[PATCH 00/13] box: garbage collection refactoring and fixes

Vladimir Davydov vdavydov.dev at gmail.com
Thu Oct 4 20:20:02 MSK 2018

Commit 9c5d851d7830 ("replication: remove old snapshot files not needed
by replicas") introduced gc_consumer types so that a consumer could pin
either WALs or checkpoints, not necessarily both. This makes sense,
because a replica doesn't need to pin any checkpoints, however the
implementation looks rather dubious: consumers of all kinds are stored
in the same binary search tree so to find the consumer that needs the
oldest checkpoint we have to linearly scan this tree, which is
inefficient and ugly (see gc_tree_first_checkpoint). This also
complicates further work on the garbage collector, in particular
auto-deletion of WAL files on ENOSPC (#3397) and persistent garbage
collector state (#3442).

So this patch set separates WAL consumers from checkpoint references:
gc_consumer can now only be used to pin WALs while to pin a checkpoint
one has to use gc_checkpoint_ref, which has a more lightweight API and
implementation (e.g. it doesn't have "advance" method, because it
doesn't make sense to advance a checkpoint consumer). Along the way,
it does some related cleanups and fixes bug #3708, which was also
introduced by the above mentioned commit.


Vladimir Davydov (13):
  vinyl: fix master crash on replica join failure
  vinyl: force deletion of runs left from unfinished indexes on restart
  gc: make gc_consumer and gc_state structs transparent
  gc: use fixed length buffer for storing consumer name
  gc: fold gc_consumer_new and gc_consumer_delete
  gc: format consumer name in gc_consumer_register
  gc: rename checkpoint_count to min_checkpoint_count
  gc: keep track of available checkpoints
  gc: cleanup garbage collection procedure
  gc: improve box.info.gc output
  gc: separate checkpoint references from wal consumers
  gc: call gc_run unconditionally when consumer is advanced
  replication: ref checkpoint needed to join replica

 src/box/CMakeLists.txt             |   1 -
 src/box/box.cc                     | 103 ++++++------
 src/box/checkpoint.c               |  72 ---------
 src/box/checkpoint.h               |  97 ------------
 src/box/gc.c                       | 312 ++++++++++++++++---------------------
 src/box/gc.h                       | 187 +++++++++++++++++-----
 src/box/lua/info.c                 |  44 ++++--
 src/box/memtx_engine.c             |   7 +
 src/box/relay.cc                   |   5 +-
 src/box/vinyl.c                    |  11 +-
 src/box/vy_scheduler.c             |   1 -
 test/replication/gc.result         |  19 ++-
 test/replication/gc.test.lua       |   8 +-
 test/vinyl/errinj.result           |  51 ++++++
 test/vinyl/errinj.test.lua         |  18 +++
 test/vinyl/errinj_gc.result        |   4 -
 test/vinyl/errinj_gc.test.lua      |   1 -
 test/vinyl/replica_rejoin.result   |   7 -
 test/vinyl/replica_rejoin.test.lua |   2 -
 19 files changed, 480 insertions(+), 470 deletions(-)
 delete mode 100644 src/box/checkpoint.c
 delete mode 100644 src/box/checkpoint.h


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