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.
On some systems with 10,000+ binlogs, show binary logs could block
log rotation for more than 10 seconds.
This patch fixes this by first caching all binary log names and
releases all mutexes while calculating the sizes of the binary logs.
Other things:
- Ensure that reinit_io_cache() sets end_of_file when moving to read_cache.
This ensures that external changes of the underlying file is known to
the cache.
- get_binlog_list() is made more efficent and show_binlogs() is changed
to call get_binlog_list()
Reviewed by Andrei Elkin
