[infinispan-dev] HotRod server and Rolling Upgrades
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 infinispan-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev
Re: [infinispan-dev] HotRod server and Rolling Upgrades
+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 ttarr...@redhat.comwrote: 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 infinispan-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev ___ infinispan-dev mailing list infinispan-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev
Re: [infinispan-dev] HotRod server and Rolling Upgrades
On 12/11/2012 02:35 PM, Dan Berindei wrote: +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. The dependency would only be on hotrod-client and optional at that. Tristan ___ infinispan-dev mailing list infinispan-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev
