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 13a61a4c84194c3374080cbf03d881d3cd6af40d  src/utils/thread.h
15
16
17#ifndef VP9_DECODER_VP9_THREAD_H_
18#define VP9_DECODER_VP9_THREAD_H_
19
20#include "./vpx_config.h"
21
22#ifdef __cplusplus
23extern "C" {
24#endif
25
26#if CONFIG_MULTITHREAD
27
28#if defined(_WIN32)
29#include <errno.h>  // NOLINT
30#include <process.h>  // NOLINT
31#include <windows.h>  // NOLINT
32typedef HANDLE pthread_t;
33typedef CRITICAL_SECTION pthread_mutex_t;
34typedef struct {
35  HANDLE waiting_sem_;
36  HANDLE received_sem_;
37  HANDLE signal_event_;
38} pthread_cond_t;
39
40//------------------------------------------------------------------------------
41// simplistic pthread emulation layer
42
43// _beginthreadex requires __stdcall
44#define THREADFN unsigned int __stdcall
45#define THREAD_RETURN(val) (unsigned int)((DWORD_PTR)val)
46
47static INLINE int pthread_create(pthread_t* const thread, const void* attr,
48                                 unsigned int (__stdcall *start)(void*),
49                                 void* arg) {
50  (void)attr;
51  *thread = (pthread_t)_beginthreadex(NULL,   /* void *security */
52                                      0,      /* unsigned stack_size */
53                                      start,
54                                      arg,
55                                      0,      /* unsigned initflag */
56                                      NULL);  /* unsigned *thrdaddr */
57  if (*thread == NULL) return 1;
58  SetThreadPriority(*thread, THREAD_PRIORITY_ABOVE_NORMAL);
59  return 0;
60}
61
62static INLINE int pthread_join(pthread_t thread, void** value_ptr) {
63  (void)value_ptr;
64  return (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0 ||
65          CloseHandle(thread) == 0);
66}
67
68// Mutex
69static INLINE int pthread_mutex_init(pthread_mutex_t *const mutex,
70                                     void* mutexattr) {
71  (void)mutexattr;
72  InitializeCriticalSection(mutex);
73  return 0;
74}
75
76static INLINE int pthread_mutex_trylock(pthread_mutex_t *const mutex) {
77  return TryEnterCriticalSection(mutex) ? 0 : EBUSY;
78}
79
80static INLINE int pthread_mutex_lock(pthread_mutex_t *const mutex) {
81  EnterCriticalSection(mutex);
82  return 0;
83}
84
85static INLINE int pthread_mutex_unlock(pthread_mutex_t *const mutex) {
86  LeaveCriticalSection(mutex);
87  return 0;
88}
89
90static INLINE int pthread_mutex_destroy(pthread_mutex_t *const mutex) {
91  DeleteCriticalSection(mutex);
92  return 0;
93}
94
95// Condition
96static INLINE int pthread_cond_destroy(pthread_cond_t *const condition) {
97  int ok = 1;
98  ok &= (CloseHandle(condition->waiting_sem_) != 0);
99  ok &= (CloseHandle(condition->received_sem_) != 0);
100  ok &= (CloseHandle(condition->signal_event_) != 0);
101  return !ok;
102}
103
104static INLINE int pthread_cond_init(pthread_cond_t *const condition,
105                                    void* cond_attr) {
106  (void)cond_attr;
107  condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
108  condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
109  condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL);
110  if (condition->waiting_sem_ == NULL ||
111      condition->received_sem_ == NULL ||
112      condition->signal_event_ == NULL) {
113    pthread_cond_destroy(condition);
114    return 1;
115  }
116  return 0;
117}
118
119static INLINE int pthread_cond_signal(pthread_cond_t *const condition) {
120  int ok = 1;
121  if (WaitForSingleObject(condition->waiting_sem_, 0) == WAIT_OBJECT_0) {
122    // a thread is waiting in pthread_cond_wait: allow it to be notified
123    ok = SetEvent(condition->signal_event_);
124    // wait until the event is consumed so the signaler cannot consume
125    // the event via its own pthread_cond_wait.
126    ok &= (WaitForSingleObject(condition->received_sem_, INFINITE) !=
127           WAIT_OBJECT_0);
128  }
129  return !ok;
130}
131
132static INLINE int pthread_cond_wait(pthread_cond_t *const condition,
133                                    pthread_mutex_t *const mutex) {
134  int ok;
135  // note that there is a consumer available so the signal isn't dropped in
136  // pthread_cond_signal
137  if (!ReleaseSemaphore(condition->waiting_sem_, 1, NULL))
138    return 1;
139  // now unlock the mutex so pthread_cond_signal may be issued
140  pthread_mutex_unlock(mutex);
141  ok = (WaitForSingleObject(condition->signal_event_, INFINITE) ==
142        WAIT_OBJECT_0);
143  ok &= ReleaseSemaphore(condition->received_sem_, 1, NULL);
144  pthread_mutex_lock(mutex);
145  return !ok;
146}
147#else  // _WIN32
148#include <pthread.h> // NOLINT
149# define THREADFN void*
150# define THREAD_RETURN(val) val
151#endif
152
153#endif  // CONFIG_MULTITHREAD
154
155// State of the worker thread object
156typedef enum {
157  NOT_OK = 0,   // object is unusable
158  OK,           // ready to work
159  WORK          // busy finishing the current task
160} VP9WorkerStatus;
161
162// Function to be called by the worker thread. Takes two opaque pointers as
163// arguments (data1 and data2), and should return false in case of error.
164typedef int (*VP9WorkerHook)(void*, void*);
165
166// Synchronize object used to launch job in the worker thread
167typedef struct {
168#if CONFIG_MULTITHREAD
169  pthread_mutex_t mutex_;
170  pthread_cond_t  condition_;
171  pthread_t       thread_;
172#endif
173  VP9WorkerStatus status_;
174  VP9WorkerHook hook;     // hook to call
175  void* data1;            // first argument passed to 'hook'
176  void* data2;            // second argument passed to 'hook'
177  int had_error;          // return value of the last call to 'hook'
178} VP9Worker;
179
180// Must be called first, before any other method.
181void vp9_worker_init(VP9Worker* const worker);
182// Must be called to initialize the object and spawn the thread. Re-entrant.
183// Will potentially launch the thread. Returns false in case of error.
184int vp9_worker_reset(VP9Worker* const worker);
185// Makes sure the previous work is finished. Returns true if worker->had_error
186// was not set and no error condition was triggered by the working thread.
187int vp9_worker_sync(VP9Worker* const worker);
188// Triggers the thread to call hook() with data1 and data2 argument. These
189// hook/data1/data2 can be changed at any time before calling this function,
190// but not be changed afterward until the next call to vp9_worker_sync().
191void vp9_worker_launch(VP9Worker* const worker);
192// This function is similar to vp9_worker_launch() except that it calls the
193// hook directly instead of using a thread. Convenient to bypass the thread
194// mechanism while still using the VP9Worker structs. vp9_worker_sync() must
195// still be called afterward (for error reporting).
196void vp9_worker_execute(VP9Worker* const worker);
197// Kill the thread and terminate the object. To use the object again, one
198// must call vp9_worker_reset() again.
199void vp9_worker_end(VP9Worker* const worker);
200
201//------------------------------------------------------------------------------
202
203#ifdef __cplusplus
204}    // extern "C"
205#endif
206
207#endif  // VP9_DECODER_VP9_THREAD_H_
208