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#include <assert.h>
#include <pthread.h>
#include <stdlib.h>
#include "fb.h"
#include "rototiller.h"
#include "threads.h"
#include "util.h"
typedef struct 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)(void *context, fb_fragment_t *fragment);
void *context;
fb_fragment_t *fragment;
rototiller_fragmenter_t fragmenter;
unsigned next_fragment;
unsigned frame_num;
pthread_t threads[];
} threads_t;
/* render fragments using the supplied render function */
static void * thread_func(void *_threads)
{
threads_t *threads = _threads;
unsigned prev_frame_num = 0;
for (;;) {
/* wait for a new frame */
pthread_mutex_lock(&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_mutex_unlock(&threads->frame_mutex);
/* render fragments */
for (;;) {
unsigned frag_num;
fb_fragment_t fragment;
frag_num = __sync_fetch_and_add(&threads->next_fragment, 1);
if (!threads->fragmenter(threads->context, threads->fragment, frag_num, &fragment))
break;
threads->render_fragment_func(threads->context, &fragment);
}
/* report as idle */
pthread_mutex_lock(&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_mutex_unlock(&threads->idle_mutex);
}
return NULL;
}
/* wait for all threads to be idle */
void threads_wait_idle(threads_t *threads)
{
pthread_mutex_lock(&threads->idle_mutex);
while (threads->n_idle < threads->n_threads)
pthread_cond_wait(&threads->idle_cond, &threads->idle_mutex);
pthread_mutex_unlock(&threads->idle_mutex);
}
/* submit a frame's fragments to the threads */
void threads_frame_submit(threads_t *threads, fb_fragment_t *fragment, rototiller_fragmenter_t fragmenter, void (*render_fragment_func)(void *context, fb_fragment_t *fragment), void *context)
{
threads_wait_idle(threads); /* XXX: likely non-blocking; already happens pre page flip */
pthread_mutex_lock(&threads->frame_mutex);
threads->fragment = fragment;
threads->fragmenter = fragmenter;
threads->render_fragment_func = render_fragment_func;
threads->context = context;
threads->frame_num++;
threads->n_idle = threads->next_fragment = 0;
pthread_cond_broadcast(&threads->frame_cond);
pthread_mutex_unlock(&threads->frame_mutex);
}
/* create threads instance, a thread per cpu is created */
threads_t * threads_create(void)
{
unsigned i, num = get_ncpus();
threads_t *threads;
threads = calloc(1, sizeof(threads_t) + sizeof(pthread_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 (i = 0; i < num; i++)
pthread_create(&threads->threads[i], NULL, thread_func, threads);
return threads;
}
/* destroy a threads instance */
void threads_destroy(threads_t *threads)
{
unsigned i;
for (i = 0; i < threads->n_threads; i++)
pthread_cancel(threads->threads[i]);
for (i = 0; i < threads->n_threads; i++)
pthread_join(threads->threads[i], 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 threads_num_threads(threads_t *threads)
{
return threads->n_threads;
}
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