(couchdb) 03/26: Handle replicator instance start time during upgrades better

[va...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

vatamane pushed a commit to branch 3.3.x
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit 61477848783daa7c02e5e7f0055aa3b058e750ca
Author: Nick Vatamaniuc <va...@gmail.com>
AuthorDate: Wed May 24 23:34:45 2023 -0400

    Handle replicator instance start time during upgrades better
    
    During cluster upgrades from 3.2 to 3.3 when instance start time switched from
    being always  `0` to an actual timestamp, replication jobs will crash when
    endpoints are upgraded. Replication jobs were started when endpoint
    emitted a `0` and then it becomes a non-`0` value which will crash the next checkpoint attempt.
    
    After the crash jobs will restart and continue fine were they left off without
    rewinding. However they will make a logging mess while they crash. All four
    workers will exit the `{checkpoint_commit_failure,...}` error. This commit make
    it the checkpoint ignore mismatches if one of the instance start times is 0.
---
 src/couch_replicator/src/couch_replicator_scheduler_job.erl | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/couch_replicator/src/couch_replicator_scheduler_job.erl b/src/couch_replicator/src/couch_replicator_scheduler_job.erl
index e16412e4a..38533c7f2 100644
--- a/src/couch_replicator/src/couch_replicator_scheduler_job.erl
+++ b/src/couch_replicator/src/couch_replicator_scheduler_job.erl
@@ -799,7 +799,15 @@ do_checkpoint(State) ->
         {target_error, Reason} ->
             {checkpoint_commit_failure,
                 <<"Failure on target commit: ", (to_binary(Reason))/binary>>};
-        {SrcInstanceStartTime, TgtInstanceStartTime} ->
+        {<<S/binary>>, <<T/binary>>} when
+            % Handle upgrades from 3.2 to 3.3 better by expecting 0 to be
+            % returned if endpoints are upgraded while the replication job is running.
+            % TODO: Remove the `0` special case in a future release (4.x or 5.x)
+            (S =:= SrcInstanceStartTime orelse S =:= <<"0">> orelse
+                SrcInstanceStartTime =:= <<"0">>) andalso
+                (T =:= TgtInstanceStartTime orelse T =:= <<"0">> orelse
+                    TgtInstanceStartTime =:= <<"0">>)
+        ->
             couch_log:notice(
                 "recording a checkpoint for `~s` -> `~s` at source update_seq ~p",
                 [SourceName, TargetName, NewSeq]