Add ResetConnectionAsync

[bgrainger]

From #178 (comment)

For advanced scenarios, it could be useful to support the following API:

class MySqlConnection
{
    public ValueTask ResetConnectionAsync(CancellationToken token = default);
}

This would send a COM_RESET_CONNECTION packet to reset the open connection. By allowing the user to manually reset the connection only when needed (e.g., a temporary table has been created or user variables were set), it would be practical to add ConnectionReset=false to the connection string and avoid its overhead when retrieving a pooled connection (see #178).

Since this is an advanced API, is a synchronous version of this method needed? (Probably not.)

[athoscouto]

Thanks for doing this @bgrainger!
Will this feature be available on 0.x or only on 1.x?

[bgrainger]

This is only in the 1.0.0 release.

While it's current tagged as -beta in NuGet, this is mostly due to the (breaking) namespace change, rather than any prerelease code quality issues.

[athoscouto]

Just tested it and couldn't make it work.

Migrated to 1.0.0-beta.4 and added ConnectionReset=False to the connection string.
Before calling MySqlConnection.DisposeAsync() I awaited MySqlConnection.ResetConnectionAsync().

I've got an "Unknown command" exception. This was at the top of the stack trace:

   at MySqlConnector.Core.ServerSession.ReceiveReplyAsyncAwaited(ValueTask`1 task) in /_/src/MySqlConnector/Core/ServerSession.cs:line 806
   at MySqlConnector.MySqlConnection.ResetConnectionAsync(CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 436

[bgrainger]

What server and version are you using? For MySQL Server, you have to be running 5.7.3 or later. For MariaDB, it needs to be 10.2.4 or later. Other MySQL-compatible backends may not support it at all.