Move SlowLogFieldProvider instantiation to node construction

SPI from plugins should be created at node startup. This commit moves
creation of SlowLogFieldProvider into node construction and passes it in
to IndicesService so that it is not recreated on each index creation.

relates elastic#102103

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

@@ -261,6 +261,7 @@ public class IndicesService extends AbstractLifecycleComponent
     private final MapperMetrics mapperMetrics;
     private final PostRecoveryMerger postRecoveryMerger;
     private final List<SearchOperationListener> searchOperationListeners;
+    final SlowLogFieldProvider slowLogFieldProvider; // pkg-private for testing
 
     @Override
     protected void doStart() {
@@ -379,6 +380,7 @@ public void onRemoval(ShardId shardId, String fieldName, boolean wasEvicted, lon
         this.timestampFieldMapperService = new TimestampFieldMapperService(settings, threadPool, this);
         this.postRecoveryMerger = new PostRecoveryMerger(settings, threadPool.executor(ThreadPool.Names.FORCE_MERGE), this::getShardOrNull);
         this.searchOperationListeners = builder.searchOperationListener;
+        this.slowLogFieldProvider = builder.slowLogFieldProvider;
     }
 
     private static final String DANGLING_INDICES_UPDATE_THREAD_NAME = "DanglingIndices#updateTask";
@@ -749,7 +751,7 @@ private synchronized IndexService createIndexService(
             () -> allowExpensiveQueries,
             indexNameExpressionResolver,
             recoveryStateFactories,
-            loadSlowLogFieldProvider(),
+            slowLogFieldProvider,
             mapperMetrics,
             searchOperationListeners
         );
@@ -828,7 +830,7 @@ public synchronized MapperService createIndexMapperServiceForValidation(IndexMet
             () -> allowExpensiveQueries,
             indexNameExpressionResolver,
             recoveryStateFactories,
-            loadSlowLogFieldProvider(),
+            slowLogFieldProvider,
             mapperMetrics,
             searchOperationListeners
         );
@@ -1434,31 +1436,6 @@ int numPendingDeletes(Index index) {
         }
     }
 
-    // pkg-private for testing
-    SlowLogFieldProvider loadSlowLogFieldProvider() {
-        List<? extends SlowLogFieldProvider> slowLogFieldProviders = pluginsService.loadServiceProviders(SlowLogFieldProvider.class);
-        return new SlowLogFieldProvider() {
-            @Override
-            public void init(IndexSettings indexSettings) {
-                slowLogFieldProviders.forEach(provider -> provider.init(indexSettings));
-            }
-
-            @Override
-            public Map<String, String> indexSlowLogFields() {
-                return slowLogFieldProviders.stream()
-                    .flatMap(provider -> provider.indexSlowLogFields().entrySet().stream())
-                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
-            }
-
-            @Override
-            public Map<String, String> searchSlowLogFields() {
-                return slowLogFieldProviders.stream()
-                    .flatMap(provider -> provider.searchSlowLogFields().entrySet().stream())
-                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
-            }
-        };
-    }
-
     /**
      * Checks if all pending deletes have completed. Used by tests to ensure we don't check directory contents
      * while deletion still ongoing. * The reason is that, on Windows, browsing the directory contents can interfere

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

@@ -23,6 +23,7 @@
 import org.elasticsearch.features.FeatureService;
 import org.elasticsearch.gateway.MetaStateService;
 import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.engine.EngineFactory;
 import org.elasticsearch.index.mapper.MapperMetrics;
@@ -76,6 +77,20 @@ public class IndicesServiceBuilder {
     CheckedBiConsumer<ShardSearchRequest, StreamOutput, IOException> requestCacheKeyDifferentiator;
     MapperMetrics mapperMetrics;
     List<SearchOperationListener> searchOperationListener = List.of();
+    SlowLogFieldProvider slowLogFieldProvider = new SlowLogFieldProvider() {
+        @Override
+        public void init(IndexSettings indexSettings) {}
+
+        @Override
+        public Map<String, String> indexSlowLogFields() {
+            return Map.of();
+        }
+
+        @Override
+        public Map<String, String> searchSlowLogFields() {
+            return Map.of();
+        }
+    };
 
     public IndicesServiceBuilder settings(Settings settings) {
         this.settings = settings;
@@ -188,6 +203,11 @@ public IndicesServiceBuilder searchOperationListeners(List<SearchOperationListen
         return this;
     }
 
+    public IndicesServiceBuilder slowLogFieldProvider(SlowLogFieldProvider slowLogFieldProvider) {
+        this.slowLogFieldProvider = slowLogFieldProvider;
+        return this;
+    }
+
     public IndicesService build() {
         Objects.requireNonNull(settings);
         Objects.requireNonNull(pluginsService);
@@ -213,6 +233,7 @@ public IndicesService build() {
         Objects.requireNonNull(snapshotCommitSuppliers);
         Objects.requireNonNull(mapperMetrics);
         Objects.requireNonNull(searchOperationListener);
+        Objects.requireNonNull(slowLogFieldProvider);
 
         // collect engine factory providers from plugins
         engineFactoryProviders = pluginsService.filterPlugins(EnginePlugin.class)

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -110,7 +110,9 @@
 import org.elasticsearch.index.IndexMode;
 import org.elasticsearch.index.IndexSettingProvider;
 import org.elasticsearch.index.IndexSettingProviders;
+import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.IndexingPressure;
+import org.elasticsearch.index.SlowLogFieldProvider;
 import org.elasticsearch.index.analysis.AnalysisRegistry;
 import org.elasticsearch.index.mapper.MapperMetrics;
 import org.elasticsearch.index.mapper.SourceFieldMetrics;
@@ -800,6 +802,30 @@ private void construct(
             new ShardSearchPhaseAPMMetrics(telemetryProvider.getMeterRegistry())
         );
 
+        List<? extends SlowLogFieldProvider> slowLogFieldProviders = pluginsService.loadServiceProviders(SlowLogFieldProvider.class);
+        // NOTE: the response of index/search slow log fields below must be calculated dynamically on every call
+        // because the responses may change dynamically at runtime
+        SlowLogFieldProvider slowLogFieldProvider = new SlowLogFieldProvider() {
+            @Override
+            public void init(IndexSettings indexSettings) {
+                slowLogFieldProviders.forEach(provider -> provider.init(indexSettings));
+            }
+
+            @Override
+            public Map<String, String> indexSlowLogFields() {
+                return slowLogFieldProviders.stream()
+                    .flatMap(provider -> provider.indexSlowLogFields().entrySet().stream())
+                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+            }
+
+            @Override
+            public Map<String, String> searchSlowLogFields() {
+                return slowLogFieldProviders.stream()
+                    .flatMap(provider -> provider.searchSlowLogFields().entrySet().stream())
+                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+            }
+        };
+
         IndicesService indicesService = new IndicesServiceBuilder().settings(settings)
             .pluginsService(pluginsService)
             .nodeEnvironment(nodeEnvironment)
@@ -821,6 +847,7 @@ private void construct(
             .requestCacheKeyDifferentiator(searchModule.getRequestCacheKeyDifferentiator())
             .mapperMetrics(mapperMetrics)
             .searchOperationListeners(searchOperationListeners)
+            .slowLogFieldProvider(slowLogFieldProvider)
             .build();
 
         final var parameters = new IndexSettingProvider.Parameters(clusterService, indicesService::createIndexMapperServiceForValidation);

server/src/test/java/org/elasticsearch/indices/IndicesServiceTests.java

@@ -803,7 +803,7 @@ public void testLoadSlowLogFieldProvider() {
         TestAnotherSlowLogFieldProvider.setFields(Map.of("key2", "value2"));
 
         var indicesService = getIndicesService();
-        SlowLogFieldProvider fieldProvider = indicesService.loadSlowLogFieldProvider();
+        SlowLogFieldProvider fieldProvider = indicesService.slowLogFieldProvider;
 
         // The map of fields from the two providers are merged to a single map of fields
         assertEquals(Map.of("key1", "value1", "key2", "value2"), fieldProvider.searchSlowLogFields());