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Portablity fixes & simple optimizations

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This commit is contained in:
monty@mysql.com
2004-08-24 18:00:45 +03:00
parent 3808e4a5cf
commit c44d4debfa
6 changed files with 31 additions and 17 deletions
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19
sql/sql_class.cc
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@ -155,11 +155,13 @@ bool foreign_key_prefix(Key *a, Key *b)
** Thread specific functions
****************************************************************************/
THD::THD():user_time(0), current_arena(this), is_fatal_error(0),
last_insert_id_used(0),
insert_id_used(0), rand_used(0), time_zone_used(0),
in_lock_tables(0), global_read_lock(0), bootstrap(0)
THD::THD()
:user_time(0), global_read_lock(0), is_fatal_error(0),
last_insert_id_used(0),
insert_id_used(0), rand_used(0), time_zone_used(0),
in_lock_tables(0), bootstrap(0)
{
current_arena= this;
host= user= priv_user= db= ip=0;
host_or_ip= "connecting host";
locked=some_tables_deleted=no_errors=password= 0;
@ -439,10 +441,13 @@ void THD::awake(bool prepare_to_die)
it is the true value but maybe current_mutex is not yet non-zero (we're
in the middle of enter_cond() and there is a "memory order
inversion"). So we test the mutex too to not lock 0.
Note that there is a small chance we fail to kill. If victim has locked
current_mutex, and hasn't entered enter_cond(), then we don't know it's
going to wait on cond. Then victim goes into its cond "forever" (until
we issue a second KILL). True we have set its thd->killed but it may not
current_mutex, but hasn't yet entered enter_cond() (which means that
current_cond and current_mutex are 0), then the victim will not get
a signal and it may wait "forever" on the cond (until
we issue a second KILL or the status it's waiting for happens).
It's true that we have set its thd->killed but it may not
see it immediately and so may have time to reach the cond_wait().
*/
if (mysys_var->current_cond && mysys_var->current_mutex)