From: Serge Petrenko via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>, gorcunov@gmail.com Cc: tarantool-patches@dev.tarantool.org Subject: Re: [Tarantool-patches] [PATCH v3 04/12] box: make promote always bump the term Date: Wed, 14 Jul 2021 21:26:47 +0300 [thread overview] Message-ID: <27e527db-99b8-0e4e-1d83-b678336a8659@tarantool.org> (raw) In-Reply-To: <fe808d3a-823d-22dc-6953-db0325db78a9@tarantool.org> 04.07.2021 15:14, Vladislav Shpilevoy пишет: > Thanks for the patch! Thanks for the review! > Did you think about making it NOP when the node is already a leader > (even in manual/off mode)? The current solution is all good except > that it makes the current leader temporary read-only until it wins > the election again, which looks strange. I would say "unexpected" for > users. Sure, why not. I'll address it in a separate commit. > See 4 comments below. > >> diff --git a/src/box/box.cc b/src/box/box.cc >> index 6a0950f44..ce37b307d 100644 >> --- a/src/box/box.cc >> +++ b/src/box/box.cc >> @@ -1687,16 +1687,19 @@ box_promote(void) >> rc = -1; >> } else { >> promote: >> - /* We cannot possibly get here in a volatile state. */ >> - assert(box_raft()->volatile_term == box_raft()->term); >> - txn_limbo_write_promote(&txn_limbo, wait_lsn, >> - box_raft()->term); >> + if (try_wait) { >> + raft_new_term(box_raft()); >> + if (box_raft_wait_persisted() < 0) > 1. What if during term WAL write another node also started promote, > won the elections and delivered the promote to us? I suppose after > the WAL write we will silently write PROMOTE for the term which > was won by somebody else, right? Can it be covered by a test? Yep, need to handle that. >> + return -1; >> + } >> + uint64_t term = box_raft()->term; >> + txn_limbo_write_promote(&txn_limbo, wait_lsn, term); >> struct synchro_request req = { >> .type = IPROTO_PROMOTE, >> .replica_id = former_leader_id, >> .origin_id = instance_id, >> .lsn = wait_lsn, >> - .term = box_raft()->term, >> + .term = term, >> }; >> txn_limbo_process(&txn_limbo, &req); >> assert(txn_limbo_is_empty(&txn_limbo)); >> diff --git a/src/box/raft.c b/src/box/raft.c >> index 7f787c0c5..17caf6f54 100644 >> --- a/src/box/raft.c >> +++ b/src/box/raft.c >> @@ -354,6 +354,42 @@ box_raft_wait_leader_found(void) >> return 0; >> } >> >> +struct raft_wait_persisted_data { >> + struct fiber *waiter; >> + uint64_t term; >> +}; >> + >> +static int >> +box_raft_wait_persisted_f(struct trigger *trig, void *event) >> +{ >> + struct raft *raft = event; >> + struct raft_wait_persisted_data *data = trig->data; >> + if (raft->term >= data->term) >> + fiber_wakeup(data->waiter); >> + return 0; >> +} >> + >> +int >> +box_raft_wait_persisted(void) >> +{ >> + if (box_raft()->term == box_raft()->volatile_term) > 2. Since it only waits for term being persisted, I would rather > call it 'wait_term_persisted'. Because there is also vote, and > you do not look at it. Ok. >> + return 0; >> + struct raft_wait_persisted_data data = { >> + .waiter = fiber(), >> + .term = box_raft()->volatile_term, >> + }; >> + struct trigger trig; >> + trigger_create(&trig, box_raft_wait_persisted_f, &data, NULL); >> + raft_on_update(box_raft(), &trig); >> + fiber_yield(); > 3. What about spurious wakeups? I could call fiber.wakeup() from > Lua on this fiber. Yep, need to handle that. I"ll do that for box_raft_wait_leader_found() as well. In a separate commit. Good catch! >> + trigger_clear(&trig); >> + if (fiber_is_cancelled()) { >> + diag_set(FiberIsCancelled); >> + return -1; >> + } >> + return 0; >> +} >> diff --git a/test/replication/gh-4114-local-space-replication.result b/test/replication/gh-4114-local-space-replication.result >> index 9b63a4b99..e71eb60a8 100644 >> --- a/test/replication/gh-4114-local-space-replication.result >> +++ b/test/replication/gh-4114-local-space-replication.result >> @@ -45,9 +45,8 @@ test_run:cmd('switch replica') >> | --- >> | - true >> | ... >> -box.info.vclock[0] >> +a = box.info.vclock[0] or 0 >> | --- >> - | - null >> | ... >> box.cfg{checkpoint_count=1} >> | --- >> @@ -77,9 +76,9 @@ box.space.test:insert{3} >> | - [3] >> | ... >> >> -box.info.vclock[0] >> +assert(box.info.vclock[0] == a + 3) >> | --- >> - | - 3 >> + | - true > 4. Why do you need these changes? I reverted this test and it passed. When the test's run after some election test, master has non-default raft term, and replica persists this term bumping vclock[0]. -- Serge Petrenko
next prev parent reply other threads:[~2021-07-14 18:34 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-28 22:12 [Tarantool-patches] [PATCH v3 00/12] forbid implicit limbo ownership transition Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 01/12] replication: always send raft state to subscribers Serge Petrenko via Tarantool-patches 2021-07-04 12:12 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-09 9:43 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 02/12] txn_limbo: fix promote term filtering Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 03/12] raft: refactor raft_new_term() Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 04/12] box: make promote always bump the term Serge Petrenko via Tarantool-patches 2021-07-04 12:14 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:26 ` Serge Petrenko via Tarantool-patches [this message] 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 05/12] replication: forbid implicit limbo owner transition Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 06/12] box: allow calling promote on a candidate Serge Petrenko via Tarantool-patches 2021-07-04 12:14 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:26 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 07/12] box: introduce `box.ctl.demote` Serge Petrenko via Tarantool-patches 2021-07-04 12:27 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:28 ` Serge Petrenko via Tarantool-patches 2021-07-21 23:28 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-23 7:44 ` Sergey Petrenko via Tarantool-patches 2021-07-26 23:50 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-29 20:56 ` Sergey Petrenko via Tarantool-patches 2021-08-01 16:19 ` Vladislav Shpilevoy via Tarantool-patches 2021-08-03 7:56 ` Serge Petrenko via Tarantool-patches 2021-08-03 23:25 ` Vladislav Shpilevoy via Tarantool-patches 2021-08-04 13:08 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 08/12] txn_limbo: persist the latest effective promote in snapshot Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 09/12] replication: encode version in JOIN request Serge Petrenko via Tarantool-patches 2021-07-04 12:27 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:28 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 10/12] replication: add META stage to JOIN Serge Petrenko via Tarantool-patches 2021-07-04 12:28 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:28 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 11/12] replication: send latest effective promote in initial join Serge Petrenko via Tarantool-patches 2021-07-04 12:28 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:28 ` Serge Petrenko via Tarantool-patches 2021-06-28 22:12 ` [Tarantool-patches] [PATCH v3 12/12] replication: send current Raft term in join response Serge Petrenko via Tarantool-patches 2021-07-04 12:29 ` Vladislav Shpilevoy via Tarantool-patches 2021-07-14 18:28 ` Serge Petrenko via Tarantool-patches 2021-08-04 22:41 ` [Tarantool-patches] [PATCH v3 00/12] forbid implicit limbo ownership transition Vladislav Shpilevoy via Tarantool-patches 2021-08-06 7:54 ` Vitaliia Ioffe via Tarantool-patches 2021-08-06 8:31 ` Kirill Yukhin via Tarantool-patches 2021-08-08 10:46 ` Vladislav Shpilevoy via Tarantool-patches 2021-08-09 7:14 ` Kirill Yukhin via Tarantool-patches
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