ref: d52fd3b32109f12e529a7f5e380c5ee8f06aefcf
dir: /lib/thread/condvar+openbsd:6.2.myr/
use std use sys use "atomic" use "common" use "futex" use "mutex" pkg thread = type cond = struct _mtx : mutex# _seq : ftxtag ;; const mkcond : (mtx : mutex# -> cond) const condwait : (cond : cond# -> void) const condsignal : (cond : cond# -> void) const condbroadcast : (cond : cond# -> void) ;; const mkcond = {mtx -> [._mtx = mtx, ._seq = 0] } const condwait = {cond var mtx = cond._mtx var seq = xget(&cond._seq) mtxunlock(mtx) ftxwait(&cond._seq, seq, -1) /* In the event of a broadcast, we need to atomically set the mutex to contended. This allows us to pass responsibility for waking up the potential other waiters from the requeue operation on to the unlocker of the mutex. */ mtxcontended(mtx) } const condsignal = {cond : cond# xadd(&cond._seq, 1) ftxwake(&cond._seq) } const condbroadcast = {cond : cond# xadd(&cond._seq, 1) sys.futex((&cond._seq : uint32#), sys.Futexrequeue, 1, (0x7fffffff : sys.timespec#), (&cond._mtx._state : uint32#)) }