commit 1bb267bd8587473c567ca76426689e33ff4c9b89
author Alexey Serbin <alexey@apache.org> Wed Oct 16 15:18:49 2019 -0700
committer Alexey Serbin <aserbin@cloudera.com> Thu Oct 17 00:57:03 2019 +0000
tree 6f47f3cab01f96a71fa9becb50ea90b80bae5226
parent d6a6b54b175032c7d13d231ef6d156ef9d0e3ab0

[clock] add exponential backoff in HybridClock::Init()

This patch introduces exponential back-off when polling the
synchronisation status of the underlying time service (i.e. calling
TimeService::WalltimeWithError()) during HybridClock::Init().  Now,
the polling interval starts with 1 millisecond and exponentially grows
up to 1 second.

Prior to this patch, the polling interval was one second, and in case
if time source synchronized faster than in one second,
HybridClock::Init() would incur extra latency (e.g., in case of tests
running with the built-in NTP client synchronized against MiniChronyd).

I verified that with the new approach ExternalMiniCluster-based tests
run faster:

  before
    [       OK ] AllTypesItest/9.TestTimestampPadding (6794 ms)

  after
    [       OK ] AllTypesItest/9.TestTimestampPadding (2730 ms)

Change-Id: I75924f1fdcf6a32684cda29bbfa959b00172b50e
Reviewed-on: http://gerrit.cloudera.org:8080/14472
Reviewed-by: Adar Dembo <adar@cloudera.com>
Tested-by: Kudu Jenkins