[Tarantool-patches] [PATCH v21 0/3] qsync: implement packet filtering (part 1)

[Tarantool-patches] [PATCH v21 0/3] qsync: implement packet filtering (part 1)

[Cyrill Gorcunov via Tarantool-patches]

Guys, please take a look once time permit, any comments are highly appreciated!

v19 (by Vlad):
 - do not modify box_issue_promote and demote (while they are
   still simply utter code duplication but whatever)
 - make txn_limbo_process being void
 - make txn_limbo_process_begin/commit/rollback being void
 - the real processing of request under the lock named as
   txn_limbo_process_core
 - testcase completely reworked (kudos to SergeP)
 - note that if we import test to the master branch without
   ordering pass it will fire assertion
 - dropped off debug info from box.info interface

v20 (by SergeP):
 - use guard for ACK processing and parameters change
 - rework test

v21 (by SergeP):
 - drop warning from txn_limbo_ack
 - rework test to use cluster helpers and ERRINJ_WAL_WRITE_COUNT
   error injection, same time drop modification of election_replica
   script

branch gorcunov/gh-6036-rollback-confirm-21
issue https://github.com/tarantool/tarantool/issues/6036
previous series https://lists.tarantool.org/tarantool-patches/20211006201522.335898-1-gorcunov@gmail.com/

Cyrill Gorcunov (3):
  latch: add latch_is_locked helper
  qsync: order access to the limbo terms
  test: add gh-6036-qsync-order test

 src/box/applier.cc                            |  12 +-
 src/box/box.cc                                |  15 +-
 src/box/relay.cc                              |  11 +-
 src/box/txn.c                                 |   2 +-
 src/box/txn_limbo.c                           |  41 +++-
 src/box/txn_limbo.h                           |  80 ++++++-
 src/lib/core/latch.h                          |  11 +
 test/replication/gh-6036-qsync-order.result   | 204 ++++++++++++++++++
 test/replication/gh-6036-qsync-order.test.lua |  97 +++++++++
 test/replication/suite.cfg                    |   1 +
 test/replication/suite.ini                    |   2 +-
 test/unit/snap_quorum_delay.cc                |   5 +-
 12 files changed, 450 insertions(+), 31 deletions(-)
 create mode 100644 test/replication/gh-6036-qsync-order.result
 create mode 100644 test/replication/gh-6036-qsync-order.test.lua


base-commit: ce5752ce235324fcefd5a3d0503fd3f8a1800d38
-- 
2.31.1

[Tarantool-patches] [PATCH v21 1/3] latch: add latch_is_locked helper

[Cyrill Gorcunov via Tarantool-patches]

To test if latch is locked.

Part-of #6036

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/lib/core/latch.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/lib/core/latch.h b/src/lib/core/latch.h
index 49c59cf63..0aaa8b634 100644
--- a/src/lib/core/latch.h
+++ b/src/lib/core/latch.h
@@ -95,6 +95,17 @@ latch_owner(struct latch *l)
 	return l->owner;
 }
 
+/**
+ * Return true if the latch is locked.
+ *
+ * @param l - latch to be tested.
+ */
+static inline bool
+latch_is_locked(const struct latch *l)
+{
+	return l->owner != NULL;
+}
+
 /**
  * Lock a latch. If the latch is already locked by another fiber,
  * waits for timeout.
-- 
2.31.1

[Tarantool-patches] [PATCH v21 2/3] qsync: order access to the limbo terms

[Cyrill Gorcunov via Tarantool-patches]

Limbo terms tracking is shared between appliers and when
one of appliers is waiting for write to complete inside
journal_write() routine, an other may need to access read
term value to figure out if promote request is valid to
apply. Due to cooperative multitasking access to the terms
is not consistent so we need to be sure that other fibers
read up to date terms (ie written to the WAL).

For this sake we use a latching mechanism, when one fiber
takes a lock for updating other readers are waiting until
the operation is complete.

For example here is a call graph of two appliers

applier 1
---------
applier_apply_tx
  (promote term = 3
   current max term = 2)
  applier_synchro_filter_tx
  apply_synchro_row
    journal_write
      (sleeping)

at this moment another applier comes in with obsolete
data and term 2

                              applier 2
                              ---------
                              applier_apply_tx
                                (term 2)
                                applier_synchro_filter_tx
                                  txn_limbo_is_replica_outdated -> false
                                journal_write (sleep)

applier 1
---------
journal wakes up
  apply_synchro_row_cb
    set max term to 3

So the applier 2 didn't notice that term 3 is already seen
and wrote obsolete data. With locking the applier 2 will
wait until applier 1 has finished its write.

Also Serge Petrenko pointed that we have somewhat similar situation
with txn_limbo_ack()[we might try to write confirm on entry while
new promote is in fly and not yet applied, so confirm might be invalid]
and txn_limbo_on_parameters_change() [where we might confirm entries
reducing quorum number while we even not a limbo owner]. Thus we need
to fix these problems as well.

We introduce the following helpers:

1) txn_limbo_process_begin: which takes a lock
2) txn_limbo_process_commit and txn_limbo_process_rollback
   which simply release the lock but have different names
   for better semantics
3) txn_limbo_process is a general function which uses x_begin
   and x_commit helper internally
4) txn_limbo_process_core to do a real job over processing the
   request, it implies that txn_limbo_process_begin been called
5) txn_limbo_ack() and txn_limbo_on_parameters_change() both
   respect current limbo owner via promote latch.

Part-of #6036

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/box/applier.cc             | 12 +++--
 src/box/box.cc                 | 15 ++++---
 src/box/relay.cc               | 11 ++---
 src/box/txn.c                  |  2 +-
 src/box/txn_limbo.c            | 41 +++++++++++++++--
 src/box/txn_limbo.h            | 80 +++++++++++++++++++++++++++++++---
 test/unit/snap_quorum_delay.cc |  5 ++-
 7 files changed, 136 insertions(+), 30 deletions(-)

diff --git a/src/box/applier.cc b/src/box/applier.cc
index b981bd436..46c36e259 100644
--- a/src/box/applier.cc
+++ b/src/box/applier.cc
@@ -857,7 +857,7 @@ apply_synchro_row_cb(struct journal_entry *entry)
 		applier_rollback_by_wal_io(entry->res);
 	} else {
 		replica_txn_wal_write_cb(synchro_entry->rcb);
-		txn_limbo_process(&txn_limbo, synchro_entry->req);
+		txn_limbo_process_core(&txn_limbo, synchro_entry->req);
 		trigger_run(&replicaset.applier.on_wal_write, NULL);
 	}
 	fiber_wakeup(synchro_entry->owner);
@@ -873,6 +873,8 @@ apply_synchro_row(uint32_t replica_id, struct xrow_header *row)
 	if (xrow_decode_synchro(row, &req) != 0)
 		goto err;
 
+	txn_limbo_process_begin(&txn_limbo);
+
 	struct replica_cb_data rcb_data;
 	struct synchro_entry entry;
 	/*
@@ -910,12 +912,16 @@ apply_synchro_row(uint32_t replica_id, struct xrow_header *row)
 	 * transactions side, including the async ones.
 	 */
 	if (journal_write(&entry.base) != 0)
-		goto err;
+		goto err_rollback;
 	if (entry.base.res < 0) {
 		diag_set_journal_res(entry.base.res);
-		goto err;
+		goto err_rollback;
 	}
+	txn_limbo_process_commit(&txn_limbo);
 	return 0;
+
+err_rollback:
+	txn_limbo_process_rollback(&txn_limbo);
 err:
 	diag_log();
 	return -1;
diff --git a/src/box/box.cc b/src/box/box.cc
index e082e1a3d..6a9be745a 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -1677,8 +1677,6 @@ box_issue_promote(uint32_t prev_leader_id, int64_t promote_lsn)
 	struct raft *raft = box_raft();
 	assert(raft->volatile_term == raft->term);
 	assert(promote_lsn >= 0);
-	txn_limbo_write_promote(&txn_limbo, promote_lsn,
-				raft->term);
 	struct synchro_request req = {
 		.type = IPROTO_RAFT_PROMOTE,
 		.replica_id = prev_leader_id,
@@ -1686,8 +1684,11 @@ box_issue_promote(uint32_t prev_leader_id, int64_t promote_lsn)
 		.lsn = promote_lsn,
 		.term = raft->term,
 	};
-	txn_limbo_process(&txn_limbo, &req);
+	txn_limbo_process_begin(&txn_limbo);
+	txn_limbo_write_promote(&txn_limbo, req.lsn, req.term);
+	txn_limbo_process_core(&txn_limbo, &req);
 	assert(txn_limbo_is_empty(&txn_limbo));
+	txn_limbo_process_commit(&txn_limbo);
 }
 
 /** A guard to block multiple simultaneous promote()/demote() invocations. */
@@ -1699,8 +1700,6 @@ box_issue_demote(uint32_t prev_leader_id, int64_t promote_lsn)
 {
 	assert(box_raft()->volatile_term == box_raft()->term);
 	assert(promote_lsn >= 0);
-	txn_limbo_write_demote(&txn_limbo, promote_lsn,
-				box_raft()->term);
 	struct synchro_request req = {
 		.type = IPROTO_RAFT_DEMOTE,
 		.replica_id = prev_leader_id,
@@ -1708,8 +1707,12 @@ box_issue_demote(uint32_t prev_leader_id, int64_t promote_lsn)
 		.lsn = promote_lsn,
 		.term = box_raft()->term,
 	};
-	txn_limbo_process(&txn_limbo, &req);
+	txn_limbo_process_begin(&txn_limbo);
+	txn_limbo_write_demote(&txn_limbo, promote_lsn,
+				box_raft()->term);
+	txn_limbo_process_core(&txn_limbo, &req);
 	assert(txn_limbo_is_empty(&txn_limbo));
+	txn_limbo_process_commit(&txn_limbo);
 }
 
 int
diff --git a/src/box/relay.cc b/src/box/relay.cc
index f5852df7b..61ef1e3a5 100644
--- a/src/box/relay.cc
+++ b/src/box/relay.cc
@@ -545,15 +545,10 @@ tx_status_update(struct cmsg *msg)
 	ack.vclock = &status->vclock;
 	/*
 	 * Let pending synchronous transactions know, which of
-	 * them were successfully sent to the replica. Acks are
-	 * collected only by the transactions originator (which is
-	 * the single master in 100% so far). Other instances wait
-	 * for master's CONFIRM message instead.
+	 * them were successfully sent to the replica.
 	 */
-	if (txn_limbo.owner_id == instance_id) {
-		txn_limbo_ack(&txn_limbo, ack.source,
-			      vclock_get(ack.vclock, instance_id));
-	}
+	txn_limbo_ack(&txn_limbo, instance_id, ack.source,
+		      vclock_get(ack.vclock, instance_id));
 	trigger_run(&replicaset.on_ack, &ack);
 
 	static const struct cmsg_hop route[] = {
diff --git a/src/box/txn.c b/src/box/txn.c
index e7fc81683..06bb85a09 100644
--- a/src/box/txn.c
+++ b/src/box/txn.c
@@ -939,7 +939,7 @@ txn_commit(struct txn *txn)
 			txn_limbo_assign_local_lsn(&txn_limbo, limbo_entry,
 						   lsn);
 			/* Local WAL write is a first 'ACK'. */
-			txn_limbo_ack(&txn_limbo, txn_limbo.owner_id, lsn);
+			txn_limbo_ack_self(&txn_limbo, lsn);
 		}
 		if (txn_limbo_wait_complete(&txn_limbo, limbo_entry) < 0)
 			goto rollback;
diff --git a/src/box/txn_limbo.c b/src/box/txn_limbo.c
index 70447caaf..176a83cb5 100644
--- a/src/box/txn_limbo.c
+++ b/src/box/txn_limbo.c
@@ -47,6 +47,7 @@ txn_limbo_create(struct txn_limbo *limbo)
 	vclock_create(&limbo->vclock);
 	vclock_create(&limbo->promote_term_map);
 	limbo->promote_greatest_term = 0;
+	latch_create(&limbo->promote_latch);
 	limbo->confirmed_lsn = 0;
 	limbo->rollback_count = 0;
 	limbo->is_in_rollback = false;
@@ -542,10 +543,23 @@ txn_limbo_read_demote(struct txn_limbo *limbo, int64_t lsn)
 }
 
 void
-txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn)
+txn_limbo_ack(struct txn_limbo *limbo, uint32_t owner_id,
+	      uint32_t replica_id, int64_t lsn)
 {
 	if (rlist_empty(&limbo->queue))
 		return;
+	/*
+	 * ACKs are collected only by the transactions originator
+	 * (which is the single master in 100% so far). Other instances
+	 * wait for master's CONFIRM message instead.
+	 *
+	 * Due to cooperative multitasking there might be limbo owner
+	 * migration in-fly (while writing data to journal), so for
+	 * simplicity sake the test for owner is done here instead
+	 * of putting this check to the callers.
+	 */
+	if (!txn_limbo_is_owner(limbo, owner_id))
+		return;
 	/*
 	 * If limbo is currently writing a rollback, it means that the whole
 	 * queue will be rolled back. Because rollback is written only for
@@ -724,11 +738,14 @@ txn_limbo_wait_empty(struct txn_limbo *limbo, double timeout)
 }
 
 void
-txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req)
+txn_limbo_process_core(struct txn_limbo *limbo,
+		       const struct synchro_request *req)
 {
+	assert(latch_is_locked(&limbo->promote_latch));
+
 	uint64_t term = req->term;
 	uint32_t origin = req->origin_id;
-	if (txn_limbo_replica_term(limbo, origin) < term) {
+	if (vclock_get(&limbo->promote_term_map, origin) < (int64_t)term) {
 		vclock_follow(&limbo->promote_term_map, origin, term);
 		if (term > limbo->promote_greatest_term)
 			limbo->promote_greatest_term = term;
@@ -786,11 +803,29 @@ txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req)
 	return;
 }
 
+void
+txn_limbo_process(struct txn_limbo *limbo,
+		  const struct synchro_request *req)
+{
+	txn_limbo_process_begin(limbo);
+	txn_limbo_process_core(limbo, req);
+	txn_limbo_process_commit(limbo);
+}
+
 void
 txn_limbo_on_parameters_change(struct txn_limbo *limbo)
 {
 	if (rlist_empty(&limbo->queue))
 		return;
+	/*
+	 * In case if we're not current leader (ie not owning the
+	 * limbo) then we should not confirm anything, otherwise
+	 * we could reduce quorum number and start writing CONFIRM
+	 * while leader node carries own maybe bigger quorum value.
+	 */
+	if (!txn_limbo_is_owner(limbo, instance_id))
+		return;
+
 	struct txn_limbo_entry *e;
 	int64_t confirm_lsn = -1;
 	rlist_foreach_entry(e, &limbo->queue, in_queue) {
diff --git a/src/box/txn_limbo.h b/src/box/txn_limbo.h
index 53e52f676..aaff444e4 100644
--- a/src/box/txn_limbo.h
+++ b/src/box/txn_limbo.h
@@ -31,6 +31,7 @@
  */
 #include "small/rlist.h"
 #include "vclock/vclock.h"
+#include "latch.h"
 
 #include <stdint.h>
 
@@ -147,6 +148,10 @@ struct txn_limbo {
 	 * limbo and raft are in sync and the terms are the same.
 	 */
 	uint64_t promote_greatest_term;
+	/**
+	 * To order access to the promote data.
+	 */
+	struct latch promote_latch;
 	/**
 	 * Maximal LSN gathered quorum and either already confirmed in WAL, or
 	 * whose confirmation is in progress right now. Any attempt to confirm
@@ -194,6 +199,23 @@ txn_limbo_is_empty(struct txn_limbo *limbo)
 	return rlist_empty(&limbo->queue);
 }
 
+/**
+ * Test if the \a owner_id is current limbo owner.
+ */
+static inline bool
+txn_limbo_is_owner(struct txn_limbo *limbo, uint32_t owner_id)
+{
+	/*
+	 * A guard needed to prevent race with in-fly promote
+	 * packets which are sitting inside journal but not yet
+	 * written.
+	 */
+	latch_lock(&limbo->promote_latch);
+	bool v = limbo->owner_id == owner_id;
+	latch_unlock(&limbo->promote_latch);
+	return v;
+}
+
 bool
 txn_limbo_is_ro(struct txn_limbo *limbo);
 
@@ -216,9 +238,12 @@ txn_limbo_last_entry(struct txn_limbo *limbo)
  * @a replica_id.
  */
 static inline uint64_t
-txn_limbo_replica_term(const struct txn_limbo *limbo, uint32_t replica_id)
+txn_limbo_replica_term(struct txn_limbo *limbo, uint32_t replica_id)
 {
-	return vclock_get(&limbo->promote_term_map, replica_id);
+	latch_lock(&limbo->promote_latch);
+	uint64_t v = vclock_get(&limbo->promote_term_map, replica_id);
+	latch_unlock(&limbo->promote_latch);
+	return v;
 }
 
 /**
@@ -226,11 +251,14 @@ txn_limbo_replica_term(const struct txn_limbo *limbo, uint32_t replica_id)
  * data from it. The check is only valid when elections are enabled.
  */
 static inline bool
-txn_limbo_is_replica_outdated(const struct txn_limbo *limbo,
+txn_limbo_is_replica_outdated(struct txn_limbo *limbo,
 			      uint32_t replica_id)
 {
-	return txn_limbo_replica_term(limbo, replica_id) <
-	       limbo->promote_greatest_term;
+	latch_lock(&limbo->promote_latch);
+	uint64_t v = vclock_get(&limbo->promote_term_map, replica_id);
+	bool res = v < limbo->promote_greatest_term;
+	latch_unlock(&limbo->promote_latch);
+	return res;
 }
 
 /**
@@ -287,7 +315,15 @@ txn_limbo_assign_lsn(struct txn_limbo *limbo, struct txn_limbo_entry *entry,
  * replica with the specified ID.
  */
 void
-txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn);
+txn_limbo_ack(struct txn_limbo *limbo, uint32_t owner_id,
+	      uint32_t replica_id, int64_t lsn);
+
+static inline void
+txn_limbo_ack_self(struct txn_limbo *limbo, int64_t lsn)
+{
+	return txn_limbo_ack(limbo, limbo->owner_id,
+			     limbo->owner_id, lsn);
+}
 
 /**
  * Block the current fiber until the transaction in the limbo
@@ -300,7 +336,37 @@ txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn);
 int
 txn_limbo_wait_complete(struct txn_limbo *limbo, struct txn_limbo_entry *entry);
 
-/** Execute a synchronous replication request. */
+/**
+ * Initiate execution of a synchronous replication request.
+ */
+static inline void
+txn_limbo_process_begin(struct txn_limbo *limbo)
+{
+	latch_lock(&limbo->promote_latch);
+}
+
+/** Commit a synchronous replication request. */
+static inline void
+txn_limbo_process_commit(struct txn_limbo *limbo)
+{
+	assert(latch_is_locked(&limbo->promote_latch));
+	latch_unlock(&limbo->promote_latch);
+}
+
+/** Rollback a synchronous replication request. */
+static inline void
+txn_limbo_process_rollback(struct txn_limbo *limbo)
+{
+	assert(latch_is_locked(&limbo->promote_latch));
+	latch_unlock(&limbo->promote_latch);
+}
+
+/** Core of processing synchronous replication request. */
+void
+txn_limbo_process_core(struct txn_limbo *limbo,
+		       const struct synchro_request *req);
+
+/** Process a synchronous replication request. */
 void
 txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req);
 
diff --git a/test/unit/snap_quorum_delay.cc b/test/unit/snap_quorum_delay.cc
index 803bbbea8..d43b4cd2c 100644
--- a/test/unit/snap_quorum_delay.cc
+++ b/test/unit/snap_quorum_delay.cc
@@ -130,7 +130,7 @@ txn_process_func(va_list ap)
 	}
 
 	txn_limbo_assign_local_lsn(&txn_limbo, entry, fake_lsn);
-	txn_limbo_ack(&txn_limbo, txn_limbo.owner_id, fake_lsn);
+	txn_limbo_ack_self(&txn_limbo, fake_lsn);
 	txn_limbo_wait_complete(&txn_limbo, entry);
 
 	switch (process_type) {
@@ -157,7 +157,8 @@ txn_confirm_func(va_list ap)
 	 * inside gc_checkpoint().
 	 */
 	fiber_sleep(0);
-	txn_limbo_ack(&txn_limbo, relay_id, fake_lsn);
+	txn_limbo_ack(&txn_limbo, txn_limbo.owner_id,
+		      relay_id, fake_lsn);
 	return 0;
 }
 
-- 
2.31.1

Re: [Tarantool-patches] [PATCH v21 2/3] qsync: order access to the limbo terms

[Serge Petrenko via Tarantool-patches]

08.10.2021 20:58, Cyrill Gorcunov пишет:
> Limbo terms tracking is shared between appliers and when
> one of appliers is waiting for write to complete inside
> journal_write() routine, an other may need to access read
> term value to figure out if promote request is valid to
> apply. Due to cooperative multitasking access to the terms
> is not consistent so we need to be sure that other fibers
> read up to date terms (ie written to the WAL).
>
> For this sake we use a latching mechanism, when one fiber
> takes a lock for updating other readers are waiting until
> the operation is complete.
>
> For example here is a call graph of two appliers

Hi! Thanks for the fixes!

Please, find a couple of minor comments below.
Other than that LGTM!

>
> applier 1
> ---------
> applier_apply_tx
>    (promote term = 3
>     current max term = 2)
>    applier_synchro_filter_tx
>    apply_synchro_row
>      journal_write
>        (sleeping)
>
> at this moment another applier comes in with obsolete
> data and term 2
>
>                                applier 2
>                                ---------
>                                applier_apply_tx
>                                  (term 2)
>                                  applier_synchro_filter_tx
>                                    txn_limbo_is_replica_outdated -> false
>                                  journal_write (sleep)
>
> applier 1
> ---------
> journal wakes up
>    apply_synchro_row_cb
>      set max term to 3
>
> So the applier 2 didn't notice that term 3 is already seen
> and wrote obsolete data. With locking the applier 2 will
> wait until applier 1 has finished its write.
>
> Also Serge Petrenko pointed that we have somewhat similar situation
> with txn_limbo_ack()[we might try to write confirm on entry while
> new promote is in fly and not yet applied, so confirm might be invalid]
> and txn_limbo_on_parameters_change() [where we might confirm entries
> reducing quorum number while we even not a limbo owner]. Thus we need
> to fix these problems as well.
>
> We introduce the following helpers:
>
> 1) txn_limbo_process_begin: which takes a lock
> 2) txn_limbo_process_commit and txn_limbo_process_rollback
>     which simply release the lock but have different names
>     for better semantics
> 3) txn_limbo_process is a general function which uses x_begin
>     and x_commit helper internally
> 4) txn_limbo_process_core to do a real job over processing the
>     request, it implies that txn_limbo_process_begin been called
> 5) txn_limbo_ack() and txn_limbo_on_parameters_change() both
>     respect current limbo owner via promote latch.
>
> Part-of #6036
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>   src/box/applier.cc             | 12 +++--
>   src/box/box.cc                 | 15 ++++---
>   src/box/relay.cc               | 11 ++---
>   src/box/txn.c                  |  2 +-
>   src/box/txn_limbo.c            | 41 +++++++++++++++--
>   src/box/txn_limbo.h            | 80 +++++++++++++++++++++++++++++++---
>   test/unit/snap_quorum_delay.cc |  5 ++-
>   7 files changed, 136 insertions(+), 30 deletions(-)
>
> diff --git a/src/box/applier.cc b/src/box/applier.cc
> index b981bd436..46c36e259 100644
> --- a/src/box/applier.cc
> +++ b/src/box/applier.cc
> @@ -857,7 +857,7 @@ apply_synchro_row_cb(struct journal_entry *entry)
>   		applier_rollback_by_wal_io(entry->res);
>   	} else {
>   		replica_txn_wal_write_cb(synchro_entry->rcb);
> -		txn_limbo_process(&txn_limbo, synchro_entry->req);
> +		txn_limbo_process_core(&txn_limbo, synchro_entry->req);
>   		trigger_run(&replicaset.applier.on_wal_write, NULL);
>   	}
>   	fiber_wakeup(synchro_entry->owner);
> @@ -873,6 +873,8 @@ apply_synchro_row(uint32_t replica_id, struct xrow_header *row)
>   	if (xrow_decode_synchro(row, &req) != 0)
>   		goto err;
>   
> +	txn_limbo_process_begin(&txn_limbo);
> +
>   	struct replica_cb_data rcb_data;
>   	struct synchro_entry entry;
>   	/*
> @@ -910,12 +912,16 @@ apply_synchro_row(uint32_t replica_id, struct xrow_header *row)
>   	 * transactions side, including the async ones.
>   	 */
>   	if (journal_write(&entry.base) != 0)
> -		goto err;
> +		goto err_rollback;
>   	if (entry.base.res < 0) {
>   		diag_set_journal_res(entry.base.res);
> -		goto err;
> +		goto err_rollback;
>   	}
> +	txn_limbo_process_commit(&txn_limbo);
>   	return 0;
> +
> +err_rollback:
> +	txn_limbo_process_rollback(&txn_limbo);
>   err:
>   	diag_log();
>   	return -1;
> diff --git a/src/box/box.cc b/src/box/box.cc
> index e082e1a3d..6a9be745a 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -1677,8 +1677,6 @@ box_issue_promote(uint32_t prev_leader_id, int64_t promote_lsn)
>   	struct raft *raft = box_raft();
>   	assert(raft->volatile_term == raft->term);
>   	assert(promote_lsn >= 0);
> -	txn_limbo_write_promote(&txn_limbo, promote_lsn,
> -				raft->term);
>   	struct synchro_request req = {
>   		.type = IPROTO_RAFT_PROMOTE,
>   		.replica_id = prev_leader_id,
> @@ -1686,8 +1684,11 @@ box_issue_promote(uint32_t prev_leader_id, int64_t promote_lsn)
>   		.lsn = promote_lsn,
>   		.term = raft->term,
>   	};
> -	txn_limbo_process(&txn_limbo, &req);
> +	txn_limbo_process_begin(&txn_limbo);
> +	txn_limbo_write_promote(&txn_limbo, req.lsn, req.term);
> +	txn_limbo_process_core(&txn_limbo, &req);
>   	assert(txn_limbo_is_empty(&txn_limbo));
> +	txn_limbo_process_commit(&txn_limbo);
>   }
>   
>   /** A guard to block multiple simultaneous promote()/demote() invocations. */
> @@ -1699,8 +1700,6 @@ box_issue_demote(uint32_t prev_leader_id, int64_t promote_lsn)
>   {
>   	assert(box_raft()->volatile_term == box_raft()->term);
>   	assert(promote_lsn >= 0);
> -	txn_limbo_write_demote(&txn_limbo, promote_lsn,
> -				box_raft()->term);
>   	struct synchro_request req = {
>   		.type = IPROTO_RAFT_DEMOTE,
>   		.replica_id = prev_leader_id,
> @@ -1708,8 +1707,12 @@ box_issue_demote(uint32_t prev_leader_id, int64_t promote_lsn)
>   		.lsn = promote_lsn,
>   		.term = box_raft()->term,
>   	};
> -	txn_limbo_process(&txn_limbo, &req);
> +	txn_limbo_process_begin(&txn_limbo);
> +	txn_limbo_write_demote(&txn_limbo, promote_lsn,
> +				box_raft()->term);
> +	txn_limbo_process_core(&txn_limbo, &req);
>   	assert(txn_limbo_is_empty(&txn_limbo));
> +	txn_limbo_process_commit(&txn_limbo);
>   }
>   
>   int
> diff --git a/src/box/relay.cc b/src/box/relay.cc
> index f5852df7b..61ef1e3a5 100644
> --- a/src/box/relay.cc
> +++ b/src/box/relay.cc
> @@ -545,15 +545,10 @@ tx_status_update(struct cmsg *msg)
>   	ack.vclock = &status->vclock;
>   	/*
>   	 * Let pending synchronous transactions know, which of
> -	 * them were successfully sent to the replica. Acks are
> -	 * collected only by the transactions originator (which is
> -	 * the single master in 100% so far). Other instances wait
> -	 * for master's CONFIRM message instead.
> +	 * them were successfully sent to the replica.
>   	 */
> -	if (txn_limbo.owner_id == instance_id) {
> -		txn_limbo_ack(&txn_limbo, ack.source,
> -			      vclock_get(ack.vclock, instance_id));
> -	}
> +	txn_limbo_ack(&txn_limbo, instance_id, ack.source,
> +		      vclock_get(ack.vclock, instance_id));
>   	trigger_run(&replicaset.on_ack, &ack);
>   
>   	static const struct cmsg_hop route[] = {
> diff --git a/src/box/txn.c b/src/box/txn.c
> index e7fc81683..06bb85a09 100644
> --- a/src/box/txn.c
> +++ b/src/box/txn.c
> @@ -939,7 +939,7 @@ txn_commit(struct txn *txn)
>   			txn_limbo_assign_local_lsn(&txn_limbo, limbo_entry,
>   						   lsn);
>   			/* Local WAL write is a first 'ACK'. */
> -			txn_limbo_ack(&txn_limbo, txn_limbo.owner_id, lsn);
> +			txn_limbo_ack_self(&txn_limbo, lsn);
>   		}
>   		if (txn_limbo_wait_complete(&txn_limbo, limbo_entry) < 0)
>   			goto rollback;
> diff --git a/src/box/txn_limbo.c b/src/box/txn_limbo.c
> index 70447caaf..176a83cb5 100644
> --- a/src/box/txn_limbo.c
> +++ b/src/box/txn_limbo.c
> @@ -47,6 +47,7 @@ txn_limbo_create(struct txn_limbo *limbo)
>   	vclock_create(&limbo->vclock);
>   	vclock_create(&limbo->promote_term_map);
>   	limbo->promote_greatest_term = 0;
> +	latch_create(&limbo->promote_latch);
>   	limbo->confirmed_lsn = 0;
>   	limbo->rollback_count = 0;
>   	limbo->is_in_rollback = false;
> @@ -542,10 +543,23 @@ txn_limbo_read_demote(struct txn_limbo *limbo, int64_t lsn)
>   }
>   
>   void
> -txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn)
> +txn_limbo_ack(struct txn_limbo *limbo, uint32_t owner_id,
> +	      uint32_t replica_id, int64_t lsn)
>   {
>   	if (rlist_empty(&limbo->queue))
>   		return;
> +	/*
> +	 * ACKs are collected only by the transactions originator
> +	 * (which is the single master in 100% so far). Other instances
> +	 * wait for master's CONFIRM message instead.
> +	 *
> +	 * Due to cooperative multitasking there might be limbo owner
> +	 * migration in-fly (while writing data to journal), so for
> +	 * simplicity sake the test for owner is done here instead
> +	 * of putting this check to the callers.
> +	 */
> +	if (!txn_limbo_is_owner(limbo, owner_id))
> +		return;

I feel like you should check for limbo->queue emptiness **after**
taking the latch. Anything may change while we sleep.

>   	/*
>   	 * If limbo is currently writing a rollback, it means that the whole
>   	 * queue will be rolled back. Because rollback is written only for
> @@ -724,11 +738,14 @@ txn_limbo_wait_empty(struct txn_limbo *limbo, double timeout)
>   }
>   
>   void
> -txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req)
> +txn_limbo_process_core(struct txn_limbo *limbo,
> +		       const struct synchro_request *req)
>   {
> +	assert(latch_is_locked(&limbo->promote_latch));
> +
>   	uint64_t term = req->term;
>   	uint32_t origin = req->origin_id;
> -	if (txn_limbo_replica_term(limbo, origin) < term) {
> +	if (vclock_get(&limbo->promote_term_map, origin) < (int64_t)term) {
>   		vclock_follow(&limbo->promote_term_map, origin, term);
>   		if (term > limbo->promote_greatest_term)
>   			limbo->promote_greatest_term = term;
> @@ -786,11 +803,29 @@ txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req)
>   	return;
>   }
>   
> +void
> +txn_limbo_process(struct txn_limbo *limbo,
> +		  const struct synchro_request *req)
> +{
> +	txn_limbo_process_begin(limbo);
> +	txn_limbo_process_core(limbo, req);
> +	txn_limbo_process_commit(limbo);
> +}
> +
>   void
>   txn_limbo_on_parameters_change(struct txn_limbo *limbo)
>   {
>   	if (rlist_empty(&limbo->queue))
>   		return;
> +	/*
> +	 * In case if we're not current leader (ie not owning the
> +	 * limbo) then we should not confirm anything, otherwise
> +	 * we could reduce quorum number and start writing CONFIRM
> +	 * while leader node carries own maybe bigger quorum value.
> +	 */
> +	if (!txn_limbo_is_owner(limbo, instance_id))
> +		return;
> +

Same as above, let's check for queue emptiness after taking the latch
(checking txn_limbo_is_owner).

>   	struct txn_limbo_entry *e;
>   	int64_t confirm_lsn = -1;
>   	rlist_foreach_entry(e, &limbo->queue, in_queue) {
> diff --git a/src/box/txn_limbo.h b/src/box/txn_limbo.h
> index 53e52f676..aaff444e4 100644
> --- a/src/box/txn_limbo.h
> +++ b/src/box/txn_limbo.h
> @@ -31,6 +31,7 @@
>    */
>   #include "small/rlist.h"
>   #include "vclock/vclock.h"
> +#include "latch.h"
>   
>   #include <stdint.h>
>   
> @@ -147,6 +148,10 @@ struct txn_limbo {
>   	 * limbo and raft are in sync and the terms are the same.
>   	 */
>   	uint64_t promote_greatest_term;
> +	/**
> +	 * To order access to the promote data.
> +	 */
> +	struct latch promote_latch;
>   	/**
>   	 * Maximal LSN gathered quorum and either already confirmed in WAL, or
>   	 * whose confirmation is in progress right now. Any attempt to confirm
> @@ -194,6 +199,23 @@ txn_limbo_is_empty(struct txn_limbo *limbo)
>   	return rlist_empty(&limbo->queue);
>   }
>   
> +/**
> + * Test if the \a owner_id is current limbo owner.
> + */
> +static inline bool
> +txn_limbo_is_owner(struct txn_limbo *limbo, uint32_t owner_id)
> +{
> +	/*
> +	 * A guard needed to prevent race with in-fly promote
> +	 * packets which are sitting inside journal but not yet
> +	 * written.
> +	 */
> +	latch_lock(&limbo->promote_latch);
> +	bool v = limbo->owner_id == owner_id;
> +	latch_unlock(&limbo->promote_latch);
> +	return v;
> +}
> +
>   bool
>   txn_limbo_is_ro(struct txn_limbo *limbo);
>   
> @@ -216,9 +238,12 @@ txn_limbo_last_entry(struct txn_limbo *limbo)
>    * @a replica_id.
>    */
>   static inline uint64_t
> -txn_limbo_replica_term(const struct txn_limbo *limbo, uint32_t replica_id)
> +txn_limbo_replica_term(struct txn_limbo *limbo, uint32_t replica_id)
>   {
> -	return vclock_get(&limbo->promote_term_map, replica_id);
> +	latch_lock(&limbo->promote_latch);
> +	uint64_t v = vclock_get(&limbo->promote_term_map, replica_id);
> +	latch_unlock(&limbo->promote_latch);
> +	return v;
>   }
>   
>   /**
> @@ -226,11 +251,14 @@ txn_limbo_replica_term(const struct txn_limbo *limbo, uint32_t replica_id)
>    * data from it. The check is only valid when elections are enabled.
>    */
>   static inline bool
> -txn_limbo_is_replica_outdated(const struct txn_limbo *limbo,
> +txn_limbo_is_replica_outdated(struct txn_limbo *limbo,
>   			      uint32_t replica_id)
>   {
> -	return txn_limbo_replica_term(limbo, replica_id) <
> -	       limbo->promote_greatest_term;
> +	latch_lock(&limbo->promote_latch);
> +	uint64_t v = vclock_get(&limbo->promote_term_map, replica_id);
> +	bool res = v < limbo->promote_greatest_term;
> +	latch_unlock(&limbo->promote_latch);
> +	return res;
>   }
>   
>   /**
> @@ -287,7 +315,15 @@ txn_limbo_assign_lsn(struct txn_limbo *limbo, struct txn_limbo_entry *entry,
>    * replica with the specified ID.
>    */
>   void
> -txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn);
> +txn_limbo_ack(struct txn_limbo *limbo, uint32_t owner_id,
> +	      uint32_t replica_id, int64_t lsn);
> +
> +static inline void
> +txn_limbo_ack_self(struct txn_limbo *limbo, int64_t lsn)
> +{
> +	return txn_limbo_ack(limbo, limbo->owner_id,
> +			     limbo->owner_id, lsn);
> +}
>   
>   /**
>    * Block the current fiber until the transaction in the limbo
> @@ -300,7 +336,37 @@ txn_limbo_ack(struct txn_limbo *limbo, uint32_t replica_id, int64_t lsn);
>   int
>   txn_limbo_wait_complete(struct txn_limbo *limbo, struct txn_limbo_entry *entry);
>   
> -/** Execute a synchronous replication request. */
> +/**
> + * Initiate execution of a synchronous replication request.
> + */
> +static inline void
> +txn_limbo_process_begin(struct txn_limbo *limbo)
> +{
> +	latch_lock(&limbo->promote_latch);
> +}
> +
> +/** Commit a synchronous replication request. */
> +static inline void
> +txn_limbo_process_commit(struct txn_limbo *limbo)
> +{
> +	assert(latch_is_locked(&limbo->promote_latch));

latch_unlock itself has an assertion, even a more strict one.
So this assertion here and in process_rollback() is extraneous.

> +	latch_unlock(&limbo->promote_latch);
> +}
> +
> +/** Rollback a synchronous replication request. */
> +static inline void
> +txn_limbo_process_rollback(struct txn_limbo *limbo)
> +{
> +	assert(latch_is_locked(&limbo->promote_latch));
> +	latch_unlock(&limbo->promote_latch);
> +}
> +
> +/** Core of processing synchronous replication request. */
> +void
> +txn_limbo_process_core(struct txn_limbo *limbo,
> +		       const struct synchro_request *req);
> +
> +/** Process a synchronous replication request. */
>   void
>   txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request *req);
>   
> diff --git a/test/unit/snap_quorum_delay.cc b/test/unit/snap_quorum_delay.cc
> index 803bbbea8..d43b4cd2c 100644
> --- a/test/unit/snap_quorum_delay.cc
> +++ b/test/unit/snap_quorum_delay.cc
> @@ -130,7 +130,7 @@ txn_process_func(va_list ap)
>   	}
>   
>   	txn_limbo_assign_local_lsn(&txn_limbo, entry, fake_lsn);
> -	txn_limbo_ack(&txn_limbo, txn_limbo.owner_id, fake_lsn);
> +	txn_limbo_ack_self(&txn_limbo, fake_lsn);
>   	txn_limbo_wait_complete(&txn_limbo, entry);
>   
>   	switch (process_type) {
> @@ -157,7 +157,8 @@ txn_confirm_func(va_list ap)
>   	 * inside gc_checkpoint().
>   	 */
>   	fiber_sleep(0);
> -	txn_limbo_ack(&txn_limbo, relay_id, fake_lsn);
> +	txn_limbo_ack(&txn_limbo, txn_limbo.owner_id,
> +		      relay_id, fake_lsn);
>   	return 0;
>   }
>   

-- 
Serge Petrenko

[Tarantool-patches] [PATCH v21 3/3] test: add gh-6036-qsync-order test

[Cyrill Gorcunov via Tarantool-patches]

To test that promotion requests are handled only when appropriate
write to WAL completes, because we update memory data before the
write finishes.

Note that without the patch this test fires assertion

> tarantool: src/box/txn_limbo.c:481: txn_limbo_read_rollback: Assertion `e->txn->signature >= 0' failed.

Part-of #6036

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 test/replication/gh-6036-qsync-order.result   | 204 ++++++++++++++++++
 test/replication/gh-6036-qsync-order.test.lua |  97 +++++++++
 test/replication/suite.cfg                    |   1 +
 test/replication/suite.ini                    |   2 +-
 4 files changed, 303 insertions(+), 1 deletion(-)
 create mode 100644 test/replication/gh-6036-qsync-order.result
 create mode 100644 test/replication/gh-6036-qsync-order.test.lua

diff --git a/test/replication/gh-6036-qsync-order.result b/test/replication/gh-6036-qsync-order.result
new file mode 100644
index 000000000..eb3e808cb
--- /dev/null
+++ b/test/replication/gh-6036-qsync-order.result
@@ -0,0 +1,204 @@
+-- test-run result file version 2
+--
+-- gh-6036: verify that terms are locked when we're inside journal
+-- write routine, because parallel appliers may ignore the fact that
+-- the term is updated already but not yet written leading to data
+-- inconsistency.
+--
+test_run = require('test_run').new()
+ | ---
+ | ...
+
+SERVERS={"election_replica1", "election_replica2", "election_replica3"}
+ | ---
+ | ...
+test_run:create_cluster(SERVERS, "replication", {args='1 nil manual 1'})
+ | ---
+ | ...
+test_run:wait_fullmesh(SERVERS)
+ | ---
+ | ...
+
+--
+-- Create a synchro space on the master node and make
+-- sure the write processed just fine.
+test_run:switch("election_replica1")
+ | ---
+ | - true
+ | ...
+box.ctl.promote()
+ | ---
+ | ...
+s = box.schema.create_space('test', {is_sync = true})
+ | ---
+ | ...
+_ = s:create_index('pk')
+ | ---
+ | ...
+s:insert{1}
+ | ---
+ | - [1]
+ | ...
+
+test_run:switch("election_replica2")
+ | ---
+ | - true
+ | ...
+test_run:wait_lsn('election_replica2', 'election_replica1')
+ | ---
+ | ...
+
+test_run:switch("election_replica3")
+ | ---
+ | - true
+ | ...
+test_run:wait_lsn('election_replica3', 'election_replica1')
+ | ---
+ | ...
+
+--
+-- Drop connection between election_replica1 and election_replica2.
+test_run:switch("election_replica1")
+ | ---
+ | - true
+ | ...
+box.cfg({                                   \
+    replication = {                         \
+        "unix/:./election_replica1.sock",   \
+        "unix/:./election_replica3.sock",   \
+    },                                      \
+})
+ | ---
+ | ...
+--
+-- Drop connection between election_replica2 and election_replica1.
+test_run:switch("election_replica2")
+ | ---
+ | - true
+ | ...
+test_run:wait_cond(function() return box.space.test:get{1} ~= nil end)
+ | ---
+ | - true
+ | ...
+box.cfg({                                   \
+    replication = {                         \
+        "unix/:./election_replica2.sock",   \
+        "unix/:./election_replica3.sock",   \
+    },                                      \
+})
+ | ---
+ | ...
+
+--
+-- Here we have the following scheme
+--
+--              election_replica3 (will be delayed)
+--              /                \
+--    election_replica1    election_replica2
+
+--
+-- Initiate disk delay in a bit tricky way: the next write will
+-- fall into forever sleep.
+test_run:switch("election_replica3")
+ | ---
+ | - true
+ | ...
+write_cnt = box.error.injection.get("ERRINJ_WAL_WRITE_COUNT")
+ | ---
+ | ...
+--
+-- Make election_replica2 been a leader and start writting data,
+-- the PROMOTE request get queued on election_replica3 and not
+-- yet processed, same time INSERT won't complete either
+-- waiting for PROMOTE completion first. Note that we
+-- enter election_replica3 as well just to be sure the PROMOTE
+-- reached it.
+test_run:switch("election_replica2")
+ | ---
+ | - true
+ | ...
+box.ctl.promote()
+ | ---
+ | ...
+test_run:switch("election_replica3")
+ | ---
+ | - true
+ | ...
+test_run:wait_cond(function() return box.error.injection.get("ERRINJ_WAL_WRITE_COUNT") > write_cnt end)
+ | ---
+ | - true
+ | ...
+box.error.injection.set("ERRINJ_WAL_DELAY", true)
+ | ---
+ | - ok
+ | ...
+test_run:switch("election_replica2")
+ | ---
+ | - true
+ | ...
+_ = require('fiber').create(function() box.space.test:insert{2} end)
+ | ---
+ | ...
+
+--
+-- The election_replica1 node has no clue that there is a new leader
+-- and continue writing data with obsolete term. Since election_replica3
+-- is delayed now the INSERT won't proceed yet but get queued.
+test_run:switch("election_replica1")
+ | ---
+ | - true
+ | ...
+_ = require('fiber').create(function() box.space.test:insert{3} end)
+ | ---
+ | ...
+
+--
+-- Finally enable election_replica3 back. Make sure the data from new election_replica2
+-- leader get writing while old leader's data ignored.
+test_run:switch("election_replica3")
+ | ---
+ | - true
+ | ...
+box.error.injection.set('ERRINJ_WAL_DELAY', false)
+ | ---
+ | - ok
+ | ...
+test_run:wait_cond(function() return box.space.test:get{2} ~= nil end)
+ | ---
+ | - true
+ | ...
+box.space.test:select{}
+ | ---
+ | - - [1]
+ |   - [2]
+ | ...
+
+test_run:switch("default")
+ | ---
+ | - true
+ | ...
+test_run:cmd('stop server election_replica1')
+ | ---
+ | - true
+ | ...
+test_run:cmd('stop server election_replica2')
+ | ---
+ | - true
+ | ...
+test_run:cmd('stop server election_replica3')
+ | ---
+ | - true
+ | ...
+
+test_run:cmd('delete server election_replica1')
+ | ---
+ | - true
+ | ...
+test_run:cmd('delete server election_replica2')
+ | ---
+ | - true
+ | ...
+test_run:cmd('delete server election_replica3')
+ | ---
+ | - true
+ | ...
diff --git a/test/replication/gh-6036-qsync-order.test.lua b/test/replication/gh-6036-qsync-order.test.lua
new file mode 100644
index 000000000..b8df170b8
--- /dev/null
+++ b/test/replication/gh-6036-qsync-order.test.lua
@@ -0,0 +1,97 @@
+--
+-- gh-6036: verify that terms are locked when we're inside journal
+-- write routine, because parallel appliers may ignore the fact that
+-- the term is updated already but not yet written leading to data
+-- inconsistency.
+--
+test_run = require('test_run').new()
+
+SERVERS={"election_replica1", "election_replica2", "election_replica3"}
+test_run:create_cluster(SERVERS, "replication", {args='1 nil manual 1'})
+test_run:wait_fullmesh(SERVERS)
+
+--
+-- Create a synchro space on the master node and make
+-- sure the write processed just fine.
+test_run:switch("election_replica1")
+box.ctl.promote()
+s = box.schema.create_space('test', {is_sync = true})
+_ = s:create_index('pk')
+s:insert{1}
+
+test_run:switch("election_replica2")
+test_run:wait_lsn('election_replica2', 'election_replica1')
+
+test_run:switch("election_replica3")
+test_run:wait_lsn('election_replica3', 'election_replica1')
+
+--
+-- Drop connection between election_replica1 and election_replica2.
+test_run:switch("election_replica1")
+box.cfg({                                   \
+    replication = {                         \
+        "unix/:./election_replica1.sock",   \
+        "unix/:./election_replica3.sock",   \
+    },                                      \
+})
+--
+-- Drop connection between election_replica2 and election_replica1.
+test_run:switch("election_replica2")
+test_run:wait_cond(function() return box.space.test:get{1} ~= nil end)
+box.cfg({                                   \
+    replication = {                         \
+        "unix/:./election_replica2.sock",   \
+        "unix/:./election_replica3.sock",   \
+    },                                      \
+})
+
+--
+-- Here we have the following scheme
+--
+--              election_replica3 (will be delayed)
+--              /                \
+--    election_replica1    election_replica2
+
+--
+-- Initiate disk delay in a bit tricky way: the next write will
+-- fall into forever sleep.
+test_run:switch("election_replica3")
+write_cnt = box.error.injection.get("ERRINJ_WAL_WRITE_COUNT")
+--
+-- Make election_replica2 been a leader and start writting data,
+-- the PROMOTE request get queued on election_replica3 and not
+-- yet processed, same time INSERT won't complete either
+-- waiting for PROMOTE completion first. Note that we
+-- enter election_replica3 as well just to be sure the PROMOTE
+-- reached it.
+test_run:switch("election_replica2")
+box.ctl.promote()
+test_run:switch("election_replica3")
+test_run:wait_cond(function() return box.error.injection.get("ERRINJ_WAL_WRITE_COUNT") > write_cnt end)
+box.error.injection.set("ERRINJ_WAL_DELAY", true)
+test_run:switch("election_replica2")
+_ = require('fiber').create(function() box.space.test:insert{2} end)
+
+--
+-- The election_replica1 node has no clue that there is a new leader
+-- and continue writing data with obsolete term. Since election_replica3
+-- is delayed now the INSERT won't proceed yet but get queued.
+test_run:switch("election_replica1")
+_ = require('fiber').create(function() box.space.test:insert{3} end)
+
+--
+-- Finally enable election_replica3 back. Make sure the data from new election_replica2
+-- leader get writing while old leader's data ignored.
+test_run:switch("election_replica3")
+box.error.injection.set('ERRINJ_WAL_DELAY', false)
+test_run:wait_cond(function() return box.space.test:get{2} ~= nil end)
+box.space.test:select{}
+
+test_run:switch("default")
+test_run:cmd('stop server election_replica1')
+test_run:cmd('stop server election_replica2')
+test_run:cmd('stop server election_replica3')
+
+test_run:cmd('delete server election_replica1')
+test_run:cmd('delete server election_replica2')
+test_run:cmd('delete server election_replica3')
diff --git a/test/replication/suite.cfg b/test/replication/suite.cfg
index 3eee0803c..ed09b2087 100644
--- a/test/replication/suite.cfg
+++ b/test/replication/suite.cfg
@@ -59,6 +59,7 @@
     "gh-6094-rs-uuid-mismatch.test.lua": {},
     "gh-6127-election-join-new.test.lua": {},
     "gh-6035-applier-filter.test.lua": {},
+    "gh-6036-qsync-order.test.lua": {},
     "election-candidate-promote.test.lua": {},
     "*": {
         "memtx": {"engine": "memtx"},
diff --git a/test/replication/suite.ini b/test/replication/suite.ini
index 77eb95f49..080e4fbf4 100644
--- a/test/replication/suite.ini
+++ b/test/replication/suite.ini
@@ -3,7 +3,7 @@ core = tarantool
 script =  master.lua
 description = tarantool/box, replication
 disabled = consistent.test.lua
-release_disabled = catch.test.lua errinj.test.lua gc.test.lua gc_no_space.test.lua before_replace.test.lua qsync_advanced.test.lua qsync_errinj.test.lua quorum.test.lua recover_missing_xlog.test.lua sync.test.lua long_row_timeout.test.lua gh-4739-vclock-assert.test.lua gh-4730-applier-rollback.test.lua gh-5140-qsync-casc-rollback.test.lua gh-5144-qsync-dup-confirm.test.lua gh-5167-qsync-rollback-snap.test.lua gh-5430-qsync-promote-crash.test.lua gh-5430-cluster-mvcc.test.lua  gh-5506-election-on-off.test.lua gh-5536-wal-limit.test.lua hang_on_synchro_fail.test.lua anon_register_gap.test.lua gh-5213-qsync-applier-order.test.lua gh-5213-qsync-applier-order-3.test.lua gh-6027-applier-error-show.test.lua gh-6032-promote-wal-write.test.lua gh-6057-qsync-confirm-async-no-wal.test.lua gh-5447-downstream-lag.test.lua gh-4040-invalid-msgpack.test.lua
+release_disabled = catch.test.lua errinj.test.lua gc.test.lua gc_no_space.test.lua before_replace.test.lua qsync_advanced.test.lua qsync_errinj.test.lua quorum.test.lua recover_missing_xlog.test.lua sync.test.lua long_row_timeout.test.lua gh-4739-vclock-assert.test.lua gh-4730-applier-rollback.test.lua gh-5140-qsync-casc-rollback.test.lua gh-5144-qsync-dup-confirm.test.lua gh-5167-qsync-rollback-snap.test.lua gh-5430-qsync-promote-crash.test.lua gh-5430-cluster-mvcc.test.lua  gh-5506-election-on-off.test.lua gh-5536-wal-limit.test.lua hang_on_synchro_fail.test.lua anon_register_gap.test.lua gh-5213-qsync-applier-order.test.lua gh-5213-qsync-applier-order-3.test.lua gh-6027-applier-error-show.test.lua gh-6032-promote-wal-write.test.lua gh-6057-qsync-confirm-async-no-wal.test.lua gh-5447-downstream-lag.test.lua gh-4040-invalid-msgpack.test.lua gh-6036-qsync-order.test.lua
 config = suite.cfg
 lua_libs = lua/fast_replica.lua lua/rlimit.lua
 use_unix_sockets = True
-- 
2.31.1

Re: [Tarantool-patches] [PATCH v21 3/3] test: add gh-6036-qsync-order test

[Serge Petrenko via Tarantool-patches]

08.10.2021 20:58, Cyrill Gorcunov пишет:

Thanks for the fixes!
There are some minor comments left.
Please, address them, and after that - LGTM.

> To test that promotion requests are handled only when appropriate
> write to WAL completes, because we update memory data before the
> write finishes.
>
> Note that without the patch this test fires assertion

Please, mention the patch you're talking about.
I know it's in the previous commit, but still.
Something like:
without the patch "qsync: order access to the limbo terms" this test 
fires an assertion
>
>> tarantool: src/box/txn_limbo.c:481: txn_limbo_read_rollback: Assertion `e->txn->signature >= 0' failed.
> Part-of #6036
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>   test/replication/gh-6036-qsync-order.result   | 204 ++++++++++++++++++
>   test/replication/gh-6036-qsync-order.test.lua |  97 +++++++++
>   test/replication/suite.cfg                    |   1 +
>   test/replication/suite.ini                    |   2 +-
>   4 files changed, 303 insertions(+), 1 deletion(-)
>   create mode 100644 test/replication/gh-6036-qsync-order.result
>   create mode 100644 test/replication/gh-6036-qsync-order.test.lua
>
> diff --git a/test/replication/gh-6036-qsync-order.result b/test/replication/gh-6036-qsync-order.result
> new file mode 100644
> index 000000000..eb3e808cb
> --- /dev/null
> +++ b/test/replication/gh-6036-qsync-order.result
> @@ -0,0 +1,204 @@
> +-- test-run result file version 2
> +--
> +-- gh-6036: verify that terms are locked when we're inside journal
> +-- write routine, because parallel appliers may ignore the fact that
> +-- the term is updated already but not yet written leading to data
> +-- inconsistency.
> +--
> +test_run = require('test_run').new()
> + | ---
> + | ...
> +
> +SERVERS={"election_replica1", "election_replica2", "election_replica3"}
> + | ---
> + | ...
> +test_run:create_cluster(SERVERS, "replication", {args='1 nil manual 1'})
> + | ---
> + | ...
> +test_run:wait_fullmesh(SERVERS)
> + | ---
> + | ...
> +
> +--
> +-- Create a synchro space on the master node and make
> +-- sure the write processed just fine.
> +test_run:switch("election_replica1")
> + | ---
> + | - true
> + | ...
> +box.ctl.promote()
> + | ---
> + | ...
> +s = box.schema.create_space('test', {is_sync = true})
> + | ---
> + | ...
> +_ = s:create_index('pk')
> + | ---
> + | ...
> +s:insert{1}
> + | ---
> + | - [1]
> + | ...
> +
> +test_run:switch("election_replica2")
> + | ---
> + | - true
> + | ...
> +test_run:wait_lsn('election_replica2', 'election_replica1')
> + | ---
> + | ...
> +
> +test_run:switch("election_replica3")
> + | ---
> + | - true
> + | ...
> +test_run:wait_lsn('election_replica3', 'election_replica1')
> + | ---
> + | ...
> +
> +--
> +-- Drop connection between election_replica1 and election_replica2.
> +test_run:switch("election_replica1")
> + | ---
> + | - true
> + | ...
> +box.cfg({                                   \
> +    replication = {                         \
> +        "unix/:./election_replica1.sock",   \
> +        "unix/:./election_replica3.sock",   \
> +    },                                      \
> +})
> + | ---
> + | ...
> +--
> +-- Drop connection between election_replica2 and election_replica1.
> +test_run:switch("election_replica2")
> + | ---
> + | - true
> + | ...
> +test_run:wait_cond(function() return box.space.test:get{1} ~= nil end)
> + | ---
> + | - true
> + | ...

This particular check is extraneous. You've already done a wait_lsn above.

> +box.cfg({                                   \
> +    replication = {                         \
> +        "unix/:./election_replica2.sock",   \
> +        "unix/:./election_replica3.sock",   \
> +    },                                      \
> +})
> + | ---
> + | ...
> +
> +--
> +-- Here we have the following scheme
> +--
> +--              election_replica3 (will be delayed)
> +--              /                \
> +--    election_replica1    election_replica2
> +
> +--
> +-- Initiate disk delay in a bit tricky way: the next write will
> +-- fall into forever sleep.
> +test_run:switch("election_replica3")
> + | ---
> + | - true
> + | ...
> +write_cnt = box.error.injection.get("ERRINJ_WAL_WRITE_COUNT")
> + | ---
> + | ...
> +--
> +-- Make election_replica2 been a leader and start writting data,
> +-- the PROMOTE request get queued on election_replica3 and not
> +-- yet processed, same time INSERT won't complete either
> +-- waiting for PROMOTE completion first. Note that we
> +-- enter election_replica3 as well just to be sure the PROMOTE
> +-- reached it.
> +test_run:switch("election_replica2")
> + | ---
> + | - true
> + | ...
> +box.ctl.promote()
> + | ---
> + | ...
> +test_run:switch("election_replica3")
> + | ---
> + | - true
> + | ...
> +test_run:wait_cond(function() return box.error.injection.get("ERRINJ_WAL_WRITE_COUNT") > write_cnt end)
> + | ---
> + | - true
> + | ...
> +box.error.injection.set("ERRINJ_WAL_DELAY", true)
> + | ---
> + | - ok

This errinj should be set before 'election_replica2' writes promote,
like it used to be in previous patch versions.

Let's set it right where you get 'ERRINJ_WAL_WRITE_COUNT'
> + | ...
> +test_run:switch("election_replica2")
> + | ---
> + | - true
> + | ...
> +_ = require('fiber').create(function() box.space.test:insert{2} end)
> + | ---
> + | ...
> +
> +--
> +-- The election_replica1 node has no clue that there is a new leader
> +-- and continue writing data with obsolete term. Since election_replica3
> +-- is delayed now the INSERT won't proceed yet but get queued.
> +test_run:switch("election_replica1")
> + | ---
> + | - true
> + | ...
> +_ = require('fiber').create(function() box.space.test:insert{3} end)
> + | ---
> + | ...
> +
> +--
> +-- Finally enable election_replica3 back. Make sure the data from new election_replica2
> +-- leader get writing while old leader's data ignored.
> +test_run:switch("election_replica3")
> + | ---
> + | - true
> + | ...
> +box.error.injection.set('ERRINJ_WAL_DELAY', false)
> + | ---
> + | - ok
> + | ...
> +test_run:wait_cond(function() return box.space.test:get{2} ~= nil end)
> + | ---
> + | - true
> + | ...
> +box.space.test:select{}
> + | ---
> + | - - [1]
> + |   - [2]
> + | ...
> +
> +test_run:switch("default")
> + | ---
> + | - true
> + | ...
> +test_run:cmd('stop server election_replica1')
> + | ---
> + | - true
> + | ...
> +test_run:cmd('stop server election_replica2')
> + | ---
> + | - true
> + | ...
> +test_run:cmd('stop server election_replica3')
> + | ---
> + | - true
> + | ...
> +
> +test_run:cmd('delete server election_replica1')
> + | ---
> + | - true
> + | ...
> +test_run:cmd('delete server election_replica2')
> + | ---
> + | - true
> + | ...
> +test_run:cmd('delete server election_replica3')
> + | ---
> + | - true
> + | ...
> diff --git a/test/replication/gh-6036-qsync-order.test.lua b/test/replication/gh-6036-qsync-order.test.lua
> new file mode 100644
> index 000000000..b8df170b8
> --- /dev/null
> +++ b/test/replication/gh-6036-qsync-order.test.lua
> @@ -0,0 +1,97 @@
> +--
> +-- gh-6036: verify that terms are locked when we're inside journal
> +-- write routine, because parallel appliers may ignore the fact that
> +-- the term is updated already but not yet written leading to data
> +-- inconsistency.
> +--
> +test_run = require('test_run').new()
> +
> +SERVERS={"election_replica1", "election_replica2", "election_replica3"}
> +test_run:create_cluster(SERVERS, "replication", {args='1 nil manual 1'})
> +test_run:wait_fullmesh(SERVERS)
> +
> +--
> +-- Create a synchro space on the master node and make
> +-- sure the write processed just fine.
> +test_run:switch("election_replica1")
> +box.ctl.promote()
> +s = box.schema.create_space('test', {is_sync = true})
> +_ = s:create_index('pk')
> +s:insert{1}
> +
> +test_run:switch("election_replica2")
> +test_run:wait_lsn('election_replica2', 'election_replica1')
> +
> +test_run:switch("election_replica3")
> +test_run:wait_lsn('election_replica3', 'election_replica1')
> +
> +--
> +-- Drop connection between election_replica1 and election_replica2.
> +test_run:switch("election_replica1")
> +box.cfg({                                   \
> +    replication = {                         \
> +        "unix/:./election_replica1.sock",   \
> +        "unix/:./election_replica3.sock",   \
> +    },                                      \
> +})
> +--
> +-- Drop connection between election_replica2 and election_replica1.
> +test_run:switch("election_replica2")
> +test_run:wait_cond(function() return box.space.test:get{1} ~= nil end)
> +box.cfg({                                   \
> +    replication = {                         \
> +        "unix/:./election_replica2.sock",   \
> +        "unix/:./election_replica3.sock",   \
> +    },                                      \
> +})
> +
> +--
> +-- Here we have the following scheme
> +--
> +--              election_replica3 (will be delayed)
> +--              /                \
> +--    election_replica1    election_replica2
> +
> +--
> +-- Initiate disk delay in a bit tricky way: the next write will
> +-- fall into forever sleep.
> +test_run:switch("election_replica3")
> +write_cnt = box.error.injection.get("ERRINJ_WAL_WRITE_COUNT")
> +--
> +-- Make election_replica2 been a leader and start writting data,
> +-- the PROMOTE request get queued on election_replica3 and not
> +-- yet processed, same time INSERT won't complete either
> +-- waiting for PROMOTE completion first. Note that we
> +-- enter election_replica3 as well just to be sure the PROMOTE
> +-- reached it.
> +test_run:switch("election_replica2")
> +box.ctl.promote()
> +test_run:switch("election_replica3")
> +test_run:wait_cond(function() return box.error.injection.get("ERRINJ_WAL_WRITE_COUNT") > write_cnt end)
> +box.error.injection.set("ERRINJ_WAL_DELAY", true)
> +test_run:switch("election_replica2")
> +_ = require('fiber').create(function() box.space.test:insert{2} end)
> +
> +--
> +-- The election_replica1 node has no clue that there is a new leader
> +-- and continue writing data with obsolete term. Since election_replica3
> +-- is delayed now the INSERT won't proceed yet but get queued.
> +test_run:switch("election_replica1")
> +_ = require('fiber').create(function() box.space.test:insert{3} end)
> +
> +--
> +-- Finally enable election_replica3 back. Make sure the data from new election_replica2
> +-- leader get writing while old leader's data ignored.
> +test_run:switch("election_replica3")
> +box.error.injection.set('ERRINJ_WAL_DELAY', false)
> +test_run:wait_cond(function() return box.space.test:get{2} ~= nil end)
> +box.space.test:select{}
> +
> +test_run:switch("default")
> +test_run:cmd('stop server election_replica1')
> +test_run:cmd('stop server election_replica2')
> +test_run:cmd('stop server election_replica3')
> +
> +test_run:cmd('delete server election_replica1')
> +test_run:cmd('delete server election_replica2')
> +test_run:cmd('delete server election_replica3')
> diff --git a/test/replication/suite.cfg b/test/replication/suite.cfg
> index 3eee0803c..ed09b2087 100644
> --- a/test/replication/suite.cfg
> +++ b/test/replication/suite.cfg
> @@ -59,6 +59,7 @@
>       "gh-6094-rs-uuid-mismatch.test.lua": {},
>       "gh-6127-election-join-new.test.lua": {},
>       "gh-6035-applier-filter.test.lua": {},
> +    "gh-6036-qsync-order.test.lua": {},
>       "election-candidate-promote.test.lua": {},
>       "*": {
>           "memtx": {"engine": "memtx"},
> diff --git a/test/replication/suite.ini b/test/replication/suite.ini
> index 77eb95f49..080e4fbf4 100644
> --- a/test/replication/suite.ini
> +++ b/test/replication/suite.ini
> @@ -3,7 +3,7 @@ core = tarantool
>   script =  master.lua
>   description = tarantool/box, replication
>   disabled = consistent.test.lua
> -release_disabled = catch.test.lua errinj.test.lua gc.test.lua gc_no_space.test.lua before_replace.test.lua qsync_advanced.test.lua qsync_errinj.test.lua quorum.test.lua recover_missing_xlog.test.lua sync.test.lua long_row_timeout.test.lua gh-4739-vclock-assert.test.lua gh-4730-applier-rollback.test.lua gh-5140-qsync-casc-rollback.test.lua gh-5144-qsync-dup-confirm.test.lua gh-5167-qsync-rollback-snap.test.lua gh-5430-qsync-promote-crash.test.lua gh-5430-cluster-mvcc.test.lua  gh-5506-election-on-off.test.lua gh-5536-wal-limit.test.lua hang_on_synchro_fail.test.lua anon_register_gap.test.lua gh-5213-qsync-applier-order.test.lua gh-5213-qsync-applier-order-3.test.lua gh-6027-applier-error-show.test.lua gh-6032-promote-wal-write.test.lua gh-6057-qsync-confirm-async-no-wal.test.lua gh-5447-downstream-lag.test.lua gh-4040-invalid-msgpack.test.lua
> +release_disabled = catch.test.lua errinj.test.lua gc.test.lua gc_no_space.test.lua before_replace.test.lua qsync_advanced.test.lua qsync_errinj.test.lua quorum.test.lua recover_missing_xlog.test.lua sync.test.lua long_row_timeout.test.lua gh-4739-vclock-assert.test.lua gh-4730-applier-rollback.test.lua gh-5140-qsync-casc-rollback.test.lua gh-5144-qsync-dup-confirm.test.lua gh-5167-qsync-rollback-snap.test.lua gh-5430-qsync-promote-crash.test.lua gh-5430-cluster-mvcc.test.lua  gh-5506-election-on-off.test.lua gh-5536-wal-limit.test.lua hang_on_synchro_fail.test.lua anon_register_gap.test.lua gh-5213-qsync-applier-order.test.lua gh-5213-qsync-applier-order-3.test.lua gh-6027-applier-error-show.test.lua gh-6032-promote-wal-write.test.lua gh-6057-qsync-confirm-async-no-wal.test.lua gh-5447-downstream-lag.test.lua gh-4040-invalid-msgpack.test.lua gh-6036-qsync-order.test.lua
>   config = suite.cfg
>   lua_libs = lua/fast_replica.lua lua/rlimit.lua
>   use_unix_sockets = True

-- 
Serge Petrenko