include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Sun, 27 Aug 2017 18:48:51 -0700
changeset 11356 0347c3e08f85
parent 11340 97cd834a843e
child 11543 53b03749a7ff
permissions -rw-r--r--
SDL_thread.h: fix os/2 defines (rev 11340:97cd834a843e was a missing patch)
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2017 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  *  \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 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>            /* 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 #elif defined(__OS2__)
   122 /*
   123  * just like the windows case above:  We compile SDL2
   124  * into a dll with Watcom's runtime statically linked.
   125  */
   126 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   127 #include <process.h>
   128 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
   129 typedef void (*pfnSDL_CurrentEndThread)(void);
   130 extern DECLSPEC SDL_Thread *SDLCALL
   131 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   132                  pfnSDL_CurrentBeginThread pfnBeginThread,
   133                  pfnSDL_CurrentEndThread pfnEndThread);
   134 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   135 #undef SDL_CreateThread
   136 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   137 #else
   138 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   139 #endif
   140 
   141 #else
   142 
   143 /**
   144  *  Create a thread.
   145  *
   146  *   Thread naming is a little complicated: Most systems have very small
   147  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   148  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   149  *    have to see what happens with your system's debugger. The name should be
   150  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   151  *   There are no requirements for thread naming conventions, so long as the
   152  *    string is null-terminated UTF-8, but these guidelines are helpful in
   153  *    choosing a name:
   154  *
   155  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   156  *
   157  *   If a system imposes requirements, SDL will try to munge the string for
   158  *    it (truncate, etc), but the original string contents will be available
   159  *    from SDL_GetThreadName().
   160  */
   161 extern DECLSPEC SDL_Thread *SDLCALL
   162 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   163 
   164 #endif
   165 
   166 /**
   167  * Get the thread name, as it was specified in SDL_CreateThread().
   168  *  This function returns a pointer to a UTF-8 string that names the
   169  *  specified thread, or NULL if it doesn't have a name. This is internal
   170  *  memory, not to be free()'d by the caller, and remains valid until the
   171  *  specified thread is cleaned up by SDL_WaitThread().
   172  */
   173 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   174 
   175 /**
   176  *  Get the thread identifier for the current thread.
   177  */
   178 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   179 
   180 /**
   181  *  Get the thread identifier for the specified thread.
   182  *
   183  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   184  */
   185 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   186 
   187 /**
   188  *  Set the priority for the current thread
   189  */
   190 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   191 
   192 /**
   193  *  Wait for a thread to finish. Threads that haven't been detached will
   194  *  remain (as a "zombie") until this function cleans them up. Not doing so
   195  *  is a resource leak.
   196  *
   197  *  Once a thread has been cleaned up through this function, the SDL_Thread
   198  *  that references it becomes invalid and should not be referenced again.
   199  *  As such, only one thread may call SDL_WaitThread() on another.
   200  *
   201  *  The return code for the thread function is placed in the area
   202  *  pointed to by \c status, if \c status is not NULL.
   203  *
   204  *  You may not wait on a thread that has been used in a call to
   205  *  SDL_DetachThread(). Use either that function or this one, but not
   206  *  both, or behavior is undefined.
   207  *
   208  *  It is safe to pass NULL to this function; it is a no-op.
   209  */
   210 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   211 
   212 /**
   213  *  A thread may be "detached" to signify that it should not remain until
   214  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   215  *  is useful for long-running threads that nothing needs to synchronize
   216  *  with or further manage. When a detached thread is done, it simply
   217  *  goes away.
   218  *
   219  *  There is no way to recover the return code of a detached thread. If you
   220  *  need this, don't detach the thread and instead use SDL_WaitThread().
   221  *
   222  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   223  *  safe to reference again, as it will become invalid immediately upon
   224  *  the detached thread's exit, instead of remaining until someone has called
   225  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   226  *  thread more than once.
   227  *
   228  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   229  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   230  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   231  *
   232  *  You may not call SDL_WaitThread() on a thread that has been detached.
   233  *  Use either that function or this one, but not both, or behavior is
   234  *  undefined.
   235  *
   236  *  It is safe to pass NULL to this function; it is a no-op.
   237  */
   238 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   239 
   240 /**
   241  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   242  *
   243  *  \return The newly created thread local storage identifier, or 0 on error
   244  *
   245  *  \code
   246  *  static SDL_SpinLock tls_lock;
   247  *  static SDL_TLSID thread_local_storage;
   248  * 
   249  *  void SetMyThreadData(void *value)
   250  *  {
   251  *      if (!thread_local_storage) {
   252  *          SDL_AtomicLock(&tls_lock);
   253  *          if (!thread_local_storage) {
   254  *              thread_local_storage = SDL_TLSCreate();
   255  *          }
   256  *          SDL_AtomicUnlock(&tls_lock);
   257  *      }
   258  *      SDL_TLSSet(thread_local_storage, value, 0);
   259  *  }
   260  *  
   261  *  void *GetMyThreadData(void)
   262  *  {
   263  *      return SDL_TLSGet(thread_local_storage);
   264  *  }
   265  *  \endcode
   266  *
   267  *  \sa SDL_TLSGet()
   268  *  \sa SDL_TLSSet()
   269  */
   270 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   271 
   272 /**
   273  *  \brief Get the value associated with a thread local storage ID for the current thread.
   274  *
   275  *  \param id The thread local storage ID
   276  *
   277  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   278  *
   279  *  \sa SDL_TLSCreate()
   280  *  \sa SDL_TLSSet()
   281  */
   282 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   283 
   284 /**
   285  *  \brief Set the value associated with a thread local storage ID for the current thread.
   286  *
   287  *  \param id The thread local storage ID
   288  *  \param value The value to associate with the ID for the current thread
   289  *  \param destructor A function called when the thread exits, to free the value.
   290  *
   291  *  \return 0 on success, -1 on error
   292  *
   293  *  \sa SDL_TLSCreate()
   294  *  \sa SDL_TLSGet()
   295  */
   296 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   297 
   298 
   299 /* Ends C function definitions when using C++ */
   300 #ifdef __cplusplus
   301 }
   302 #endif
   303 #include "close_code.h"
   304 
   305 #endif /* SDL_thread_h_ */
   306 
   307 /* vi: set ts=4 sw=4 expandtab: */