Making Reshard work smoothly with Atomic Transactions

[GuptaManan100]

Description

This PR makes the changes required to make Reshard work with Atomic transactions. Before these changes, Resharding won't wait for prepared atomic transactions to go through, and we could be in a situation where a prepared transaction is unable to commit on the source shards because we have stopped query service on it. At the same time, that prepared transaction won't exist on the target shards, leading to us being unable to commit a prepared transaction altogether.

This PR fixes this situation by changing the RefreshState RPC that Resharding is using. Now, when vttablet is executing the RefreshState RPC, if it decides that query service needs to be stopped, it first turns off the two pc engine from accepting new prepared transactions and then waits for the current prepared transactions until they're resolved. This ensures Resharding doesn't proceed until all the prepared transactions have concluded.

This PR adds fuzzer and stress tests to verify that the changes work as intended. The changes in this PR are different from the ones proposed in the RFC #16245 (comment), because we found that this solution is more elegant and easier to implement than the one proposed there.

Related Issue(s)

• Fixes RFC: Atomic Distributed Transactions #16245

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 was added or is not required

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 67.74194% with 20 lines in your changes missing coverage. Please review.

Project coverage is 69.43%. Comparing base (766bc64) to head (85c1c34).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vttablet/tabletserver/tabletserver.go	20.00%	12 Missing ⚠️
go/vt/vttablet/tabletmanager/rpc_replication.go	0.00%	3 Missing ⚠️
go/vt/vttablet/tabletmanager/tm_init.go	57.14%	3 Missing ⚠️
go/vt/vttablet/tabletmanager/tm_state.go	86.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16844      +/-   ##
==========================================
- Coverage   69.43%   69.43%   -0.01%     
==========================================
  Files        1571     1571              
  Lines      203086   203239     +153     
==========================================
+ Hits       141013   141113     +100     
- Misses      62073    62126      +53     

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[rohit-nayak-ps]

Elegant solution!

[mattlord]

LGTM. I only had some minor nits, requests, suggestions. Nice work on this, @GuptaManan100 !

[GuptaManan100]

Thank you for the reviews everyone! 🚀 I've addressed the review comments and am merging the PR now.