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 "src/utils/thread_utils.h"
17#include "src/utils/utils.h"
18
19#ifdef WEBP_USE_THREAD
20
21#if defined(_WIN32)
22
23#include <windows.h>
24typedef HANDLE pthread_t;
25typedef CRITICAL_SECTION pthread_mutex_t;
26
27#if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater
28#define USE_WINDOWS_CONDITION_VARIABLE
29typedef CONDITION_VARIABLE pthread_cond_t;
30#else
31typedef 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
53typedef struct {
54 pthread_mutex_t mutex_;
55 pthread_cond_t condition_;
56 pthread_t thread_;
57} WebPWorkerImpl;
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
75static 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
98static 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
105static 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
115static int pthread_mutex_lock(pthread_mutex_t* const mutex) {
116 EnterCriticalSection(mutex);
117 return 0;
118}
119
120static int pthread_mutex_unlock(pthread_mutex_t* const mutex) {
121 LeaveCriticalSection(mutex);
122 return 0;
123}
124
125static int pthread_mutex_destroy(pthread_mutex_t* const mutex) {
126 DeleteCriticalSection(mutex);
127 return 0;
128}
129
130// Condition
131static 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
143static 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
161static 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
178static 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)) return 1;
187 // now unlock the mutex so pthread_cond_signal may be issued
188 pthread_mutex_unlock(mutex);
189 ok = (WaitForSingleObject(condition->signal_event_, INFINITE) ==
190 WAIT_OBJECT_0);
191 ok &= ReleaseSemaphore(condition->received_sem_, 1, NULL);
192 pthread_mutex_lock(mutex);
193#endif
194 return !ok;
195}
196
197#else // !_WIN32
198# define THREADFN void*
199# define THREAD_RETURN(val) val
200#endif // _WIN32
201
202//------------------------------------------------------------------------------
203
204static THREADFN ThreadLoop(void* ptr) {
205 WebPWorker* const worker = (WebPWorker*)ptr;
206 WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_;
207 int done = 0;
208 while (!done) {
209 pthread_mutex_lock(&impl->mutex_);
210 while (worker->status_ == OK) { // wait in idling mode
211 pthread_cond_wait(&impl->condition_, &impl->mutex_);
212 }
213 if (worker->status_ == WORK) {
214 WebPGetWorkerInterface()->Execute(worker);
215 worker->status_ = OK;
216 } else if (worker->status_ == NOT_OK) { // finish the worker
217 done = 1;
218 }
219 // signal to the main thread that we're done (for Sync())
220 // Note the associated mutex does not need to be held when signaling the
221 // condition. Unlocking the mutex first may improve performance in some
222 // implementations, avoiding the case where the waiting thread can't
223 // reacquire the mutex when woken.
224 pthread_mutex_unlock(&impl->mutex_);
225 pthread_cond_signal(&impl->condition_);
226 }
227 return THREAD_RETURN(NULL); // Thread is finished
228}
229
230// main thread state control
231static void ChangeState(WebPWorker* const worker, WebPWorkerStatus new_status) {
232 // No-op when attempting to change state on a thread that didn't come up.
233 // Checking status_ without acquiring the lock first would result in a data
234 // race.
235 WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_;
236 if (impl == NULL) return;
237
238 pthread_mutex_lock(&impl->mutex_);
239 if (worker->status_ >= OK) {
240 // wait for the worker to finish
241 while (worker->status_ != OK) {
242 pthread_cond_wait(&impl->condition_, &impl->mutex_);
243 }
244 // assign new status and release the working thread if needed
245 if (new_status != OK) {
246 worker->status_ = new_status;
247 // Note the associated mutex does not need to be held when signaling the
248 // condition. Unlocking the mutex first may improve performance in some
249 // implementations, avoiding the case where the waiting thread can't
250 // reacquire the mutex when woken.
251 pthread_mutex_unlock(&impl->mutex_);
252 pthread_cond_signal(&impl->condition_);
253 return;
254 }
255 }
256 pthread_mutex_unlock(&impl->mutex_);
257}
258
259#endif // WEBP_USE_THREAD
260
261//------------------------------------------------------------------------------
262
263static void Init(WebPWorker* const worker) {
264 memset(worker, 0, sizeof(*worker));
265 worker->status_ = NOT_OK;
266}
267
268static int Sync(WebPWorker* const worker) {
269#ifdef WEBP_USE_THREAD
270 ChangeState(worker, OK);
271#endif
272 assert(worker->status_ <= OK);
273 return !worker->had_error;
274}
275
276static int Reset(WebPWorker* const worker) {
277 int ok = 1;
278 worker->had_error = 0;
279 if (worker->status_ < OK) {
280#ifdef WEBP_USE_THREAD
281 WebPWorkerImpl* const impl =
282 (WebPWorkerImpl*)WebPSafeCalloc(1, sizeof(WebPWorkerImpl));
283 worker->impl_ = (void*)impl;
284 if (worker->impl_ == NULL) {
285 return 0;
286 }
287 if (pthread_mutex_init(&impl->mutex_, NULL)) {
288 goto Error;
289 }
290 if (pthread_cond_init(&impl->condition_, NULL)) {
291 pthread_mutex_destroy(&impl->mutex_);
292 goto Error;
293 }
294 pthread_mutex_lock(&impl->mutex_);
295 ok = !pthread_create(&impl->thread_, NULL, ThreadLoop, worker);
296 if (ok) worker->status_ = OK;
297 pthread_mutex_unlock(&impl->mutex_);
298 if (!ok) {
299 pthread_mutex_destroy(&impl->mutex_);
300 pthread_cond_destroy(&impl->condition_);
301 Error:
302 WebPSafeFree(impl);
303 worker->impl_ = NULL;
304 return 0;
305 }
306#else
307 worker->status_ = OK;
308#endif
309 } else if (worker->status_ > OK) {
310 ok = Sync(worker);
311 }
312 assert(!ok || (worker->status_ == OK));
313 return ok;
314}
315
316static void Execute(WebPWorker* const worker) {
317 if (worker->hook != NULL) {
318 worker->had_error |= !worker->hook(worker->data1, worker->data2);
319 }
320}
321
322static void Launch(WebPWorker* const worker) {
323#ifdef WEBP_USE_THREAD
324 ChangeState(worker, WORK);
325#else
326 Execute(worker);
327#endif
328}
329
330static void End(WebPWorker* const worker) {
331#ifdef WEBP_USE_THREAD
332 if (worker->impl_ != NULL) {
333 WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_;
334 ChangeState(worker, NOT_OK);
335 pthread_join(impl->thread_, NULL);
336 pthread_mutex_destroy(&impl->mutex_);
337 pthread_cond_destroy(&impl->condition_);
338 WebPSafeFree(impl);
339 worker->impl_ = NULL;
340 }
341#else
342 worker->status_ = NOT_OK;
343 assert(worker->impl_ == NULL);
344#endif
345 assert(worker->status_ == NOT_OK);
346}
347
348//------------------------------------------------------------------------------
349
350static WebPWorkerInterface g_worker_interface = {
351 Init, Reset, Sync, Launch, Execute, End
352};
353
354int WebPSetWorkerInterface(const WebPWorkerInterface* const winterface) {
355 if (winterface == NULL ||
356 winterface->Init == NULL || winterface->Reset == NULL ||
357 winterface->Sync == NULL || winterface->Launch == NULL ||
358 winterface->Execute == NULL || winterface->End == NULL) {
359 return 0;
360 }
361 g_worker_interface = *winterface;
362 return 1;
363}
364
365const WebPWorkerInterface* WebPGetWorkerInterface(void) {
366 return &g_worker_interface;
367}
368
369//------------------------------------------------------------------------------
370