rfe11310: AGConnPool should rollback when borrowing

tests-added: none
tests-run:   java-bigger-test
performance: pool will always rollback on borrow

<release-notes>
rfe11310: AGConnPool should rollback when borrowing

Pool will now always rollback when borrowing a connection.
This makes the transaction catch up to the most recent.

The 'testOnBorrow' property for the pool is now
redundant, so generally not recommended.
</release-notes>

Change-Id: I7f74a59669a1d3915ff2e02cd9b15fb7f6686995
Reviewed-on: https://gerrit.franz.com:9080/1944
Reviewed-by: Ahmon Dancy <dancy@franz.com>
Reviewed-by: John O'Rourke <jor@franz.com>
Tested-by: Kevin Layer <layer@franz.com>

src/com/franz/agraph/pool/AGConnFactory.java

@@ -98,6 +98,9 @@ private synchronized AGRepository createRepo(AGCatalog cat) throws Exception {
 	}
 
 	protected void activateConnection(AGRepositoryConnection conn) throws RepositoryException {
+		// rollback to transaction will catch up to the most recent
+		conn.rollback();
+
 		switch (props.session) {
 		case SHARED:
 			if (!conn.isAutoCommit()) {
@@ -125,6 +128,11 @@ protected void activateConnection(AGRepositoryConnection conn) throws Repository
 		}
 	}
 
+	/**
+	 * Calls {@link AGRepositoryConnection#rollback()} and
+	 * resets {@link AGRepositoryConnection#setAutoCommit(boolean)}
+	 * if it has changed.
+	 */
 	@Override
 	public void activateObject(Object obj) throws Exception {
 		activateConnection( (AGRepositoryConnection) obj);
@@ -139,9 +147,8 @@ public void destroyObject(Object obj) throws Exception {
 	public void passivateObject(Object obj) throws Exception {
 		AGRepositoryConnection conn = (AGRepositoryConnection) obj;
 		if (!conn.isAutoCommit() && conn.getRepository().isWritable()) {
+			// rollback to free resources on server
 			conn.rollback();
-			// TODO MH: any reason to do this?
-			//conn.setAutoCommit(true);
 		}
 	}
 

src/com/franz/agraph/pool/AGConnPool.java

@@ -44,7 +44,6 @@
  * 		AGConnProp.session, AGConnProp.Session.DEDICATED,
  * 		AGPoolProp.shutdownHook, true,
  * 		AGPoolProp.maxActive, 10,
- * 		AGPoolProp.testOnBorrow, true,
  * 		AGPoolProp.initialSize, 2);
  * 	AGRepositoryConnection conn = pool.borrowConnection();
  * 	try {

src/com/franz/agraph/pool/AGPoolProp.java

@@ -77,8 +77,11 @@ public enum AGPoolProp {
 	maxWait,
 
 	/**
-	 * Calls {@link AGRepositoryConnection#size(org.openrdf.model.Resource...)}
-	 * - Important, because sessions may timeout while idle in the pool.
+	 * Calls {@link AGRepositoryConnection#size(org.openrdf.model.Resource...)}.
+	 * 
+	 * Redundant because {@link AGConnFactory#activateObject(Object)}
+	 * always calls {@link AGRepositoryConnection#rollback()}.
+	 * 
 	 * @see GenericObjectPool#setTestOnBorrow(boolean)
 	 * @see AGConnFactory#validateObject(Object)
 	 */