+1 to eliminate the value wrappers. -1 to adding a dependency from core to server-core, if you feel creating and maintaining a separate MigrationRemoteCacheStore is too much work I'd rather we moved CacheValue to core.
If we move CacheValue to core, I think we can do the re-wrapping on the rawValues branch and avoid adding another setting to the RCS configuration. On Tue, Dec 11, 2012 at 3:02 PM, Tristan Tarrant <[email protected]>wrote: > So, > I thought we had everything ready to go for HotRod rolling upgrades: > > > - have HotRod server full of data (the "source") > - configure a new HotRod server (the "target") with a RemoteCacheStore > pointing to the "source" (using "rawValues") > - clients switch over to the "target" server which on cache misses > should seamlessly fetch entries from the "source" > - issue a "dump keys" on the source > - fetch the "dumped keys" from the target > - disable the RCS on the target and switch off the "source" for good > - PROFIT$$$ > > Unfortunately there is a teeny tiny flaw in the plan: entries in a > HotRod-managed cache are ByteArrayKey/CacheValue pairs and unfortunately, > when the "target" reads from the RCS they get unwrapped into their byte[] > equivalents. > > The solutions we have are: > > 1. have a special marshaller placed on the RemoteCacheStore's > RemoteCacheManager which rewraps the entries. Unfortunately marshallers > can't distinguish between keys and values, so this would probably require > some horrid ThreadLocal trickery > 2. Add a new option to RemoteCacheStore so that it rewraps entries in > the ByteArrayKey/CacheValue format. Unfortunately the CacheValue class is > part of server-core, but the dependency could be made optional, and in the > context of the Rolling Upgrade scenario it is a non-issue, since it will be > in the classpath > 3. Introduce a new MigrationRemoteCacheStore which does the same as > the above, but without changing RCS itself. > > My personal favourite is number 2, but I trust your better judgement. > > I think these are merely workarounds and we should have a better way for > "entry wrappers" (such as the cache servers) to "localize" the entries for > their own particular needs. Also I believe we need a better way to attach > metadata to entries in a portable way so that we don't need these value > wrappers. > > Tristan > > _______________________________________________ > infinispan-dev mailing list > [email protected] > https://lists.jboss.org/mailman/listinfo/infinispan-dev >
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