Mike Percy has posted comments on this change. Change subject: Create ConsensusMetadataService ......................................................................
Patch Set 2: (19 comments) http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/consensus/consensus_meta_service-test.cc File src/kudu/consensus/consensus_meta_service-test.cc: PS2, Line 31: ConsensusMetadataServiceTest > how does overwrite behave? is it allowed? likely should have a test. Done PS2, Line 38: OVERRIDE > use c++11 style overrides Done PS2, Line 68: ASSERT_OK(cmeta_service_->Load(kTabletId, &cmeta)); > no testing that it matches what you expect? Done http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/consensus/consensus_meta_service.cc File src/kudu/consensus/consensus_meta_service.cc: PS2, Line 42: RETURN_NOT_OK(ConsensusMetadata::Create(fs_manager_, tablet_id, fs_manager_->uuid(), : config, current_term, cmeta_out)); > is it strictly necessary to do the create under the lock? I was thinking it would be a rare enough operation but I suppose it was a bit too simplistic. I've updated this with a scheme that involves a map and a condition variable to get callers to block on outstanding operations on the cmeta instance they are accessing instead of holding the lock across the whole set while performing I/O. http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/consensus/consensus_meta_service.h File src/kudu/consensus/consensus_meta_service.h: PS2, Line 33: ConsensusMetadataService > class header doc Done PS2, Line 39: // On success, returns OK. > nit: we generally omit this (otherwise all the methods would have to have i Done PS2, Line 51: // Delete the ConsensusMetadata instance keyed by 'tablet_id'. > is the delete permanent, or do we leave something lying around? can you tal Permanent. Done PS2, Line 53: // Returns an error if the cmeta instance exists but cannot be deleted. > why wouldn't we be able to delete it? Could be a FS permissions issue or something like that. http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/consensus/raft_consensus_quorum-test.cc File src/kudu/consensus/raft_consensus_quorum-test.cc: PS2, Line 575: > nit no longer need to leave this space Done http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/integration-tests/tablet_copy-itest.cc File src/kudu/integration-tests/tablet_copy-itest.cc: PS2, Line 56: using kudu::consensus::ConsensusMetadataService; > nit: "consensus" goes after "client" :) ah, right :) http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/integration-tests/ts_recovery-itest.cc File src/kudu/integration-tests/ts_recovery-itest.cc: Line 25: #include "kudu/consensus/log-test-base.h" > warning: #includes are not sorted properly [llvm-include-order] Done http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tablet/tablet_bootstrap.cc File src/kudu/tablet/tablet_bootstrap.cc: Line 78: > spurious change Done PS2, Line 169: meta > consider renaming this param to "tablet_meta" I did consider it but I think if we want to do that it should be a separate patch. It's literally everywhere. http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tablet/tablet_replica-test.cc File src/kudu/tablet/tablet_replica-test.cc: PS2, Line 24: #include "kudu/common/wire_protocol.h" > interesting, I'd think this one came before the one above, but apparently n Yeah... llvm-tidy's lexicographic include sort order is mostly fine but I don't like this quirk either (- before . before _ in ASCII) Line 62: using consensus::OpIdEquals; > warning: using decl 'OpIdEquals' is unused [misc-unused-using-decls] Done http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tserver/tablet_copy_client.cc File src/kudu/tserver/tablet_copy_client.cc: PS2, Line 104: cmeta_service_(std::move(cmeta_service)), > I see you're using move there but const refs elsewhere? any particular reas In this case we are holding a ref to the cmeta service so as long as that's the case this makes sense. As of C++11 this approach is easier for the compiler to optimize from what I understand. There are a bunch of articles on this around, e.g. http://www.codesynthesis.com/~boris/blog/2012/06/19/efficient-argument-passing-cxx11-part1/ In general we are trying to prefer pass-by-value + move over pass-by-constref + copy. Of course, in cases where you don't plan to copy, pass-by-constref probably still makes more sense. http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tserver/tablet_copy_client.h File src/kudu/tserver/tablet_copy_client.h: PS2, Line 74: scoped_refptr > use const ref this is legit because TabletCopyClient keeps a ref to ConsensusMetadataService http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tserver/ts_tablet_manager.cc File src/kudu/tserver/ts_tablet_manager.cc: PS2, Line 1067: const scoped_refptr<consensus::ConsensusMetadataService>& > if you don't need to increase the refcount consider passing a raw pointer Why? Passing it this way provides useful information, i.e. that this is refcounted, and passing a const ref doesn't increment the refcount so there is no perf hit. http://gerrit.cloudera.org:8080/#/c/7191/2/src/kudu/tserver/ts_tablet_manager.h File src/kudu/tserver/ts_tablet_manager.h: PS2, Line 289: const > does the const server a purpose here? It simply enforces the invariant that it's set (actually, it's created) in the constructor and that the instance is never replaced, so we get a per-TSTabletManager "singleton". -- To view, visit http://gerrit.cloudera.org:8080/7191 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: Ia30c05dd0feec2b7530205f4d17dfc079a1c3451 Gerrit-PatchSet: 2 Gerrit-Project: kudu Gerrit-Branch: master Gerrit-Owner: Mike Percy <mpe...@apache.org> Gerrit-Reviewer: Alexey Serbin <aser...@cloudera.com> Gerrit-Reviewer: David Ribeiro Alves <davidral...@gmail.com> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Mike Percy <mpe...@apache.org> Gerrit-Reviewer: Tidy Bot Gerrit-HasComments: Yes
