/**
* Main function for the worker thread.
*/
static void
worker_thread_main(void *thread_)
{
workerthread_t *thread = thread_;
threadpool_t *pool = thread->in_pool;
workqueue_entry_t *work;
workqueue_reply_t result;
tor_mutex_acquire(&pool->lock);
while (1) {
/* lock must be held at this point. */
while (worker_thread_has_work(thread)) {
/* lock must be held at this point. */
if (thread->in_pool->generation != thread->generation) {
void *arg = thread->in_pool->update_args[thread->index];
thread->in_pool->update_args[thread->index] = NULL;
workqueue_reply_t (*update_fn)(void*,void*) =
thread->in_pool->update_fn;
thread->generation = thread->in_pool->generation;
tor_mutex_release(&pool->lock);
workqueue_reply_t r = update_fn(thread->state, arg);
if (r != WQ_RPL_REPLY) {
return;
}
tor_mutex_acquire(&pool->lock);
continue;
}
work = TOR_TAILQ_FIRST(&pool->work);
TOR_TAILQ_REMOVE(&pool->work, work, next_work);
work->pending = 0;
tor_mutex_release(&pool->lock);
/* We run the work function without holding the thread lock. This
* is the main thread's first opportunity to give us more work. */
result = work->fn(thread->state, work->arg);
/* Queue the reply for the main thread. */
queue_reply(thread->reply_queue, work);
/* We may need to exit the thread. */
if (result != WQ_RPL_REPLY) {
return;
}
tor_mutex_acquire(&pool->lock);
}
/* At this point the lock is held, and there is no work in this thread's
* queue. */
/* TODO: support an idle-function */
/* Okay. Now, wait till somebody has work for us. */
if (tor_cond_wait(&pool->condition, &pool->lock, NULL) < 0) {
log_warn(LD_GENERAL, "Fail tor_cond_wait.");
}
}
}
static bool _ui_call_update(void) {
ui_page_update_fn_t update_fn = pgm_read_word(ui_func_update + ui.page);
return update_fn();
}
/**
* Works with any update function.
*/
static void run_main_loop( void (*update_fn)( LoopData*, bool ), LoopData* data, real_t ups )
{
assert( data->running && ups > 0 );
// maximum number of frame skips before we force a render
static const int MAX_SKIPS = 3;
// the maximum possible lag time, lag is capped here
static const int MAX_LAG_TIME = 100;
// frequency at which to print frame rate info
static const int FRAME_RATE_PRINT_TIME = 600;
int period = static_cast< int >( 1000.0 / ups ); // frame period in milliseconds
// how far we are behind the target framerate
int lag_time = 0;
// the number of updates since the last render
int num_skips = 0;
// time since last frame counter start
int frame_rate_counter_start = SDL_GetTicks();
// frame rate counter
int frame_rate_counter = 0;
int total_frame_time = 0;
while ( *data->running ) {
int start_time = SDL_GetTicks();
// update, only if we are not too far behind, or if we've skipped too many frames
if ( lag_time < period || num_skips >= MAX_SKIPS ) {
// update
update_fn( data, false );
num_skips = 0;
frame_rate_counter++;
} else {
update_fn( data, true );
num_skips++;
}
if ( frame_rate_counter == FRAME_RATE_PRINT_TIME ) {
int curr_time = SDL_GetTicks();
printf( "frame rate: %f, avg frame time: %f\n",
FRAME_RATE_PRINT_TIME * 1000 / real_t(curr_time - frame_rate_counter_start),
real_t(total_frame_time) / FRAME_RATE_PRINT_TIME
);
frame_rate_counter_start = curr_time;
frame_rate_counter = 0;
total_frame_time = 0;
}
// compute sleep time until end of period, may be negative
int end_time = SDL_GetTicks();
int time_diff = end_time - start_time;
int sleep_time = period - time_diff - lag_time;
total_frame_time += time_diff;
// always yield at least once to keep system responsive
SDL_Delay( 1 );
if ( sleep_time > 0 ) {
// sleep until end of period
while ( int(SDL_GetTicks()) < end_time + sleep_time ) {
SDL_Delay( sleep_time - 1 );
}
// if we oversleep, add to lag. note this must be nonnegative
// because of the while loop above
lag_time = (int)(SDL_GetTicks()) - (end_time + sleep_time);
} else {
// otherwise mark how much we're falling behind
// sleep time is negative here, so it's like adding the time we went over
lag_time = -sleep_time;
}
// cap the lag time to avoid lots of skips
if ( lag_time > MAX_LAG_TIME ) {
lag_time = MAX_LAG_TIME;
}
}
}