Part of MDEV-5336 Implement LOCK FOR BACKUP
Originally both table metadata lock and global read lock protection
were acquired before getting TABLE from table cache. This will be
reordered in a future commit with MDL_BACKUP_XXX locks so that we
first take table metadata lock, then get TABLE from table cache, then
acquire analogue of global read lock.
This patch both simplifies FLUSH TABLES code, makes FLUSH TABLES to
lock less and also enables FLUSH TABLES code to be used with backup
locks.
The usage of FLUSH TABLES changes slightly:
- FLUSH TABLES without any arguments will now only close not used tables
and tables locked by the FLUSH TABLES connection. All not used table
shares will be closed.
Tables locked by the FLUSH TABLES connection will be reopened and
re-locked after all others has stoped using the table (as before).
If there was no locked tables, then FLUSH TABLES is instant and will
not cause any waits.
FLUSH TABLES will not wait for any in use table.
- FLUSH TABLES with a table list, will ensure that the tables are closed
before statement returns. The code is now only using MDL locks and not
table share versions, which simplices the code greatly. One visible
change is that the server will wait for the end of the transaction that
are using the tables. Before FLUSH TABLES only waited for the statements
to end.
Signed-off-by: Monty <monty@mariadb.org>
The cause of this was several different bugs:
- When using binary logging with binlog_row_image=FULL
the all bits in read_set was set, which caused a
different (wrong) pattern for marking vcol_set.
- TABLE::mark_virtual_columns_for_write() didn't in all
cases mark vcol_set with the vcol_field.
- TABLE::update_virtual_fields() has to update all
vcol fields on REPLACE if binary logging with FULL
is used.
- VCOL_UPDATE_INDEXED should update all vcol fields part
of an index that was not updated by VCOL_UPDATE_FOR_READ
- max_row_length() calculated length of NULL and not
used fields. This didn't cause any crash, but used
more memory than needed.
