VReplication: Add stream DDL processing stats

[mattlord]

Description

This adds stats to track the DDL processing actions taken in currently running VReplication streams based on the workflow's configured value of --on-ddl.

Manual test

git checkout main && make build

pushd examples/local

./101_initial_cluster.sh; mysql < ../common/insert_commerce_data.sql; ./201_customer_tablets.sh ; ./202_move_tables.sh

primaryuid=$(vtctldclient GetTablets --keyspace customer --tablet-type primary --shard "0" | awk '{print $1}' | cut -d- -f2 | bc)

mysql commerce -e "alter table customer modify email varchar(128)"
curl -s localhost:15200/debug/vars | grep -i VReplicationDDLActions

vtctldclient workflow --keyspace customer update --workflow commerce2customer --on-ddl=exec

mysql commerce -e "alter table customer modify email varchar(100)"
curl -s localhost:15${primaryuid}/debug/vars | grep -i VReplicationDDLActions

./401_teardown.sh
popd

Final output:

❯ curl -s localhost:15${primaryuid}/debug/vars | grep -i VReplicationDDLActions
"VReplicationDDLActions": {"commerce2customer.1.EXEC": 1, "commerce2customer.1.IGNORE": 1},

Related Issue(s)

• Fixes: Feature Request: Add vttablet metric for vplayer DDL actions #15758

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation: Document new stat added in https://github.com/vitessio/vitess/pull/15769 website#1731

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 54.16667% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 68.45%. Comparing base (14b36d0) to head (ee0bd6f).
Report is 12 commits behind head on main.

Files	Patch %	Lines
go/vt/vttablet/tabletmanager/vreplication/stats.go	41.66%	7 Missing ⚠️
go/vt/vttablet/tabletmanager/vdiff/controller.go	0.00%	2 Missing ⚠️
go/vt/vttablet/tabletmanager/vdiff/table_differ.go	0.00%	1 Missing ⚠️
...vt/vttablet/tabletmanager/vdiff/workflow_differ.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15769      +/-   ##
==========================================
+ Coverage   68.39%   68.45%   +0.06%     
==========================================
  Files        1556     1558       +2     
  Lines      195422   195836     +414     
==========================================
+ Hits       133666   134069     +403     
- Misses      61756    61767      +11     

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[deepthi]

Any idea whether these tags are case-sensitive? I mean when filtering using PromQL. In this case, there is only 1 tag, but for multi-label counters, you might want to filter that way.

[mattlord]

Yes, I believe they are. For example this returns values in grafana with prometheus:

vttablet_errors{error_code="ABORTED"}

But these do not:

vttablet_errors{error_code="aborted"}

vttablet_errors{error_CODE="ABORTED"}