Merge "Cache in metric registry"

gerrit-server/src/main/java/com/google/gerrit/metrics/CallbackMetric.java

@@ -24,4 +24,5 @@ import com.google.gerrit.extensions.registration.RegistrationHandle;
  * @param <V> type of the metric value, typically Integer or Long.
  */
 public interface CallbackMetric<V> extends RegistrationHandle {
+  public void prune();
 }

gerrit-server/src/main/java/com/google/gerrit/metrics/CallbackMetric0.java

@@ -37,4 +37,7 @@ public abstract class CallbackMetric0<V> implements CallbackMetric<V> {
    * @param value current value.
    */
   public abstract void set(V value);
+
+  @Override
+  public void prune() {}
 }

gerrit-server/src/main/java/com/google/gerrit/metrics/CallbackMetric1.java

@@ -33,6 +33,7 @@ public abstract class CallbackMetric1<F1, V> implements CallbackMetric<V> {
   public abstract void forceCreate(F1 field1);
 
   /** Prune any submetrics that were not assigned during this trigger. */
+  @Override
   public void prune() {
   }
 }

gerrit-server/src/main/java/com/google/gerrit/metrics/dropwizard/DropWizardMetricMaker.java

@@ -46,6 +46,7 @@ import com.google.gerrit.metrics.Timer2;
 import com.google.gerrit.metrics.Timer3;
 import com.google.gerrit.metrics.proc.JGitMetricModule;
 import com.google.gerrit.metrics.proc.ProcMetricModule;
+import com.google.gerrit.server.cache.CacheMetrics;
 import com.google.inject.Inject;
 import com.google.inject.Scopes;
 import com.google.inject.Singleton;
@@ -75,6 +76,7 @@ public class DropWizardMetricMaker extends MetricMaker {
 
       install(new ProcMetricModule());
       install(new JGitMetricModule());
+      bind(CacheMetrics.class);
     }
   }
 

gerrit-server/src/main/java/com/google/gerrit/server/cache/CacheMetrics.java

@@ -0,0 +1,90 @@
+package com.google.gerrit.server.cache;
+
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheStats;
+import com.google.common.collect.ImmutableSet;
+import com.google.gerrit.extensions.registration.DynamicMap;
+import com.google.gerrit.metrics.CallbackMetric;
+import com.google.gerrit.metrics.CallbackMetric1;
+import com.google.gerrit.metrics.Description;
+import com.google.gerrit.metrics.Field;
+import com.google.gerrit.metrics.MetricMaker;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import java.util.Set;
+
+@Singleton
+public class CacheMetrics {
+  private static final Field<String> F_NAME = Field.ofString("cache_name");
+
+  @Inject
+  public CacheMetrics(MetricMaker metrics,
+      final DynamicMap<Cache<?, ?>> cacheMap) {
+    final CallbackMetric1<String, Long> memEnt =
+        metrics.newCallbackMetric("caches/memory_cached", Long.class,
+            new Description("Memory entries").setGauge().setUnit("entries"),
+            F_NAME);
+    final CallbackMetric1<String, Double> memHit =
+        metrics.newCallbackMetric("caches/memory_hit_ratio", Double.class,
+            new Description("Memory hit ratio").setGauge().setUnit("percent"),
+            F_NAME);
+    final CallbackMetric1<String, Long> memEvict =
+        metrics.newCallbackMetric("caches/memory_eviction_count", Long.class,
+            new Description("Memory eviction count").setGauge()
+                .setUnit("evicted entries"),
+            F_NAME);
+    final CallbackMetric1<String, Long> perDiskEnt =
+        metrics.newCallbackMetric("caches/disk_cached", Long.class,
+            new Description("Disk entries used by persistent cache").setGauge()
+                .setUnit("entries"),
+            F_NAME);
+    final CallbackMetric1<String, Double> perDiskHit =
+        metrics.newCallbackMetric("caches/disk_hit_ratio", Double.class,
+            new Description("Disk hit ratio for persistent cache").setGauge()
+                .setUnit("percent"),
+            F_NAME);
+
+    final Set<CallbackMetric<?>> cacheMetrics =
+        ImmutableSet.<CallbackMetric<?>> of(memEnt, memHit, memEvict,
+            perDiskEnt, perDiskHit);
+
+    metrics.newTrigger(cacheMetrics, new Runnable() {
+      @Override
+      public void run() {
+        for (DynamicMap.Entry<Cache<?, ?>> e : cacheMap) {
+          Cache<?, ?> c = e.getProvider().get();
+          String name = metricNameOf(e);
+          CacheStats cstats = c.stats();
+          memEnt.set(name, c.size());
+          memHit.set(name, cstats.hitRate() * 100);
+          memEvict.set(name, cstats.evictionCount());
+          if (c instanceof PersistentCache) {
+            PersistentCache.DiskStats d = ((PersistentCache) c).diskStats();
+            perDiskEnt.set(name, d.size());
+            perDiskHit.set(name, hitRatio(d));
+          }
+        }
+        for (CallbackMetric<?> cbm : cacheMetrics) {
+          cbm.prune();
+        }
+      }
+    });
+  }
+
+  private static double hitRatio(PersistentCache.DiskStats d) {
+    if (d.requestCount() <= 0) {
+      return 100;
+    }
+    return ((double) d.hitCount() / d.requestCount() * 100);
+  }
+
+  private static String metricNameOf(DynamicMap.Entry<Cache<?, ?>> e) {
+    if ("gerrit".equals(e.getPluginName())) {
+      return e.getExportName();
+    } else {
+      return String.format("plugin/%s/%s", e.getPluginName(),
+          e.getExportName());
+    }
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/config/ListCaches.java

@@ -58,15 +58,19 @@ public class ListCaches implements RestReadView<ConfigResource> {
     this.cacheMap = cacheMap;
   }
 
+  public Map<String, CacheInfo> getCacheInfos() {
+    Map<String, CacheInfo> cacheInfos = new TreeMap<>();
+    for (DynamicMap.Entry<Cache<?, ?>> e : cacheMap) {
+      cacheInfos.put(cacheNameOf(e.getPluginName(), e.getExportName()),
+          new CacheInfo(e.getProvider().get()));
+    }
+    return cacheInfos;
+  }
+
   @Override
   public Object apply(ConfigResource rsrc) {
     if (format == null) {
-      Map<String, CacheInfo> cacheInfos = new TreeMap<>();
-      for (DynamicMap.Entry<Cache<?, ?>> e : cacheMap) {
-        cacheInfos.put(cacheNameOf(e.getPluginName(), e.getExportName()),
-            new CacheInfo(e.getProvider().get()));
-      }
-      return cacheInfos;
+      return getCacheInfos();
     } else {
       List<String> cacheNames = new ArrayList<>();
       for (DynamicMap.Entry<Cache<?, ?>> e : cacheMap) {