From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp50.i.mail.ru (smtp50.i.mail.ru [94.100.177.110]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 255BF4696C4 for ; Fri, 14 Feb 2020 00:53:15 +0300 (MSK) From: sergepetrenko Date: Fri, 14 Feb 2020 00:53:00 +0300 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v2 4/4] replication: do not promote local_vclock_at_subscribe unnecessarily List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: alexander.turenko@tarantool.org, v.shpilevoy@tarantool.org, kostja.osipov@gmail.com Cc: tarantool-patches@dev.tarantool.org From: Serge Petrenko When master processes a subscribe response, it responds with its vclock at the moment of receiving the request. However, the fiber processing the request may yield on coio_write_xrow, when sending the response to the replica. In the meantime, master may apply additional rows coming from the replica after it has issued SUBSCRIBE. Then in relay_subscribe master sets its local vclock_at_subscribe to a possibly updated value of replicaset.vclock So, set local_vclock_at_subscribe to a remembered value, rather than an updated one. Follow-up #4739 --- src/box/box.cc | 2 +- src/box/relay.cc | 13 +++++++++++-- src/box/relay.h | 3 ++- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/src/box/box.cc b/src/box/box.cc index 952d60ad1..7dec1ae6b 100644 --- a/src/box/box.cc +++ b/src/box/box.cc @@ -1871,7 +1871,7 @@ box_process_subscribe(struct ev_io *io, struct xrow_header *header) * indefinitely). */ relay_subscribe(replica, io->fd, header->sync, &replica_clock, - replica_version_id); + replica_version_id, &vclock); } void diff --git a/src/box/relay.cc b/src/box/relay.cc index b89632273..b69646446 100644 --- a/src/box/relay.cc +++ b/src/box/relay.cc @@ -676,7 +676,8 @@ relay_subscribe_f(va_list ap) /** Replication acceptor fiber handler. */ void relay_subscribe(struct replica *replica, int fd, uint64_t sync, - struct vclock *replica_clock, uint32_t replica_version_id) + struct vclock *replica_clock, uint32_t replica_version_id, + struct vclock *clock_at_subscribe) { assert(replica->anon || replica->id != REPLICA_ID_NIL); struct relay *relay = replica->relay; @@ -699,7 +700,15 @@ relay_subscribe(struct replica *replica, int fd, uint64_t sync, replica_on_relay_stop(replica); }); - vclock_copy(&relay->local_vclock_at_subscribe, &replicaset.vclock); + /* + * It's too late to remember replicaset.vclock as local + * vclock at subscribe. It might have incremented while we + * were writing a subscribe response, and we don't want to + * replicate back rows originating from the replica and + * having arrived later than replica has issued + * SUBSCRIBE. + */ + vclock_copy(&relay->local_vclock_at_subscribe, clock_at_subscribe); relay->r = recovery_new(cfg_gets("wal_dir"), false, replica_clock); vclock_copy(&relay->tx.vclock, replica_clock); diff --git a/src/box/relay.h b/src/box/relay.h index e1782d78f..54ebd6731 100644 --- a/src/box/relay.h +++ b/src/box/relay.h @@ -124,6 +124,7 @@ relay_final_join(int fd, uint64_t sync, struct vclock *start_vclock, */ void relay_subscribe(struct replica *replica, int fd, uint64_t sync, - struct vclock *replica_vclock, uint32_t replica_version_id); + struct vclock *replica_vclock, uint32_t replica_version_id, + struct vclock *clock_at_subscribe); #endif /* TARANTOOL_REPLICATION_RELAY_H_INCLUDED */ -- 2.20.1 (Apple Git-117)