Renamed RetryingTransaction to RetryingTransactionHelper, HibernateRetryingTransaction

to HibernateRetryingTransactionHelper.  Changed propagation mode of AVM transactions to
PROPAGATION_REQUIRED and tweaked to not retry in a transaction that wasn't started
locally.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/BRANCHES/WCM-DEV2/root@3389 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/avm/RetryingTransactionHelper.java

@@ -0,0 +1,18 @@
+package org.alfresco.repo.avm;
+
+/**
+ * Interface for a retrying transaction. All operations, so far,
+ * in the AVM repository are idempotent and can thus be retried
+ * when a transaction fails for synchronization reasons.
+ * @author britt
+ */
+interface RetryingTransactionHelper
+{
+    /**
+     * Perform a set of operations under a single transaction.
+     * Keep trying if the operation fails because of a concurrency issue.
+     * @param callback The worker.
+     * @param write Whether this is a write operation.
+     */
+    public void perform(RetryingTransactionCallback callback, boolean write);
+}