Merged BRANCHES/DEV/mward/head_cachestats to HEAD:

89575: ACE-3327: Work In Progress. TX cache statistics.
   89642: ACE-3327: Exposes statistics through JMX. Adds hit ratio.
   89649: ACE-3327: Added "@since 5.0" to new classes.
   89691: ACE-3327: improved TransactionalCache stats tests.
   89743: ACE-3327: fixed lack of thread safety for InMemoryCacheStatistics.
   89752: ACE-3327: now possible to disable/enable tx cache statistics per-cache with properties.



git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@89798 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/cache/CacheStatistics.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2005-2014 Alfresco Software Limited.
+ *
+ * This file is part of Alfresco
+ *
+ * Alfresco is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Alfresco is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.alfresco.repo.cache;
+
+import org.alfresco.repo.cache.TransactionStats.OpType;
+
+/**
+ * Centralised cache statistics service. Transactional caches participating
+ * in statistical collection will provide their data to this service using the
+ * {@link #add(String, TransactionStats)} method. The data is then aggregated
+ * so that, for example, the hit ratio for a particular cache may be retrieved.
+ * 
+ * @since 5.0
+ * @author Matt Ward
+ */
+public interface CacheStatistics
+{
+    /**
+     * Add new details to the system wide cache statistics.
+     */
+    void add(String cacheName, TransactionStats stats);
+    
+    /**
+     * Get the number of occurrences of the given operation type,
+     * retrieve the number of cache hits that have happened to the cache.
+     * 
+     * @param cacheName Name of the cache.
+     * @param opType    Type of cache operation.
+     * @return long count
+     */
+    long count(String cacheName, OpType opType);
+    
+    /**
+     * The mean time in nanoseconds for all operations of the given type.
+     * 
+     * @param cacheName  The cache name.
+     * @param opType     Type of operation, e.g. cache hits.
+     * @return Time in nanos (double) or NaN if not available yet.
+     */
+    double meanTime(String cacheName, OpType opType);
+    
+    /**
+     * The hit ratio for the given cache, where 1.0 is the maximum possible
+     * value and 0.0 represents a cache that has never successfully
+     * returned a previously cached value. 
+     * 
+     * @param cacheName  The cache name.
+     * @return ratio (double)
+     */
+    double hitMissRatio(String cacheName); 
+}