Build fix - missing dependancy for previous build fix from DM ACL merge performance teaks

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@9058 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/security/permissions/impl/SimplePermissionReference.java

@@ -24,6 +24,10 @@
  */
 package org.alfresco.repo.security.permissions.impl;
 
+import java.util.HashMap;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
 import org.alfresco.service.namespace.QName;
 
 /**
@@ -38,6 +42,54 @@ public final class SimplePermissionReference extends AbstractPermissionReference
      */
     private static final long serialVersionUID = 637302438293417818L;
 
+    private static ReadWriteLock lock = new ReentrantReadWriteLock();
+
+    private static HashMap<QName, HashMap<String, SimplePermissionReference>> instances = new HashMap<QName, HashMap<String, SimplePermissionReference>>();
+
+    public static SimplePermissionReference getPermissionReference(QName qName, String name)
+    {
+        lock.readLock().lock();
+        try
+        {
+            HashMap<String, SimplePermissionReference> typed = instances.get(qName);
+            if(typed != null)
+            {
+                SimplePermissionReference instance = typed.get(name);
+                if(instance != null)
+                {
+                    return instance;
+                }
+            }
+        }
+        finally
+        {
+            lock.readLock().unlock();
+        }
+        
+        lock.writeLock().lock();
+        try
+        {
+            HashMap<String, SimplePermissionReference> typed = instances.get(qName);
+            if(typed == null)
+            {
+                typed = new HashMap<String, SimplePermissionReference>();
+                instances.put(qName, typed);
+            }
+            SimplePermissionReference instance = typed.get(name);
+            if(instance == null)
+            {
+                instance = new SimplePermissionReference(qName, name);
+                typed.put(name, instance);
+            }
+            return instance;
+        }
+        finally
+        {
+            lock.writeLock().unlock();
+        }
+    }
+    
+    
     /*
      * The type
      */
@@ -49,7 +101,7 @@ public final class SimplePermissionReference extends AbstractPermissionReference
     private String name;
     
     
-    public SimplePermissionReference(QName qName, String name)
+    protected SimplePermissionReference(QName qName, String name)
     {
         super();
         this.qName = qName;