// main entry point
int VP8EncAnalyze(VP8Encoder* const enc) {
int ok = 1;
const int do_segments =
enc->config_->emulate_jpeg_size || // We need the complexity evaluation.
(enc->segment_hdr_.num_segments_ > 1) ||
(enc->method_ == 0); // for method 0, we need preds_[] to be filled.
if (do_segments) {
const int last_row = enc->mb_h_;
// We give a little more than a half work to the main thread.
const int split_row = (9 * last_row + 15) >> 4;
const int total_mb = last_row * enc->mb_w_;
#ifdef WEBP_USE_THREAD
const int kMinSplitRow = 2; // minimal rows needed for mt to be worth it
const int do_mt = (enc->thread_level_ > 0) && (split_row >= kMinSplitRow);
#else
const int do_mt = 0;
#endif
const WebPWorkerInterface* const worker_interface =
WebPGetWorkerInterface();
SegmentJob main_job;
if (do_mt) {
SegmentJob side_job;
// Note the use of '&' instead of '&&' because we must call the functions
// no matter what.
InitSegmentJob(enc, &main_job, 0, split_row);
InitSegmentJob(enc, &side_job, split_row, last_row);
// we don't need to call Reset() on main_job.worker, since we're calling
// WebPWorkerExecute() on it
ok &= worker_interface->Reset(&side_job.worker);
// launch the two jobs in parallel
if (ok) {
worker_interface->Launch(&side_job.worker);
worker_interface->Execute(&main_job.worker);
ok &= worker_interface->Sync(&side_job.worker);
ok &= worker_interface->Sync(&main_job.worker);
}
worker_interface->End(&side_job.worker);
if (ok) MergeJobs(&side_job, &main_job); // merge results together
} else {
// Even for single-thread case, we use the generic Worker tools.
InitSegmentJob(enc, &main_job, 0, last_row);
worker_interface->Execute(&main_job.worker);
ok &= worker_interface->Sync(&main_job.worker);
}
worker_interface->End(&main_job.worker);
if (ok) {
enc->alpha_ = main_job.alpha / total_mb;
enc->uv_alpha_ = main_job.uv_alpha / total_mb;
AssignSegments(enc, main_job.alphas);
}
} else { // Use only one default segment.
// initialize the job struct with some TODOs
static void InitSegmentJob(VP8Encoder* const enc, SegmentJob* const job,
int start_row, int end_row) {
WebPGetWorkerInterface()->Init(&job->worker);
job->worker.data1 = job;
job->worker.data2 = &job->it;
job->worker.hook = (WebPWorkerHook)DoSegmentsJob;
VP8IteratorInit(enc, &job->it);
VP8IteratorSetRow(&job->it, start_row);
VP8IteratorSetCountDown(&job->it, (end_row - start_row) * enc->mb_w_);
memset(job->alphas, 0, sizeof(job->alphas));
job->alpha = 0;
job->uv_alpha = 0;
// only one of both jobs can record the progress, since we don't
// expect the user's hook to be multi-thread safe
job->delta_progress = (start_row == 0) ? 20 : 0;
}
static THREADFN ThreadLoop(void* ptr) {
WebPWorker* const worker = (WebPWorker*)ptr;
WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_;
int done = 0;
while (!done) {
pthread_mutex_lock(&impl->mutex_);
while (worker->status_ == OK) { // wait in idling mode
pthread_cond_wait(&impl->condition_, &impl->mutex_);
}
if (worker->status_ == WORK) {
WebPGetWorkerInterface()->Execute(worker);
worker->status_ = OK;
} else if (worker->status_ == NOT_OK) { // finish the worker
done = 1;
}
// signal to the main thread that we're done (for Sync())
pthread_cond_signal(&impl->condition_);
pthread_mutex_unlock(&impl->mutex_);
}
return THREAD_RETURN(NULL); // Thread is finished
}
