Add ESQL telemetry collection

docs/reference/cluster/stats.asciidoc

@@ -1396,7 +1396,7 @@ as a human-readable string.
 
 
 `_search`:::
-(object) Contains the information about the <<modules-cross-cluster-search, {ccs}>> usage in the cluster.
+(object) Contains the information about the <<modules-cross-cluster-search, {ccs}>> usage.
 +
 .Properties of `_search`
 [%collapsible%open]

server/src/main/java/org/elasticsearch/TransportVersions.java

@@ -146,7 +146,9 @@ static TransportVersion def(int id) {
     public static final TransportVersion ERROR_TRACE_IN_TRANSPORT_HEADER = def(8_811_00_0);
     public static final TransportVersion FAILURE_STORE_ENABLED_BY_CLUSTER_SETTING = def(8_812_00_0);
     public static final TransportVersion SIMULATE_IGNORED_FIELDS = def(8_813_00_0);
-    public static final TransportVersion ESQL_CCS_TELEMETRY_STATS = def(8_814_00_0);
+    public static final TransportVersion TRANSFORMS_UPGRADE_MODE = def(8_814_00_0);
+    public static final TransportVersion NODE_SHUTDOWN_EPHEMERAL_ID_ADDED = def(8_815_00_0);
+    public static final TransportVersion ESQL_CCS_TELEMETRY_STATS = def(8_816_00_0);
 
     /*
      * STOP! READ THIS FIRST! No, really,

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/CCSUsageTelemetry.java

@@ -108,9 +108,13 @@ public String getName() {
     private final Map<String, LongAdder> clientCounts;
     private final Map<String, PerClusterCCSTelemetry> byRemoteCluster;
     // Should we calculate separate metrics per MRT?
-    private boolean useMRT = true;
+    private final boolean useMRT;
 
     public CCSUsageTelemetry() {
+        this(true);
+    }
+
+    public CCSUsageTelemetry(boolean useMRT) {
         this.byRemoteCluster = new ConcurrentHashMap<>();
         totalCount = new LongAdder();
         successCount = new LongAdder();
@@ -122,10 +126,6 @@ public CCSUsageTelemetry() {
         skippedRemotes = new LongAdder();
         featureCounts = new ConcurrentHashMap<>();
         clientCounts = new ConcurrentHashMap<>();
-    }
-
-    public CCSUsageTelemetry(boolean useMRT) {
-        this();
         this.useMRT = useMRT;
     }
 

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodeResponse.java

@@ -31,8 +31,8 @@ public class ClusterStatsNodeResponse extends BaseNodeResponse {
     private final ClusterHealthStatus clusterStatus;
     private final SearchUsageStats searchUsageStats;
     private final RepositoryUsageStats repositoryUsageStats;
-    private final CCSTelemetrySnapshot ccsMetrics;
-    private final CCSTelemetrySnapshot esqlMetrics;
+    private final CCSTelemetrySnapshot searchCcsMetrics;
+    private final CCSTelemetrySnapshot esqlCcsMetrics;
 
     public ClusterStatsNodeResponse(StreamInput in) throws IOException {
         super(in);
@@ -47,15 +47,15 @@ public ClusterStatsNodeResponse(StreamInput in) throws IOException {
         }
         if (in.getTransportVersion().onOrAfter(TransportVersions.V_8_16_0)) {
             repositoryUsageStats = RepositoryUsageStats.readFrom(in);
-            ccsMetrics = new CCSTelemetrySnapshot(in);
+            searchCcsMetrics = new CCSTelemetrySnapshot(in);
         } else {
             repositoryUsageStats = RepositoryUsageStats.EMPTY;
-            ccsMetrics = new CCSTelemetrySnapshot();
+            searchCcsMetrics = new CCSTelemetrySnapshot();
         }
         if (in.getTransportVersion().onOrAfter(TransportVersions.ESQL_CCS_TELEMETRY_STATS)) {
-            esqlMetrics = new CCSTelemetrySnapshot(in);
+            esqlCcsMetrics = new CCSTelemetrySnapshot(in);
         } else {
-            esqlMetrics = new CCSTelemetrySnapshot();
+            esqlCcsMetrics = new CCSTelemetrySnapshot();
         }
     }
 
@@ -77,8 +77,8 @@ public ClusterStatsNodeResponse(
         this.clusterStatus = clusterStatus;
         this.searchUsageStats = Objects.requireNonNull(searchUsageStats);
         this.repositoryUsageStats = Objects.requireNonNull(repositoryUsageStats);
-        this.ccsMetrics = ccsTelemetrySnapshot;
-        this.esqlMetrics = esqlTelemetrySnapshot;
+        this.searchCcsMetrics = ccsTelemetrySnapshot;
+        this.esqlCcsMetrics = esqlTelemetrySnapshot;
     }
 
     public NodeInfo nodeInfo() {
@@ -109,12 +109,12 @@ public RepositoryUsageStats repositoryUsageStats() {
         return repositoryUsageStats;
     }
 
-    public CCSTelemetrySnapshot getCcsMetrics() {
-        return ccsMetrics;
+    public CCSTelemetrySnapshot getSearchCcsMetrics() {
+        return searchCcsMetrics;
     }
 
-    public CCSTelemetrySnapshot getEsqlMetrics() {
-        return esqlMetrics;
+    public CCSTelemetrySnapshot getEsqlCcsMetrics() {
+        return esqlCcsMetrics;
     }
 
     @Override
@@ -129,10 +129,10 @@ public void writeTo(StreamOutput out) throws IOException {
         }
         if (out.getTransportVersion().onOrAfter(TransportVersions.V_8_16_0)) {
             repositoryUsageStats.writeTo(out);
-            ccsMetrics.writeTo(out);
+            searchCcsMetrics.writeTo(out);
         } // else just drop these stats, ok for bwc
         if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_CCS_TELEMETRY_STATS)) {
-            esqlMetrics.writeTo(out);
+            esqlCcsMetrics.writeTo(out);
         }
     }
 

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsResponse.java

@@ -72,8 +72,8 @@ public ClusterStatsResponse(
             }
         }
         nodes.forEach(node -> {
-            ccsMetrics.add(node.getCcsMetrics());
-            esqlMetrics.add(node.getEsqlMetrics());
+            ccsMetrics.add(node.getSearchCcsMetrics());
+            esqlMetrics.add(node.getEsqlCcsMetrics());
         });
         this.status = status;
         this.clusterSnapshotStats = clusterSnapshotStats;