SDL_thread.h (13574B)
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 * SDL will make system changes as necessary in order to apply the thread priority. 58 * Code which attempts to control thread state related to priority should be aware 59 * that calling SDL_SetThreadPriority may alter such state. 60 * SDL_HINT_THREAD_PRIORITY_POLICY can be used to control aspects of this behavior. 61 * 62 * \note On many systems you require special privileges to set high or time critical priority. 63 */ 64 typedef enum { 65 SDL_THREAD_PRIORITY_LOW, 66 SDL_THREAD_PRIORITY_NORMAL, 67 SDL_THREAD_PRIORITY_HIGH, 68 SDL_THREAD_PRIORITY_TIME_CRITICAL 69 } SDL_ThreadPriority; 70 71 /** 72 * The function passed to SDL_CreateThread(). 73 * It is passed a void* user context parameter and returns an int. 74 */ 75 typedef int (SDLCALL * SDL_ThreadFunction) (void *data); 76 77 #if defined(__WIN32__) 78 /** 79 * \file SDL_thread.h 80 * 81 * We compile SDL into a DLL. This means, that it's the DLL which 82 * creates a new thread for the calling process with the SDL_CreateThread() 83 * API. There is a problem with this, that only the RTL of the SDL2.DLL will 84 * be initialized for those threads, and not the RTL of the calling 85 * application! 86 * 87 * To solve this, we make a little hack here. 88 * 89 * We'll always use the caller's _beginthread() and _endthread() APIs to 90 * start a new thread. This way, if it's the SDL2.DLL which uses this API, 91 * then the RTL of SDL2.DLL will be used to create the new thread, and if it's 92 * the application, then the RTL of the application will be used. 93 * 94 * So, in short: 95 * Always use the _beginthread() and _endthread() of the calling runtime 96 * library! 97 */ 98 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD 99 #include <process.h> /* _beginthreadex() and _endthreadex() */ 100 101 typedef uintptr_t (__cdecl * pfnSDL_CurrentBeginThread) 102 (void *, unsigned, unsigned (__stdcall *func)(void *), 103 void * /*arg*/, unsigned, unsigned * /* threadID */); 104 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code); 105 106 #ifndef SDL_beginthread 107 #define SDL_beginthread _beginthreadex 108 #endif 109 #ifndef SDL_endthread 110 #define SDL_endthread _endthreadex 111 #endif 112 113 /** 114 * Create a thread. 115 */ 116 extern DECLSPEC SDL_Thread *SDLCALL 117 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data, 118 pfnSDL_CurrentBeginThread pfnBeginThread, 119 pfnSDL_CurrentEndThread pfnEndThread); 120 121 extern DECLSPEC SDL_Thread *SDLCALL 122 SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *), 123 const char *name, const size_t stacksize, void *data, 124 pfnSDL_CurrentBeginThread pfnBeginThread, 125 pfnSDL_CurrentEndThread pfnEndThread); 126 127 128 /** 129 * Create a thread. 130 */ 131 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API 132 #undef SDL_CreateThread 133 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 134 #undef SDL_CreateThreadWithStackSize 135 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 136 #else 137 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 138 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)SDL_endthread) 139 #endif 140 141 #elif defined(__OS2__) 142 /* 143 * just like the windows case above: We compile SDL2 144 * into a dll with Watcom's runtime statically linked. 145 */ 146 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD 147 148 #ifndef __EMX__ 149 #include <process.h> 150 #else 151 #include <stdlib.h> 152 #endif 153 154 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/); 155 typedef void (*pfnSDL_CurrentEndThread)(void); 156 157 #ifndef SDL_beginthread 158 #define SDL_beginthread _beginthread 159 #endif 160 #ifndef SDL_endthread 161 #define SDL_endthread _endthread 162 #endif 163 164 extern DECLSPEC SDL_Thread *SDLCALL 165 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data, 166 pfnSDL_CurrentBeginThread pfnBeginThread, 167 pfnSDL_CurrentEndThread pfnEndThread); 168 extern DECLSPEC SDL_Thread *SDLCALL 169 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data, 170 pfnSDL_CurrentBeginThread pfnBeginThread, 171 pfnSDL_CurrentEndThread pfnEndThread); 172 173 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API 174 #undef SDL_CreateThread 175 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 176 #undef SDL_CreateThreadWithStackSize 177 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 178 #else 179 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 180 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 181 #endif 182 183 #else 184 185 /** 186 * Create a thread with a default stack size. 187 * 188 * This is equivalent to calling: 189 * SDL_CreateThreadWithStackSize(fn, name, 0, data); 190 */ 191 extern DECLSPEC SDL_Thread *SDLCALL 192 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data); 193 194 /** 195 * Create a thread. 196 * 197 * Thread naming is a little complicated: Most systems have very small 198 * limits for the string length (Haiku has 32 bytes, Linux currently has 16, 199 * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll 200 * have to see what happens with your system's debugger. The name should be 201 * UTF-8 (but using the naming limits of C identifiers is a better bet). 202 * There are no requirements for thread naming conventions, so long as the 203 * string is null-terminated UTF-8, but these guidelines are helpful in 204 * choosing a name: 205 * 206 * http://stackoverflow.com/questions/149932/naming-conventions-for-threads 207 * 208 * If a system imposes requirements, SDL will try to munge the string for 209 * it (truncate, etc), but the original string contents will be available 210 * from SDL_GetThreadName(). 211 * 212 * The size (in bytes) of the new stack can be specified. Zero means "use 213 * the system default" which might be wildly different between platforms 214 * (x86 Linux generally defaults to eight megabytes, an embedded device 215 * might be a few kilobytes instead). 216 * 217 * In SDL 2.1, stacksize will be folded into the original SDL_CreateThread 218 * function. 219 */ 220 extern DECLSPEC SDL_Thread *SDLCALL 221 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data); 222 223 #endif 224 225 /** 226 * Get the thread name, as it was specified in SDL_CreateThread(). 227 * This function returns a pointer to a UTF-8 string that names the 228 * specified thread, or NULL if it doesn't have a name. This is internal 229 * memory, not to be free()'d by the caller, and remains valid until the 230 * specified thread is cleaned up by SDL_WaitThread(). 231 */ 232 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread); 233 234 /** 235 * Get the thread identifier for the current thread. 236 */ 237 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void); 238 239 /** 240 * Get the thread identifier for the specified thread. 241 * 242 * Equivalent to SDL_ThreadID() if the specified thread is NULL. 243 */ 244 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread); 245 246 /** 247 * Set the priority for the current thread 248 */ 249 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority); 250 251 /** 252 * Wait for a thread to finish. Threads that haven't been detached will 253 * remain (as a "zombie") until this function cleans them up. Not doing so 254 * is a resource leak. 255 * 256 * Once a thread has been cleaned up through this function, the SDL_Thread 257 * that references it becomes invalid and should not be referenced again. 258 * As such, only one thread may call SDL_WaitThread() on another. 259 * 260 * The return code for the thread function is placed in the area 261 * pointed to by \c status, if \c status is not NULL. 262 * 263 * You may not wait on a thread that has been used in a call to 264 * SDL_DetachThread(). Use either that function or this one, but not 265 * both, or behavior is undefined. 266 * 267 * It is safe to pass NULL to this function; it is a no-op. 268 */ 269 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status); 270 271 /** 272 * A thread may be "detached" to signify that it should not remain until 273 * another thread has called SDL_WaitThread() on it. Detaching a thread 274 * is useful for long-running threads that nothing needs to synchronize 275 * with or further manage. When a detached thread is done, it simply 276 * goes away. 277 * 278 * There is no way to recover the return code of a detached thread. If you 279 * need this, don't detach the thread and instead use SDL_WaitThread(). 280 * 281 * Once a thread is detached, you should usually assume the SDL_Thread isn't 282 * safe to reference again, as it will become invalid immediately upon 283 * the detached thread's exit, instead of remaining until someone has called 284 * SDL_WaitThread() to finally clean it up. As such, don't detach the same 285 * thread more than once. 286 * 287 * If a thread has already exited when passed to SDL_DetachThread(), it will 288 * stop waiting for a call to SDL_WaitThread() and clean up immediately. 289 * It is not safe to detach a thread that might be used with SDL_WaitThread(). 290 * 291 * You may not call SDL_WaitThread() on a thread that has been detached. 292 * Use either that function or this one, but not both, or behavior is 293 * undefined. 294 * 295 * It is safe to pass NULL to this function; it is a no-op. 296 */ 297 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread); 298 299 /** 300 * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific. 301 * 302 * \return The newly created thread local storage identifier, or 0 on error 303 * 304 * \code 305 * static SDL_SpinLock tls_lock; 306 * static SDL_TLSID thread_local_storage; 307 * 308 * void SetMyThreadData(void *value) 309 * { 310 * if (!thread_local_storage) { 311 * SDL_AtomicLock(&tls_lock); 312 * if (!thread_local_storage) { 313 * thread_local_storage = SDL_TLSCreate(); 314 * } 315 * SDL_AtomicUnlock(&tls_lock); 316 * } 317 * SDL_TLSSet(thread_local_storage, value, 0); 318 * } 319 * 320 * void *GetMyThreadData(void) 321 * { 322 * return SDL_TLSGet(thread_local_storage); 323 * } 324 * \endcode 325 * 326 * \sa SDL_TLSGet() 327 * \sa SDL_TLSSet() 328 */ 329 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void); 330 331 /** 332 * \brief Get the value associated with a thread local storage ID for the current thread. 333 * 334 * \param id The thread local storage ID 335 * 336 * \return The value associated with the ID for the current thread, or NULL if no value has been set. 337 * 338 * \sa SDL_TLSCreate() 339 * \sa SDL_TLSSet() 340 */ 341 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id); 342 343 /** 344 * \brief Set the value associated with a thread local storage ID for the current thread. 345 * 346 * \param id The thread local storage ID 347 * \param value The value to associate with the ID for the current thread 348 * \param destructor A function called when the thread exits, to free the value. 349 * 350 * \return 0 on success, -1 on error 351 * 352 * \sa SDL_TLSCreate() 353 * \sa SDL_TLSGet() 354 */ 355 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*)); 356 357 358 /* Ends C function definitions when using C++ */ 359 #ifdef __cplusplus 360 } 361 #endif 362 #include "close_code.h" 363 364 #endif /* SDL_thread_h_ */ 365 366 /* vi: set ts=4 sw=4 expandtab: */