Prepared statements are sent to the master instead of all servers.
The planned functionality to store the types of the prepared statements was not implemented
and all executions of prepared statements are sent to the master. Because of this the preparations
should be all sent to the master server instead of sending them to all servers.
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
Before these changes when max_sescmd_history was used the session
was closed when the limit was exceeded. With this change, when the
limit is exceeded the recovery of slaves and the session command history
are both disabled. This will allow the sessions to continue while still
keeping the old functionality of limited salve replacement.
The disable_sescmd_history and disable_slave_recovery parameters were combined
so that disabling the session command history will also disable slave recovery.
This way no harm can be done with disable_sescmd_history.
routeQuery calls route_single_stmt, which requires the GWBUF to be
contiguous. Earlier it was made contiguous (if needed) in
route_single_stmt. However, since the process of making a GWBUF
contiguous causes the original buffer to be freed, this would lead
to a double free later in routeQuery that frees the passed buffer.
This is prevented now by making the buffer contiguous before calling
route_single_stmt.
In the end of execute_sescmd_in_backend the buffer was consumed
in case the protocol function failed. Or actually if it returned
something else but 1.
In the case of mysql_backend, the buffer is always freed when
authorizing and either consumed or placed on the dcb writequeue
when the data is written.
That is, it is never ok to consume the buffer in this function.
The end-result is likely to be an abort.
