[Tarantool-patches] [PATCH 04/11] vinyl: fix 0 division in case of canceled dump

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

It can happen, that vinyl index dump is scheduled, but the index
is dropped before the dump starts. In this case the dump task is
finished with 0 dump time. The time then is used in a log message
to obtain dump rate as byte count / dump time. Since dump time is
0, this is undefined behaviour. Moreover, it was not even a dump,
so nothing to log here.

Also dump time is used to update throttling parameters in
vy_regulator. Here if the dump took 0 time, there was no a dump,
so it is just ignored.

Part of #4609
---
 src/box/vy_regulator.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/box/vy_regulator.c b/src/box/vy_regulator.c
index a6604c9f3..8ec7e25d6 100644
--- a/src/box/vy_regulator.c
+++ b/src/box/vy_regulator.c
@@ -291,9 +291,11 @@ vy_regulator_dump_complete(struct vy_regulator *regulator,
 	vy_quota_set_rate_limit(regulator->quota, VY_QUOTA_RESOURCE_MEMORY,
 				regulator->dump_bandwidth);
 
-	say_info("dumped %zu bytes in %.1f s, rate %.1f MB/s",
-		 mem_dumped, dump_duration,
-		 mem_dumped / dump_duration / 1024 / 1024);
+	if (dump_duration > 0) {
+		say_info("dumped %zu bytes in %.1f s, rate %.1f MB/s",
+			 mem_dumped, dump_duration,
+			 mem_dumped / dump_duration / 1024 / 1024);
+	}
 }
 
 void
@@ -420,7 +422,7 @@ vy_regulator_update_rate_limit(struct vy_regulator *regulator,
 	double compaction_time = stat->compaction_time - last->compaction_time;
 	*last = *stat;
 
-	if (dump_input < (ssize_t)VY_DUMP_SIZE_ACCT_MIN)
+	if (dump_input < (ssize_t)VY_DUMP_SIZE_ACCT_MIN || compaction_time == 0)
 		return;
 
 	recent->dump_count += dump_count;
-- 
2.21.1 (Apple Git-122.3)