implement cache statistics

scm-core/src/main/java/sonia/scm/cache/Cache.java

@@ -102,7 +102,7 @@ public interface Cache<K, V>
    * Returns the number of entries in the cache.
    *
    * @return number of entries in the cache
-   * 
+   *
    * @since 2.0.0
    */
   public int size();
@@ -118,4 +118,15 @@ public interface Cache<K, V>
    * @return The cached element with the specified key or null
    */
   public V get(K key);
+
+  /**
+   * Returns performance statistics of the cache or null if the cache does not
+   * support statistics. The returned statistic is a snapshot of the current
+   * performance.
+   *
+   * @return performance statistics or null
+   *
+   * @since 2.0.0
+   */
+  public CacheStatistics getStatistics();
 }

scm-core/src/main/java/sonia/scm/cache/CacheStatistics.java

@@ -0,0 +1,209 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.cache;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.base.Objects;
+
+/**
+ * Statistics about the performance of a {@link Cache}.
+ * Instances of this class are immutable.
+ *
+ * @author Sebastian Sdorra
+ * @since 2.0.0
+ */
+public final class CacheStatistics
+{
+
+  /**
+   * Constructs a new performance statistic for a {@link Cache}.
+   *
+   *
+   * @param name name of the cache
+   * @param hitCount hit count
+   * @param missCount miss count
+   */
+  public CacheStatistics(String name, long hitCount, long missCount)
+  {
+    this.name = name;
+    this.hitCount = hitCount;
+    this.missCount = missCount;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean equals(Object obj)
+  {
+    if (obj == null)
+    {
+      return false;
+    }
+
+    if (getClass() != obj.getClass())
+    {
+      return false;
+    }
+
+    final CacheStatistics other = (CacheStatistics) obj;
+
+    return Objects.equal(name, other.name)
+      && Objects.equal(hitCount, other.hitCount)
+      && Objects.equal(missCount, other.missCount);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public int hashCode()
+  {
+    return Objects.hashCode(name, hitCount, missCount);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public String toString()
+  {
+    //J-
+    return Objects.toStringHelper(this)
+                  .add("name", name)
+                  .add("hitCount", hitCount)
+                  .add("missCount", missCount)
+                  .toString();
+    //J+
+  }
+
+  //~--- get methods ----------------------------------------------------------
+
+  /**
+   * Returns number of times requested elements were found in the cache.
+   *
+   *
+   * @return number of cache hits
+   */
+  public long getHitCount()
+  {
+    return hitCount;
+  }
+
+  /**
+   * Returns the ratio of cache requests which were hits.
+   *
+   *
+   * @return ratio of cache hits
+   */
+  public double getHitRate()
+  {
+    return ratio(hitCount);
+  }
+
+  /**
+   * Returns number of times a requested element was not found in the cache.
+   *
+   *
+   * @return number of cache misses
+   */
+  public long getMissCount()
+  {
+    return missCount;
+  }
+
+  /**
+   * Returns the ratio of cache requests which were misses.
+   *
+   *
+   * @return ratio of cache misses
+   */
+  public double getMissRate()
+  {
+    return ratio(missCount);
+  }
+
+  /**
+   * Returns name of the cache.
+   *
+   *
+   * @return name of the cache
+   */
+  public String getName()
+  {
+    return name;
+  }
+
+  /**
+   * Returns the total number of requests, this includes hits and misses.
+   *
+   *
+   * @return numer of requests
+   */
+  public long getRequestCount()
+  {
+    return hitCount + missCount;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Calculates the ratio of a counter.
+   *
+   *
+   * @param counter counter
+   *
+   * @return rate of counter
+   */
+  private double ratio(long counter)
+  {
+    long requestCount = getRequestCount();
+
+    return (requestCount == 0)
+      ? 1.0
+      : (double) counter / requestCount;
+  }
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** hit count */
+  private final long hitCount;
+
+  /** miss count */
+  private final long missCount;
+
+  /** name of cache */
+  private final String name;
+}

scm-core/src/test/java/sonia/scm/cache/CacheStatisticsTest.java

@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.cache;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+public class CacheStatisticsTest
+{
+
+  /**
+   * Method description
+   *
+   */
+  @Test
+  public void testCounters()
+  {
+    CacheStatistics stats = new CacheStatistics("", 12, 3);
+
+    assertEquals(12, stats.getHitCount());
+    assertEquals(3, stats.getMissCount());
+    assertEquals(15, stats.getRequestCount());
+  }
+
+  /**
+   * Method description
+   *
+   */
+  @Test
+  public void testRates()
+  {
+    CacheStatistics stats = new CacheStatistics("", 12, 3);
+
+    assertEquals(0.8d, stats.getHitRate(), 0.0);
+    assertEquals(0.2d, stats.getMissRate(), 0.0);
+  }
+}

scm-webapp/src/main/java/sonia/scm/cache/GuavaCache.java

@@ -47,6 +47,7 @@ import org.slf4j.LoggerFactory;
 import java.util.Collection;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  *
@@ -111,6 +112,10 @@ public class GuavaCache<K, V>
     {
       this.copyStrategy = copyStrategy;
     }
+    else
+    {
+      this.copyStrategy = CopyStrategy.NONE;
+    }
   }
 
   //~--- methods --------------------------------------------------------------
@@ -266,19 +271,42 @@ public class GuavaCache<K, V>
     if (value != null)
     {
       value = copyStrategy.copyOnRead(value);
+      hitCount.incrementAndGet();
+    }
+    else
+    {
+      missCount.incrementAndGet();
     }
 
     return value;
   }
 
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  @Override
+  public CacheStatistics getStatistics()
+  {
+    return new CacheStatistics(name, hitCount.get(), missCount.get());
+  }
+
   //~--- fields ---------------------------------------------------------------
 
   /** Field description */
-  private com.google.common.cache.Cache<K, V> cache;
+  private final com.google.common.cache.Cache<K, V> cache;
 
   /** Field description */
-  private CopyStrategy copyStrategy = CopyStrategy.NONE;
+  private final CopyStrategy copyStrategy;
 
   /** Field description */
-  private String name;
+  private final AtomicLong hitCount = new AtomicLong();
+
+  /** Field description */
+  private final AtomicLong missCount = new AtomicLong();
+
+  /** Field description */
+  private final String name;
 }

scm-webapp/src/main/resources/config/gcache.xml

@@ -93,7 +93,7 @@
     expireAfterWrite="5400"
   />
   
-  <!-- new repository api -->
+  <!-- repository api -->
   
   <!--
     Changeset cache

scm-webapp/src/test/java/sonia/scm/cache/CacheTestBase.java

@@ -46,6 +46,7 @@ import sonia.scm.util.IOUtil;
 import static org.hamcrest.Matchers.*;
 
 import static org.junit.Assert.*;
+import org.junit.Assume;
 
 /**
  *
@@ -180,6 +181,30 @@ public abstract class CacheTestBase
     assertNotNull(cache.get("a-1"));
     assertNotNull(cache.get("a-2"));
   }
+  
+  @Test
+  public void testCacheStatistics(){
+    CacheStatistics stats = cache.getStatistics();
+    // skip test if implementation does not support stats
+    Assume.assumeTrue( stats != null );
+    assertEquals("test", stats.getName());
+    assertEquals(0l, stats.getHitCount());
+    assertEquals(0l, stats.getMissCount());
+    cache.put("test-1", "test123");
+    cache.put("test-2", "test456");
+    cache.get("test-1");
+    cache.get("test-1");
+    cache.get("test-1");
+    cache.get("test-3");
+    // check that stats have not changed
+    assertEquals(0l, stats.getHitCount());
+    assertEquals(0l, stats.getMissCount());
+    stats = cache.getStatistics();
+    assertEquals(3l, stats.getHitCount());
+    assertEquals(1l, stats.getMissCount());
+    assertEquals(0.75d, stats.getHitRate(), 0.0d);
+    assertEquals(0.25d, stats.getMissRate(), 0.0d);
+  }
 
   /**
    * Method description