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 priority.
58 */
59typedef enum {
60 SDL_THREAD_PRIORITY_LOW,
61 SDL_THREAD_PRIORITY_NORMAL,
62 SDL_THREAD_PRIORITY_HIGH
63} SDL_ThreadPriority;
64
65/**
66 * The function passed to SDL_CreateThread().
67 * It is passed a void* user context parameter and returns an int.
68 */
69typedef 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> /* _beginthreadex() and _endthreadex() */
94
95typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
96 (void *, unsigned, unsigned (__stdcall *func)(void *),
97 void * /*arg*/, unsigned, unsigned * /* threadID */);
98typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
99
100/**
101 * Create a thread.
102 */
103extern DECLSPEC SDL_Thread *SDLCALL
104SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
105 pfnSDL_CurrentBeginThread pfnBeginThread,
106 pfnSDL_CurrentEndThread pfnEndThread);
107
108/**
109 * Create a thread.
110 */
111#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
112#undef SDL_CreateThread
113#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
114#else
115#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
116#endif
117
118#elif defined(__OS2__)
119/*
120 * just like the windows case above: We compile SDL2
121 * into a dll with Watcom's runtime statically linked.
122 */
123#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
124#ifndef __EMX__
125#include <process.h>
126#else
127#include <stdlib.h>
128#endif
129typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
130typedef void (*pfnSDL_CurrentEndThread)(void);
131extern DECLSPEC SDL_Thread *SDLCALL
132SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
133 pfnSDL_CurrentBeginThread pfnBeginThread,
134 pfnSDL_CurrentEndThread pfnEndThread);
135#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
136#undef SDL_CreateThread
137#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
138#else
139#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
140#endif
141
142#else
143
144/**
145 * Create a thread.
146 *
147 * Thread naming is a little complicated: Most systems have very small
148 * limits for the string length (Haiku has 32 bytes, Linux currently has 16,
149 * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
150 * have to see what happens with your system's debugger. The name should be
151 * UTF-8 (but using the naming limits of C identifiers is a better bet).
152 * There are no requirements for thread naming conventions, so long as the
153 * string is null-terminated UTF-8, but these guidelines are helpful in
154 * choosing a name:
155 *
156 * http://stackoverflow.com/questions/149932/naming-conventions-for-threads
157 *
158 * If a system imposes requirements, SDL will try to munge the string for
159 * it (truncate, etc), but the original string contents will be available
160 * from SDL_GetThreadName().
161 */
162extern DECLSPEC SDL_Thread *SDLCALL
163SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
164
165#endif
166
167/**
168 * Get the thread name, as it was specified in SDL_CreateThread().
169 * This function returns a pointer to a UTF-8 string that names the
170 * specified thread, or NULL if it doesn't have a name. This is internal
171 * memory, not to be free()'d by the caller, and remains valid until the
172 * specified thread is cleaned up by SDL_WaitThread().
173 */
174extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
175
176/**
177 * Get the thread identifier for the current thread.
178 */
179extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
180
181/**
182 * Get the thread identifier for the specified thread.
183 *
184 * Equivalent to SDL_ThreadID() if the specified thread is NULL.
185 */
186extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
187
188/**
189 * Set the priority for the current thread
190 */
191extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
192
193/**
194 * Wait for a thread to finish. Threads that haven't been detached will
195 * remain (as a "zombie") until this function cleans them up. Not doing so
196 * is a resource leak.
197 *
198 * Once a thread has been cleaned up through this function, the SDL_Thread
199 * that references it becomes invalid and should not be referenced again.
200 * As such, only one thread may call SDL_WaitThread() on another.
201 *
202 * The return code for the thread function is placed in the area
203 * pointed to by \c status, if \c status is not NULL.
204 *
205 * You may not wait on a thread that has been used in a call to
206 * SDL_DetachThread(). Use either that function or this one, but not
207 * both, or behavior is undefined.
208 *
209 * It is safe to pass NULL to this function; it is a no-op.
210 */
211extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
212
213/**
214 * A thread may be "detached" to signify that it should not remain until
215 * another thread has called SDL_WaitThread() on it. Detaching a thread
216 * is useful for long-running threads that nothing needs to synchronize
217 * with or further manage. When a detached thread is done, it simply
218 * goes away.
219 *
220 * There is no way to recover the return code of a detached thread. If you
221 * need this, don't detach the thread and instead use SDL_WaitThread().
222 *
223 * Once a thread is detached, you should usually assume the SDL_Thread isn't
224 * safe to reference again, as it will become invalid immediately upon
225 * the detached thread's exit, instead of remaining until someone has called
226 * SDL_WaitThread() to finally clean it up. As such, don't detach the same
227 * thread more than once.
228 *
229 * If a thread has already exited when passed to SDL_DetachThread(), it will
230 * stop waiting for a call to SDL_WaitThread() and clean up immediately.
231 * It is not safe to detach a thread that might be used with SDL_WaitThread().
232 *
233 * You may not call SDL_WaitThread() on a thread that has been detached.
234 * Use either that function or this one, but not both, or behavior is
235 * undefined.
236 *
237 * It is safe to pass NULL to this function; it is a no-op.
238 */
239extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
240
241/**
242 * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
243 *
244 * \return The newly created thread local storage identifier, or 0 on error
245 *
246 * \code
247 * static SDL_SpinLock tls_lock;
248 * static SDL_TLSID thread_local_storage;
249 *
250 * void SetMyThreadData(void *value)
251 * {
252 * if (!thread_local_storage) {
253 * SDL_AtomicLock(&tls_lock);
254 * if (!thread_local_storage) {
255 * thread_local_storage = SDL_TLSCreate();
256 * }
257 * SDL_AtomicUnlock(&tls_lock);
258 * }
259 * SDL_TLSSet(thread_local_storage, value, 0);
260 * }
261 *
262 * void *GetMyThreadData(void)
263 * {
264 * return SDL_TLSGet(thread_local_storage);
265 * }
266 * \endcode
267 *
268 * \sa SDL_TLSGet()
269 * \sa SDL_TLSSet()
270 */
271extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
272
273/**
274 * \brief Get the value associated with a thread local storage ID for the current thread.
275 *
276 * \param id The thread local storage ID
277 *
278 * \return The value associated with the ID for the current thread, or NULL if no value has been set.
279 *
280 * \sa SDL_TLSCreate()
281 * \sa SDL_TLSSet()
282 */
283extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
284
285/**
286 * \brief Set the value associated with a thread local storage ID for the current thread.
287 *
288 * \param id The thread local storage ID
289 * \param value The value to associate with the ID for the current thread
290 * \param destructor A function called when the thread exits, to free the value.
291 *
292 * \return 0 on success, -1 on error
293 *
294 * \sa SDL_TLSCreate()
295 * \sa SDL_TLSGet()
296 */
297extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
298
299
300/* Ends C function definitions when using C++ */
301#ifdef __cplusplus
302}
303#endif
304#include "close_code.h"
305
306#endif /* SDL_thread_h_ */
307
308/* vi: set ts=4 sw=4 expandtab: */
309