Wrap errors happening during PRS in a new vterrors code

[frouioui]

Description

This Pull Request adds a new vterrors code (VT15001) that will wrap the common errors found in the situation described by #17668.

The errors listed in #17668 now look like this:

target: ks.0.primary: vttablet: rpc error: code = FailedPrecondition desc = VT15001: session invalidated: close/reopen connection if applicable: wrong tablet type: PRIMARY, want: REPLICA or [] (errno 1105) (sqlstate HY000) during query: insert into vt_insert_test(id, msg) values (162, 'test 162')

target: ks.0.primary: VT15001: session invalidated: close/reopen connection if applicable: vttablet: rpc error: code = Unavailable desc = connection error: desc = "transport: Error while dialing: dial tcp 127.0.0.1:7108: connect: connection refused" (errno 1105) (sqlstate HY000) during query: insert into vt_insert_test(id, msg) values (650, 'test 650')

target: ks.0.primary: VT15001: session invalidated: close/reopen connection if applicable: tablet: cell:"zone1" uid:101 is either down or nonexistent (errno 1105) (sqlstate HY000) during query: insert into vt_insert_test(id, msg) values (1029, 'test 1029')

Related Issue(s)

• Closes Enable applications to detect stalled connections during PRS #17668

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 48.48485% with 17 lines in your changes missing coverage. Please review.

Project coverage is 67.74%. Comparing base (770dcf0) to head (a41541a).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vterrors/vterrorsgen/main.go	0.00%	10 Missing ⚠️
go/vt/vttablet/grpctabletconn/conn.go	50.00%	4 Missing ⚠️
go/vt/vtgate/executorcontext/vcursor_impl.go	0.00%	2 Missing ⚠️
go/vt/discovery/healthcheck.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17669      +/-   ##
==========================================
- Coverage   67.75%   67.74%   -0.02%     
==========================================
  Files        1587     1587              
  Lines      255778   255808      +30     
==========================================
- Hits       173309   173287      -22     
- Misses      82469    82521      +52     

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[deepthi]

"session invalidated" may be misleading

• if you are in a transaction, that needs to be closed, and a new transaction opened.
• if you are not in a transaction, a retry is probably what you need to do.
  @harshit-gangal wdyt?

[harshit-gangal]

It is the transaction which no longer exists. They can continue to use the same connection.
"rollback", followed by a retry is fine.
outside of transaction, retry is enough as Deepthi pointed.
All 3 error message should have different error code as they happen at different point in time of PRS/ERS

[deepthi]

Notes from further offline discussion:

• In order to close the transaction, you have to issue a COMMIT or a ROLLBACK from the client. Because the vtgate-level transaction is effectively pinned to the primary tablets of participating shards, these will also produce errors
• An idea to mitigate these is for us to close the transaction at the vtgate level so that the ROLLBACK becomes a no-op instead of resulting in an error.

We need to spend some more time exploring these options.