SDL  2.0
SDL_thread.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2019 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__) && !defined(HAVE_LIBC)
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 
96 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
97  (void *, unsigned, unsigned (__stdcall *func)(void *),
98  void * /*arg*/, unsigned, unsigned * /* threadID */);
99 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
100 
101 /**
102  * Create a thread.
103  */
105 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
106  pfnSDL_CurrentBeginThread pfnBeginThread,
107  pfnSDL_CurrentEndThread pfnEndThread);
108 
110 SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *),
111  const char *name, const size_t stacksize, void *data,
112  pfnSDL_CurrentBeginThread pfnBeginThread,
113  pfnSDL_CurrentEndThread pfnEndThread);
114 
115 
116 /**
117  * Create a thread.
118  */
119 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
120 #undef SDL_CreateThread
121 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
122 #undef SDL_CreateThreadWithStackSize
123 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
124 #else
125 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
126 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
127 #endif
128 
129 #elif defined(__OS2__)
130 /*
131  * just like the windows case above: We compile SDL2
132  * into a dll with Watcom's runtime statically linked.
133  */
134 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
135 #ifndef __EMX__
136 #include <process.h>
137 #else
138 #include <stdlib.h>
139 #endif
140 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
141 typedef void (*pfnSDL_CurrentEndThread)(void);
143 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
144  pfnSDL_CurrentBeginThread pfnBeginThread,
145  pfnSDL_CurrentEndThread pfnEndThread);
147 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
148  pfnSDL_CurrentBeginThread pfnBeginThread,
149  pfnSDL_CurrentEndThread pfnEndThread);
150 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
151 #undef SDL_CreateThread
152 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
153 #undef SDL_CreateThreadWithStackSize
154 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
155 #else
156 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
157 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
158 #endif
159 
160 #else
161 
162 /**
163  * Create a thread with a default stack size.
164  *
165  * This is equivalent to calling:
166  * SDL_CreateThreadWithStackSize(fn, name, 0, data);
167  */
169 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
170 
171 /**
172  * Create a thread.
173  *
174  * Thread naming is a little complicated: Most systems have very small
175  * limits for the string length (Haiku has 32 bytes, Linux currently has 16,
176  * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
177  * have to see what happens with your system's debugger. The name should be
178  * UTF-8 (but using the naming limits of C identifiers is a better bet).
179  * There are no requirements for thread naming conventions, so long as the
180  * string is null-terminated UTF-8, but these guidelines are helpful in
181  * choosing a name:
182  *
183  * http://stackoverflow.com/questions/149932/naming-conventions-for-threads
184  *
185  * If a system imposes requirements, SDL will try to munge the string for
186  * it (truncate, etc), but the original string contents will be available
187  * from SDL_GetThreadName().
188  *
189  * The size (in bytes) of the new stack can be specified. Zero means "use
190  * the system default" which might be wildly different between platforms
191  * (x86 Linux generally defaults to eight megabytes, an embedded device
192  * might be a few kilobytes instead).
193  *
194  * In SDL 2.1, stacksize will be folded into the original SDL_CreateThread
195  * function.
196  */
198 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
199 
200 #endif
201 
202 /**
203  * Get the thread name, as it was specified in SDL_CreateThread().
204  * This function returns a pointer to a UTF-8 string that names the
205  * specified thread, or NULL if it doesn't have a name. This is internal
206  * memory, not to be free()'d by the caller, and remains valid until the
207  * specified thread is cleaned up by SDL_WaitThread().
208  */
209 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
210 
211 /**
212  * Get the thread identifier for the current thread.
213  */
215 
216 /**
217  * Get the thread identifier for the specified thread.
218  *
219  * Equivalent to SDL_ThreadID() if the specified thread is NULL.
220  */
222 
223 /**
224  * Set the priority for the current thread
225  */
227 
228 /**
229  * Wait for a thread to finish. Threads that haven't been detached will
230  * remain (as a "zombie") until this function cleans them up. Not doing so
231  * is a resource leak.
232  *
233  * Once a thread has been cleaned up through this function, the SDL_Thread
234  * that references it becomes invalid and should not be referenced again.
235  * As such, only one thread may call SDL_WaitThread() on another.
236  *
237  * The return code for the thread function is placed in the area
238  * pointed to by \c status, if \c status is not NULL.
239  *
240  * You may not wait on a thread that has been used in a call to
241  * SDL_DetachThread(). Use either that function or this one, but not
242  * both, or behavior is undefined.
243  *
244  * It is safe to pass NULL to this function; it is a no-op.
245  */
246 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
247 
248 /**
249  * A thread may be "detached" to signify that it should not remain until
250  * another thread has called SDL_WaitThread() on it. Detaching a thread
251  * is useful for long-running threads that nothing needs to synchronize
252  * with or further manage. When a detached thread is done, it simply
253  * goes away.
254  *
255  * There is no way to recover the return code of a detached thread. If you
256  * need this, don't detach the thread and instead use SDL_WaitThread().
257  *
258  * Once a thread is detached, you should usually assume the SDL_Thread isn't
259  * safe to reference again, as it will become invalid immediately upon
260  * the detached thread's exit, instead of remaining until someone has called
261  * SDL_WaitThread() to finally clean it up. As such, don't detach the same
262  * thread more than once.
263  *
264  * If a thread has already exited when passed to SDL_DetachThread(), it will
265  * stop waiting for a call to SDL_WaitThread() and clean up immediately.
266  * It is not safe to detach a thread that might be used with SDL_WaitThread().
267  *
268  * You may not call SDL_WaitThread() on a thread that has been detached.
269  * Use either that function or this one, but not both, or behavior is
270  * undefined.
271  *
272  * It is safe to pass NULL to this function; it is a no-op.
273  */
274 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
275 
276 /**
277  * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
278  *
279  * \return The newly created thread local storage identifier, or 0 on error
280  *
281  * \code
282  * static SDL_SpinLock tls_lock;
283  * static SDL_TLSID thread_local_storage;
284  *
285  * void SetMyThreadData(void *value)
286  * {
287  * if (!thread_local_storage) {
288  * SDL_AtomicLock(&tls_lock);
289  * if (!thread_local_storage) {
290  * thread_local_storage = SDL_TLSCreate();
291  * }
292  * SDL_AtomicUnlock(&tls_lock);
293  * }
294  * SDL_TLSSet(thread_local_storage, value, 0);
295  * }
296  *
297  * void *GetMyThreadData(void)
298  * {
299  * return SDL_TLSGet(thread_local_storage);
300  * }
301  * \endcode
302  *
303  * \sa SDL_TLSGet()
304  * \sa SDL_TLSSet()
305  */
307 
308 /**
309  * \brief Get the value associated with a thread local storage ID for the current thread.
310  *
311  * \param id The thread local storage ID
312  *
313  * \return The value associated with the ID for the current thread, or NULL if no value has been set.
314  *
315  * \sa SDL_TLSCreate()
316  * \sa SDL_TLSSet()
317  */
318 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
319 
320 /**
321  * \brief Set the value associated with a thread local storage ID for the current thread.
322  *
323  * \param id The thread local storage ID
324  * \param value The value to associate with the ID for the current thread
325  * \param destructor A function called when the thread exits, to free the value.
326  *
327  * \return 0 on success, -1 on error
328  *
329  * \sa SDL_TLSCreate()
330  * \sa SDL_TLSGet()
331  */
332 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
333 
334 
335 /* Ends C function definitions when using C++ */
336 #ifdef __cplusplus
337 }
338 #endif
339 #include "close_code.h"
340 
341 #endif /* SDL_thread_h_ */
342 
343 /* vi: set ts=4 sw=4 expandtab: */
SDL_GetThreadName
const char * SDL_GetThreadName(SDL_Thread *thread)
Definition: SDL_thread.c:452
DECLSPEC
#define DECLSPEC
Definition: SDL_internal.h:48
SDL_TLSID
unsigned int SDL_TLSID
Definition: SDL_thread.h:52
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_ThreadFunction
int(* SDL_ThreadFunction)(void *data)
Definition: SDL_thread.h:70
SDL_atomic.h
SDL_SetThreadPriority
int SDL_SetThreadPriority(SDL_ThreadPriority priority)
Definition: SDL_thread.c:462
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_Thread::status
int status
Definition: SDL_thread_c.h:58
SDL_Thread
Definition: SDL_thread_c.h:54
SDL_THREAD_PRIORITY_LOW
@ SDL_THREAD_PRIORITY_LOW
Definition: SDL_thread.h:60
func
GLenum func
Definition: SDL_opengl_glext.h:657
close_code.h
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
begin_code.h
SDL_CreateThreadWithStackSize
SDL_Thread * SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data)
SDL_DetachThread
void SDL_DetachThread(SDL_Thread *thread)
Definition: SDL_thread.c:483
SDL_CreateThread
SDL_Thread * SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data)
SDL_mutex.h
name
GLuint const GLchar * name
Definition: SDL_opengl_glext.h:660
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:468
SDL_threadID
unsigned long SDL_threadID
Definition: SDL_thread.h:49
SDL_GetThreadID
SDL_threadID SDL_GetThreadID(SDL_Thread *thread)
Definition: SDL_thread.c:439
value
GLsizei const GLfloat * value
Definition: SDL_opengl_glext.h:698
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
const SDL_PRINTF_FORMAT_STRING char int const SDL_PRINTF_FORMAT_STRING char int const SDL_PRINTF_FORMAT_STRING char int const SDL_PRINTF_FORMAT_STRING char const char const SDL_SCANF_FORMAT_STRING 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