…tributes. (go-sql-driver#1640)

Reduce the use of `errBadConnNoWrite` to improve maintainability.

ResetSession() and IsValid() checks if the buffer is busy. This reduces
the risk of busy buffer error during connection in use. In principle,
the risk of this is zero. So I removed errBadConnNoWrite when checking
the busy buffer.

After this change, only `writePacke()` returns errBadConnNoWrite.

Additionally, I do not send COM_QUIT when readPacket() encounter read error.
It caused "busy buffer" error too and hide real errors.

ErrBadConn needs special care to ensure it is safe to retry.
To improve maintenance, I don't want to use the error where I don't have to.

Additionally, update the old comment about Go's bug that had been fixed long time ago.

Since we dropped Go 1.20 support, we do not need double buffering.

This pull request stop double buffering and simplify buffer
implementation a lot.

Fix go-sql-driver#1435

Fix go-sql-driver#1646

Implemented the SQL compression protocol. This new feature is enabled by:

* Adding `compress=true` in DSN.
* `cfg.Apply(Compress(True))`

Co-authored-by: Brigitte Lamarche <[email protected]>
Co-authored-by: Julien Schmidt <[email protected]>
Co-authored-by: Jeffrey Charles <[email protected]>
Co-authored-by: Jeff Hodges <[email protected]>
Co-authored-by: Daniel Montoya <[email protected]>
Co-authored-by: Justin Li <[email protected]>
Co-authored-by: Dave Stubbs <[email protected]>
Co-authored-by: Linh Tran Tuan <[email protected]>
Co-authored-by: Robert R. Russell <[email protected]>
Co-authored-by: INADA Naoki <[email protected]>
Co-authored-by: Kieron Woodhouse <[email protected]>
Co-authored-by: Alexey Palazhchenko <[email protected]>
Co-authored-by: Reed Allman <[email protected]>
Co-authored-by: Joe Mann <[email protected]>

Recent Go does inlinine functions well.
Using `LittleEndian.Put*` would better for readability and minimize bound check.

Additionally, Go 1.19 introduced `LittleEndian.Append*`. It reduce more code.

Remove `stringToInt()` and use `strconv.Atoi` instead.

…river#1660)

auth_data contains last NUL.

Fix go-sql-driver#1666

Signed-off-by: Bes Dollma (bdollma) <[email protected]>

TestIssue1567 fails by max_connections error. This makes our CI unhappy.

https://github.com/go-sql-driver/mysql/actions/runs/12904961433/job/35984402310

Fix go-sql-driver#1664.

Fix go-sql-driver#1618

As of Go 1.21, toolchain versions must use the 1.N.P syntax.
https://go.dev/doc/toolchain#version