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#include <assert.h>
#include <pthread.h>
#include <stdlib.h>
#include "til.h"
#include "til_fb.h"
#include "til_threads.h"
#include "til_util.h"
typedef struct til_thread_t {
til_threads_t *threads;
pthread_t pthread;
unsigned id;
} til_thread_t;
typedef struct til_threads_t {
unsigned n_threads;
pthread_mutex_t idle_mutex;
pthread_cond_t idle_cond;
unsigned n_idle;
pthread_mutex_t frame_mutex;
pthread_cond_t frame_cond;
void (*render_fragment_func)(til_module_context_t *context, unsigned ticks, unsigned cpu, til_fb_fragment_t *fragment);
void *context;
til_fb_fragment_t *fragment;
til_frame_plan_t frame_plan;
unsigned ticks;
unsigned next_fragment;
unsigned frame_num;
til_thread_t threads[];
} til_threads_t;
/* render fragments using the supplied render function */
static void * thread_func(void *_thread)
{
til_thread_t *thread = _thread;
til_threads_t *threads = thread->threads;
unsigned prev_frame_num = 0;
pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
for (;;) {
/* wait for a new frame */
pthread_mutex_lock(&threads->frame_mutex);
pthread_cleanup_push((void (*)(void *))pthread_mutex_unlock, &threads->frame_mutex);
while (threads->frame_num == prev_frame_num)
pthread_cond_wait(&threads->frame_cond, &threads->frame_mutex);
prev_frame_num = threads->frame_num;
pthread_cleanup_pop(1);
if (threads->frame_plan.cpu_affinity) { /* render only fragments for my thread->id */
unsigned frag_num = thread->id;
/* This is less performant, since we'll spin until our fragnum comes up,
* rather than just rendering whatever's next whenever we're available.
*
* Some modules allocate persistent per-cpu state affecting the contents of fragments,
* which may require a consistent mapping of CPU to fragnum across frames.
*/
for (;;) {
til_fb_fragment_t fragment;
while (!__sync_bool_compare_and_swap(&threads->next_fragment, frag_num, frag_num + 1));
if (!threads->frame_plan.fragmenter(threads->context, threads->fragment, frag_num, &fragment))
break;
threads->render_fragment_func(threads->context, threads->ticks, thread->id, &fragment);
frag_num += threads->n_threads;
}
} else { /* render *any* available fragment */
for (;;) {
unsigned frag_num;
til_fb_fragment_t fragment;
frag_num = __sync_fetch_and_add(&threads->next_fragment, 1);
if (!threads->frame_plan.fragmenter(threads->context, threads->fragment, frag_num, &fragment))
break;
threads->render_fragment_func(threads->context, threads->ticks, thread->id, &fragment);
}
}
/* report as idle */
pthread_mutex_lock(&threads->idle_mutex);
pthread_cleanup_push((void (*)(void *))pthread_mutex_unlock, &threads->idle_mutex);
threads->n_idle++;
if (threads->n_idle == threads->n_threads) /* Frame finished! Notify potential waiter. */
pthread_cond_signal(&threads->idle_cond);
pthread_cleanup_pop(1);
}
return NULL;
}
/* wait for all threads to be idle */
void til_threads_wait_idle(til_threads_t *threads)
{
pthread_mutex_lock(&threads->idle_mutex);
pthread_cleanup_push((void (*)(void *))pthread_mutex_unlock, &threads->idle_mutex);
while (threads->n_idle < threads->n_threads)
pthread_cond_wait(&threads->idle_cond, &threads->idle_mutex);
pthread_cleanup_pop(1);
}
/* submit a frame's fragments to the threads */
void til_threads_frame_submit(til_threads_t *threads, til_fb_fragment_t *fragment, til_frame_plan_t *frame_plan, void (*render_fragment_func)(til_module_context_t *context, unsigned ticks, unsigned cpu, til_fb_fragment_t *fragment), til_module_context_t *context, unsigned ticks)
{
til_threads_wait_idle(threads); /* XXX: likely non-blocking; already happens pre page flip */
pthread_mutex_lock(&threads->frame_mutex);
pthread_cleanup_push((void (*)(void *))pthread_mutex_unlock, &threads->frame_mutex);
threads->fragment = fragment;
threads->frame_plan = *frame_plan;
threads->render_fragment_func = render_fragment_func;
threads->context = context;
threads->ticks = ticks;
threads->frame_num++;
threads->n_idle = threads->next_fragment = 0;
pthread_cond_broadcast(&threads->frame_cond);
pthread_cleanup_pop(1);
}
/* create threads instance, a thread per cpu is created */
til_threads_t * til_threads_create(void)
{
unsigned num = til_get_ncpus();
til_threads_t *threads;
threads = calloc(1, sizeof(til_threads_t) + sizeof(til_thread_t) * num);
if (!threads)
return NULL;
threads->n_idle = threads->n_threads = num;
pthread_mutex_init(&threads->idle_mutex, NULL);
pthread_cond_init(&threads->idle_cond, NULL);
pthread_mutex_init(&threads->frame_mutex, NULL);
pthread_cond_init(&threads->frame_cond, NULL);
for (unsigned i = 0; i < num; i++) {
til_thread_t *thread = &threads->threads[i];
thread->threads = threads;
thread->id = i;
pthread_create(&thread->pthread, NULL, thread_func, thread);
}
return threads;
}
/* destroy a threads instance */
void til_threads_destroy(til_threads_t *threads)
{
for (unsigned i = 0; i < threads->n_threads; i++)
pthread_cancel(threads->threads[i].pthread);
for (unsigned i = 0; i < threads->n_threads; i++)
pthread_join(threads->threads[i].pthread, NULL);
pthread_mutex_destroy(&threads->idle_mutex);
pthread_cond_destroy(&threads->idle_cond);
pthread_mutex_destroy(&threads->frame_mutex);
pthread_cond_destroy(&threads->frame_cond);
free(threads);
}
/* return the number of threads */
unsigned til_threads_num_threads(til_threads_t *threads)
{
return threads->n_threads;
}
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