include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Mon, 21 Aug 2017 13:01:22 -0700
changeset 11340 97cd834a843e
parent 11284 3db78361e751
child 11356 0347c3e08f85
permissions -rw-r--r--
SDL_thread.h: add missing os/2 defines.

(essentially replicates the windows case || SDL1.2 case.)
     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 /*
   124  * just like the windows case above:  We compile SDL2
   125  * into a dll with Watcom's runtime statically linked.
   126  */
   127 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   128 #include <process.h>
   129 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void *arg);
   130 typedef void (*pfnSDL_CurrentEndThread)(void);
   131 #undef SDL_CreateThread
   132 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   133 
   134 #else
   135 
   136 /**
   137  *  Create a thread.
   138  *
   139  *   Thread naming is a little complicated: Most systems have very small
   140  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   141  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   142  *    have to see what happens with your system's debugger. The name should be
   143  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   144  *   There are no requirements for thread naming conventions, so long as the
   145  *    string is null-terminated UTF-8, but these guidelines are helpful in
   146  *    choosing a name:
   147  *
   148  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   149  *
   150  *   If a system imposes requirements, SDL will try to munge the string for
   151  *    it (truncate, etc), but the original string contents will be available
   152  *    from SDL_GetThreadName().
   153  */
   154 extern DECLSPEC SDL_Thread *SDLCALL
   155 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   156 
   157 #endif
   158 
   159 /**
   160  * Get the thread name, as it was specified in SDL_CreateThread().
   161  *  This function returns a pointer to a UTF-8 string that names the
   162  *  specified thread, or NULL if it doesn't have a name. This is internal
   163  *  memory, not to be free()'d by the caller, and remains valid until the
   164  *  specified thread is cleaned up by SDL_WaitThread().
   165  */
   166 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   167 
   168 /**
   169  *  Get the thread identifier for the current thread.
   170  */
   171 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   172 
   173 /**
   174  *  Get the thread identifier for the specified thread.
   175  *
   176  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   177  */
   178 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   179 
   180 /**
   181  *  Set the priority for the current thread
   182  */
   183 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   184 
   185 /**
   186  *  Wait for a thread to finish. Threads that haven't been detached will
   187  *  remain (as a "zombie") until this function cleans them up. Not doing so
   188  *  is a resource leak.
   189  *
   190  *  Once a thread has been cleaned up through this function, the SDL_Thread
   191  *  that references it becomes invalid and should not be referenced again.
   192  *  As such, only one thread may call SDL_WaitThread() on another.
   193  *
   194  *  The return code for the thread function is placed in the area
   195  *  pointed to by \c status, if \c status is not NULL.
   196  *
   197  *  You may not wait on a thread that has been used in a call to
   198  *  SDL_DetachThread(). Use either that function or this one, but not
   199  *  both, or behavior is undefined.
   200  *
   201  *  It is safe to pass NULL to this function; it is a no-op.
   202  */
   203 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   204 
   205 /**
   206  *  A thread may be "detached" to signify that it should not remain until
   207  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   208  *  is useful for long-running threads that nothing needs to synchronize
   209  *  with or further manage. When a detached thread is done, it simply
   210  *  goes away.
   211  *
   212  *  There is no way to recover the return code of a detached thread. If you
   213  *  need this, don't detach the thread and instead use SDL_WaitThread().
   214  *
   215  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   216  *  safe to reference again, as it will become invalid immediately upon
   217  *  the detached thread's exit, instead of remaining until someone has called
   218  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   219  *  thread more than once.
   220  *
   221  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   222  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   223  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   224  *
   225  *  You may not call SDL_WaitThread() on a thread that has been detached.
   226  *  Use either that function or this one, but not both, or behavior is
   227  *  undefined.
   228  *
   229  *  It is safe to pass NULL to this function; it is a no-op.
   230  */
   231 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   232 
   233 /**
   234  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   235  *
   236  *  \return The newly created thread local storage identifier, or 0 on error
   237  *
   238  *  \code
   239  *  static SDL_SpinLock tls_lock;
   240  *  static SDL_TLSID thread_local_storage;
   241  * 
   242  *  void SetMyThreadData(void *value)
   243  *  {
   244  *      if (!thread_local_storage) {
   245  *          SDL_AtomicLock(&tls_lock);
   246  *          if (!thread_local_storage) {
   247  *              thread_local_storage = SDL_TLSCreate();
   248  *          }
   249  *          SDL_AtomicUnlock(&tls_lock);
   250  *      }
   251  *      SDL_TLSSet(thread_local_storage, value, 0);
   252  *  }
   253  *  
   254  *  void *GetMyThreadData(void)
   255  *  {
   256  *      return SDL_TLSGet(thread_local_storage);
   257  *  }
   258  *  \endcode
   259  *
   260  *  \sa SDL_TLSGet()
   261  *  \sa SDL_TLSSet()
   262  */
   263 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   264 
   265 /**
   266  *  \brief Get the value associated with a thread local storage ID for the current thread.
   267  *
   268  *  \param id The thread local storage ID
   269  *
   270  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   271  *
   272  *  \sa SDL_TLSCreate()
   273  *  \sa SDL_TLSSet()
   274  */
   275 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   276 
   277 /**
   278  *  \brief Set the value associated with a thread local storage ID for the current thread.
   279  *
   280  *  \param id The thread local storage ID
   281  *  \param value The value to associate with the ID for the current thread
   282  *  \param destructor A function called when the thread exits, to free the value.
   283  *
   284  *  \return 0 on success, -1 on error
   285  *
   286  *  \sa SDL_TLSCreate()
   287  *  \sa SDL_TLSGet()
   288  */
   289 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   290 
   291 
   292 /* Ends C function definitions when using C++ */
   293 #ifdef __cplusplus
   294 }
   295 #endif
   296 #include "close_code.h"
   297 
   298 #endif /* SDL_thread_h_ */
   299 
   300 /* vi: set ts=4 sw=4 expandtab: */