VReplication: recover from closed connection

[shlomi-noach]

Description

When vreplicator fails, check if its connection is closed, and if so, reopen it. This addresses #17248 where the binlog connection auto closes itself in response to a bad commit (MySQL error 1180), but will just as well apply to any situation where the connection closes. It's imperative to open the connection so as to be able to set state/message.

Related Issue(s)

Fixes #17248

Checklist

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Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 56.25000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 67.39%. Comparing base (216fd70) to head (4c9eb03).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...vttablet/tabletmanager/vreplication/vreplicator.go	70.00%	3 Missing ⚠️
go/vt/binlog/binlogplayer/dbclient.go	0.00%	2 Missing ⚠️
go/vt/binlog/binlogplayer/fake_dbclient.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #17249   +/-   ##
=======================================
  Coverage   67.39%   67.39%           
=======================================
  Files        1570     1570           
  Lines      252917   252930   +13     
=======================================
+ Hits       170446   170470   +24     
+ Misses      82471    82460   -11     

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[frouioui]

Shouldn't we check if the context was not canceled before trying to reconnect?

[shlomi-noach]

Good observation -- but not in this case. We absolutely must try and issue vr.setMessage(err.Error()) so as to persist the error and the state of the stream.

[frouioui]

Left a comment, otherwise LGTM