Make some CS Applier NOOPs Cheaper (#79098)

Short-circuiting a few spots where we needlessly diff maps or iterate over all indices.

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

@@ -18,6 +18,7 @@
 import org.elasticsearch.cluster.metadata.DataStream;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.cluster.metadata.Metadata;
+import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
 import org.elasticsearch.common.settings.Settings;
@@ -83,12 +84,16 @@ protected void doClose() {
     @Override
     public void applyClusterState(ClusterChangedEvent event) {
         final Metadata metadata = event.state().metadata();
+        final ImmutableOpenMap<String, IndexMetadata> indices = metadata.indices();
+        if (indices == event.previousState().metadata().indices()) {
+            return;
+        }
 
         // clear out mappers for indices that no longer exist or whose timestamp range is no longer known
         fieldTypesByIndex.keySet().removeIf(index -> hasUsefulTimestampField(metadata.index(index)) == false);
 
         // capture mappers for indices that do exist
-        for (IndexMetadata indexMetadata : metadata.indices().values()) {
+        for (IndexMetadata indexMetadata : indices.values()) {
             final Index index = indexMetadata.getIndex();
 
             if (hasUsefulTimestampField(indexMetadata) && fieldTypesByIndex.containsKey(index) == false) {

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/IndexLifecycleService.java

@@ -279,8 +279,11 @@ public void clusterChanged(ClusterChangedEvent event) {
     public void applyClusterState(ClusterChangedEvent event) {
         if (event.localNodeMaster()) { // only act if we are master, otherwise
             // keep idle until elected
-            if (event.state().metadata().custom(IndexLifecycleMetadata.TYPE) != null) {
-                policyRegistry.update(event.state());
+            final IndexLifecycleMetadata ilmMetadata = event.state().metadata().custom(IndexLifecycleMetadata.TYPE);
+            // only update the policy registry if we just became the master node or if the ilm metadata changed
+            if (ilmMetadata != null && (event.previousState().nodes().isLocalNodeElectedMaster() == false
+                    || ilmMetadata != event.previousState().metadata().custom(IndexLifecycleMetadata.TYPE))) {
+                policyRegistry.update(ilmMetadata);
             }
         }
     }

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/PolicyStepsRegistry.java

@@ -91,8 +91,7 @@ Map<String, Map<Step.StepKey, Step>> getStepMap() {
         return stepMap;
     }
 
-    public void update(ClusterState clusterState) {
-        final IndexLifecycleMetadata meta = clusterState.metadata().custom(IndexLifecycleMetadata.TYPE);
+    public void update(IndexLifecycleMetadata meta) {
         assert meta != null : "IndexLifecycleMetadata cannot be null when updating the policy steps registry";
 
         DiffableUtils.MapDiff<String, LifecyclePolicyMetadata, Map<String, LifecyclePolicyMetadata>> mapDiff =

x-pack/plugin/ilm/src/test/java/org/elasticsearch/xpack/ilm/ExecuteStepsUpdateTaskTests.java

@@ -139,7 +139,7 @@ private IndexMetadata setupIndexPolicy(String policyName) {
             .metadata(metadata)
             .nodes(DiscoveryNodes.builder().localNodeId(nodeId).masterNodeId(nodeId).add(masterNode).build())
             .build();
-        policyStepsRegistry.update(clusterState);
+        policyStepsRegistry.update(clusterState.metadata().custom(IndexLifecycleMetadata.TYPE));
         return indexMetadata;
     }
 
@@ -197,7 +197,7 @@ public void testExecuteInvalidStartStep() throws Exception {
                 .put(IndexMetadata.builder(clusterState.getMetadata().index(index))
                     .putCustom(ILM_CUSTOM_METADATA_KEY, lifecycleState.build().asMap()))).build();
 
-        policyStepsRegistry.update(clusterState);
+        policyStepsRegistry.update(clusterState.metadata().custom(IndexLifecycleMetadata.TYPE));
 
         Step invalidStep = new MockClusterStateActionStep(firstStepKey, secondStepKey);
         long now = randomNonNegativeLong();
@@ -301,6 +301,6 @@ private void setStateToKey(StepKey stepKey) throws IOException {
             .metadata(Metadata.builder(clusterState.getMetadata())
                 .put(IndexMetadata.builder(clusterState.getMetadata().index(index))
                     .putCustom(ILM_CUSTOM_METADATA_KEY, lifecycleState.build().asMap()))).build();
-        policyStepsRegistry.update(clusterState);
+        policyStepsRegistry.update(clusterState.metadata().custom(IndexLifecycleMetadata.TYPE));
     }
 }

x-pack/plugin/ilm/src/test/java/org/elasticsearch/xpack/ilm/PolicyStepsRegistryTests.java

@@ -232,7 +232,7 @@ public void testUpdateFromNothingToSomethingToNothing() throws Exception {
         PolicyStepsRegistry registry = new PolicyStepsRegistry(NamedXContentRegistry.EMPTY, client, null);
 
         // add new policy
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
 
         assertThat(registry.getFirstStep(newPolicy.getName()), equalTo(policySteps.get(0)));
         assertThat(registry.getLifecyclePolicyMap().size(), equalTo(1));
@@ -252,15 +252,15 @@ public void testUpdateFromNothingToSomethingToNothing() throws Exception {
                         .putCustom(ILM_CUSTOM_METADATA_KEY, newIndexState.build().asMap())))
                 .nodes(DiscoveryNodes.builder().localNodeId(nodeId).masterNodeId(nodeId).add(masterNode).build())
                 .build();
-            registry.update(currentState);
+            registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
             assertThat(registeredStepsForPolicy.get(step.getKey()), equalTo(step));
             assertThat(registry.getStep(metadata.index(index), step.getKey()), equalTo(step));
         }
 
         Map<String, LifecyclePolicyMetadata> registryPolicyMap = registry.getLifecyclePolicyMap();
         Map<String, Step> registryFirstStepMap = registry.getFirstStepMap();
         Map<String, Map<Step.StepKey, Step>> registryStepMap = registry.getStepMap();
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
         assertThat(registry.getLifecyclePolicyMap(), equalTo(registryPolicyMap));
         assertThat(registry.getFirstStepMap(), equalTo(registryFirstStepMap));
         assertThat(registry.getStepMap(), equalTo(registryStepMap));
@@ -271,7 +271,7 @@ public void testUpdateFromNothingToSomethingToNothing() throws Exception {
             .metadata(
                 Metadata.builder(metadata)
                     .putCustom(IndexLifecycleMetadata.TYPE, lifecycleMetadata)).build();
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
         assertTrue(registry.getLifecyclePolicyMap().isEmpty());
         assertTrue(registry.getFirstStepMap().isEmpty());
         assertTrue(registry.getStepMap().isEmpty());
@@ -305,7 +305,7 @@ public void testUpdateChangedPolicy() {
             .build();
         PolicyStepsRegistry registry = new PolicyStepsRegistry(NamedXContentRegistry.EMPTY, client, null);
         // add new policy
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
 
         // swap out policy
         newPolicy = LifecyclePolicyTests.randomTestLifecyclePolicy(policyName);
@@ -314,7 +314,7 @@ public void testUpdateChangedPolicy() {
                 randomNonNegativeLong(), randomNonNegativeLong())), OperationMode.RUNNING);
         currentState = ClusterState.builder(currentState)
             .metadata(Metadata.builder(metadata).putCustom(IndexLifecycleMetadata.TYPE, lifecycleMetadata)).build();
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
         // TODO(talevy): assert changes... right now we do not support updates to policies. will require internal cleanup
     }
 
@@ -383,7 +383,7 @@ public void testUpdatePolicyButNoPhaseChangeIndexStepsDontChange() throws Except
         PolicyStepsRegistry registry = new PolicyStepsRegistry(REGISTRY, client, null);
 
         // add new policy
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
 
         Map<Step.StepKey, Step> registeredStepsForPolicy = registry.getStepMap().get(newPolicy.getName());
         Step shrinkStep = registeredStepsForPolicy.entrySet().stream()
@@ -409,7 +409,7 @@ public void testUpdatePolicyButNoPhaseChangeIndexStepsDontChange() throws Except
         currentState = ClusterState.builder(ClusterName.DEFAULT).metadata(metadata).build();
 
         // Update the policies
-        registry.update(currentState);
+        registry.update(currentState.metadata().custom(IndexLifecycleMetadata.TYPE));
 
         registeredStepsForPolicy = registry.getStepMap().get(newPolicy.getName());
         shrinkStep = registeredStepsForPolicy.entrySet().stream()