[CAY-1594] DI extension point: turning on/off cross-ObjectContext synchronization

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1M2
• Fix Version/s: 3.1M3
• Assignee: Dzmitry Kazimirchyk
• Reporter: Andrus Adamchik
• Created: 27/Jul/11 08:17
• Updated: 02/Aug/11 07:45
• Resolved: 02/Aug/11 07:45

Description

This is a new DI extension point - a strategy that defines whether changes from one ObjectContext are propagated to other ObjectContexts (in the same VM, or cross-VM, it should work the same). Similar to CAY-1586 (a strategy for retaining objects in the ObjectStore) this can be a single strategy class that uses a property that defines whether synchronization is to occur. The default is "true".

Some docs on synchronization is provided here: http://cayenne.apache.org/doc30/turning-off-context-synchronization.html

Turning off syncing may have a number of benefits:

1. If the app is running on the cluster, and remote synchronization is turned off, inconsistency is introduced - contexts local to a committing context get the changes, remote - don't.

2. Better performance - synchronization (even though run asynchronously) , has O(N) performance in respect to the number of contexts in the system. This is not scalable.

3. Optimistic locking may actually become usable. Currently optimistic locking in a typical webapp may not detect changes to objects due to background synchronization. While I haven't tried it with syncing being off, my assertion is that it will become more deterministic.