create FM objects w/ reference count of one

patch by jbellis

git-svn-id: https://svn.apache.org/repos/asf/cassandra/trunk@1152416 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/cassandra/cache/FreeableMemory.java

@@ -28,14 +28,17 @@
 
 public class FreeableMemory extends Memory
 {
-    AtomicInteger references = new AtomicInteger(0);
+    AtomicInteger references = new AtomicInteger(1);
 
     public FreeableMemory(long size)
     {
         super(size);
     }
 
-    /** @return true if we succeed in referencing before the reference count reaches zero */
+    /**
+     * @return true if we succeed in referencing before the reference count reaches zero.
+     * (A FreeableMemory object is created with a reference count of one.)
+     */
     public boolean reference()
     {
         while (true)

src/java/org/apache/cassandra/cache/SerializingCache.java

@@ -155,7 +155,6 @@ public void put(K key, V value)
         if (mem == null)
             return; // out of memory.  never mind.
 
-        mem.reference();
         FreeableMemory old = map.put(key, mem);
         if (old != null)
             old.unreference();

test/unit/org/apache/cassandra/cache/CacheProviderTest.java

@@ -48,6 +48,8 @@ public class CacheProviderTest extends SchemaLoader
     private void simpleCase(ColumnFamily cf, ICache<String, ColumnFamily> cache)
     {
         cache.put(key1, cf);
+        assert cache.get(key1) != null;
+
         assertDigests(cache.get(key1), cf);
         cache.put(key2, cf);
         cache.put(key3, cf);