Tarantool development patches archive
 help / color / mirror / Atom feed
From: Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: tml <tarantool-patches@dev.tarantool.org>
Cc: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Subject: [Tarantool-patches] [PATCH 2/3] box/info: report replication.X.downstream.lag value
Date: Thu, 21 Jan 2021 20:17:51 +0300	[thread overview]
Message-ID: <20210121171753.186891-3-gorcunov@gmail.com> (raw)
In-Reply-To: <20210121171753.186891-1-gorcunov@gmail.com>

This is basically a reflection of replication.X.upstream.lag value.
The upstream lag can be considered as transaction RTT in direction
from master to replica, in turn downstream lag is the reverse and
represents RTT from replica to master.

An example of output is (on replica node)

 | 2:
 |   id: 2
 |   uuid: 8bb22366-cd21-492e-98df-693884be11bd
 |   lsn: 0
 |   downstream:
 |     status: follow
 |     idle: 0.55381065199617
 |     vclock: {1: 119}
 |     lag: 0.00019168853759766

In case if there some old replicas which are not sending
timestamp in vclock encoding we simply don't show lag
field for backward compatibility sake.

Closes #5447

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/box/lua/info.c |  9 ++++++++-
 src/box/relay.cc   | 17 +++++++++++++++++
 src/box/relay.h    |  8 ++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index c4c9fa0a0..b36c2e6f4 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -132,17 +132,24 @@ lbox_pushrelay(lua_State *L, struct relay *relay)
 	lua_pushstring(L, "status");
 
 	switch(relay_get_state(relay)) {
-	case RELAY_FOLLOW:
+	case RELAY_FOLLOW: {
+		double lag = relay_lag(relay);
 		lua_pushstring(L, "follow");
 		lua_settable(L, -3);
 		lua_pushstring(L, "vclock");
 		lbox_pushvclock(L, relay_vclock(relay));
 		lua_settable(L, -3);
+		if (lag != 0) {
+			lua_pushstring(L, "lag");
+			lua_pushnumber(L, relay_lag(relay));
+			lua_settable(L, -3);
+		}
 		lua_pushstring(L, "idle");
 		lua_pushnumber(L, ev_monotonic_now(loop()) -
 			       relay_last_row_time(relay));
 		lua_settable(L, -3);
 		break;
+	}
 	case RELAY_STOPPED:
 	{
 		lua_pushstring(L, "stopped");
diff --git a/src/box/relay.cc b/src/box/relay.cc
index df04f8198..9265a26b3 100644
--- a/src/box/relay.cc
+++ b/src/box/relay.cc
@@ -138,6 +138,8 @@ struct relay {
 	struct stailq pending_gc;
 	/** Time when last row was sent to peer. */
 	double last_row_time;
+	/** Number of seconds this master is prior the remote replica. */
+	double lag;
 	/** Relay sync state. */
 	enum relay_state state;
 
@@ -179,6 +181,12 @@ relay_last_row_time(const struct relay *relay)
 	return relay->last_row_time;
 }
 
+double
+relay_lag(const struct relay *relay)
+{
+	return relay->lag;
+}
+
 static void
 relay_send(struct relay *relay, struct xrow_header *packet);
 static void
@@ -197,6 +205,7 @@ relay_new(struct replica *replica)
 	}
 	relay->replica = replica;
 	relay->last_row_time = ev_monotonic_now(loop());
+	relay->lag = 0;
 	fiber_cond_create(&relay->reader_cond);
 	diag_create(&relay->diag);
 	stailq_create(&relay->pending_gc);
@@ -219,6 +228,7 @@ relay_start(struct relay *relay, int fd, uint64_t sync,
 	relay->sync = sync;
 	relay->state = RELAY_FOLLOW;
 	relay->last_row_time = ev_monotonic_now(loop());
+	relay->lag = 0;
 }
 
 void
@@ -558,6 +568,13 @@ relay_reader_f(va_list ap)
 			/* vclock is followed while decoding, zeroing it. */
 			vclock_create(&relay->recv_vclock);
 			xrow_decode_vclock_xc(&xrow, &relay->recv_vclock);
+			/*
+			 * Old versions may send not a timestamp but
+			 * zeroified memory field. We can use +0 as
+			 * as sign that there is nothing encoded.
+			 */
+			if (xrow.tm != 0)
+				relay->lag = ev_now(loop()) - xrow.tm;
 			fiber_cond_signal(&relay->reader_cond);
 		}
 	} catch (Exception *e) {
diff --git a/src/box/relay.h b/src/box/relay.h
index b32e2ea2a..ec9d16925 100644
--- a/src/box/relay.h
+++ b/src/box/relay.h
@@ -93,6 +93,14 @@ relay_vclock(const struct relay *relay);
 double
 relay_last_row_time(const struct relay *relay);
 
+/**
+ * Returns relay's lag
+ * @param relay relay
+ * @returns relay's lag
+ */
+double
+relay_lag(const struct relay *relay);
+
 /**
  * Send a Raft update request to the relay channel. It is not
  * guaranteed that it will be delivered. The connection may break.
-- 
2.29.2


  parent reply	other threads:[~2021-01-21 17:19 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21 17:17 [Tarantool-patches] [PATCH 0/3] box/info: report replication.X.downstream.lag Cyrill Gorcunov via Tarantool-patches
2021-01-21 17:17 ` [Tarantool-patches] [PATCH 1/3] xrow: encode timestamp into vclock message Cyrill Gorcunov via Tarantool-patches
2021-01-31 17:43   ` Vladislav Shpilevoy via Tarantool-patches
2021-01-21 17:17 ` Cyrill Gorcunov via Tarantool-patches [this message]
2021-01-27 11:56   ` [Tarantool-patches] [PATCH 2/3] box/info: report replication.X.downstream.lag value Serge Petrenko via Tarantool-patches
2021-01-27 12:12     ` Cyrill Gorcunov via Tarantool-patches
2021-01-27 14:04       ` Serge Petrenko via Tarantool-patches
2021-01-27 14:38         ` Cyrill Gorcunov via Tarantool-patches
2021-01-27 14:44           ` Serge Petrenko via Tarantool-patches
2021-01-31 17:45   ` Vladislav Shpilevoy via Tarantool-patches
2021-01-21 17:17 ` [Tarantool-patches] [PATCH 3/3] test: replication/status -- fetch downstream lag field Cyrill Gorcunov via Tarantool-patches
2021-01-31 17:46   ` Vladislav Shpilevoy via Tarantool-patches
2021-01-21 17:17 ` Cyrill Gorcunov via Tarantool-patches
2021-01-21 17:23   ` Cyrill Gorcunov via Tarantool-patches

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210121171753.186891-3-gorcunov@gmail.com \
    --to=tarantool-patches@dev.tarantool.org \
    --cc=gorcunov@gmail.com \
    --cc=v.shpilevoy@tarantool.org \
    --subject='Re: [Tarantool-patches] [PATCH 2/3] box/info: report replication.X.downstream.lag value' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox