include/SDL_thread.h
author Ryan C. Gordon <icculus@icculus.org>
Thu, 14 Nov 2013 11:51:24 -0500
changeset 7981 6d538bc1b395
parent 7978 70ac84e49797
child 8094 9efaae827924
permissions -rw-r--r--
Renamed things named after BeOS to be named after Haiku instead.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2013 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 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 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   115 
   116 #else
   117 
   118 /**
   119  *  Create a thread.
   120  *
   121  *   Thread naming is a little complicated: Most systems have very small
   122  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   123  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   124  *    have to see what happens with your system's debugger. The name should be
   125  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   126  *   There are no requirements for thread naming conventions, so long as the
   127  *    string is null-terminated UTF-8, but these guidelines are helpful in
   128  *    choosing a name:
   129  *
   130  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   131  *
   132  *   If a system imposes requirements, SDL will try to munge the string for
   133  *    it (truncate, etc), but the original string contents will be available
   134  *    from SDL_GetThreadName().
   135  */
   136 extern DECLSPEC SDL_Thread *SDLCALL
   137 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   138 
   139 #endif
   140 
   141 /**
   142  * Get the thread name, as it was specified in SDL_CreateThread().
   143  *  This function returns a pointer to a UTF-8 string that names the
   144  *  specified thread, or NULL if it doesn't have a name. This is internal
   145  *  memory, not to be free()'d by the caller, and remains valid until the
   146  *  specified thread is cleaned up by SDL_WaitThread().
   147  */
   148 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   149 
   150 /**
   151  *  Get the thread identifier for the current thread.
   152  */
   153 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   154 
   155 /**
   156  *  Get the thread identifier for the specified thread.
   157  *
   158  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   159  */
   160 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   161 
   162 /**
   163  *  Set the priority for the current thread
   164  */
   165 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   166 
   167 /**
   168  *  Wait for a thread to finish. Threads that haven't been detached will
   169  *  remain (as a "zombie") until this function cleans them up. Not doing so
   170  *  is a resource leak.
   171  *
   172  *  Once a thread has been cleaned up through this function, the SDL_Thread
   173  *  that references it becomes invalid and should not be referenced again.
   174  *  As such, only one thread may call SDL_WaitThread() on another.
   175  *
   176  *  The return code for the thread function is placed in the area
   177  *  pointed to by \c status, if \c status is not NULL.
   178  *
   179  *  You may not wait on a thread that has been used in a call to
   180  *  SDL_DetachThread(). Use either that function or this one, but not
   181  *  both, or behavior is undefined.
   182  *
   183  *  It is safe to pass NULL to this function; it is a no-op.
   184  */
   185 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   186 
   187 /**
   188  *  A thread may be "detached" to signify that it should not remain until
   189  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   190  *  is useful for long-running threads that nothing needs to synchronize
   191  *  with or further manage. When a detached thread is done, it simply
   192  *  goes away.
   193  *
   194  *  There is no way to recover the return code of a detached thread. If you
   195  *  need this, don't detach the thread and instead use SDL_WaitThread().
   196  *
   197  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   198  *  safe to reference again, as it will become invalid immediately upon
   199  *  the detached thread's exit, instead of remaining until someone has called
   200  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   201  *  thread more than once.
   202  *
   203  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   204  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   205  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   206  *
   207  *  You may not call SDL_WaitThread() on a thread that has been detached.
   208  *  Use either that function or this one, but not both, or behavior is
   209  *  undefined.
   210  *
   211  *  It is safe to pass NULL to this function; it is a no-op.
   212  */
   213 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   214 
   215 /**
   216  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   217  *
   218  *  \return The newly created thread local storage identifier, or 0 on error
   219  *
   220  *  \code
   221  *  static SDL_SpinLock tls_lock;
   222  *  static SDL_TLSID thread_local_storage;
   223  * 
   224  *  void SetMyThreadData(void *value)
   225  *  {
   226  *      if (!thread_local_storage) {
   227  *          SDL_AtomicLock(&tls_lock);
   228  *          if (!thread_local_storage) {
   229  *              thread_local_storage = SDL_TLSCreate();
   230  *          }
   231  *          SDL_AtomicUnLock(&tls_lock);
   232  *      }
   233  *      SDL_TLSSet(thread_local_storage, value);
   234  *  }
   235  *  
   236  *  void *GetMyThreadData(void)
   237  *  {
   238  *      return SDL_TLSGet(thread_local_storage);
   239  *  }
   240  *  \endcode
   241  *
   242  *  \sa SDL_TLSGet()
   243  *  \sa SDL_TLSSet()
   244  */
   245 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   246 
   247 /**
   248  *  \brief Get the value associated with a thread local storage ID for the current thread.
   249  *
   250  *  \param id The thread local storage ID
   251  *
   252  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   253  *
   254  *  \sa SDL_TLSCreate()
   255  *  \sa SDL_TLSSet()
   256  */
   257 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   258 
   259 /**
   260  *  \brief Set the value associated with a thread local storage ID for the current thread.
   261  *
   262  *  \param id The thread local storage ID
   263  *  \param value The value to associate with the ID for the current thread
   264  *  \param destructor A function called when the thread exits, to free the value.
   265  *
   266  *  \return 0 on success, -1 on error
   267  *
   268  *  \sa SDL_TLSCreate()
   269  *  \sa SDL_TLSGet()
   270  */
   271 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (*destructor)(void*));
   272 
   273 
   274 /* Ends C function definitions when using C++ */
   275 #ifdef __cplusplus
   276 }
   277 #endif
   278 #include "close_code.h"
   279 
   280 #endif /* _SDL_thread_h */
   281 
   282 /* vi: set ts=4 sw=4 expandtab: */