include/SDL_thread.h
author Ryan C. Gordon <icculus@icculus.org>
Thu, 11 Oct 2018 16:40:01 -0400
changeset 12317 d147224c0f28
parent 11952 d82e6e63c632
child 12318 69ebb2ebced0
permissions -rw-r--r--
thread: make SDL_CreateThreadWithStackSize() a public API.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2018 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 or time critical priority.
    58  */
    59 typedef enum {
    60     SDL_THREAD_PRIORITY_LOW,
    61     SDL_THREAD_PRIORITY_NORMAL,
    62     SDL_THREAD_PRIORITY_HIGH,
    63     SDL_THREAD_PRIORITY_TIME_CRITICAL
    64 } SDL_ThreadPriority;
    65 
    66 /**
    67  *  The function passed to SDL_CreateThread().
    68  *  It is passed a void* user context parameter and returns an int.
    69  */
    70 typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
    71 
    72 #if defined(__WIN32__) && !defined(HAVE_LIBC)
    73 /**
    74  *  \file SDL_thread.h
    75  *
    76  *  We compile SDL into a DLL. This means, that it's the DLL which
    77  *  creates a new thread for the calling process with the SDL_CreateThread()
    78  *  API. There is a problem with this, that only the RTL of the SDL2.DLL will
    79  *  be initialized for those threads, and not the RTL of the calling
    80  *  application!
    81  *
    82  *  To solve this, we make a little hack here.
    83  *
    84  *  We'll always use the caller's _beginthread() and _endthread() APIs to
    85  *  start a new thread. This way, if it's the SDL2.DLL which uses this API,
    86  *  then the RTL of SDL2.DLL will be used to create the new thread, and if it's
    87  *  the application, then the RTL of the application will be used.
    88  *
    89  *  So, in short:
    90  *  Always use the _beginthread() and _endthread() of the calling runtime
    91  *  library!
    92  */
    93 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
    94 #include <process.h> /* _beginthreadex() and _endthreadex() */
    95 
    96 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
    97                    (void *, unsigned, unsigned (__stdcall *func)(void *),
    98                     void * /*arg*/, unsigned, unsigned * /* threadID */);
    99 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
   100 
   101 /**
   102  *  Create a thread.
   103  */
   104 extern DECLSPEC SDL_Thread *SDLCALL
   105 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   106                  pfnSDL_CurrentBeginThread pfnBeginThread,
   107                  pfnSDL_CurrentEndThread pfnEndThread);
   108 
   109 extern DECLSPEC SDL_Thread *SDLCALL
   110 SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *),
   111                  const char *name, const size_t stacksize, void *data,
   112                  pfnSDL_CurrentBeginThread pfnBeginThread,
   113                  pfnSDL_CurrentEndThread pfnEndThread);
   114 
   115 
   116 /**
   117  *  Create a thread.
   118  */
   119 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   120 #undef SDL_CreateThread
   121 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   122 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   123 #else
   124 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   125 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   126 #endif
   127 
   128 #elif defined(__OS2__)
   129 /*
   130  * just like the windows case above:  We compile SDL2
   131  * into a dll with Watcom's runtime statically linked.
   132  */
   133 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   134 #ifndef __EMX__
   135 #include <process.h>
   136 #else
   137 #include <stdlib.h>
   138 #endif
   139 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
   140 typedef void (*pfnSDL_CurrentEndThread)(void);
   141 extern DECLSPEC SDL_Thread *SDLCALL
   142 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   143                  pfnSDL_CurrentBeginThread pfnBeginThread,
   144                  pfnSDL_CurrentEndThread pfnEndThread);
   145 extern DECLSPEC SDL_Thread *SDLCALL
   146 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
   147                  pfnSDL_CurrentBeginThread pfnBeginThread,
   148                  pfnSDL_CurrentEndThread pfnEndThread);
   149 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   150 #undef SDL_CreateThread
   151 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   152 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   153 #else
   154 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   155 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   156 #endif
   157 
   158 #else
   159 
   160 /**
   161  *  Create a thread with a default stack size.
   162  *
   163  *  This is equivalent to calling:
   164  *  SDL_CreateThreadWithStackSize(fn, name, 0, data);
   165  */
   166 extern DECLSPEC SDL_Thread *SDLCALL
   167 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   168 
   169 /**
   170  *  Create a thread.
   171  *
   172  *   Thread naming is a little complicated: Most systems have very small
   173  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   174  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   175  *    have to see what happens with your system's debugger. The name should be
   176  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   177  *   There are no requirements for thread naming conventions, so long as the
   178  *    string is null-terminated UTF-8, but these guidelines are helpful in
   179  *    choosing a name:
   180  *
   181  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   182  *
   183  *   If a system imposes requirements, SDL will try to munge the string for
   184  *    it (truncate, etc), but the original string contents will be available
   185  *    from SDL_GetThreadName().
   186  *
   187  *   The size (in bytes) of the new stack can be specified. Zero means "use
   188  *    the system default" which might be wildly different between platforms
   189  *    (x86 Linux generally defaults to eight megabytes, an embedded device
   190  *    might be a few kilobytes instead).
   191  *
   192  *   In SDL 2.1, stacksize will be folded into the original SDL_CreateThread
   193  *    function.
   194  */
   195 extern DECLSPEC SDL_Thread *SDLCALL
   196 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
   197 
   198 #endif
   199 
   200 /**
   201  * Get the thread name, as it was specified in SDL_CreateThread().
   202  *  This function returns a pointer to a UTF-8 string that names the
   203  *  specified thread, or NULL if it doesn't have a name. This is internal
   204  *  memory, not to be free()'d by the caller, and remains valid until the
   205  *  specified thread is cleaned up by SDL_WaitThread().
   206  */
   207 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   208 
   209 /**
   210  *  Get the thread identifier for the current thread.
   211  */
   212 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   213 
   214 /**
   215  *  Get the thread identifier for the specified thread.
   216  *
   217  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   218  */
   219 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   220 
   221 /**
   222  *  Set the priority for the current thread
   223  */
   224 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   225 
   226 /**
   227  *  Wait for a thread to finish. Threads that haven't been detached will
   228  *  remain (as a "zombie") until this function cleans them up. Not doing so
   229  *  is a resource leak.
   230  *
   231  *  Once a thread has been cleaned up through this function, the SDL_Thread
   232  *  that references it becomes invalid and should not be referenced again.
   233  *  As such, only one thread may call SDL_WaitThread() on another.
   234  *
   235  *  The return code for the thread function is placed in the area
   236  *  pointed to by \c status, if \c status is not NULL.
   237  *
   238  *  You may not wait on a thread that has been used in a call to
   239  *  SDL_DetachThread(). Use either that function or this one, but not
   240  *  both, or behavior is undefined.
   241  *
   242  *  It is safe to pass NULL to this function; it is a no-op.
   243  */
   244 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   245 
   246 /**
   247  *  A thread may be "detached" to signify that it should not remain until
   248  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   249  *  is useful for long-running threads that nothing needs to synchronize
   250  *  with or further manage. When a detached thread is done, it simply
   251  *  goes away.
   252  *
   253  *  There is no way to recover the return code of a detached thread. If you
   254  *  need this, don't detach the thread and instead use SDL_WaitThread().
   255  *
   256  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   257  *  safe to reference again, as it will become invalid immediately upon
   258  *  the detached thread's exit, instead of remaining until someone has called
   259  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   260  *  thread more than once.
   261  *
   262  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   263  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   264  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   265  *
   266  *  You may not call SDL_WaitThread() on a thread that has been detached.
   267  *  Use either that function or this one, but not both, or behavior is
   268  *  undefined.
   269  *
   270  *  It is safe to pass NULL to this function; it is a no-op.
   271  */
   272 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   273 
   274 /**
   275  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   276  *
   277  *  \return The newly created thread local storage identifier, or 0 on error
   278  *
   279  *  \code
   280  *  static SDL_SpinLock tls_lock;
   281  *  static SDL_TLSID thread_local_storage;
   282  * 
   283  *  void SetMyThreadData(void *value)
   284  *  {
   285  *      if (!thread_local_storage) {
   286  *          SDL_AtomicLock(&tls_lock);
   287  *          if (!thread_local_storage) {
   288  *              thread_local_storage = SDL_TLSCreate();
   289  *          }
   290  *          SDL_AtomicUnlock(&tls_lock);
   291  *      }
   292  *      SDL_TLSSet(thread_local_storage, value, 0);
   293  *  }
   294  *  
   295  *  void *GetMyThreadData(void)
   296  *  {
   297  *      return SDL_TLSGet(thread_local_storage);
   298  *  }
   299  *  \endcode
   300  *
   301  *  \sa SDL_TLSGet()
   302  *  \sa SDL_TLSSet()
   303  */
   304 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   305 
   306 /**
   307  *  \brief Get the value associated with a thread local storage ID for the current thread.
   308  *
   309  *  \param id The thread local storage ID
   310  *
   311  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   312  *
   313  *  \sa SDL_TLSCreate()
   314  *  \sa SDL_TLSSet()
   315  */
   316 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   317 
   318 /**
   319  *  \brief Set the value associated with a thread local storage ID for the current thread.
   320  *
   321  *  \param id The thread local storage ID
   322  *  \param value The value to associate with the ID for the current thread
   323  *  \param destructor A function called when the thread exits, to free the value.
   324  *
   325  *  \return 0 on success, -1 on error
   326  *
   327  *  \sa SDL_TLSCreate()
   328  *  \sa SDL_TLSGet()
   329  */
   330 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   331 
   332 
   333 /* Ends C function definitions when using C++ */
   334 #ifdef __cplusplus
   335 }
   336 #endif
   337 #include "close_code.h"
   338 
   339 #endif /* SDL_thread_h_ */
   340 
   341 /* vi: set ts=4 sw=4 expandtab: */