You will need to read and update the object in a transaction which
will throw an exception on commit if another thread updates the same
entity. You can then refresh the object and try again. Also look
into memcache which has an atomic counter increment method that is
much faster than reading and writing to the datastore. The downside
is that the counts could be reset so you may need to periodically
store them in the datastore.
On 8 Apr 2010, at 16:17, mscwd01 wrote:
Hey,
How do you ensure, once you have queried an object from the datastore,
that another call to that object cannot be made?
I basically have a bunch of objects with counters which get
incremented during each call to that object.
What I need to ensure is the object doesn't get called by two threads,
each of which increment the counter by 1 and persist the object back
to the datastore, only for the counter to be incremented by 1 and not
by 2.
Thanks
--
You received this message because you are subscribed to the Google
Groups "Google App Engine for Java" group.
To post to this group, send email to google-appengine-java@googlegroups.com
.
To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com
.
For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en
.
--
You received this message because you are subscribed to the Google Groups "Google
App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/google-appengine-java?hl=en.
