Emit block cache metrics

core/src/main/java/org/apache/accumulo/core/metrics/MetricsProducer.java

@@ -667,6 +667,15 @@ public interface MetricsProducer {
   String METRICS_UPDATE_WALOG_WRITE = METRICS_UPDATE_PREFIX + "walog.write";
   String METRICS_UPDATE_MUTATION_ARRAY_SIZE = METRICS_UPDATE_PREFIX + "mutation.arrays.size";
 
+  String METRICS_BLOCKCACHE_PREFIX = "accumulo.blockcache.";
+  String METRICS_BLOCKCACHE_INDEX_HITCOUNT = METRICS_BLOCKCACHE_PREFIX + "index.hitcount";
+  String METRICS_BLOCKCACHE_INDEX_REQUESTCOUNT = METRICS_BLOCKCACHE_PREFIX + "index.requestcount";
+  String METRICS_BLOCKCACHE_DATA_HITCOUNT = METRICS_BLOCKCACHE_PREFIX + "data.hitcount";
+  String METRICS_BLOCKCACHE_DATA_REQUESTCOUNT = METRICS_BLOCKCACHE_PREFIX + "data.requestcount";
+  String METRICS_BLOCKCACHE_SUMMARY_HITCOUNT = METRICS_BLOCKCACHE_PREFIX + "summary.hitcount";
+  String METRICS_BLOCKCACHE_SUMMARY_REQUESTCOUNT =
+      METRICS_BLOCKCACHE_PREFIX + "summary.requestcount";
+
   /**
    * Build Micrometer Meter objects and register them with the registry
    */

server/tserver/src/main/java/org/apache/accumulo/tserver/BlockCacheMetrics.java

@@ -0,0 +1,61 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.accumulo.tserver;
+
+import java.util.function.ToDoubleFunction;
+
+import org.apache.accumulo.core.metrics.MetricsProducer;
+import org.apache.accumulo.core.spi.cache.BlockCache;
+
+import io.micrometer.core.instrument.FunctionCounter;
+import io.micrometer.core.instrument.MeterRegistry;
+
+public class BlockCacheMetrics implements MetricsProducer {
+
+  BlockCache indexCache;
+  BlockCache dataCache;
+  BlockCache summaryCache;
+
+  public BlockCacheMetrics(BlockCache indexCache, BlockCache dataCache, BlockCache summaryCache) {
+    this.indexCache = indexCache;
+    this.dataCache = dataCache;
+    this.summaryCache = summaryCache;
+  }
+
+  @Override
+  public void registerMetrics(MeterRegistry registry) {
+    ToDoubleFunction<BlockCache> getHitCount = cache -> cache.getStats().hitCount();
+    ToDoubleFunction<BlockCache> getRequestCount = cache -> cache.getStats().requestCount();
+
+    FunctionCounter.builder(METRICS_BLOCKCACHE_INDEX_HITCOUNT, indexCache, getHitCount)
+        .description("Index block cache hit count").register(registry);
+    FunctionCounter.builder(METRICS_BLOCKCACHE_INDEX_REQUESTCOUNT, indexCache, getRequestCount)
+        .description("Index block cache request count").register(registry);
+
+    FunctionCounter.builder(METRICS_BLOCKCACHE_DATA_HITCOUNT, dataCache, getHitCount)
+        .description("Data block cache hit count").register(registry);
+    FunctionCounter.builder(METRICS_BLOCKCACHE_DATA_REQUESTCOUNT, dataCache, getRequestCount)
+        .description("Data block cache request count").register(registry);
+
+    FunctionCounter.builder(METRICS_BLOCKCACHE_SUMMARY_HITCOUNT, summaryCache, getHitCount)
+        .description("Summary block cache hit count").register(registry);
+    FunctionCounter.builder(METRICS_BLOCKCACHE_SUMMARY_REQUESTCOUNT, summaryCache, getRequestCount)
+        .description("Summary block cache request count").register(registry);
+  }
+}

server/tserver/src/main/java/org/apache/accumulo/tserver/ScanServer.java

@@ -203,6 +203,7 @@ private TabletMetadataLoader(Ample ample) {
   private ServiceLock scanServerLock;
   protected TabletServerScanMetrics scanMetrics;
   private ScanServerMetrics scanServerMetrics;
+  private BlockCacheMetrics blockCacheMetrics;
 
   private ZooCache managerLockCache;
 
@@ -380,8 +381,10 @@ public void run() {
 
     scanMetrics = new TabletServerScanMetrics();
     scanServerMetrics = new ScanServerMetrics(tabletMetadataCache);
+    blockCacheMetrics = new BlockCacheMetrics(resourceManager.getIndexCache(),
+        resourceManager.getDataCache(), resourceManager.getSummaryCache());
 
-    metricsInfo.addMetricsProducers(scanMetrics, scanServerMetrics);
+    metricsInfo.addMetricsProducers(scanMetrics, scanServerMetrics, blockCacheMetrics);
     metricsInfo.init();
     // We need to set the compaction manager so that we don't get an NPE in CompactableImpl.close
 

server/tserver/src/main/java/org/apache/accumulo/tserver/TabletServer.java

@@ -187,6 +187,7 @@ public class TabletServer extends AbstractServer implements TabletHostingServer
   TabletServerScanMetrics scanMetrics;
   TabletServerMinCMetrics mincMetrics;
   CompactionExecutorsMetrics ceMetrics;
+  BlockCacheMetrics blockCacheMetrics;
 
   @Override
   public TabletServerScanMetrics getScanMetrics() {
@@ -759,16 +760,19 @@ public void run() {
       throw new RuntimeException("Failed to start the tablet client service", e1);
     }
 
-    MetricsInfo metricsInfo = getContext().getMetricsInfo();
+    MetricsInfo metricsInfo = context.getMetricsInfo();
     metricsInfo.addServiceTags(getApplicationName(), clientAddress);
 
     metrics = new TabletServerMetrics(this);
     updateMetrics = new TabletServerUpdateMetrics();
     scanMetrics = new TabletServerScanMetrics();
     mincMetrics = new TabletServerMinCMetrics();
     ceMetrics = new CompactionExecutorsMetrics();
+    blockCacheMetrics = new BlockCacheMetrics(this.resourceManager.getIndexCache(),
+        this.resourceManager.getDataCache(), this.resourceManager.getSummaryCache());
 
-    metricsInfo.addMetricsProducers(metrics, updateMetrics, scanMetrics, mincMetrics, ceMetrics);
+    metricsInfo.addMetricsProducers(metrics, updateMetrics, scanMetrics, mincMetrics, ceMetrics,
+        blockCacheMetrics);
     metricsInfo.init();
 
     this.compactionManager = new CompactionManager(() -> Iterators