SDL  2.0
SDL_thread.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2020 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 or time critical priority.
58  */
59 typedef enum {
65 
66 /**
67  * The function passed to SDL_CreateThread().
68  * It is passed a void* user context parameter and returns an int.
69  */
70 typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
71 
72 #if defined(__WIN32__)
73 /**
74  * \file SDL_thread.h
75  *
76  * We compile SDL into a DLL. This means, that it's the DLL which
77  * creates a new thread for the calling process with the SDL_CreateThread()
78  * API. There is a problem with this, that only the RTL of the SDL2.DLL will
79  * be initialized for those threads, and not the RTL of the calling
80  * application!
81  *
82  * To solve this, we make a little hack here.
83  *
84  * We'll always use the caller's _beginthread() and _endthread() APIs to
85  * start a new thread. This way, if it's the SDL2.DLL which uses this API,
86  * then the RTL of SDL2.DLL will be used to create the new thread, and if it's
87  * the application, then the RTL of the application will be used.
88  *
89  * So, in short:
90  * Always use the _beginthread() and _endthread() of the calling runtime
91  * library!
92  */
93 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
94 #include <process.h> /* _beginthreadex() and _endthreadex() */
95 
97  (void *, unsigned, unsigned (__stdcall *func)(void *),
98  void * /*arg*/, unsigned, unsigned * /* threadID */);
99 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
100 
101 #ifndef SDL_beginthread
102 #define SDL_beginthread _beginthreadex
103 #endif
104 #ifndef SDL_endthread
105 #define SDL_endthread _endthreadex
106 #endif
107 
108 /**
109  * Create a thread.
110  */
113  pfnSDL_CurrentBeginThread pfnBeginThread,
114  pfnSDL_CurrentEndThread pfnEndThread);
115 
118  const char *name, const size_t stacksize, void *data,
119  pfnSDL_CurrentBeginThread pfnBeginThread,
120  pfnSDL_CurrentEndThread pfnEndThread);
121 
122 
123 /**
124  * Create a thread.
125  */
126 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
127 #undef SDL_CreateThread
128 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
129 #undef SDL_CreateThreadWithStackSize
130 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
131 #else
132 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
133 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)SDL_endthread)
134 #endif
135 
136 #elif defined(__OS2__)
137 /*
138  * just like the windows case above: We compile SDL2
139  * into a dll with Watcom's runtime statically linked.
140  */
141 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
142 
143 #ifndef __EMX__
144 #include <process.h>
145 #else
146 #include <stdlib.h>
147 #endif
148 
149 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
150 typedef void (*pfnSDL_CurrentEndThread)(void);
151 
152 #ifndef SDL_beginthread
153 #define SDL_beginthread _beginthread
154 #endif
155 #ifndef SDL_endthread
156 #define SDL_endthread _endthread
157 #endif
158 
160 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
161  pfnSDL_CurrentBeginThread pfnBeginThread,
162  pfnSDL_CurrentEndThread pfnEndThread);
164 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
165  pfnSDL_CurrentBeginThread pfnBeginThread,
166  pfnSDL_CurrentEndThread pfnEndThread);
167 
168 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
169 #undef SDL_CreateThread
170 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
171 #undef SDL_CreateThreadWithStackSize
172 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
173 #else
174 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
175 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
176 #endif
177 
178 #else
179 
180 /**
181  * Create a thread with a default stack size.
182  *
183  * This is equivalent to calling:
184  * SDL_CreateThreadWithStackSize(fn, name, 0, data);
185  */
187 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
188 
189 /**
190  * Create a thread.
191  *
192  * Thread naming is a little complicated: Most systems have very small
193  * limits for the string length (Haiku has 32 bytes, Linux currently has 16,
194  * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
195  * have to see what happens with your system's debugger. The name should be
196  * UTF-8 (but using the naming limits of C identifiers is a better bet).
197  * There are no requirements for thread naming conventions, so long as the
198  * string is null-terminated UTF-8, but these guidelines are helpful in
199  * choosing a name:
200  *
201  * http://stackoverflow.com/questions/149932/naming-conventions-for-threads
202  *
203  * If a system imposes requirements, SDL will try to munge the string for
204  * it (truncate, etc), but the original string contents will be available
205  * from SDL_GetThreadName().
206  *
207  * The size (in bytes) of the new stack can be specified. Zero means "use
208  * the system default" which might be wildly different between platforms
209  * (x86 Linux generally defaults to eight megabytes, an embedded device
210  * might be a few kilobytes instead).
211  *
212  * In SDL 2.1, stacksize will be folded into the original SDL_CreateThread
213  * function.
214  */
216 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
217 
218 #endif
219 
220 /**
221  * Get the thread name, as it was specified in SDL_CreateThread().
222  * This function returns a pointer to a UTF-8 string that names the
223  * specified thread, or NULL if it doesn't have a name. This is internal
224  * memory, not to be free()'d by the caller, and remains valid until the
225  * specified thread is cleaned up by SDL_WaitThread().
226  */
227 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
228 
229 /**
230  * Get the thread identifier for the current thread.
231  */
233 
234 /**
235  * Get the thread identifier for the specified thread.
236  *
237  * Equivalent to SDL_ThreadID() if the specified thread is NULL.
238  */
240 
241 /**
242  * Set the priority for the current thread
243  */
245 
246 /**
247  * Wait for a thread to finish. Threads that haven't been detached will
248  * remain (as a "zombie") until this function cleans them up. Not doing so
249  * is a resource leak.
250  *
251  * Once a thread has been cleaned up through this function, the SDL_Thread
252  * that references it becomes invalid and should not be referenced again.
253  * As such, only one thread may call SDL_WaitThread() on another.
254  *
255  * The return code for the thread function is placed in the area
256  * pointed to by \c status, if \c status is not NULL.
257  *
258  * You may not wait on a thread that has been used in a call to
259  * SDL_DetachThread(). Use either that function or this one, but not
260  * both, or behavior is undefined.
261  *
262  * It is safe to pass NULL to this function; it is a no-op.
263  */
264 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
265 
266 /**
267  * A thread may be "detached" to signify that it should not remain until
268  * another thread has called SDL_WaitThread() on it. Detaching a thread
269  * is useful for long-running threads that nothing needs to synchronize
270  * with or further manage. When a detached thread is done, it simply
271  * goes away.
272  *
273  * There is no way to recover the return code of a detached thread. If you
274  * need this, don't detach the thread and instead use SDL_WaitThread().
275  *
276  * Once a thread is detached, you should usually assume the SDL_Thread isn't
277  * safe to reference again, as it will become invalid immediately upon
278  * the detached thread's exit, instead of remaining until someone has called
279  * SDL_WaitThread() to finally clean it up. As such, don't detach the same
280  * thread more than once.
281  *
282  * If a thread has already exited when passed to SDL_DetachThread(), it will
283  * stop waiting for a call to SDL_WaitThread() and clean up immediately.
284  * It is not safe to detach a thread that might be used with SDL_WaitThread().
285  *
286  * You may not call SDL_WaitThread() on a thread that has been detached.
287  * Use either that function or this one, but not both, or behavior is
288  * undefined.
289  *
290  * It is safe to pass NULL to this function; it is a no-op.
291  */
292 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
293 
294 /**
295  * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
296  *
297  * \return The newly created thread local storage identifier, or 0 on error
298  *
299  * \code
300  * static SDL_SpinLock tls_lock;
301  * static SDL_TLSID thread_local_storage;
302  *
303  * void SetMyThreadData(void *value)
304  * {
305  * if (!thread_local_storage) {
306  * SDL_AtomicLock(&tls_lock);
307  * if (!thread_local_storage) {
308  * thread_local_storage = SDL_TLSCreate();
309  * }
310  * SDL_AtomicUnlock(&tls_lock);
311  * }
312  * SDL_TLSSet(thread_local_storage, value, 0);
313  * }
314  *
315  * void *GetMyThreadData(void)
316  * {
317  * return SDL_TLSGet(thread_local_storage);
318  * }
319  * \endcode
320  *
321  * \sa SDL_TLSGet()
322  * \sa SDL_TLSSet()
323  */
325 
326 /**
327  * \brief Get the value associated with a thread local storage ID for the current thread.
328  *
329  * \param id The thread local storage ID
330  *
331  * \return The value associated with the ID for the current thread, or NULL if no value has been set.
332  *
333  * \sa SDL_TLSCreate()
334  * \sa SDL_TLSSet()
335  */
336 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
337 
338 /**
339  * \brief Set the value associated with a thread local storage ID for the current thread.
340  *
341  * \param id The thread local storage ID
342  * \param value The value to associate with the ID for the current thread
343  * \param destructor A function called when the thread exits, to free the value.
344  *
345  * \return 0 on success, -1 on error
346  *
347  * \sa SDL_TLSCreate()
348  * \sa SDL_TLSGet()
349  */
350 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
351 
352 
353 /* Ends C function definitions when using C++ */
354 #ifdef __cplusplus
355 }
356 #endif
357 #include "close_code.h"
358 
359 #endif /* SDL_thread_h_ */
360 
361 /* vi: set ts=4 sw=4 expandtab: */
SDL_GetThreadName
const char * SDL_GetThreadName(SDL_Thread *thread)
Definition: SDL_thread.c:458
SDL_CreateThread
#define SDL_CreateThread(fn, name, data)
Definition: SDL_thread.h:132
DECLSPEC
#define DECLSPEC
Definition: SDL_internal.h:48
pfnSDL_CurrentEndThread
void(__cdecl * pfnSDL_CurrentEndThread)(unsigned code)
Definition: SDL_thread.h:99
SDL_TLSSet
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
SDL_Thread::stacksize
size_t stacksize
Definition: SDL_thread_c.h:62
SDL_atomic.h
SDL_SetThreadPriority
int SDL_SetThreadPriority(SDL_ThreadPriority priority)
Definition: SDL_thread.c:468
pfnSDL_CurrentBeginThread
uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)(void *, unsigned, unsigned(__stdcall *func)(void *), void *, unsigned, unsigned *)
Definition: SDL_thread.h:97
SDL_error.h
SDL_THREAD_PRIORITY_TIME_CRITICAL
@ SDL_THREAD_PRIORITY_TIME_CRITICAL
Definition: SDL_thread.h:63
SDLCALL
#define SDLCALL
Definition: SDL_internal.h:49
SDL_THREAD_PRIORITY_HIGH
@ SDL_THREAD_PRIORITY_HIGH
Definition: SDL_thread.h:62
SDL_CreateThreadWithStackSize
#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data)
Definition: SDL_thread.h:133
SDL_Thread::status
int status
Definition: SDL_thread_c.h:58
SDL_Thread
Definition: SDL_thread_c.h:55
SDL_THREAD_PRIORITY_LOW
@ SDL_THREAD_PRIORITY_LOW
Definition: SDL_thread.h:60
func
GLenum func
Definition: SDL_opengl_glext.h:660
close_code.h
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
begin_code.h
SDL_DetachThread
void SDL_DetachThread(SDL_Thread *thread)
Definition: SDL_thread.c:489
SDL_mutex.h
SDL_TLSID
unsigned int SDL_TLSID
Definition: SDL_thread.h:52
name
GLuint const GLchar * name
Definition: SDL_opengl_glext.h:663
SDL_ThreadID
SDL_threadID SDL_ThreadID(void)
Definition: SDL_systhread.c:48
SDL_WaitThread
void SDL_WaitThread(SDL_Thread *thread, int *status)
Definition: SDL_thread.c:474
SDL_ThreadFunction
int(* SDL_ThreadFunction)(void *data)
Definition: SDL_thread.h:70
SDL_threadID
unsigned long SDL_threadID
Definition: SDL_thread.h:49
SDL_GetThreadID
SDL_threadID SDL_GetThreadID(SDL_Thread *thread)
Definition: SDL_thread.c:445
value
GLsizei const GLfloat * value
Definition: SDL_opengl_glext.h:701
SDL_stdinc.h
SDL_TLSGet
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_THREAD_PRIORITY_NORMAL
@ SDL_THREAD_PRIORITY_NORMAL
Definition: SDL_thread.h:61
SDL_TLSCreate
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_dynapi_procs.h:509
void
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
Definition: SDL_dynapi_procs.h:89
SDL_ThreadPriority
SDL_ThreadPriority
Definition: SDL_thread.h:59
uintptr_t
unsigned int uintptr_t
Definition: SDL_config_windows.h:70