1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2014 Sam Lantinga <slouken (at) 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 priority. 58 */ 59 typedef 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 */ 69 typedef 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 SDL.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 SDL.DLL which uses this API, 85 * then the RTL of SDL.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> /* This has _beginthread() and _endthread() defined! */ 94 95 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread) (void *, unsigned, 96 unsigned (__stdcall * 97 func) (void 98 *), 99 void *arg, unsigned, 100 unsigned *threadID); 101 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code); 102 103 /** 104 * Create a thread. 105 */ 106 extern DECLSPEC SDL_Thread *SDLCALL 107 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data, 108 pfnSDL_CurrentBeginThread pfnBeginThread, 109 pfnSDL_CurrentEndThread pfnEndThread); 110 111 /** 112 * Create a thread. 113 */ 114 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API 115 #undef SDL_CreateThread 116 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex) 117 #else 118 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex) 119 #endif 120 121 #else 122 123 /** 124 * Create a thread. 125 * 126 * Thread naming is a little complicated: Most systems have very small 127 * limits for the string length (Haiku has 32 bytes, Linux currently has 16, 128 * Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll 129 * have to see what happens with your system's debugger. The name should be 130 * UTF-8 (but using the naming limits of C identifiers is a better bet). 131 * There are no requirements for thread naming conventions, so long as the 132 * string is null-terminated UTF-8, but these guidelines are helpful in 133 * choosing a name: 134 * 135 * http://stackoverflow.com/questions/149932/naming-conventions-for-threads 136 * 137 * If a system imposes requirements, SDL will try to munge the string for 138 * it (truncate, etc), but the original string contents will be available 139 * from SDL_GetThreadName(). 140 */ 141 extern DECLSPEC SDL_Thread *SDLCALL 142 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data); 143 144 #endif 145 146 /** 147 * Get the thread name, as it was specified in SDL_CreateThread(). 148 * This function returns a pointer to a UTF-8 string that names the 149 * specified thread, or NULL if it doesn't have a name. This is internal 150 * memory, not to be free()'d by the caller, and remains valid until the 151 * specified thread is cleaned up by SDL_WaitThread(). 152 */ 153 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread); 154 155 /** 156 * Get the thread identifier for the current thread. 157 */ 158 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void); 159 160 /** 161 * Get the thread identifier for the specified thread. 162 * 163 * Equivalent to SDL_ThreadID() if the specified thread is NULL. 164 */ 165 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread); 166 167 /** 168 * Set the priority for the current thread 169 */ 170 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority); 171 172 /** 173 * Wait for a thread to finish. Threads that haven't been detached will 174 * remain (as a "zombie") until this function cleans them up. Not doing so 175 * is a resource leak. 176 * 177 * Once a thread has been cleaned up through this function, the SDL_Thread 178 * that references it becomes invalid and should not be referenced again. 179 * As such, only one thread may call SDL_WaitThread() on another. 180 * 181 * The return code for the thread function is placed in the area 182 * pointed to by \c status, if \c status is not NULL. 183 * 184 * You may not wait on a thread that has been used in a call to 185 * SDL_DetachThread(). Use either that function or this one, but not 186 * both, or behavior is undefined. 187 * 188 * It is safe to pass NULL to this function; it is a no-op. 189 */ 190 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status); 191 192 /** 193 * A thread may be "detached" to signify that it should not remain until 194 * another thread has called SDL_WaitThread() on it. Detaching a thread 195 * is useful for long-running threads that nothing needs to synchronize 196 * with or further manage. When a detached thread is done, it simply 197 * goes away. 198 * 199 * There is no way to recover the return code of a detached thread. If you 200 * need this, don't detach the thread and instead use SDL_WaitThread(). 201 * 202 * Once a thread is detached, you should usually assume the SDL_Thread isn't 203 * safe to reference again, as it will become invalid immediately upon 204 * the detached thread's exit, instead of remaining until someone has called 205 * SDL_WaitThread() to finally clean it up. As such, don't detach the same 206 * thread more than once. 207 * 208 * If a thread has already exited when passed to SDL_DetachThread(), it will 209 * stop waiting for a call to SDL_WaitThread() and clean up immediately. 210 * It is not safe to detach a thread that might be used with SDL_WaitThread(). 211 * 212 * You may not call SDL_WaitThread() on a thread that has been detached. 213 * Use either that function or this one, but not both, or behavior is 214 * undefined. 215 * 216 * It is safe to pass NULL to this function; it is a no-op. 217 */ 218 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread); 219 220 /** 221 * \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific. 222 * 223 * \return The newly created thread local storage identifier, or 0 on error 224 * 225 * \code 226 * static SDL_SpinLock tls_lock; 227 * static SDL_TLSID thread_local_storage; 228 * 229 * void SetMyThreadData(void *value) 230 * { 231 * if (!thread_local_storage) { 232 * SDL_AtomicLock(&tls_lock); 233 * if (!thread_local_storage) { 234 * thread_local_storage = SDL_TLSCreate(); 235 * } 236 * SDL_AtomicUnLock(&tls_lock); 237 * } 238 * SDL_TLSSet(thread_local_storage, value); 239 * } 240 * 241 * void *GetMyThreadData(void) 242 * { 243 * return SDL_TLSGet(thread_local_storage); 244 * } 245 * \endcode 246 * 247 * \sa SDL_TLSGet() 248 * \sa SDL_TLSSet() 249 */ 250 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void); 251 252 /** 253 * \brief Get the value associated with a thread local storage ID for the current thread. 254 * 255 * \param id The thread local storage ID 256 * 257 * \return The value associated with the ID for the current thread, or NULL if no value has been set. 258 * 259 * \sa SDL_TLSCreate() 260 * \sa SDL_TLSSet() 261 */ 262 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id); 263 264 /** 265 * \brief Set the value associated with a thread local storage ID for the current thread. 266 * 267 * \param id The thread local storage ID 268 * \param value The value to associate with the ID for the current thread 269 * \param destructor A function called when the thread exits, to free the value. 270 * 271 * \return 0 on success, -1 on error 272 * 273 * \sa SDL_TLSCreate() 274 * \sa SDL_TLSGet() 275 */ 276 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (*destructor)(void*)); 277 278 279 /* Ends C function definitions when using C++ */ 280 #ifdef __cplusplus 281 } 282 #endif 283 #include "close_code.h" 284 285 #endif /* _SDL_thread_h */ 286 287 /* vi: set ts=4 sw=4 expandtab: */ 288
