On Windows systems, occurrences of ERROR_SHARING_VIOLATION due to
conflicting share modes between processes accessing the same file can
result in CreateFile failures.
mysys' my_open() already incorporates a workaround by implementing
wait/retry logic on Windows.
But this does not help if files are opened using shell redirection like
mysqltest traditionally did it, i.e via
--echo exec "some text" > output_file
In such cases, it is cmd.exe, that opens the output_file, and it
won't do any sharing-violation retries.
This commit addresses the issue by introducing a new built-in command,
'write_line', in mysqltest. This new command serves as a brief alternative
to 'write_file', with a single line output, that also resolves variables
like "exec" would.
Internally, this command will use my_open(), and therefore retry-on-error
logic.
Hopefully this will eliminate the very sporadic "can't open file because
it is used by another process" error on CI.
MDEV-20578 Got error 126 when executing undo undo_key_delete
upon Aria crash recovery
The crash happens in this scenario:
- Table with unique keys and non unique keys
- Batch insert (LOAD DATA or INSERT ... SELECT) with REPLACE
- Some insert succeeds followed by duplicate key error
In the above scenario the table gets corrupted.
The bug was that we don't generate any undo entry for the
failed insert as the whole insert can be ignored by undo.
The code did however not take into account that when bulk
insert is used, we would write cached keys to the file on
failure and undo would wrongly ignore these.
Fixed by moving the writing of the cache keys after we write
the aborted-insert event to the log.
