[Tarantool-patches] [PATCH v4 07/12] raft: filter rows based on known peer terms

[Serge Petrenko]

16.04.2021 19:25, Serge Petrenko пишет:
> Start writing the actual leader term together with the PROMOTE request
> and process terms in PROMOTE requests on receiver side.
>
> Make applier only apply synchronous transactions from the instance which
> has the greatest term as received in PROMOTE requests.
>
> Closes #5445
>

A couple of fixes on top:
Only apply  PROMOTE when it's for a greater term than already received.
If promote tries to confirm entries for instance id other than 
limbo->owner_id
rollback everything that's unconfirmed.

=========================================

diff --git a/src/box/txn_limbo.c b/src/box/txn_limbo.c
index 14e87cd3d..5f72c891f 100644
--- a/src/box/txn_limbo.c
+++ b/src/box/txn_limbo.c
@@ -643,14 +643,21 @@ complete:
  }

  void
-txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request 
*req)
+txn_limbo_process(struct txn_limbo *limbo, struct synchro_request *req)
  {
         uint64_t term = req->term;
         uint32_t origin = req->origin_id;
         if (txn_limbo_replica_term(limbo, origin) < term) {
                 vclock_follow(&limbo->promote_term_map, origin, term);
-               if (term > limbo->promote_greatest_term)
+               if (term > limbo->promote_greatest_term) {
                         limbo->promote_greatest_term = term;
+               } else if (req->type == IPROTO_PROMOTE) {
+                       /*
+                        * PROMOTE for an old term should be ignored.
+                        * For CONFIRM and ROLLBACK term is unused.
+                        */
+                       return;
+               }
         }
         if (req->replica_id == REPLICA_ID_NIL) {
                 /*
@@ -665,7 +672,15 @@ txn_limbo_process(struct txn_limbo *limbo, const 
struct synchro_request *req)
                  * data from an old leader, who has just started and 
written
                  * confirm right on synchronous transaction recovery.
                  */
-               return;
+               if (req->type != IPROTO_PROMOTE) {
+                       return;
+               } else {
+                       /*
+                        * A PROMOTE request for a foreign master - roll 
back
+                        * everyting in limbo.
+                        */
+                       req->lsn = 0;
+               }
         }
         switch (req->type) {
         case IPROTO_CONFIRM:
diff --git a/src/box/txn_limbo.h b/src/box/txn_limbo.h
index e409ac657..a06fabccc 100644
--- a/src/box/txn_limbo.h
+++ b/src/box/txn_limbo.h
@@ -302,7 +302,7 @@ txn_limbo_wait_complete(struct txn_limbo *limbo, 
struct txn_limbo_entry *entry);

  /** Execute a synchronous replication request. */
  void
-txn_limbo_process(struct txn_limbo *limbo, const struct synchro_request 
*req);
+txn_limbo_process(struct txn_limbo *limbo, struct synchro_request *req);

  /**
   * Waiting for confirmation of all "sync" transactions

===========================================

-- 
Serge Petrenko