SDL  2.0
SDL_thread.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2017 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 
22 #ifndef SDL_thread_h_
23 #define SDL_thread_h_
24 
25 /**
26  * \file SDL_thread.h
27  *
28  * Header for the SDL thread management routines.
29  */
30 
31 #include "SDL_stdinc.h"
32 #include "SDL_error.h"
33 
34 /* Thread synchronization primitives */
35 #include "SDL_atomic.h"
36 #include "SDL_mutex.h"
37 
38 #include "begin_code.h"
39 /* Set up for C function definitions, even when using C++ */
40 #ifdef __cplusplus
41 extern "C" {
42 #endif
43 
44 /* The SDL thread structure, defined in SDL_thread.c */
45 struct SDL_Thread;
46 typedef struct SDL_Thread SDL_Thread;
47 
48 /* The SDL thread ID */
49 typedef unsigned long SDL_threadID;
50 
51 /* Thread local storage ID, 0 is the invalid ID */
52 typedef unsigned int SDL_TLSID;
53 
54 /**
55  * The SDL thread priority.
56  *
57  * \note On many systems you require special privileges to set high priority.
58  */
59 typedef enum {
64 
65 /**
66  * The function passed to SDL_CreateThread().
67  * It is passed a void* user context parameter and returns an int.
68  */
69 typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
70 
71 #if defined(__WIN32__) && !defined(HAVE_LIBC)
72 /**
73  * \file SDL_thread.h
74  *
75  * We compile SDL into a DLL. This means, that it's the DLL which
76  * creates a new thread for the calling process with the SDL_CreateThread()
77  * API. There is a problem with this, that only the RTL of the SDL2.DLL will
78  * be initialized for those threads, and not the RTL of the calling
79  * application!
80  *
81  * To solve this, we make a little hack here.
82  *
83  * We'll always use the caller's _beginthread() and _endthread() APIs to
84  * start a new thread. This way, if it's the SDL2.DLL which uses this API,
85  * then the RTL of SDL2.DLL will be used to create the new thread, and if it's
86  * the application, then the RTL of the application will be used.
87  *
88  * So, in short:
89  * Always use the _beginthread() and _endthread() of the calling runtime
90  * library!
91  */
92 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
93 #include <process.h> /* This has _beginthread() and _endthread() defined! */
94 
95 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread) (void *, unsigned,
96  unsigned (__stdcall *
97  func) (void
98  *),
99  void *arg, unsigned,
100  unsigned *threadID);
101 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
102 
103 /**
104  * Create a thread.
105  */
107 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
108  pfnSDL_CurrentBeginThread pfnBeginThread,
109  pfnSDL_CurrentEndThread pfnEndThread);
110 
111 /**
112  * Create a thread.
113  */
114 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
115 #undef SDL_CreateThread
116 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
117 #else
118 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
119 #endif
120 
121 #elif defined(__OS2__)
122 /*
123  * just like the windows case above: We compile SDL2
124  * into a dll with Watcom's runtime statically linked.
125  */
126 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
127 #include <process.h>
128 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
129 typedef void (*pfnSDL_CurrentEndThread)(void);
131 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
132  pfnSDL_CurrentBeginThread pfnBeginThread,
133  pfnSDL_CurrentEndThread pfnEndThread);
134 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
135 #undef SDL_CreateThread
136 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
137 #else
138 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
139 #endif
140 
141 #else
142 
143 /**
144  * Create a thread.
145  *
146  * Thread naming is a little complicated: Most systems have very small
147  * limits for the string length (Haiku has 32 bytes, Linux currently has 16,
148  * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
149  * have to see what happens with your system's debugger. The name should be
150  * UTF-8 (but using the naming limits of C identifiers is a better bet).
151  * There are no requirements for thread naming conventions, so long as the
152  * string is null-terminated UTF-8, but these guidelines are helpful in
153  * choosing a name:
154  *
155  * http://stackoverflow.com/questions/149932/naming-conventions-for-threads
156  *
157  * If a system imposes requirements, SDL will try to munge the string for
158  * it (truncate, etc), but the original string contents will be available
159  * from SDL_GetThreadName().
160  */
162 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
163 
164 #endif
165 
166 /**
167  * Get the thread name, as it was specified in SDL_CreateThread().
168  * This function returns a pointer to a UTF-8 string that names the
169  * specified thread, or NULL if it doesn't have a name. This is internal
170  * memory, not to be free()'d by the caller, and remains valid until the
171  * specified thread is cleaned up by SDL_WaitThread().
172  */
173 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
174 
175 /**
176  * Get the thread identifier for the current thread.
177  */
178 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
179 
180 /**
181  * Get the thread identifier for the specified thread.
182  *
183  * Equivalent to SDL_ThreadID() if the specified thread is NULL.
184  */
185 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
186 
187 /**
188  * Set the priority for the current thread
189  */
191 
192 /**
193  * Wait for a thread to finish. Threads that haven't been detached will
194  * remain (as a "zombie") until this function cleans them up. Not doing so
195  * is a resource leak.
196  *
197  * Once a thread has been cleaned up through this function, the SDL_Thread
198  * that references it becomes invalid and should not be referenced again.
199  * As such, only one thread may call SDL_WaitThread() on another.
200  *
201  * The return code for the thread function is placed in the area
202  * pointed to by \c status, if \c status is not NULL.
203  *
204  * You may not wait on a thread that has been used in a call to
205  * SDL_DetachThread(). Use either that function or this one, but not
206  * both, or behavior is undefined.
207  *
208  * It is safe to pass NULL to this function; it is a no-op.
209  */
210 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
211 
212 /**
213  * A thread may be "detached" to signify that it should not remain until
214  * another thread has called SDL_WaitThread() on it. Detaching a thread
215  * is useful for long-running threads that nothing needs to synchronize
216  * with or further manage. When a detached thread is done, it simply
217  * goes away.
218  *
219  * There is no way to recover the return code of a detached thread. If you
220  * need this, don't detach the thread and instead use SDL_WaitThread().
221  *
222  * Once a thread is detached, you should usually assume the SDL_Thread isn't
223  * safe to reference again, as it will become invalid immediately upon
224  * the detached thread's exit, instead of remaining until someone has called
225  * SDL_WaitThread() to finally clean it up. As such, don't detach the same
226  * thread more than once.
227  *
228  * If a thread has already exited when passed to SDL_DetachThread(), it will
229  * stop waiting for a call to SDL_WaitThread() and clean up immediately.
230  * It is not safe to detach a thread that might be used with SDL_WaitThread().
231  *
232  * You may not call SDL_WaitThread() on a thread that has been detached.
233  * Use either that function or this one, but not both, or behavior is
234  * undefined.
235  *
236  * It is safe to pass NULL to this function; it is a no-op.
237  */
238 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
239 
240 /**
241  * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
242  *
243  * \return The newly created thread local storage identifier, or 0 on error
244  *
245  * \code
246  * static SDL_SpinLock tls_lock;
247  * static SDL_TLSID thread_local_storage;
248  *
249  * void SetMyThreadData(void *value)
250  * {
251  * if (!thread_local_storage) {
252  * SDL_AtomicLock(&tls_lock);
253  * if (!thread_local_storage) {
254  * thread_local_storage = SDL_TLSCreate();
255  * }
256  * SDL_AtomicUnlock(&tls_lock);
257  * }
258  * SDL_TLSSet(thread_local_storage, value, 0);
259  * }
260  *
261  * void *GetMyThreadData(void)
262  * {
263  * return SDL_TLSGet(thread_local_storage);
264  * }
265  * \endcode
266  *
267  * \sa SDL_TLSGet()
268  * \sa SDL_TLSSet()
269  */
270 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
271 
272 /**
273  * \brief Get the value associated with a thread local storage ID for the current thread.
274  *
275  * \param id The thread local storage ID
276  *
277  * \return The value associated with the ID for the current thread, or NULL if no value has been set.
278  *
279  * \sa SDL_TLSCreate()
280  * \sa SDL_TLSSet()
281  */
282 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
283 
284 /**
285  * \brief Set the value associated with a thread local storage ID for the current thread.
286  *
287  * \param id The thread local storage ID
288  * \param value The value to associate with the ID for the current thread
289  * \param destructor A function called when the thread exits, to free the value.
290  *
291  * \return 0 on success, -1 on error
292  *
293  * \sa SDL_TLSCreate()
294  * \sa SDL_TLSGet()
295  */
296 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
297 
298 
299 /* Ends C function definitions when using C++ */
300 #ifdef __cplusplus
301 }
302 #endif
303 #include "close_code.h"
304 
305 #endif /* SDL_thread_h_ */
306 
307 /* vi: set ts=4 sw=4 expandtab: */
SDL_TLSID SDL_TLSCreate(void)
Create an identifier that is globally visible to all threads but refers to data that is thread-specif...
Definition: SDL_thread.c:34
SDL_threadID SDL_ThreadID(void)
Definition: SDL_systhread.c:48
const char * SDL_GetThreadName(SDL_Thread *thread)
Definition: SDL_thread.c:450
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
int(* SDL_ThreadFunction)(void *data)
Definition: SDL_thread.h:69
void SDL_WaitThread(SDL_Thread *thread, int *status)
Definition: SDL_thread.c:466
GLuint const GLchar * name
unsigned int SDL_TLSID
Definition: SDL_thread.h:52
void * SDL_TLSGet(SDL_TLSID id)
Get the value associated with a thread local storage ID for the current thread.
Definition: SDL_thread.c:41
SDL_threadID SDL_GetThreadID(SDL_Thread *thread)
Definition: SDL_thread.c:437
int SDL_TLSSet(SDL_TLSID id, const void *value, void(*destructor)(void *))
Set the value associated with a thread local storage ID for the current thread.
Definition: SDL_thread.c:53
#define DECLSPEC
Definition: SDL_internal.h:44
int SDL_SetThreadPriority(SDL_ThreadPriority priority)
Definition: SDL_thread.c:460
GLsizei const GLfloat * value
unsigned int uintptr_t
void SDL_DetachThread(SDL_Thread *thread)
Definition: SDL_thread.c:481
GLenum func
SDL_Thread * SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data)
SDL_ThreadPriority
Definition: SDL_thread.h:59
SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char const char SDL_SCANF_FORMAT_STRING const char return SDL_ThreadFunction const char void return Uint32 return Uint32 void
#define SDLCALL
Definition: SDL_internal.h:45
unsigned long SDL_threadID
Definition: SDL_thread.h:49