Added method to check that a read-only or read-write txn is present

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@16326 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/transaction/AlfrescoTransactionSupport.java

@@ -172,6 +172,29 @@ public abstract class AlfrescoTransactionSupport
         }
     }
     
+    /**
+     * Checks the state of the current transaction and throws an exception if a transaction
+     * is not present or if the transaction is not read-write, if required.
+     * 
+     * @param requireReadWrite          <tt>true</tt> if the transaction must be read-write
+     * 
+     * @since 3.2
+     */
+    public static void checkTransactionReadState(boolean requireReadWrite)
+    {
+        if (!TransactionSynchronizationManager.isSynchronizationActive())
+        {
+            throw new IllegalStateException(
+                    "The current operation requires an active " +
+                    (requireReadWrite ? "read-write" : "") +
+                    "transaction.");
+        }
+        if (TransactionSynchronizationManager.isCurrentTransactionReadOnly() && requireReadWrite)
+        {
+            throw new IllegalStateException("The current operation requires an active read-write transaction.");
+        }
+    }
+    
     /**
      * Are there any pending changes which must be synchronized with the store?
      *