[Tarantool-patches] [PATCH v2 0/3] qsync: evaluate replication_synchro_quorum dynamically

[Cyrill Gorcunov <gorcunov@gmail.com>]

From the issue description:

 > The reason is that users will likely not understand how the option
 > should be configured properly, and will break something accidentally.
 > So this idea about allowance to write an expression on the cluster
 > size allows to specify the canonical N/2 + 1 formula, and not update
 > it manually on all instances, when a new node is added, or an existing
 > one is deleted.

Guys, take a look please once time permit. I decided to not split series
too much since otherwise the overall picture disappear.

What have been changed since Serge's comments:

 - keep replication_synchro_quorum been skipped at bootstrap in load_cfg.lua
 - eliminate redundant say_info calls
 - call quorum update routine from replica_set_id/replica_clear_id
 - use replicaset.registered_count directly when evaluating the formula
 - make quorum evaluation procedure always return value in allowed range,
   the only error which may happen here is some syntax error or Lua evaluation
   errors
 - a test has been added

Now the things I don't like, and would prefer to remake somehow but not
sure yet about a better way

 - box_renew_replication_synchro_quorum routine called every time replica_set_id
   or replica_clear_id is called, this is very weird to see box_ module routine
   from inside of a replicaset.

   Maybe we better setup some trigger and simply run it on set_id/clear_id, this
   way replicaset code will be more self consistent from box?

Any comments are highly appreciated!

issue https://github.com/tarantool/tarantool/issues/5446
branch gorcunov/gh-5446-eval-quorum-3

Cyrill Gorcunov (3):
  cfg: add cfg_isnumber helper
  cfg: support symbolic evaluation of replication_synchro_quorum
  test: add replication/gh-5446-sqync-eval-quorum.test.lua

 src/box/box.cc                                | 115 ++++++++++++-
 src/box/box.h                                 |   1 +
 src/box/lua/load_cfg.lua                      |   2 +-
 src/box/replication.cc                        |   4 +
 src/cfg.c                                     |   9 +
 src/cfg.h                                     |   6 +
 .../gh-5446-sqync-eval-quorum.result          | 156 ++++++++++++++++++
 .../gh-5446-sqync-eval-quorum.test.lua        |  62 +++++++
 test/replication/replica-quorum-1.lua         |   1 +
 test/replication/replica-quorum-2.lua         |   1 +
 test/replication/replica-quorum-3.lua         |   1 +
 test/replication/replica-quorum-4.lua         |   1 +
 test/replication/replica-quorum.lua           |  13 ++
 13 files changed, 367 insertions(+), 5 deletions(-)
 create mode 100644 test/replication/gh-5446-sqync-eval-quorum.result
 create mode 100644 test/replication/gh-5446-sqync-eval-quorum.test.lua
 create mode 120000 test/replication/replica-quorum-1.lua
 create mode 120000 test/replication/replica-quorum-2.lua
 create mode 120000 test/replication/replica-quorum-3.lua
 create mode 120000 test/replication/replica-quorum-4.lua
 create mode 100644 test/replication/replica-quorum.lua


base-commit: 546499c9c001e30cbd2598946c9c0589b8e30f53
-- 
2.26.2