I opened HBASE-15638 Shade protobuf but should probably raise the larger intent here. You fellows might have an opinion (smile).
We need to shade PB so we can move to a different version. We need to move to a different version because we want to save on buffer copies -- newer versions of PB have some 'unsafe' facility so we can save on copies before serializing -- but we also want to be able to keep our data off heap always. Currently, our PB version expects byte arrays (2.5.0). Later versions of PBs have some support for ByteBuffer handling but even then, the BBs are expected to be onheap so we can't pass DirectByteBuffers (TODO: add support to PB to work w/ DBBs -- and BBs w/o copy -- and push these changes upstream). On an initial pass, the only difficult part seems to be interaction with HDFS in asyncwal (might just pull in the HDFS messages). The plan was to remove all references to protobuf and just have all modules depend on our hbase-protocol module. We'd bundle our PB in hbase-protocol.*.jar with packages offset to be at org.apache.hbase.shaded.com.google.protobuf. This way, our shading mess is contained some. Suggestions, opinions, all welcome. This project is part of the Ram and Anoop offheaping of the readpath and generally saving allocations effort. St.Ack
