Add 'record-native-stats' option to jcache (fixes #460)

When true, this enables stats collection via Caffeine.recordStats()
on the underlying cache. The statistics can be accessed by using
JCache's unwrap method, thereby registering into another metrics
system (e.g. micrometer).

Author: kmclaughlin

jcache/src/main/java/com/github/benmanes/caffeine/jcache/CacheFactory.java

@@ -160,6 +160,10 @@ public CacheProxy<K, V> build() {
       evicts |= configureExpireAfterAccess();
       evicts |= configureExpireVariably();
 
+      if (config.isNativeStatisticsEnabled()) {
+        caffeine.recordStats();
+      }
+
       JCacheEvictionListener<K, V> evictionListener = null;
       if (evicts) {
         evictionListener = new JCacheEvictionListener<>(dispatcher, statistics);

jcache/src/main/java/com/github/benmanes/caffeine/jcache/configuration/CaffeineConfiguration.java

@@ -23,7 +23,6 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.ForkJoinPool;
 
-import org.checkerframework.checker.nullness.qual.Nullable;
 import javax.cache.configuration.CacheEntryListenerConfiguration;
 import javax.cache.configuration.CompleteConfiguration;
 import javax.cache.configuration.Factory;
@@ -32,6 +31,8 @@
 import javax.cache.integration.CacheLoader;
 import javax.cache.integration.CacheWriter;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import com.github.benmanes.caffeine.cache.Expiry;
 import com.github.benmanes.caffeine.cache.Ticker;
 import com.github.benmanes.caffeine.cache.Weigher;
@@ -68,6 +69,7 @@ public final class CaffeineConfiguration<K, V> implements CompleteConfiguration<
   private @Nullable Long expireAfterWriteNanos;
   private @Nullable Long maximumWeight;
   private @Nullable Long maximumSize;
+  private boolean nativeStatistics;
 
   public CaffeineConfiguration() {
     delegate = new MutableConfiguration<>();
@@ -84,6 +86,7 @@ public CaffeineConfiguration(CompleteConfiguration<K, V> configuration) {
       refreshAfterWriteNanos = config.refreshAfterWriteNanos;
       expireAfterAccessNanos = config.expireAfterAccessNanos;
       expireAfterWriteNanos = config.expireAfterWriteNanos;
+      nativeStatistics = config.nativeStatistics;
       executorFactory = config.executorFactory;
       expiryFactory = config.expiryFactory;
       copierFactory = config.copierFactory;
@@ -205,6 +208,26 @@ public void setStoreByValue(boolean isStoreByValue) {
     delegate.setStoreByValue(isStoreByValue);
   }
 
+  /**
+   * Checks whether native statistics collection is enabled in this cache.
+   * <p>
+   * The default value is <code>false</code>.
+   *
+   * @return true if native statistics collection is enabled
+   */
+  public boolean isNativeStatisticsEnabled() {
+    return nativeStatistics;
+  }
+
+  /**
+   * Sets whether native statistics gathering is enabled on a cache.
+   *
+   * @param enabled true to enable native statistics, false to disable.
+   */
+  public void setNativeStatisticsEnabled(boolean enabled) {
+    this.nativeStatistics = enabled;
+  }
+
   @Override
   public boolean isStatisticsEnabled() {
     return delegate.isStatisticsEnabled();

jcache/src/main/java/com/github/benmanes/caffeine/jcache/configuration/TypesafeConfigurator.java

@@ -229,8 +229,9 @@ private void addWriteThrough() {
       }
     }
 
-    /** Adds the JMX monitoring settings. */
+    /** Adds the monitoring settings. */
     private void addMonitoring() {
+      configuration.setNativeStatisticsEnabled(merged.getBoolean("monitoring.native-statistics"));
       configuration.setStatisticsEnabled(merged.getBoolean("monitoring.statistics"));
       configuration.setManagementEnabled(merged.getBoolean("monitoring.management"));
     }

jcache/src/main/resources/reference.conf

@@ -46,12 +46,15 @@ caffeine.jcache {
       writer = null
     }
 
-    # The JMX monitoring configuration
+    # The monitoring configuration
     monitoring {
-      # If cache statistics should be recorded and externalized
+      # If Caffeine's statistics should be recorded (manually externalized via Cache#unwrap)
+      native-statistics = false
+
+      # If JCache statistics should be recorded and externalized via JMX
       statistics = false
 
-      # If the configuration should be externalized
+      # If the configuration should be externalized via JMX
       management = false
     }
 

jcache/src/test/java/com/github/benmanes/caffeine/jcache/configuration/TypesafeConfigurationTest.java

@@ -83,6 +83,7 @@ public void testCache2() {
 
     assertThat(config2.get().getKeyType(), is(String.class));
     assertThat(config2.get().getValueType(), is(Integer.class));
+    assertThat(config2.get().isNativeStatisticsEnabled(), is(false));
     assertThat(config2.get().getExecutorFactory().create(), is(ForkJoinPool.commonPool()));
   }
 
@@ -107,6 +108,7 @@ static void checkTestCache(CaffeineConfiguration<?, ?> config) {
     assertThat(config.getExecutorFactory().create(), is(instanceOf(TestExecutor.class)));
     assertThat(config.getCacheLoaderFactory().create(), is(instanceOf(TestCacheLoader.class)));
     assertThat(config.getCacheWriter(), is(instanceOf(TestCacheWriter.class)));
+    assertThat(config.isNativeStatisticsEnabled(), is(true));
     assertThat(config.isStatisticsEnabled(), is(true));
     assertThat(config.isManagementEnabled(), is(true));
 

jcache/src/test/resources/application.conf

@@ -24,6 +24,7 @@ caffeine.jcache {
     monitoring {
       statistics = true
       management = true
+      native-statistics = true
     }
 
     policy {