[Tarantool-patches] [PATCH v3 0/3] qsync: evaluate replication_synchro_quorum dynamically

[Cyrill Gorcunov]

>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.

v2 (by Serge):
 - 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

v3 (by Serge, Mons, Vlad):
 - use replica.lua in tests
 - use N symbol in formula
 - use lua_pcall when evaluating a formula
 - make formula more safe itself, provide various math helpers
 - use box_update_replication_synchro_quorum name as a general
   updater from replication code
 - do not forget to update raft election quorum inside
   box_update_replication_synchro_quorum
 - print warns inside functions evaluator if value get out of bounds

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                                | 142 +++++++++++++++-
 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 +
 12 files changed, 379 insertions(+), 7 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


base-commit: bd03dfc76c0b76f56374c3e66052e2af0c50ae65
-- 
2.26.2