include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Tue, 23 Oct 2018 12:40:25 -0700
changeset 12354 7846ac86d46e
parent 12318 69ebb2ebced0
permissions -rw-r--r--
Fixed reinitializing the SDL joystick subsystem on Android
     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 #undef SDL_CreateThreadWithStackSize
   123 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   124 #else
   125 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   126 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   127 #endif
   128 
   129 #elif defined(__OS2__)
   130 /*
   131  * just like the windows case above:  We compile SDL2
   132  * into a dll with Watcom's runtime statically linked.
   133  */
   134 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   135 #ifndef __EMX__
   136 #include <process.h>
   137 #else
   138 #include <stdlib.h>
   139 #endif
   140 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
   141 typedef void (*pfnSDL_CurrentEndThread)(void);
   142 extern DECLSPEC SDL_Thread *SDLCALL
   143 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   144                  pfnSDL_CurrentBeginThread pfnBeginThread,
   145                  pfnSDL_CurrentEndThread pfnEndThread);
   146 extern DECLSPEC SDL_Thread *SDLCALL
   147 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
   148                  pfnSDL_CurrentBeginThread pfnBeginThread,
   149                  pfnSDL_CurrentEndThread pfnEndThread);
   150 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   151 #undef SDL_CreateThread
   152 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   153 #undef SDL_CreateThreadWithStackSize
   154 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   155 #else
   156 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   157 #define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   158 #endif
   159 
   160 #else
   161 
   162 /**
   163  *  Create a thread with a default stack size.
   164  *
   165  *  This is equivalent to calling:
   166  *  SDL_CreateThreadWithStackSize(fn, name, 0, data);
   167  */
   168 extern DECLSPEC SDL_Thread *SDLCALL
   169 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   170 
   171 /**
   172  *  Create a thread.
   173  *
   174  *   Thread naming is a little complicated: Most systems have very small
   175  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   176  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   177  *    have to see what happens with your system's debugger. The name should be
   178  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   179  *   There are no requirements for thread naming conventions, so long as the
   180  *    string is null-terminated UTF-8, but these guidelines are helpful in
   181  *    choosing a name:
   182  *
   183  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   184  *
   185  *   If a system imposes requirements, SDL will try to munge the string for
   186  *    it (truncate, etc), but the original string contents will be available
   187  *    from SDL_GetThreadName().
   188  *
   189  *   The size (in bytes) of the new stack can be specified. Zero means "use
   190  *    the system default" which might be wildly different between platforms
   191  *    (x86 Linux generally defaults to eight megabytes, an embedded device
   192  *    might be a few kilobytes instead).
   193  *
   194  *   In SDL 2.1, stacksize will be folded into the original SDL_CreateThread
   195  *    function.
   196  */
   197 extern DECLSPEC SDL_Thread *SDLCALL
   198 SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
   199 
   200 #endif
   201 
   202 /**
   203  * Get the thread name, as it was specified in SDL_CreateThread().
   204  *  This function returns a pointer to a UTF-8 string that names the
   205  *  specified thread, or NULL if it doesn't have a name. This is internal
   206  *  memory, not to be free()'d by the caller, and remains valid until the
   207  *  specified thread is cleaned up by SDL_WaitThread().
   208  */
   209 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   210 
   211 /**
   212  *  Get the thread identifier for the current thread.
   213  */
   214 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   215 
   216 /**
   217  *  Get the thread identifier for the specified thread.
   218  *
   219  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   220  */
   221 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   222 
   223 /**
   224  *  Set the priority for the current thread
   225  */
   226 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   227 
   228 /**
   229  *  Wait for a thread to finish. Threads that haven't been detached will
   230  *  remain (as a "zombie") until this function cleans them up. Not doing so
   231  *  is a resource leak.
   232  *
   233  *  Once a thread has been cleaned up through this function, the SDL_Thread
   234  *  that references it becomes invalid and should not be referenced again.
   235  *  As such, only one thread may call SDL_WaitThread() on another.
   236  *
   237  *  The return code for the thread function is placed in the area
   238  *  pointed to by \c status, if \c status is not NULL.
   239  *
   240  *  You may not wait on a thread that has been used in a call to
   241  *  SDL_DetachThread(). Use either that function or this one, but not
   242  *  both, or behavior is undefined.
   243  *
   244  *  It is safe to pass NULL to this function; it is a no-op.
   245  */
   246 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   247 
   248 /**
   249  *  A thread may be "detached" to signify that it should not remain until
   250  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   251  *  is useful for long-running threads that nothing needs to synchronize
   252  *  with or further manage. When a detached thread is done, it simply
   253  *  goes away.
   254  *
   255  *  There is no way to recover the return code of a detached thread. If you
   256  *  need this, don't detach the thread and instead use SDL_WaitThread().
   257  *
   258  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   259  *  safe to reference again, as it will become invalid immediately upon
   260  *  the detached thread's exit, instead of remaining until someone has called
   261  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   262  *  thread more than once.
   263  *
   264  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   265  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   266  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   267  *
   268  *  You may not call SDL_WaitThread() on a thread that has been detached.
   269  *  Use either that function or this one, but not both, or behavior is
   270  *  undefined.
   271  *
   272  *  It is safe to pass NULL to this function; it is a no-op.
   273  */
   274 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   275 
   276 /**
   277  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   278  *
   279  *  \return The newly created thread local storage identifier, or 0 on error
   280  *
   281  *  \code
   282  *  static SDL_SpinLock tls_lock;
   283  *  static SDL_TLSID thread_local_storage;
   284  * 
   285  *  void SetMyThreadData(void *value)
   286  *  {
   287  *      if (!thread_local_storage) {
   288  *          SDL_AtomicLock(&tls_lock);
   289  *          if (!thread_local_storage) {
   290  *              thread_local_storage = SDL_TLSCreate();
   291  *          }
   292  *          SDL_AtomicUnlock(&tls_lock);
   293  *      }
   294  *      SDL_TLSSet(thread_local_storage, value, 0);
   295  *  }
   296  *  
   297  *  void *GetMyThreadData(void)
   298  *  {
   299  *      return SDL_TLSGet(thread_local_storage);
   300  *  }
   301  *  \endcode
   302  *
   303  *  \sa SDL_TLSGet()
   304  *  \sa SDL_TLSSet()
   305  */
   306 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   307 
   308 /**
   309  *  \brief Get the value associated with a thread local storage ID for the current thread.
   310  *
   311  *  \param id The thread local storage ID
   312  *
   313  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   314  *
   315  *  \sa SDL_TLSCreate()
   316  *  \sa SDL_TLSSet()
   317  */
   318 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   319 
   320 /**
   321  *  \brief Set the value associated with a thread local storage ID for the current thread.
   322  *
   323  *  \param id The thread local storage ID
   324  *  \param value The value to associate with the ID for the current thread
   325  *  \param destructor A function called when the thread exits, to free the value.
   326  *
   327  *  \return 0 on success, -1 on error
   328  *
   329  *  \sa SDL_TLSCreate()
   330  *  \sa SDL_TLSGet()
   331  */
   332 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   333 
   334 
   335 /* Ends C function definitions when using C++ */
   336 #ifdef __cplusplus
   337 }
   338 #endif
   339 #include "close_code.h"
   340 
   341 #endif /* SDL_thread_h_ */
   342 
   343 /* vi: set ts=4 sw=4 expandtab: */