mirrors/ecl
1
Fork 0
mirror of https://gitlab.com/embeddable-common-lisp/ecl.git synced 2026-01-24 05:21:20 -08:00
Code Issues Projects Releases Packages Wiki Activity

threading: fix barrier implementation

Browse source 
The logic im mp_barrier_wait is wrong. decrement_counter returns
    the value of the counter __before__ it is decremented. Before
    the fix, the counter decremented until it reached 0 and then the
    next arriving thread would get stuck in decrement_counter. Also,
    interrupts were not reenabled in all cases.
This commit is contained in:
Marius Gerbershagen 2018-01-26 20:56:16 +01:00
parent 6449d67337
commit e458caf652
1 changed files with 4 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

7
src/c/threads/barrier.d
View file

@ -143,21 +143,22 @@ mp_barrier_wait(cl_object barrier)
}
ecl_disable_interrupts_env(the_env);
counter = decrement_counter(&barrier->barrier.arrivers_count);
if (counter == 0) {
if (counter == 1) {
print_lock("barrier %p saturated", barrier, barrier);
/* There are (count-1) threads in the queue and we
* are the last one. We thus unblock all threads and
* proceed. */
mp_barrier_unblock(1, barrier);
ecl_enable_interrupts_env(the_env);
mp_barrier_unblock(1, barrier);
output = @':unblocked';
} else if (counter > 0) {
} else if (counter > 1) {
print_lock("barrier %p waiting", barrier, barrier);
ecl_enable_interrupts_env(the_env);
ecl_wait_on(the_env, barrier_wait_condition, barrier);
output = ECL_T;
} else {
print_lock("barrier %p pass-through", barrier, barrier);
ecl_enable_interrupts_env(the_env);
/* Barrier disabled */
output = ECL_NIL;
}