[ML] Create and inject APM Inference Metrics (elastic#111293)

We are migrating from in-memory cumulative counter to an Time Series
Data Stream delta counter.  The goal is to avoid metrics suddenly
dropping to zero when a node restarts, hopefully increasing accuracy of
the metric.

Co-authored-by: Jonathan Buttner <[email protected]>

server/src/main/java/org/elasticsearch/inference/ServiceSettings.java

@@ -9,6 +9,7 @@
 package org.elasticsearch.inference;
 
 import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
+import org.elasticsearch.core.Nullable;
 import org.elasticsearch.index.mapper.vectors.DenseVectorFieldMapper;
 import org.elasticsearch.xcontent.ToXContentObject;
 
@@ -48,5 +49,6 @@ default DenseVectorFieldMapper.ElementType elementType() {
      * be chosen when initializing a deployment within their service. In this situation, return null.
      * @return the model used to perform inference or null if the model is not defined
      */
+    @Nullable
     String modelId();
 }

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferencePlugin.java

@@ -26,6 +26,7 @@
 import org.elasticsearch.indices.SystemIndexDescriptor;
 import org.elasticsearch.inference.InferenceServiceExtension;
 import org.elasticsearch.inference.InferenceServiceRegistry;
+import org.elasticsearch.node.PluginComponentBinding;
 import org.elasticsearch.plugins.ActionPlugin;
 import org.elasticsearch.plugins.ExtensiblePlugin;
 import org.elasticsearch.plugins.MapperPlugin;
@@ -84,8 +85,8 @@
 import org.elasticsearch.xpack.inference.services.huggingface.elser.HuggingFaceElserService;
 import org.elasticsearch.xpack.inference.services.mistral.MistralService;
 import org.elasticsearch.xpack.inference.services.openai.OpenAiService;
-import org.elasticsearch.xpack.inference.telemetry.InferenceAPMStats;
-import org.elasticsearch.xpack.inference.telemetry.StatsMap;
+import org.elasticsearch.xpack.inference.telemetry.ApmInferenceStats;
+import org.elasticsearch.xpack.inference.telemetry.InferenceStats;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -196,10 +197,10 @@ public Collection<?> createComponents(PluginServices services) {
         var actionFilter = new ShardBulkInferenceActionFilter(registry, modelRegistry);
         shardBulkInferenceActionFilter.set(actionFilter);
 
-        var statsFactory = new InferenceAPMStats.Factory(services.telemetryProvider().getMeterRegistry());
-        var statsMap = new StatsMap<>(InferenceAPMStats::key, statsFactory::newInferenceRequestAPMCounter);
+        var meterRegistry = services.telemetryProvider().getMeterRegistry();
+        var stats = new PluginComponentBinding<>(InferenceStats.class, ApmInferenceStats.create(meterRegistry));
 
-        return List.of(modelRegistry, registry, httpClientManager, statsMap);
+        return List.of(modelRegistry, registry, httpClientManager, stats);
     }
 
     @Override

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportInferenceAction.java

@@ -21,22 +21,26 @@
 import org.elasticsearch.transport.TransportService;
 import org.elasticsearch.xpack.core.inference.action.InferenceAction;
 import org.elasticsearch.xpack.inference.registry.ModelRegistry;
+import org.elasticsearch.xpack.inference.telemetry.InferenceStats;
 
 public class TransportInferenceAction extends HandledTransportAction<InferenceAction.Request, InferenceAction.Response> {
 
     private final ModelRegistry modelRegistry;
     private final InferenceServiceRegistry serviceRegistry;
+    private final InferenceStats inferenceStats;
 
     @Inject
     public TransportInferenceAction(
         TransportService transportService,
         ActionFilters actionFilters,
         ModelRegistry modelRegistry,
-        InferenceServiceRegistry serviceRegistry
+        InferenceServiceRegistry serviceRegistry,
+        InferenceStats inferenceStats
     ) {
         super(InferenceAction.NAME, transportService, actionFilters, InferenceAction.Request::new, EsExecutors.DIRECT_EXECUTOR_SERVICE);
         this.modelRegistry = modelRegistry;
         this.serviceRegistry = serviceRegistry;
+        this.inferenceStats = inferenceStats;
     }
 
     @Override
@@ -76,6 +80,7 @@ protected void doExecute(Task task, InferenceAction.Request request, ActionListe
                     unparsedModel.settings(),
                     unparsedModel.secrets()
                 );
+            inferenceStats.incrementRequestCount(model);
             inferOnService(model, request, service.get(), delegate);
         });
 

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/cohere/embeddings/CohereEmbeddingsModel.java

@@ -28,7 +28,7 @@ public static CohereEmbeddingsModel of(CohereEmbeddingsModel model, Map<String,
     }
 
     public CohereEmbeddingsModel(
-        String modelId,
+        String inferenceId,
         TaskType taskType,
         String service,
         Map<String, Object> serviceSettings,
@@ -37,7 +37,7 @@ public CohereEmbeddingsModel(
         ConfigurationParseContext context
     ) {
         this(
-            modelId,
+            inferenceId,
             taskType,
             service,
             CohereEmbeddingsServiceSettings.fromMap(serviceSettings, context),

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/openai/embeddings/OpenAiEmbeddingsServiceSettings.java

@@ -150,7 +150,7 @@ public OpenAiEmbeddingsServiceSettings(
         @Nullable RateLimitSettings rateLimitSettings
     ) {
         this.uri = uri;
-        this.modelId = modelId;
+        this.modelId = Objects.requireNonNull(modelId);
         this.organizationId = organizationId;
         this.similarity = similarity;
         this.dimensions = dimensions;

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/telemetry/ApmInferenceStats.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.inference.telemetry;
+
+import org.elasticsearch.inference.Model;
+import org.elasticsearch.telemetry.metric.LongCounter;
+import org.elasticsearch.telemetry.metric.MeterRegistry;
+
+import java.util.HashMap;
+import java.util.Objects;
+
+public class ApmInferenceStats implements InferenceStats {
+    private final LongCounter inferenceAPMRequestCounter;
+
+    public ApmInferenceStats(LongCounter inferenceAPMRequestCounter) {
+        this.inferenceAPMRequestCounter = Objects.requireNonNull(inferenceAPMRequestCounter);
+    }
+
+    @Override
+    public void incrementRequestCount(Model model) {
+        var service = model.getConfigurations().getService();
+        var taskType = model.getTaskType();
+        var modelId = model.getServiceSettings().modelId();
+
+        var attributes = new HashMap<String, Object>(5);
+        attributes.put("service", service);
+        attributes.put("task_type", taskType.toString());
+        if (modelId != null) {
+            attributes.put("model_id", modelId);
+        }
+
+        inferenceAPMRequestCounter.incrementBy(1, attributes);
+    }
+
+    public static ApmInferenceStats create(MeterRegistry meterRegistry) {
+        return new ApmInferenceStats(
+            meterRegistry.registerLongCounter(
+                "es.inference.requests.count.total",
+                "Inference API request counts for a particular service, task type, model ID",
+                "operations"
+            )
+        );
+    }
+}

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/telemetry/InferenceStats.java

@@ -8,52 +8,14 @@
 package org.elasticsearch.xpack.inference.telemetry;
 
 import org.elasticsearch.inference.Model;
-import org.elasticsearch.inference.TaskType;
-import org.elasticsearch.xpack.core.inference.InferenceRequestStats;
 
-import java.util.Objects;
-import java.util.concurrent.atomic.LongAdder;
+public interface InferenceStats {
 
-public class InferenceStats implements Stats {
-    protected final String service;
-    protected final TaskType taskType;
-    protected final String modelId;
-    protected final LongAdder counter = new LongAdder();
+    /**
+     * Increment the counter for a particular value in a thread safe manner.
+     * @param model the model to increment request count for
+     */
+    void incrementRequestCount(Model model);
 
-    public static String key(Model model) {
-        StringBuilder builder = new StringBuilder();
-        builder.append(model.getConfigurations().getService());
-        builder.append(":");
-        builder.append(model.getTaskType());
-
-        if (model.getServiceSettings().modelId() != null) {
-            builder.append(":");
-            builder.append(model.getServiceSettings().modelId());
-        }
-
-        return builder.toString();
-    }
-
-    public InferenceStats(Model model) {
-        Objects.requireNonNull(model);
-
-        service = model.getConfigurations().getService();
-        taskType = model.getTaskType();
-        modelId = model.getServiceSettings().modelId();
-    }
-
-    @Override
-    public void increment() {
-        counter.increment();
-    }
-
-    @Override
-    public long getCount() {
-        return counter.sum();
-    }
-
-    @Override
-    public InferenceRequestStats toSerializableForm() {
-        return new InferenceRequestStats(service, taskType, modelId, getCount());
-    }
+    InferenceStats NOOP = model -> {};
 }