Scripting: Move script_cache into _nodes/stats

Updated `_nodes/stats`:
 * Remove `script_cache`
 * Update `script` in `_node/stats` to include stats per context:

```
      "script": {
        "compilations": 1,
        "cache_evictions": 0,
        "compilation_limit_triggered": 0,
        "contexts":[
          {
            "context": "aggregation_selector",
            "compilations": 0,
            "cache_evictions": 0,
            "compilation_limit_triggered": 0
          },

```

Refs: elastic#50152

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

@@ -19,7 +19,6 @@
 
 package org.elasticsearch.action.admin.cluster.node.stats;
 
-import org.elasticsearch.Version;
 import org.elasticsearch.action.support.nodes.BaseNodeResponse;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodeRole;
@@ -38,7 +37,6 @@
 import org.elasticsearch.monitor.os.OsStats;
 import org.elasticsearch.monitor.process.ProcessStats;
 import org.elasticsearch.node.AdaptiveSelectionStats;
-import org.elasticsearch.script.ScriptCacheStats;
 import org.elasticsearch.script.ScriptStats;
 import org.elasticsearch.threadpool.ThreadPoolStats;
 import org.elasticsearch.transport.TransportStats;
@@ -83,9 +81,6 @@ public class NodeStats extends BaseNodeResponse implements ToXContentFragment {
     @Nullable
     private ScriptStats scriptStats;
 
-    @Nullable
-    private ScriptCacheStats scriptCacheStats;
-
     @Nullable
     private DiscoveryStats discoveryStats;
 
@@ -113,11 +108,6 @@ public NodeStats(StreamInput in) throws IOException {
         discoveryStats = in.readOptionalWriteable(DiscoveryStats::new);
         ingestStats = in.readOptionalWriteable(IngestStats::new);
         adaptiveSelectionStats = in.readOptionalWriteable(AdaptiveSelectionStats::new);
-        if (in.getVersion().onOrAfter(Version.V_7_8_0)) {
-            scriptCacheStats = in.readOptionalWriteable(ScriptCacheStats::new);
-        } else {
-            scriptCacheStats = null;
-        }
     }
 
     public NodeStats(DiscoveryNode node, long timestamp, @Nullable NodeIndicesStats indices,
@@ -127,8 +117,7 @@ public NodeStats(DiscoveryNode node, long timestamp, @Nullable NodeIndicesStats
                      @Nullable ScriptStats scriptStats,
                      @Nullable DiscoveryStats discoveryStats,
                      @Nullable IngestStats ingestStats,
-                     @Nullable AdaptiveSelectionStats adaptiveSelectionStats,
-                     @Nullable ScriptCacheStats scriptCacheStats) {
+                     @Nullable AdaptiveSelectionStats adaptiveSelectionStats) {
         super(node);
         this.timestamp = timestamp;
         this.indices = indices;
@@ -144,7 +133,6 @@ public NodeStats(DiscoveryNode node, long timestamp, @Nullable NodeIndicesStats
         this.discoveryStats = discoveryStats;
         this.ingestStats = ingestStats;
         this.adaptiveSelectionStats = adaptiveSelectionStats;
-        this.scriptCacheStats = scriptCacheStats;
     }
 
     public long getTimestamp() {
@@ -239,11 +227,6 @@ public AdaptiveSelectionStats getAdaptiveSelectionStats() {
         return adaptiveSelectionStats;
     }
 
-    @Nullable
-    public ScriptCacheStats getScriptCacheStats() {
-        return scriptCacheStats;
-    }
-
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
@@ -266,9 +249,6 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalWriteable(discoveryStats);
         out.writeOptionalWriteable(ingestStats);
         out.writeOptionalWriteable(adaptiveSelectionStats);
-        if (out.getVersion().onOrAfter(Version.V_7_8_0)) {
-            out.writeOptionalWriteable(scriptCacheStats);
-        }
     }
 
     @Override
@@ -332,9 +312,6 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         if (getAdaptiveSelectionStats() != null) {
             getAdaptiveSelectionStats().toXContent(builder, params);
         }
-        if (getScriptCacheStats() != null) {
-            getScriptCacheStats().toXContent(builder, params);
-        }
         return builder;
     }
 }

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

@@ -119,8 +119,7 @@ public NodeStats stats(CommonStatsFlags indices, boolean os, boolean process, bo
                 script ? scriptService.stats() : null,
                 discoveryStats ? discovery.stats() : null,
                 ingest ? ingestService.stats() : null,
-                adaptiveSelection ? responseCollectorService.getAdaptiveStats(searchTransportService.getPendingSearchRequests()) : null,
-                scriptCache ? scriptService.cacheStats() : null
+                adaptiveSelection ? responseCollectorService.getAdaptiveStats(searchTransportService.getPendingSearchRequests()) : null
         );
     }
 

server/src/main/java/org/elasticsearch/script/ScriptCache.java

@@ -132,8 +132,8 @@ static <T extends Throwable> void rethrow(Throwable t) throws T {
         throw (T) t;
     }
 
-    public ScriptStats stats() {
-        return scriptMetrics.stats();
+    public ScriptContextStats stats(String context) {
+        return scriptMetrics.stats(context);
     }
 
     /**

server/src/main/java/org/elasticsearch/script/ScriptMetrics.java

@@ -26,10 +26,6 @@ public class ScriptMetrics {
     final CounterMetric cacheEvictionsMetric = new CounterMetric();
     final CounterMetric compilationLimitTriggered = new CounterMetric();
 
-    public ScriptStats stats() {
-        return new ScriptStats(compilationsMetric.count(), cacheEvictionsMetric.count(), compilationLimitTriggered.count());
-    }
-
     public void onCompilation() {
         compilationsMetric.inc();
     }
@@ -41,4 +37,12 @@ public void onCacheEviction() {
     public void onCompilationLimit() {
         compilationLimitTriggered.inc();
     }
-}
+
+    public ScriptContextStats stats(String context) {
+        return new ScriptContextStats(
+            context,
+            compilationsMetric.count(),
+            cacheEvictionsMetric.count(),
+            compilationLimitTriggered.count()
+        );
+    }}

server/src/main/java/org/elasticsearch/script/ScriptService.java

@@ -541,10 +541,6 @@ public ScriptStats stats() {
         return cacheHolder.get().stats();
     }
 
-    public ScriptCacheStats cacheStats() {
-        return cacheHolder.get().cacheStats();
-    }
-
     @Override
     public void applyClusterState(ClusterChangedEvent event) {
         clusterState = event.state();
@@ -604,15 +600,11 @@ ScriptCache get(String context) {
         }
 
         ScriptStats stats() {
-            return ScriptStats.sum(contextCache.values().stream().map(AtomicReference::get).map(ScriptCache::stats)::iterator);
-        }
-
-        ScriptCacheStats cacheStats() {
-            Map<String, ScriptStats> context = new HashMap<>(contextCache.size());
-            for (String name: contextCache.keySet()) {
-                context.put(name, contextCache.get(name).get().stats());
+            List<ScriptContextStats> stats = new ArrayList<>(contextCache.size());
+            for (Map.Entry<String, AtomicReference<ScriptCache>> entry : contextCache.entrySet()) {
+                stats.add(entry.getValue().get().stats(entry.getKey()));
             }
-            return new ScriptCacheStats(context);
+            return new ScriptStats(stats);
         }
 
         /**