Interface update, per-method Contexts.

filter/txnBuf/doc.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 // Package txnBuf contains a transaction buffer filter for the datastore
 // service.
 //
 // By default, datastore transactions take a snapshot of the entity group as
 // soon as you Get or Put into it. All subsequent Get (and query) operations
 // reflect the state of the ORIGINAL transaction snapshot, regardless of any
@@ skipping 55 matching lines @@
 //     not affect the query results (e.g. the query has snapshot consistency
 //     from the moment that it begins iteration). Note, however, that datastore
 //     operations within the callback are still synchronized. This behavior is
 //     so that the user is not forced to buffer all of the query results before
 //     doing work with them, but can treat the query like a stream of events,
 //     if they so choose.
 //
 //   - The changing of namespace inside of a transaction is undefined... This is
 //     just generally a terrible idea anyway, but I thought it was worth
 //     mentioning.
+//
+//   - Currently, the soft transactions are not directly accessible using the
+//     CurrentTransaction interface; it returns the wrapped datastore's
+//     transaction. While this is still correct, it could definitely be made
+//     more useful by adding transaction buffer metadata to the returned
+//     object.
 package txnBuf