1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2021 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 #if defined(__WIN32__) 39 #include <process.h> /* _beginthreadex() and _endthreadex() */ 40 #endif 41 #if defined(__OS2__) /* for _beginthread() and _endthread() */ 42 #ifndef __EMX__ 43 #include <process.h> 44 #else 45 #include <stdlib.h> 46 #endif 47 #endif 48 49 #include "begin_code.h" 50 /* Set up for C function definitions, even when using C++ */ 51 #ifdef __cplusplus 52 extern "C" { 53 #endif 54 55 /* The SDL thread structure, defined in SDL_thread.c */ 56 struct SDL_Thread; 57 typedef struct SDL_Thread SDL_Thread; 58 59 /* The SDL thread ID */ 60 typedef unsigned long SDL_threadID; 61 62 /* Thread local storage ID, 0 is the invalid ID */ 63 typedef unsigned int SDL_TLSID; 64 65 /** 66 * The SDL thread priority. 67 * 68 * SDL will make system changes as necessary in order to apply the thread priority. 69 * Code which attempts to control thread state related to priority should be aware 70 * that calling SDL_SetThreadPriority may alter such state. 71 * SDL_HINT_THREAD_PRIORITY_POLICY can be used to control aspects of this behavior. 72 * 73 * \note On many systems you require special privileges to set high or time critical priority. 74 */ 75 typedef enum { 76 SDL_THREAD_PRIORITY_LOW, 77 SDL_THREAD_PRIORITY_NORMAL, 78 SDL_THREAD_PRIORITY_HIGH, 79 SDL_THREAD_PRIORITY_TIME_CRITICAL 80 } SDL_ThreadPriority; 81 82 /** 83 * The function passed to SDL_CreateThread(). 84 * 85 * \param data what was passed as `data` to SDL_CreateThread() 86 * \returns a value that can be reported through SDL_WaitThread(). 87 */ 88 typedef int (SDLCALL * SDL_ThreadFunction) (void *data); 89 90 91 #if defined(__WIN32__) 92 /** 93 * \file SDL_thread.h 94 * 95 * We compile SDL into a DLL. This means, that it's the DLL which 96 * creates a new thread for the calling process with the SDL_CreateThread() 97 * API. There is a problem with this, that only the RTL of the SDL2.DLL will 98 * be initialized for those threads, and not the RTL of the calling 99 * application! 100 * 101 * To solve this, we make a little hack here. 102 * 103 * We'll always use the caller's _beginthread() and _endthread() APIs to 104 * start a new thread. This way, if it's the SDL2.DLL which uses this API, 105 * then the RTL of SDL2.DLL will be used to create the new thread, and if it's 106 * the application, then the RTL of the application will be used. 107 * 108 * So, in short: 109 * Always use the _beginthread() and _endthread() of the calling runtime 110 * library! 111 */ 112 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD 113 114 typedef uintptr_t (__cdecl * pfnSDL_CurrentBeginThread) 115 (void *, unsigned, unsigned (__stdcall *func)(void *), 116 void * /*arg*/, unsigned, unsigned * /* threadID */); 117 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code); 118 119 #ifndef SDL_beginthread 120 #define SDL_beginthread _beginthreadex 121 #endif 122 #ifndef SDL_endthread 123 #define SDL_endthread _endthreadex 124 #endif 125 126 extern DECLSPEC SDL_Thread *SDLCALL 127 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data, 128 pfnSDL_CurrentBeginThread pfnBeginThread, 129 pfnSDL_CurrentEndThread pfnEndThread); 130 131 extern DECLSPEC SDL_Thread *SDLCALL 132 SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *), 133 const char *name, const size_t stacksize, void *data, 134 pfnSDL_CurrentBeginThread pfnBeginThread, 135 pfnSDL_CurrentEndThread pfnEndThread); 136 137 138 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API 139 #undef SDL_CreateThread 140 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 141 #undef SDL_CreateThreadWithStackSize 142 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 143 #else 144 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 145 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)SDL_endthread) 146 #endif 147 148 #elif defined(__OS2__) 149 /* 150 * just like the windows case above: We compile SDL2 151 * into a dll with Watcom's runtime statically linked. 152 */ 153 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD 154 155 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/); 156 typedef void (*pfnSDL_CurrentEndThread)(void); 157 158 #ifndef SDL_beginthread 159 #define SDL_beginthread _beginthread 160 #endif 161 #ifndef SDL_endthread 162 #define SDL_endthread _endthread 163 #endif 164 165 extern DECLSPEC SDL_Thread *SDLCALL 166 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data, 167 pfnSDL_CurrentBeginThread pfnBeginThread, 168 pfnSDL_CurrentEndThread pfnEndThread); 169 extern DECLSPEC SDL_Thread *SDLCALL 170 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data, 171 pfnSDL_CurrentBeginThread pfnBeginThread, 172 pfnSDL_CurrentEndThread pfnEndThread); 173 174 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API 175 #undef SDL_CreateThread 176 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 177 #undef SDL_CreateThreadWithStackSize 178 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 179 #else 180 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 181 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread) 182 #endif 183 184 #else 185 186 /** 187 * Create a new thread with a default stack size. 188 * 189 * This is equivalent to calling: 190 * 191 * ```c 192 * SDL_CreateThreadWithStackSize(fn, name, 0, data); 193 * ``` 194 * 195 * \param fn the SDL_ThreadFunction function to call in the new thread 196 * \param name the name of the thread 197 * \param data a pointer that is passed to `fn` 198 * \returns an opaque pointer to the new thread object on success, NULL if the 199 * new thread could not be created; call SDL_GetError() for more 200 * information. 201 * 202 * \since This function is available since SDL 2.0.0. 203 * 204 * \sa SDL_CreateThreadWithStackSize 205 * \sa SDL_WaitThread 206 */ 207 extern DECLSPEC SDL_Thread *SDLCALL 208 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data); 209 210 /** 211 * Create a new thread with a specific stack size. 212 * 213 * SDL makes an attempt to report `name` to the system, so that debuggers can 214 * display it. Not all platforms support this. 215 * 216 * Thread naming is a little complicated: Most systems have very small limits 217 * for the string length (Haiku has 32 bytes, Linux currently has 16, Visual 218 * C++ 6.0 has _nine_!), and possibly other arbitrary rules. You'll have to 219 * see what happens with your system's debugger. The name should be UTF-8 (but 220 * using the naming limits of C identifiers is a better bet). There are no 221 * requirements for thread naming conventions, so long as the string is 222 * null-terminated UTF-8, but these guidelines are helpful in choosing a name: 223 * 224 * https://stackoverflow.com/questions/149932/naming-conventions-for-threads 225 * 226 * If a system imposes requirements, SDL will try to munge the string for it 227 * (truncate, etc), but the original string contents will be available from 228 * SDL_GetThreadName(). 229 * 230 * The size (in bytes) of the new stack can be specified. Zero means "use the 231 * system default" which might be wildly different between platforms. x86 232 * Linux generally defaults to eight megabytes, an embedded device might be a 233 * few kilobytes instead. You generally need to specify a stack that is a 234 * multiple of the system's page size (in many cases, this is 4 kilobytes, but 235 * check your system documentation). 236 * 237 * In SDL 2.1, stack size will be folded into the original SDL_CreateThread 238 * function, but for backwards compatibility, this is currently a separate 239 * function. 240 * 241 * \param fn the SDL_ThreadFunction function to call in the new thread 242 * \param name the name of the thread 243 * \param stacksize the size, in bytes, to allocate for the new thread stack. 244 * \param data a pointer that is passed to `fn` 245 * \returns an opaque pointer to the new thread object on success, NULL if the 246 * new thread could not be created; call SDL_GetError() for more 247 * information. 248 * 249 * \since This function is available since SDL 2.0.9. 250 * 251 * \sa SDL_WaitThread 252 */ 253 extern DECLSPEC SDL_Thread *SDLCALL 254 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data); 255 256 #endif 257 258 /** 259 * Get the thread name as it was specified in SDL_CreateThread(). 260 * 261 * This is internal memory, not to be freed by the caller, and remains valid 262 * until the specified thread is cleaned up by SDL_WaitThread(). 263 * 264 * \param thread the thread to query 265 * \returns a pointer to a UTF-8 string that names the specified thread, or 266 * NULL if it doesn't have a name. 267 * 268 * \since This function is available since SDL 2.0.0. 269 * 270 * \sa SDL_CreateThread 271 */ 272 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread); 273 274 /** 275 * Get the thread identifier for the current thread. 276 * 277 * This thread identifier is as reported by the underlying operating system. 278 * If SDL is running on a platform that does not support threads the return 279 * value will always be zero. 280 * 281 * This function also returns a valid thread ID when called from the main 282 * thread. 283 * 284 * \returns the ID of the current thread. 285 * 286 * \since This function is available since SDL 2.0.0. 287 * 288 * \sa SDL_GetThreadID 289 */ 290 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void); 291 292 /** 293 * Get the thread identifier for the specified thread. 294 * 295 * This thread identifier is as reported by the underlying operating system. 296 * If SDL is running on a platform that does not support threads the return 297 * value will always be zero. 298 * 299 * \param thread the thread to query 300 * \returns the ID of the specified thread, or the ID of the current thread if 301 * `thread` is NULL. 302 * 303 * \since This function is available since SDL 2.0.0. 304 * 305 * \sa SDL_ThreadID 306 */ 307 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread); 308 309 /** 310 * Set the priority for the current thread. 311 * 312 * Note that some platforms will not let you alter the priority (or at least, 313 * promote the thread to a higher priority) at all, and some require you to be 314 * an administrator account. Be prepared for this to fail. 315 * 316 * \param priority the SDL_ThreadPriority to set 317 * \returns 0 on success or a negative error code on failure; call 318 * SDL_GetError() for more information. 319 * 320 * \since This function is available since SDL 2.0.0. 321 */ 322 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority); 323 324 /** 325 * Wait for a thread to finish. 326 * 327 * Threads that haven't been detached will remain (as a "zombie") until this 328 * function cleans them up. Not doing so is a resource leak. 329 * 330 * Once a thread has been cleaned up through this function, the SDL_Thread 331 * that references it becomes invalid and should not be referenced again. As 332 * such, only one thread may call SDL_WaitThread() on another. 333 * 334 * The return code for the thread function is placed in the area pointed to by 335 * `status`, if `status` is not NULL. 336 * 337 * You may not wait on a thread that has been used in a call to 338 * SDL_DetachThread(). Use either that function or this one, but not both, or 339 * behavior is undefined. 340 * 341 * It is safe to pass a NULL thread to this function; it is a no-op. 342 * 343 * Note that the thread pointer is freed by this function and is not valid 344 * afterward. 345 * 346 * \param thread the SDL_Thread pointer that was returned from the 347 * SDL_CreateThread() call that started this thread 348 * \param status pointer to an integer that will receive the value returned 349 * from the thread function by its 'return', or NULL to not 350 * receive such value back. 351 * 352 * \since This function is available since SDL 2.0.0. 353 * 354 * \sa SDL_CreateThread 355 * \sa SDL_DetachThread 356 */ 357 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status); 358 359 /** 360 * Let a thread clean up on exit without intervention. 361 * 362 * A thread may be "detached" to signify that it should not remain until 363 * another thread has called SDL_WaitThread() on it. Detaching a thread is 364 * useful for long-running threads that nothing needs to synchronize with or 365 * further manage. When a detached thread is done, it simply goes away. 366 * 367 * There is no way to recover the return code of a detached thread. If you 368 * need this, don't detach the thread and instead use SDL_WaitThread(). 369 * 370 * Once a thread is detached, you should usually assume the SDL_Thread isn't 371 * safe to reference again, as it will become invalid immediately upon the 372 * detached thread's exit, instead of remaining until someone has called 373 * SDL_WaitThread() to finally clean it up. As such, don't detach the same 374 * thread more than once. 375 * 376 * If a thread has already exited when passed to SDL_DetachThread(), it will 377 * stop waiting for a call to SDL_WaitThread() and clean up immediately. It is 378 * not safe to detach a thread that might be used with SDL_WaitThread(). 379 * 380 * You may not call SDL_WaitThread() on a thread that has been detached. Use 381 * either that function or this one, but not both, or behavior is undefined. 382 * 383 * It is safe to pass NULL to this function; it is a no-op. 384 * 385 * \param thread the SDL_Thread pointer that was returned from the 386 * SDL_CreateThread() call that started this thread 387 * 388 * \since This function is available since SDL 2.0.2. 389 * 390 * \sa SDL_CreateThread 391 * \sa SDL_WaitThread 392 */ 393 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread); 394 395 /** 396 * Create a piece of thread-local storage. 397 * 398 * This creates an identifier that is globally visible to all threads but 399 * refers to data that is thread-specific. 400 * 401 * \returns the newly created thread local storage identifier or 0 on error. 402 * 403 * \since This function is available since SDL 2.0.0. 404 * 405 * \sa SDL_TLSGet 406 * \sa SDL_TLSSet 407 */ 408 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void); 409 410 /** 411 * Get the current thread's value associated with a thread local storage ID. 412 * 413 * \param id the thread local storage ID 414 * \returns the value associated with the ID for the current thread or NULL if 415 * no value has been set; call SDL_GetError() for more information. 416 * 417 * \since This function is available since SDL 2.0.0. 418 * 419 * \sa SDL_TLSCreate 420 * \sa SDL_TLSSet 421 */ 422 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id); 423 424 /** 425 * Set the current thread's value associated with a thread local storage ID. 426 * 427 * The function prototype for `destructor` is: 428 * 429 * ```c 430 * void destructor(void *value) 431 * ``` 432 * 433 * where its parameter `value` is what was passed as `value` to SDL_TLSSet(). 434 * 435 * \param id the thread local storage ID 436 * \param value the value to associate with the ID for the current thread 437 * \param destructor a function called when the thread exits, to free the 438 * value 439 * \returns 0 on success or a negative error code on failure; call 440 * SDL_GetError() for more information. 441 * 442 * \since This function is available since SDL 2.0.0. 443 * 444 * \sa SDL_TLSCreate 445 * \sa SDL_TLSGet 446 */ 447 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*)); 448 449 /** 450 * Cleanup all TLS data for this thread. 451 * 452 * \since This function is available since SDL 2.0.16. 453 */ 454 extern DECLSPEC void SDLCALL SDL_TLSCleanup(void); 455 456 /* Ends C function definitions when using C++ */ 457 #ifdef __cplusplus 458 } 459 #endif 460 #include "close_code.h" 461 462 #endif /* SDL_thread_h_ */ 463 464 /* vi: set ts=4 sw=4 expandtab: */ 465