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
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
41extern "C" {
42#endif
43
44/* The SDL thread structure, defined in SDL_thread.c */
45struct SDL_Thread;
46typedef struct SDL_Thread SDL_Thread;
47
48/* The SDL thread ID */
49typedef unsigned long SDL_threadID;
50
51/* Thread local storage ID, 0 is the invalid ID */
52typedef 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 */
59typedef enum {
60 SDL_THREAD_PRIORITY_LOW,
61 SDL_THREAD_PRIORITY_NORMAL,
62 SDL_THREAD_PRIORITY_HIGH,
63 SDL_THREAD_PRIORITY_TIME_CRITICAL
64} SDL_ThreadPriority;
65
66/**
67 * The function passed to SDL_CreateThread().
68 * It is passed a void* user context parameter and returns an int.
69 */
70typedef 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
96typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
97 (void *, unsigned, unsigned (__stdcall *func)(void *),
98 void * /*arg*/, unsigned, unsigned * /* threadID */);
99typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
100
101/**
102 * Create a thread.
103 */
104extern DECLSPEC SDL_Thread *SDLCALL
105SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
106 pfnSDL_CurrentBeginThread pfnBeginThread,
107 pfnSDL_CurrentEndThread pfnEndThread);
108
109extern DECLSPEC SDL_Thread *SDLCALL
110SDL_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
140typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
141typedef void (*pfnSDL_CurrentEndThread)(void);
142extern DECLSPEC SDL_Thread *SDLCALL
143SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
144 pfnSDL_CurrentBeginThread pfnBeginThread,
145 pfnSDL_CurrentEndThread pfnEndThread);
146extern DECLSPEC SDL_Thread *SDLCALL
147SDL_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 */
168extern DECLSPEC SDL_Thread *SDLCALL
169SDL_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 */
197extern DECLSPEC SDL_Thread *SDLCALL
198SDL_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 */
209extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
210
211/**
212 * Get the thread identifier for the current thread.
213 */
214extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
215
216/**
217 * Get the thread identifier for the specified thread.
218 *
219 * Equivalent to SDL_ThreadID() if the specified thread is NULL.
220 */
221extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
222
223/**
224 * Set the priority for the current thread
225 */
226extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
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 */
246extern 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 */
274extern 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 */
306extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
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 */
318extern 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 */
332extern 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: */
344