[ZODB-Dev] ZEO and replication of BTree based objects

[Jeremy Hylton]

On Wed, 2003-06-11 at 08:28, Christian Reis wrote:
> On Wed, Jun 04, 2003 at 04:36:09PM -0400, Jeremy Hylton wrote:
> > ZEO uses invalidation-based cache consistency.  When one
> > client modifies an object, the other clients receive
> > invalidation messages.  The other clients don't load the
> > object unless they attempt to read it.
> 
> Am I correct in assuming the invalidation messages are only used to
> raise ReadConflictError when one of the other clients already has a
> version of the object in its cache?

There are two caches, the in-memory object cache and the on-disk pickle
cache.  The invalidations provide cache consistency for both of those
caches.  In the case of the in-memory cache, ReadConflictErrors help
provide consistency when an invalidation arrives during a transaction.

Jeremy