One of the features of the Ceph OSDs is the ability to do complex compound operations atomically. Things like "write object + set xattr" or "read xattr + read object data" or even "verify xattr foo = bar, and if so, write object data". Compound operations are built as a vector<OSDOp>, where each OSDOp has the description of the operation and an input bufferlist. For results, however, results accumulate in a single buffer and the caller is responsible for picking through the pile for the results of those operations. That clearly sucks. Enter wip-op-data-mux branch, https://github.com/NewDreamNetwork/ceph/commits/wip-op-data-mux First, we rename OSDOp::data -> indata, and add an outdata. We also add an rval so you can get the result code for individual operations. The MOSDOpReply message encoding is updated to pass that over the wire to the client. (This is upwards and downwards compatible change.) https://github.com/NewDreamNetwork/ceph/commit/a8558284db178cfaf07a20bc475e7366c7903ffd The OSD is updated to actually put results in those OSDOp fields: https://github.com/NewDreamNetwork/ceph/commit/ff55d2f310312bb5390326dcc35961d39ccad416 Conveniently, that change doesn't actually affect the resulting encoding for old clients, except that the OSDOp::op::payload_len is now filled in properly--and nobody ever looked at that before. Old (and new) clients will still see the haystack. Then, we extend the Objecter (client-side) ObjectOperation methods for read operations (read(..), getxattr(..), etc.) to take pointer arguments for where the results go: https://github.com/NewDreamNetwork/ceph/commit/fe077832b915175b8ed7880c1fa285309c642563 and the Objecter will sift through the haystack and fill those guys in when the reply comes back. Finally, the librados ObjectReadOperations are similarly updated: https://github.com/NewDreamNetwork/ceph/commit/920bd5685c195e0a3c1c3c43f124fe904a73c9b3 Currently the arguments are optional, but I'm updating the rgw callers now and it makes things _way_ cleaner. It's probably best to make them required so that librados users don't need to have internal knowledge of how we encoding things over the wire, e.g. for things like stat(). I haven't finished testing this yet. Mainly I want to know if the Objecter internal API and librados external API changes make sense. And/or if there are any alternative ideas about how this should be approached... sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
