More transactional code for the Memrata device.

Check if the update can proceed on inserts and updatest, fix the overwrite
stuff (again).  Probably still wrong, but I'll wait until I can run the
test suite to fix it.

Add support for setting the transaction state on commit/rollback; walk
the session handle and for every data-source cursor, call an underlying
commit or rollback function.  I don't see another solution, so I'm doing
this until Michael weighs in: I'm adding private WT_CURSOR methods the
data-source code sets, which is flatly wrong, but the other approaches
seem worse.

Another WT_EXTENSION_API method: the transaction_snapshot_isolation method
returns if snapshot isolation is configured for the current transaction.

Change the WT_EXTENSION_API transaction_id method to return the transaction
ID; it's no more likely to fail than the other transaction methods, and
I don't see them failing in the future either.   It's a little dangerous,
but I'd rather keep error handling simple if we can.

1 files changed, 11 insertions, 1 deletions

diff --git a/examples/c/ex_data_source.c b/examples/c/ex_data_source.c
index 662dcdc8b1d..35dfa9182af 100644
--- a/examples/c/ex_data_source.c
+++ b/examples/c/ex_data_source.c
@@ -155,11 +155,21 @@ static int my_cursor_insert(WT_CURSOR *wtcursor)
 	int ret;
 
 	{
+	int is_snapshot_isolation;
+	/*! [WT_EXTENSION transaction snapshot isolation] */
+	is_snapshot_isolation =
+	    wt_api->transaction_snapshot_isolation(wt_api, session);
+	/*! [WT_EXTENSION transaction snapshot isolation] */
+	(void)is_snapshot_isolation;
+	}
+
+	{
 	/*! [WT_EXTENSION transaction ID] */
 	uint64_t transaction_id;
 
-	ret = wt_api->transaction_id(wt_api, session, &transaction_id);
+	transaction_id = wt_api->transaction_id(wt_api, session);
 	/*! [WT_EXTENSION transaction ID] */
+	(void)transaction_id;
 	}
 
 	{