SDL  2.0
SDL_syscond.cpp
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "../../SDL_internal.h"
22 
23 extern "C" {
24 #include "SDL_thread.h"
25 }
26 
27 #include <chrono>
28 #include <condition_variable>
29 #include <ratio>
30 #include <system_error>
31 
32 #include "SDL_sysmutex_c.h"
33 
34 struct SDL_cond
35 {
36  std::condition_variable_any cpp_cond;
37 };
38 
39 /* Create a condition variable */
40 extern "C"
41 SDL_cond *
43 {
44  /* Allocate and initialize the condition variable */
45  try {
46  SDL_cond * cond = new SDL_cond;
47  return cond;
48  } catch (std::system_error & ex) {
49  SDL_SetError("unable to create a C++ condition variable: code=%d; %s", ex.code(), ex.what());
50  return NULL;
51  } catch (std::bad_alloc &) {
53  return NULL;
54  }
55 }
56 
57 /* Destroy a condition variable */
58 extern "C"
59 void
61 {
62  if (cond) {
63  delete cond;
64  }
65 }
66 
67 /* Restart one of the threads that are waiting on the condition variable */
68 extern "C"
69 int
71 {
72  if (!cond) {
73  SDL_SetError("Passed a NULL condition variable");
74  return -1;
75  }
76 
77  cond->cpp_cond.notify_one();
78  return 0;
79 }
80 
81 /* Restart all threads that are waiting on the condition variable */
82 extern "C"
83 int
85 {
86  if (!cond) {
87  SDL_SetError("Passed a NULL condition variable");
88  return -1;
89  }
90 
91  cond->cpp_cond.notify_all();
92  return 0;
93 }
94 
95 /* Wait on the condition variable for at most 'ms' milliseconds.
96  The mutex must be locked before entering this function!
97  The mutex is unlocked during the wait, and locked again after the wait.
98 
99 Typical use:
100 
101 Thread A:
102  SDL_LockMutex(lock);
103  while ( ! condition ) {
104  SDL_CondWait(cond, lock);
105  }
106  SDL_UnlockMutex(lock);
107 
108 Thread B:
109  SDL_LockMutex(lock);
110  ...
111  condition = true;
112  ...
113  SDL_CondSignal(cond);
114  SDL_UnlockMutex(lock);
115  */
116 extern "C"
117 int
119 {
120  if (!cond) {
121  SDL_SetError("Passed a NULL condition variable");
122  return -1;
123  }
124 
125  if (!mutex) {
126  SDL_SetError("Passed a NULL mutex variable");
127  return -1;
128  }
129 
130  try {
131  std::unique_lock<std::recursive_mutex> cpp_lock(mutex->cpp_mutex, std::adopt_lock_t());
132  if (ms == SDL_MUTEX_MAXWAIT) {
133  cond->cpp_cond.wait(
134  cpp_lock
135  );
136  cpp_lock.release();
137  return 0;
138  } else {
139  auto wait_result = cond->cpp_cond.wait_for(
140  cpp_lock,
141  std::chrono::duration<Uint32, std::milli>(ms)
142  );
143  cpp_lock.release();
144  if (wait_result == std::cv_status::timeout) {
145  return SDL_MUTEX_TIMEDOUT;
146  } else {
147  return 0;
148  }
149  }
150  } catch (std::system_error & ex) {
151  SDL_SetError("unable to wait on a C++ condition variable: code=%d; %s", ex.code(), ex.what());
152  return -1;
153  }
154 }
155 
156 /* Wait on the condition variable forever */
157 extern "C"
158 int
160 {
161  return SDL_CondWaitTimeout(cond, mutex, SDL_MUTEX_MAXWAIT);
162 }
163 
164 /* vi: set ts=4 sw=4 expandtab: */
int SDL_CondWait(SDL_cond *cond, SDL_mutex *mutex)
void SDL_DestroyCond(SDL_cond *cond)
Definition: SDL_syscond.cpp:60
std::recursive_mutex cpp_mutex
uint32_t Uint32
Definition: SDL_stdinc.h:181
static SDL_mutex * mutex
Definition: testlock.c:23
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
int SDL_CondSignal(SDL_cond *cond)
Definition: SDL_syscond.cpp:70
int SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms)
SDL_cond * SDL_CreateCond(void)
Definition: SDL_syscond.cpp:42
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
pthread_cond_t cond
Definition: SDL_syscond.c:34
#define NULL
Definition: begin_code.h:164
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
#define SDL_SetError
GLbitfield GLuint64 timeout
int SDL_CondBroadcast(SDL_cond *cond)
Definition: SDL_syscond.cpp:84
std::condition_variable_any cpp_cond
Definition: SDL_syscond.cpp:36