsVersion : "settings version should be present for indices created on or after 7.0.0";
+            }
             return builder.build();
         }
     }

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

@@ -51,6 +51,7 @@
 import java.util.Set;
 
 import static org.elasticsearch.action.support.ContextPreservingActionListener.wrapPreservingContext;
+import static org.elasticsearch.index.IndexSettings.same;
 
 /**
  * Service responsible for submitting update index settings requests
@@ -187,6 +188,14 @@ public ClusterState execute(ClusterState currentState) {
                     }
                 }
 
+                // increment settings versions
+                for (final String index : actualIndices) {
+                    if (same(currentState.metaData().index(index).getSettings(), metaDataBuilder.get(index).getSettings()) == false) {
+                        final IndexMetaData.Builder builder = IndexMetaData.builder(metaDataBuilder.get(index));
+                        builder.settingsVersion(1 + builder.settingsVersion());
+                        metaDataBuilder.put(builder);
+                    }
+                }
 
                 ClusterState updatedState = ClusterState.builder(currentState).metaData(metaDataBuilder).routingTable(routingTableBuilder.build()).blocks(blocks).build();
 
@@ -220,9 +229,9 @@ public ClusterState execute(ClusterState currentState) {
      */
     private static void maybeUpdateClusterBlock(String[] actualIndices, ClusterBlocks.Builder blocks, ClusterBlock block, Setting<Boolean> setting, Settings openSettings) {
         if (setting.exists(openSettings)) {
-            final boolean updateReadBlock = setting.get(openSettings);
+            final boolean updateBlock = setting.get(openSettings);
             for (String index : actualIndices) {
-                if (updateReadBlock) {
+                if (updateBlock) {
                     blocks.addIndexBlock(index, block);
                 } else {
                     blocks.removeIndexBlock(index, block);

server/src/main/java/org/elasticsearch/cluster/routing/allocation/AllocationService.java

@@ -254,6 +254,13 @@ private ClusterState adaptAutoExpandReplicas(ClusterState clusterState) {
                 // operation which make these copies stale
                 routingTableBuilder.updateNumberOfReplicas(numberOfReplicas, indices);
                 metaDataBuilder.updateNumberOfReplicas(numberOfReplicas, indices);
+                // update settings version for each index
+                for (final String index : indices) {
+                    final IndexMetaData indexMetaData = metaDataBuilder.get(index);
+                    final IndexMetaData.Builder indexMetaDataBuilder =
+                            new IndexMetaData.Builder(indexMetaData).settingsVersion(1 + indexMetaData.getSettingsVersion());
+                    metaDataBuilder.put(indexMetaDataBuilder);
+                }
                 logger.info("updating number_of_replicas to [{}] for indices {}", numberOfReplicas, indices);
             }
             final ClusterState fixedState = ClusterState.builder(clusterState).routingTable(routingTableBuilder.build())

server/src/main/java/org/elasticsearch/index/IndexService.java

@@ -24,6 +24,8 @@
 import org.apache.lucene.search.Sort;
 import org.apache.lucene.store.AlreadyClosedException;
 import org.apache.lucene.util.Accountable;
+import org.elasticsearch.Assertions;
+import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.client.Client;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
@@ -617,9 +619,27 @@ public IndexMetaData getMetaData() {
     }
 
     @Override
-    public synchronized void updateMetaData(final IndexMetaData metadata) {
+    public synchronized void updateMetaData(final IndexMetaData currentIndexMetaData, final IndexMetaData newIndexMetaData) {
         final Translog.Durability oldTranslogDurability = indexSettings.getTranslogDurability();
-        if (indexSettings.updateIndexMetaData(metadata)) {
+
+        final boolean updateIndexMetaData = indexSettings.updateIndexMetaData(newIndexMetaData);
+
+        if (Assertions.ENABLED
+                && currentIndexMetaData != null
+                && currentIndexMetaData.getCreationVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            final long currentSettingsVersion = currentIndexMetaData.getSettingsVersion();
+            final long newSettingsVersion = newIndexMetaData.getSettingsVersion();
+            if (currentSettingsVersion == newSettingsVersion) {
+                assert updateIndexMetaData == false;
+            } else {
+                assert updateIndexMetaData;
+                assert currentSettingsVersion < newSettingsVersion :
+                        "expected current settings version [" + currentSettingsVersion + "] "
+                                + "to be less than new settings version [" + newSettingsVersion + "]";
+            }
+        }
+
+        if (updateIndexMetaData) {
             for (final IndexShard shard : this.shards.values()) {
                 try {
                     shard.onSettingsChanged();

server/src/main/java/org/elasticsearch/index/IndexSettings.java

@@ -604,17 +604,28 @@ public synchronized boolean updateIndexMetaData(IndexMetaData indexMetaData) {
             throw new IllegalArgumentException("uuid mismatch on settings update expected: " + getUUID() + " but was: " + newUUID);
         }
         this.indexMetaData = indexMetaData;
-        final Settings existingSettings = this.settings;
-        if (existingSettings.filter(IndexScopedSettings.INDEX_SETTINGS_KEY_PREDICATE)
-            .equals(newSettings.filter(IndexScopedSettings.INDEX_SETTINGS_KEY_PREDICATE))) {
+        final Settings newIndexSettings = Settings.builder().put(nodeSettings).put(newSettings).build();
+        if (same(this.settings, newIndexSettings)) {
             // nothing to update, same settings
             return false;
         }
         scopedSettings.applySettings(newSettings);
-        this.settings = Settings.builder().put(nodeSettings).put(newSettings).build();
+        this.settings = newIndexSettings;
         return true;
     }
 
+    /**
+     * Compare the specified settings for equality.
+     *
+     * @param left  the left settings
+     * @param right the right settings
+     * @return true if the settings are the same, otherwise false
+     */
+    public static boolean same(final Settings left, final Settings right) {
+        return left.filter(IndexScopedSettings.INDEX_SETTINGS_KEY_PREDICATE)
+                .equals(right.filter(IndexScopedSettings.INDEX_SETTINGS_KEY_PREDICATE));
+    }
+
     /**
      * Returns the translog durability for this index.
      */

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

@@ -559,7 +559,7 @@ public synchronized void verifyIndexMetadata(IndexMetaData metaData, IndexMetaDa
             closeables.add(() -> service.close("metadata verification", false));
             service.mapperService().merge(metaData, MapperService.MergeReason.MAPPING_RECOVERY);
             if (metaData.equals(metaDataUpdate) == false) {
-                service.updateMetaData(metaDataUpdate);
+                service.updateMetaData(metaData, metaDataUpdate);
             }
         } finally {
             IOUtils.close(closeables);

server/src/main/java/org/elasticsearch/indices/cluster/IndicesClusterStateService.java

@@ -488,7 +488,7 @@ private void updateIndices(ClusterChangedEvent event) {
             final IndexMetaData newIndexMetaData = state.metaData().index(index);
             assert newIndexMetaData != null : "index " + index + " should have been removed by deleteIndices";
             if (ClusterChangedEvent.indexMetaDataChanged(currentIndexMetaData, newIndexMetaData)) {
-                indexService.updateMetaData(newIndexMetaData);
+                indexService.updateMetaData(currentIndexMetaData, newIndexMetaData);
                 try {
                     if (indexService.updateMapping(currentIndexMetaData, newIndexMetaData) && sendRefreshMapping) {
                         nodeMappingRefreshAction.nodeMappingRefresh(state.nodes().getMasterNode(),
@@ -771,9 +771,12 @@ public interface AllocatedIndex<T extends Shard> extends Iterable<T>, IndexCompo
         IndexSettings getIndexSettings();
 
         /**
-         * Updates the meta data of this index. Changes become visible through {@link #getIndexSettings()}
+         * Updates the metadata of this index. Changes become visible through {@link #getIndexSettings()}.
+         *
+         * @param currentIndexMetaData the current index metadata
+         * @param newIndexMetaData the new index metadata
          */
-        void updateMetaData(IndexMetaData indexMetaData);
+        void updateMetaData(IndexMetaData currentIndexMetaData, IndexMetaData newIndexMetaData);
 
         /**
          * Checks if index requires refresh from master.