The check for rotate event conditions was wrong which led to false error
message about unexpected binlog file and position combinations.
The position of the last event was reset every time a file was opened which
caused problems when the binlog file was rotated. The slave's current positions
were compared to the position where the last event started and because the
last_event_pos variable didn't point to the rotate event of the previous binlog,
the slave's never got the rotate event.
The router->last_written is used to store the position where the last event was
written. The replication header is also stored in a separate structure in
the router which is used later when the last packet of a multi-packet event
arrives.
The unsafe slave position is no longer an error and will be treated the
same way if no events are available i.e. the slaves are no longer disconnected.
The log messages now have more information such as the current committed
transaction event being processed and the number of events sent by the
current thread.
Slave request for a log_pos behind binlog file size may result in a
disconnection or replication error:
if binlog file is latest one slave get disconnected otherwise an error
message is returned and replication stops
In blr_open_binlog the refcnt increase of file which is already
open is protected by router->fileslock. In blr_close_binlog the
decrease of the refcnt was protected by file->lock.
This lead to a situation where it was possible that a file was
closed and the file instance freed, even though it just had been
taken into use by somebody else.
This is now fixed by solely using the router->fileslock for protecting
the increase and decrease of the refcnt.
The log manager variables lm_enabled_log_files_bitmask, log_ses_count
and tls_log_info that earlier were declared separately in every
c-file are now declared in the log_manager.h header.
Changed log messages for blr_read_binlog, added slave send error feaure.
When blr_read_binlog detects an error an error message with 1236 code
is sent to the slave and it will stop the replication to binlogrouter
