include/SDL_thread.h
author Manuel Alfayate Corchete <redwindwanderer@gmail.com>
Mon, 03 Aug 2020 22:24:49 +0200
changeset 13974 c47a91919b1e
parent 13848 fef703b8c076
permissions -rw-r--r--
kmsdrm: update SwapWindow fn, moving it to triple-buffer.
     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: */