int fiber_sleep(uint32_t seconds, uint32_t useconds)
{
if(!fiber_loop) {
fiber_do_real_sleep(seconds, useconds);
return FIBER_SUCCESS;
}
//this code should really use ev_timer_init(), but ev_timer_init has compile warnings.
ev_timer timer_event = {};
ev_set_cb(&timer_event, &timer_trigger);
const double sleep_time = seconds + useconds * 0.000001;
timer_event.at = sleep_time;
timer_event.repeat = 0;
fiber_spinlock_lock(&fiber_loop_spinlock);
fiber_manager_t* const manager = fiber_manager_get();
fiber_t* const this_fiber = manager->current_fiber;
timer_event.data = this_fiber;
ev_timer_start(fiber_loop, &timer_event);
this_fiber->state = FIBER_STATE_WAITING;
manager->spinlock_to_unlock = &fiber_loop_spinlock;
fiber_manager_yield(manager);
return FIBER_SUCCESS;
}
int fiber_rwlock_wrlock(fiber_rwlock_t* rwlock)
{
assert(rwlock);
fiber_rwlock_state_t current_state;
while(1) {
const uint64_t snapshot = rwlock->state.blob;
current_state.blob = snapshot;
if(current_state.blob != 0) {
current_state.state.waiting_writers += 1;
if(__sync_bool_compare_and_swap(&rwlock->state.blob, snapshot, current_state.blob)) {
//currently locked or a reader is waiting - be friendly and wait
fiber_manager_wait_in_mpsc_queue(fiber_manager_get(), &rwlock->write_waiters);
break;
}
} else {
current_state.state.write_locked = 1;
if(__sync_bool_compare_and_swap(&rwlock->state.blob, snapshot, current_state.blob)) {
//currently write locked
break;
}
}
}
return FIBER_SUCCESS;
}
void fiber_manager_yield(fiber_manager_t* manager)
{
assert(fiber_manager_state == FIBER_MANAGER_STATE_STARTED);
assert(manager);
if(wsd_work_stealing_deque_size(manager->schedule_from) == 0) {
wsd_work_stealing_deque_t* const temp = manager->schedule_from;
manager->schedule_from = manager->store_to;
manager->store_to = temp;
}
do {
manager->yield_count += 1;
//occasionally steal some work from threads with more load
if((manager->yield_count & 1023) == 0) {
fiber_load_balance(manager);
}
if(wsd_work_stealing_deque_size(manager->schedule_from) > 0) {
fiber_t* const new_fiber = (fiber_t*)wsd_work_stealing_deque_pop_bottom(manager->schedule_from);
if(new_fiber != WSD_EMPTY && new_fiber != WSD_ABORT) {
fiber_t* const old_fiber = manager->current_fiber;
if(old_fiber->state == FIBER_STATE_RUNNING) {
old_fiber->state = FIBER_STATE_READY;
manager->to_schedule = old_fiber;/* must schedule it *after* fiber_swap_context, else another thread can start executing an invalid context */
}
manager->current_fiber = new_fiber;
new_fiber->state = FIBER_STATE_RUNNING;
write_barrier();
fiber_swap_context(&old_fiber->context, &new_fiber->context);
fiber_manager_do_maintenance();
}
}
} while((manager = fiber_manager_get()) && FIBER_STATE_WAITING == manager->current_fiber->state && fiber_load_balance(manager));
}
int fiber_wait_for_event(int fd, uint32_t events)
{
ev_io fd_event = {};
int poll_events = 0;
if(events & FIBER_POLL_IN) {
poll_events |= EV_READ;
}
if(events & FIBER_POLL_OUT) {
poll_events |= EV_WRITE;
}
//this code should really use ev_io_init(), but ev_io_init has compile warnings.
ev_set_cb(&fd_event, &fd_ready);
ev_io_set(&fd_event, fd, poll_events);
fiber_spinlock_lock(&fiber_loop_spinlock);
fiber_manager_t* const manager = fiber_manager_get();
manager->event_wait_count += 1;
fiber_t* const this_fiber = manager->current_fiber;
fd_event.data = this_fiber;
ev_io_start(fiber_loop, &fd_event);
this_fiber->state = FIBER_STATE_WAITING;
manager->spinlock_to_unlock = &fiber_loop_spinlock;
fiber_manager_yield(manager);
return FIBER_SUCCESS;
}
static void timer_trigger(struct ev_loop* loop, ev_timer* watcher, int revents)
{
ev_timer_stop(loop, watcher);
fiber_manager_t* const manager = fiber_manager_get();
fiber_t* const the_fiber = watcher->data;
the_fiber->state = FIBER_STATE_READY;
fiber_manager_schedule(manager, the_fiber);
++num_events_triggered;
}
int fiber_rwlock_rdunlock(fiber_rwlock_t* rwlock)
{
assert(rwlock);
fiber_rwlock_state_t current_state;
while(1) {
const uint64_t snapshot = rwlock->state.blob;
current_state.blob = snapshot;
assert(current_state.state.reader_count > 0);
assert(!current_state.state.write_locked);
current_state.state.reader_count -= 1;
if(!current_state.state.reader_count) {
//if we're the last reader then we are responsible to wake up waiters
if(current_state.state.waiting_writers) {
//no fiber will acquire the lock while waiting_writers != 0
current_state.state.write_locked = 1;
current_state.state.waiting_writers -= 1;
if(__sync_bool_compare_and_swap(&rwlock->state.blob, snapshot, current_state.blob)) {
fiber_manager_wake_from_mpsc_queue(fiber_manager_get(), &rwlock->write_waiters, 1);
break;
}
continue;
}
if(current_state.state.waiting_readers) {
//no fiber will acquire the lock while waiting_readers != 0
current_state.state.reader_count = current_state.state.waiting_readers;
current_state.state.waiting_readers = 0;
if(__sync_bool_compare_and_swap(&rwlock->state.blob, snapshot, current_state.blob)) {
fiber_manager_wake_from_mpsc_queue(fiber_manager_get(), &rwlock->read_waiters, current_state.state.reader_count);
break;
}
continue;
}
}
if(__sync_bool_compare_and_swap(&rwlock->state.blob, snapshot, current_state.blob)) {
break;
}
}
return FIBER_SUCCESS;
}
int fiber_manager_set_total_kernel_threads(size_t num_threads)
{
if(fiber_manager_get_state() != FIBER_MANAGER_STATE_NONE) {
errno = EINVAL;
return FIBER_ERROR;
}
fiber_mananger_thread_queues = calloc(2 * num_threads, sizeof(*fiber_mananger_thread_queues));
assert(fiber_mananger_thread_queues);
fiber_manager_threads = calloc(num_threads, sizeof(*fiber_manager_threads));
assert(fiber_manager_threads);
fiber_manager_num_threads = num_threads;
fiber_managers = calloc(num_threads, sizeof(*fiber_managers));
assert(fiber_managers);
fiber_manager_t* const main_manager = fiber_manager_get();
fiber_mananger_thread_queues[0] = main_manager->queue_one;
fiber_mananger_thread_queues[1] = main_manager->queue_two;
fiber_managers[0] = main_manager;
fiber_manager_state = FIBER_MANAGER_STATE_STARTED;
size_t i;
for(i = 1; i < num_threads; ++i) {
fiber_manager_t* const new_manager = fiber_manager_create();
assert(new_manager);
fiber_mananger_thread_queues[2 * i] = new_manager->queue_one;
fiber_mananger_thread_queues[2 * i + 1] = new_manager->queue_two;
new_manager->id = i;
fiber_managers[i] = new_manager;
}
pthread_create_function pthread_create_func = (pthread_create_function)fiber_load_symbol("pthread_create");
assert(pthread_create_func);
for(i = 1; i < num_threads; ++i) {
if(pthread_create_func(&fiber_manager_threads[i], NULL, &fiber_manager_thread_func, fiber_managers[i])) {
assert(0 && "failed to create kernel thread");
fiber_manager_state = FIBER_MANAGER_STATE_ERROR;
abort();
return FIBER_ERROR;
}
}
return FIBER_SUCCESS;
}
void fiber_manager_do_maintenance()
{
fiber_manager_t* const manager = fiber_manager_get();
if(manager->to_schedule) {
assert(manager->to_schedule->state == FIBER_STATE_READY);
wsd_work_stealing_deque_push_bottom(manager->store_to, manager->to_schedule);
manager->to_schedule = NULL;
}
if(manager->mpsc_to_push.fifo) {
mpsc_fifo_push(manager->mpsc_to_push.fifo, manager->mpsc_to_push.node);
memset(&manager->mpsc_to_push, 0, sizeof(manager->mpsc_to_push));
}
if(manager->mutex_to_unlock) {
fiber_mutex_t* const to_unlock = manager->mutex_to_unlock;
manager->mutex_to_unlock = NULL;
fiber_mutex_unlock_internal(to_unlock);
}
}
static void* fiber_manager_thread_func(void* param)
{
/* set the thread local, then start running fibers */
#ifdef USE_COMPILER_THREAD_LOCAL
fiber_the_manager = (fiber_manager_t*)param;
#else
if(!pthread_setspecific_func) {
pthread_setspecific_func = (pthread_setspecific_function)fiber_load_symbol("pthread_setspecific");
}
const int ret = pthread_setspecific_func(fiber_manager_key, param);
if(ret) {
assert(0 && "pthread_setspecific() failed!");
abort();
}
#endif
while(1) {
/* always call fiber_manager_get(), because this *thread* fiber will actually switch threads */
fiber_manager_yield(fiber_manager_get());
}
return NULL;
}
int fiber_poll_events()
{
if(!fiber_loop) {
return FIBER_EVENT_NOTINIT;
}
if(!fiber_spinlock_trylock(&fiber_loop_spinlock)) {
return FIBER_EVENT_TRYAGAIN;
}
if(!fiber_loop) {
fiber_spinlock_unlock(&fiber_loop_spinlock);
return FIBER_EVENT_NOTINIT;
}
fiber_manager_get()->poll_count += 1;
num_events_triggered = 0;
ev_run(fiber_loop, EVRUN_NOWAIT);
const int local_copy = num_events_triggered;
fiber_spinlock_unlock(&fiber_loop_spinlock);
return local_copy;
}
size_t fiber_poll_events_blocking(uint32_t seconds, uint32_t useconds)
{
if(!fiber_loop) {
fiber_do_real_sleep(seconds, useconds);
return 0;
}
load_load_barrier();//needed to ensure we read fiber_loop first - we need a valid active_thread count,
//so init writes active_threads then fiber_loop, we read here in the reverse order
//only allow the final thread to perform a blocking poll - this prevents the
//thread from locking out other threads trying to register for events
const int local_count = __sync_sub_and_fetch(&active_threads, 1);
assert(local_count >= 0);
if(local_count > 0) {
fiber_do_real_sleep(seconds, useconds);
__sync_add_and_fetch(&active_threads, 1);
return 0;
}
fiber_spinlock_lock(&fiber_loop_spinlock);
if(!fiber_loop) {
__sync_add_and_fetch(&active_threads, 1);
fiber_spinlock_unlock(&fiber_loop_spinlock);
return 0;
}
num_events_triggered = 0;
fiber_manager_get()->poll_count += 1;
ev_run(fiber_loop, EVRUN_ONCE);
const int local_copy = num_events_triggered;
fiber_spinlock_unlock(&fiber_loop_spinlock);
__sync_add_and_fetch(&active_threads, 1);
return local_copy;
}
