1// Copyright 2013 Google Inc. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the COPYING file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8// -----------------------------------------------------------------------------
9//
10// Multi-threaded worker
11//
12// Original source:
13//  http://git.chromium.org/webm/libwebp.git
14//  100644 blob 264210ba2807e4da47eb5d18c04cf869d89b9784  src/utils/thread.c
15
16#include <assert.h>
17#include <string.h>   // for memset()
18#include "./vp9_thread.h"
19#include "vpx_mem/vpx_mem.h"
20
21#if CONFIG_MULTITHREAD
22
23struct VP9WorkerImpl {
24  pthread_mutex_t mutex_;
25  pthread_cond_t  condition_;
26  pthread_t       thread_;
27};
28
29//------------------------------------------------------------------------------
30
31static void execute(VP9Worker *const worker);  // Forward declaration.
32
33static THREADFN thread_loop(void *ptr) {
34  VP9Worker *const worker = (VP9Worker*)ptr;
35  int done = 0;
36  while (!done) {
37    pthread_mutex_lock(&worker->impl_->mutex_);
38    while (worker->status_ == OK) {   // wait in idling mode
39      pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
40    }
41    if (worker->status_ == WORK) {
42      execute(worker);
43      worker->status_ = OK;
44    } else if (worker->status_ == NOT_OK) {   // finish the worker
45      done = 1;
46    }
47    // signal to the main thread that we're done (for sync())
48    pthread_cond_signal(&worker->impl_->condition_);
49    pthread_mutex_unlock(&worker->impl_->mutex_);
50  }
51  return THREAD_RETURN(NULL);    // Thread is finished
52}
53
54// main thread state control
55static void change_state(VP9Worker *const worker,
56                         VP9WorkerStatus new_status) {
57  // No-op when attempting to change state on a thread that didn't come up.
58  // Checking status_ without acquiring the lock first would result in a data
59  // race.
60  if (worker->impl_ == NULL) return;
61
62  pthread_mutex_lock(&worker->impl_->mutex_);
63  if (worker->status_ >= OK) {
64    // wait for the worker to finish
65    while (worker->status_ != OK) {
66      pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
67    }
68    // assign new status and release the working thread if needed
69    if (new_status != OK) {
70      worker->status_ = new_status;
71      pthread_cond_signal(&worker->impl_->condition_);
72    }
73  }
74  pthread_mutex_unlock(&worker->impl_->mutex_);
75}
76
77#endif  // CONFIG_MULTITHREAD
78
79//------------------------------------------------------------------------------
80
81static void init(VP9Worker *const worker) {
82  memset(worker, 0, sizeof(*worker));
83  worker->status_ = NOT_OK;
84}
85
86static int sync(VP9Worker *const worker) {
87#if CONFIG_MULTITHREAD
88  change_state(worker, OK);
89#endif
90  assert(worker->status_ <= OK);
91  return !worker->had_error;
92}
93
94static int reset(VP9Worker *const worker) {
95  int ok = 1;
96  worker->had_error = 0;
97  if (worker->status_ < OK) {
98#if CONFIG_MULTITHREAD
99    worker->impl_ = (VP9WorkerImpl*)vpx_calloc(1, sizeof(*worker->impl_));
100    if (worker->impl_ == NULL) {
101      return 0;
102    }
103    if (pthread_mutex_init(&worker->impl_->mutex_, NULL)) {
104      goto Error;
105    }
106    if (pthread_cond_init(&worker->impl_->condition_, NULL)) {
107      pthread_mutex_destroy(&worker->impl_->mutex_);
108      goto Error;
109    }
110    pthread_mutex_lock(&worker->impl_->mutex_);
111    ok = !pthread_create(&worker->impl_->thread_, NULL, thread_loop, worker);
112    if (ok) worker->status_ = OK;
113    pthread_mutex_unlock(&worker->impl_->mutex_);
114    if (!ok) {
115      pthread_mutex_destroy(&worker->impl_->mutex_);
116      pthread_cond_destroy(&worker->impl_->condition_);
117 Error:
118      vpx_free(worker->impl_);
119      worker->impl_ = NULL;
120      return 0;
121    }
122#else
123    worker->status_ = OK;
124#endif
125  } else if (worker->status_ > OK) {
126    ok = sync(worker);
127  }
128  assert(!ok || (worker->status_ == OK));
129  return ok;
130}
131
132static void execute(VP9Worker *const worker) {
133  if (worker->hook != NULL) {
134    worker->had_error |= !worker->hook(worker->data1, worker->data2);
135  }
136}
137
138static void launch(VP9Worker *const worker) {
139#if CONFIG_MULTITHREAD
140  change_state(worker, WORK);
141#else
142  execute(worker);
143#endif
144}
145
146static void end(VP9Worker *const worker) {
147#if CONFIG_MULTITHREAD
148  if (worker->impl_ != NULL) {
149    change_state(worker, NOT_OK);
150    pthread_join(worker->impl_->thread_, NULL);
151    pthread_mutex_destroy(&worker->impl_->mutex_);
152    pthread_cond_destroy(&worker->impl_->condition_);
153    vpx_free(worker->impl_);
154    worker->impl_ = NULL;
155  }
156#else
157  worker->status_ = NOT_OK;
158  assert(worker->impl_ == NULL);
159#endif
160  assert(worker->status_ == NOT_OK);
161}
162
163//------------------------------------------------------------------------------
164
165static VP9WorkerInterface g_worker_interface = {
166  init, reset, sync, launch, execute, end
167};
168
169int vp9_set_worker_interface(const VP9WorkerInterface* const winterface) {
170  if (winterface == NULL ||
171      winterface->init == NULL || winterface->reset == NULL ||
172      winterface->sync == NULL || winterface->launch == NULL ||
173      winterface->execute == NULL || winterface->end == NULL) {
174    return 0;
175  }
176  g_worker_interface = *winterface;
177  return 1;
178}
179
180const VP9WorkerInterface *vp9_get_worker_interface(void) {
181  return &g_worker_interface;
182}
183
184//------------------------------------------------------------------------------
185