1 // Copyright 2011 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 // Author: Skal (pascal.massimino@gmail.com)
13
14 #include <assert.h>
15 #include <string.h> // for memset()
16 #include "./thread.h"
17 #include "./utils.h"
18
19 #ifdef WEBP_USE_THREAD
20
21 #if defined(_WIN32)
22
23 #include <windows.h>
24 typedef HANDLE pthread_t;
25 typedef CRITICAL_SECTION pthread_mutex_t;
26
27 #if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater
28 #define USE_WINDOWS_CONDITION_VARIABLE
29 typedef CONDITION_VARIABLE pthread_cond_t;
30 #else
31 typedef struct {
32 HANDLE waiting_sem_;
33 HANDLE received_sem_;
34 HANDLE signal_event_;
35 } pthread_cond_t;
36 #endif // _WIN32_WINNT >= 0x600
37
38 #ifndef WINAPI_FAMILY_PARTITION
39 #define WINAPI_PARTITION_DESKTOP 1
40 #define WINAPI_FAMILY_PARTITION(x) x
41 #endif
42
43 #if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
44 #define USE_CREATE_THREAD
45 #endif
46
47 #else // !_WIN32
48
49 #include <pthread.h>
50
51 #endif // _WIN32
52
53 struct WebPWorkerImpl {
54 pthread_mutex_t mutex_;
55 pthread_cond_t condition_;
56 pthread_t thread_;
57 };
58
59 #if defined(_WIN32)
60
61 //------------------------------------------------------------------------------
62 // simplistic pthread emulation layer
63
64 #include <process.h>
65
66 // _beginthreadex requires __stdcall
67 #define THREADFN unsigned int __stdcall
68 #define THREAD_RETURN(val) (unsigned int)((DWORD_PTR)val)
69
70 #if _WIN32_WINNT >= 0x0501 // Windows XP or greater
71 #define WaitForSingleObject(obj, timeout) \
72 WaitForSingleObjectEx(obj, timeout, FALSE /*bAlertable*/)
73 #endif
74
pthread_create(pthread_t * const thread,const void * attr,unsigned int (__stdcall * start)(void *),void * arg)75 static int pthread_create(pthread_t* const thread, const void* attr,
76 unsigned int (__stdcall *start)(void*), void* arg) {
77 (void)attr;
78 #ifdef USE_CREATE_THREAD
79 *thread = CreateThread(NULL, /* lpThreadAttributes */
80 0, /* dwStackSize */
81 start,
82 arg,
83 0, /* dwStackSize */
84 NULL); /* lpThreadId */
85 #else
86 *thread = (pthread_t)_beginthreadex(NULL, /* void *security */
87 0, /* unsigned stack_size */
88 start,
89 arg,
90 0, /* unsigned initflag */
91 NULL); /* unsigned *thrdaddr */
92 #endif
93 if (*thread == NULL) return 1;
94 SetThreadPriority(*thread, THREAD_PRIORITY_ABOVE_NORMAL);
95 return 0;
96 }
97
pthread_join(pthread_t thread,void ** value_ptr)98 static int pthread_join(pthread_t thread, void** value_ptr) {
99 (void)value_ptr;
100 return (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0 ||
101 CloseHandle(thread) == 0);
102 }
103
104 // Mutex
pthread_mutex_init(pthread_mutex_t * const mutex,void * mutexattr)105 static int pthread_mutex_init(pthread_mutex_t* const mutex, void* mutexattr) {
106 (void)mutexattr;
107 #if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater
108 InitializeCriticalSectionEx(mutex, 0 /*dwSpinCount*/, 0 /*Flags*/);
109 #else
110 InitializeCriticalSection(mutex);
111 #endif
112 return 0;
113 }
114
pthread_mutex_lock(pthread_mutex_t * const mutex)115 static int pthread_mutex_lock(pthread_mutex_t* const mutex) {
116 EnterCriticalSection(mutex);
117 return 0;
118 }
119
pthread_mutex_unlock(pthread_mutex_t * const mutex)120 static int pthread_mutex_unlock(pthread_mutex_t* const mutex) {
121 LeaveCriticalSection(mutex);
122 return 0;
123 }
124
pthread_mutex_destroy(pthread_mutex_t * const mutex)125 static int pthread_mutex_destroy(pthread_mutex_t* const mutex) {
126 DeleteCriticalSection(mutex);
127 return 0;
128 }
129
130 // Condition
pthread_cond_destroy(pthread_cond_t * const condition)131 static int pthread_cond_destroy(pthread_cond_t* const condition) {
132 int ok = 1;
133 #ifdef USE_WINDOWS_CONDITION_VARIABLE
134 (void)condition;
135 #else
136 ok &= (CloseHandle(condition->waiting_sem_) != 0);
137 ok &= (CloseHandle(condition->received_sem_) != 0);
138 ok &= (CloseHandle(condition->signal_event_) != 0);
139 #endif
140 return !ok;
141 }
142
pthread_cond_init(pthread_cond_t * const condition,void * cond_attr)143 static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) {
144 (void)cond_attr;
145 #ifdef USE_WINDOWS_CONDITION_VARIABLE
146 InitializeConditionVariable(condition);
147 #else
148 condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
149 condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
150 condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL);
151 if (condition->waiting_sem_ == NULL ||
152 condition->received_sem_ == NULL ||
153 condition->signal_event_ == NULL) {
154 pthread_cond_destroy(condition);
155 return 1;
156 }
157 #endif
158 return 0;
159 }
160
pthread_cond_signal(pthread_cond_t * const condition)161 static int pthread_cond_signal(pthread_cond_t* const condition) {
162 int ok = 1;
163 #ifdef USE_WINDOWS_CONDITION_VARIABLE
164 WakeConditionVariable(condition);
165 #else
166 if (WaitForSingleObject(condition->waiting_sem_, 0) == WAIT_OBJECT_0) {
167 // a thread is waiting in pthread_cond_wait: allow it to be notified
168 ok = SetEvent(condition->signal_event_);
169 // wait until the event is consumed so the signaler cannot consume
170 // the event via its own pthread_cond_wait.
171 ok &= (WaitForSingleObject(condition->received_sem_, INFINITE) !=
172 WAIT_OBJECT_0);
173 }
174 #endif
175 return !ok;
176 }
177
pthread_cond_wait(pthread_cond_t * const condition,pthread_mutex_t * const mutex)178 static int pthread_cond_wait(pthread_cond_t* const condition,
179 pthread_mutex_t* const mutex) {
180 int ok;
181 #ifdef USE_WINDOWS_CONDITION_VARIABLE
182 ok = SleepConditionVariableCS(condition, mutex, INFINITE);
183 #else
184 // note that there is a consumer available so the signal isn't dropped in
185 // pthread_cond_signal
186 if (!ReleaseSemaphore(condition->waiting_sem_, 1, NULL))
187 return 1;
188 // now unlock the mutex so pthread_cond_signal may be issued
189 pthread_mutex_unlock(mutex);
190 ok = (WaitForSingleObject(condition->signal_event_, INFINITE) ==
191 WAIT_OBJECT_0);
192 ok &= ReleaseSemaphore(condition->received_sem_, 1, NULL);
193 pthread_mutex_lock(mutex);
194 #endif
195 return !ok;
196 }
197
198 #else // !_WIN32
199 # define THREADFN void*
200 # define THREAD_RETURN(val) val
201 #endif // _WIN32
202
203 //------------------------------------------------------------------------------
204
205 static void Execute(WebPWorker* const worker); // Forward declaration.
206
ThreadLoop(void * ptr)207 static THREADFN ThreadLoop(void* ptr) {
208 WebPWorker* const worker = (WebPWorker*)ptr;
209 int done = 0;
210 while (!done) {
211 pthread_mutex_lock(&worker->impl_->mutex_);
212 while (worker->status_ == OK) { // wait in idling mode
213 pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
214 }
215 if (worker->status_ == WORK) {
216 Execute(worker);
217 worker->status_ = OK;
218 } else if (worker->status_ == NOT_OK) { // finish the worker
219 done = 1;
220 }
221 // signal to the main thread that we're done (for Sync())
222 pthread_cond_signal(&worker->impl_->condition_);
223 pthread_mutex_unlock(&worker->impl_->mutex_);
224 }
225 return THREAD_RETURN(NULL); // Thread is finished
226 }
227
228 // main thread state control
ChangeState(WebPWorker * const worker,WebPWorkerStatus new_status)229 static void ChangeState(WebPWorker* const worker,
230 WebPWorkerStatus new_status) {
231 // No-op when attempting to change state on a thread that didn't come up.
232 // Checking status_ without acquiring the lock first would result in a data
233 // race.
234 if (worker->impl_ == NULL) return;
235
236 pthread_mutex_lock(&worker->impl_->mutex_);
237 if (worker->status_ >= OK) {
238 // wait for the worker to finish
239 while (worker->status_ != OK) {
240 pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
241 }
242 // assign new status and release the working thread if needed
243 if (new_status != OK) {
244 worker->status_ = new_status;
245 pthread_cond_signal(&worker->impl_->condition_);
246 }
247 }
248 pthread_mutex_unlock(&worker->impl_->mutex_);
249 }
250
251 #endif // WEBP_USE_THREAD
252
253 //------------------------------------------------------------------------------
254
Init(WebPWorker * const worker)255 static void Init(WebPWorker* const worker) {
256 memset(worker, 0, sizeof(*worker));
257 worker->status_ = NOT_OK;
258 }
259
Sync(WebPWorker * const worker)260 static int Sync(WebPWorker* const worker) {
261 #ifdef WEBP_USE_THREAD
262 ChangeState(worker, OK);
263 #endif
264 assert(worker->status_ <= OK);
265 return !worker->had_error;
266 }
267
Reset(WebPWorker * const worker)268 static int Reset(WebPWorker* const worker) {
269 int ok = 1;
270 worker->had_error = 0;
271 if (worker->status_ < OK) {
272 #ifdef WEBP_USE_THREAD
273 worker->impl_ = (WebPWorkerImpl*)WebPSafeCalloc(1, sizeof(*worker->impl_));
274 if (worker->impl_ == NULL) {
275 return 0;
276 }
277 if (pthread_mutex_init(&worker->impl_->mutex_, NULL)) {
278 goto Error;
279 }
280 if (pthread_cond_init(&worker->impl_->condition_, NULL)) {
281 pthread_mutex_destroy(&worker->impl_->mutex_);
282 goto Error;
283 }
284 pthread_mutex_lock(&worker->impl_->mutex_);
285 ok = !pthread_create(&worker->impl_->thread_, NULL, ThreadLoop, worker);
286 if (ok) worker->status_ = OK;
287 pthread_mutex_unlock(&worker->impl_->mutex_);
288 if (!ok) {
289 pthread_mutex_destroy(&worker->impl_->mutex_);
290 pthread_cond_destroy(&worker->impl_->condition_);
291 Error:
292 WebPSafeFree(worker->impl_);
293 worker->impl_ = NULL;
294 return 0;
295 }
296 #else
297 worker->status_ = OK;
298 #endif
299 } else if (worker->status_ > OK) {
300 ok = Sync(worker);
301 }
302 assert(!ok || (worker->status_ == OK));
303 return ok;
304 }
305
Execute(WebPWorker * const worker)306 static void Execute(WebPWorker* const worker) {
307 if (worker->hook != NULL) {
308 worker->had_error |= !worker->hook(worker->data1, worker->data2);
309 }
310 }
311
Launch(WebPWorker * const worker)312 static void Launch(WebPWorker* const worker) {
313 #ifdef WEBP_USE_THREAD
314 ChangeState(worker, WORK);
315 #else
316 Execute(worker);
317 #endif
318 }
319
End(WebPWorker * const worker)320 static void End(WebPWorker* const worker) {
321 #ifdef WEBP_USE_THREAD
322 if (worker->impl_ != NULL) {
323 ChangeState(worker, NOT_OK);
324 pthread_join(worker->impl_->thread_, NULL);
325 pthread_mutex_destroy(&worker->impl_->mutex_);
326 pthread_cond_destroy(&worker->impl_->condition_);
327 WebPSafeFree(worker->impl_);
328 worker->impl_ = NULL;
329 }
330 #else
331 worker->status_ = NOT_OK;
332 assert(worker->impl_ == NULL);
333 #endif
334 assert(worker->status_ == NOT_OK);
335 }
336
337 //------------------------------------------------------------------------------
338
339 static WebPWorkerInterface g_worker_interface = {
340 Init, Reset, Sync, Launch, Execute, End
341 };
342
WebPSetWorkerInterface(const WebPWorkerInterface * const winterface)343 int WebPSetWorkerInterface(const WebPWorkerInterface* const winterface) {
344 if (winterface == NULL ||
345 winterface->Init == NULL || winterface->Reset == NULL ||
346 winterface->Sync == NULL || winterface->Launch == NULL ||
347 winterface->Execute == NULL || winterface->End == NULL) {
348 return 0;
349 }
350 g_worker_interface = *winterface;
351 return 1;
352 }
353
WebPGetWorkerInterface(void)354 const WebPWorkerInterface* WebPGetWorkerInterface(void) {
355 return &g_worker_interface;
356 }
357
358 //------------------------------------------------------------------------------
359