int jl_safepoint_start_gc(void)
{
#ifdef JULIA_ENABLE_THREADING
// The thread should have set this already
assert(jl_get_ptls_states()->gc_state == JL_GC_STATE_WAITING);
jl_mutex_lock_nogc(&safepoint_lock);
// In case multiple threads enter the GC at the same time, only allow
// one of them to actually run the collection. We can't just let the
// master thread do the GC since it might be running unmanaged code
// and can take arbitrarily long time before hitting a safe point.
if (jl_atomic_compare_exchange(&jl_gc_running, 0, 1) != 0) {
jl_mutex_unlock_nogc(&safepoint_lock);
jl_safepoint_wait_gc();
return 0;
}
jl_safepoint_enable(1);
jl_safepoint_enable(2);
jl_mutex_unlock_nogc(&safepoint_lock);
return 1;
#else
// For single thread, GC should not call itself (in finalizers) before
// setting `jl_gc_running` to false so this should never happen.
assert(!jl_gc_running);
jl_gc_running = 1;
return 1;
#endif
}
/* multiq_insert()
*/
static inline int multiq_insert(jl_task_t *task, int16_t priority)
{
jl_ptls_t ptls = jl_get_ptls_states();
uint64_t rn;
task->prio = priority;
do {
rn = cong(heap_p, cong_unbias, &ptls->rngseed);
} while (!jl_mutex_trylock_nogc(&heaps[rn].lock));
if (heaps[rn].ntasks >= tasks_per_heap) {
jl_mutex_unlock_nogc(&heaps[rn].lock);
jl_error("multiq insertion failed, increase #tasks per heap");
return -1;
}
heaps[rn].tasks[heaps[rn].ntasks++] = task;
sift_up(&heaps[rn], heaps[rn].ntasks-1);
jl_mutex_unlock_nogc(&heaps[rn].lock);
int16_t prio = jl_atomic_load(&heaps[rn].prio);
if (task->prio < prio)
jl_atomic_compare_exchange(&heaps[rn].prio, prio, task->prio);
return 0;
}
