include/SDL_thread.h
author Marius Gripsgard <marius@ubports.com>
Sat, 13 Jan 2018 01:58:11 +0100
changeset 11826 13d922b387db
parent 11811 5d94cb6b24d3
permissions -rw-r--r--
Mir: Handle close window events
     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 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> /* _beginthreadex() and _endthreadex() */
    94 
    95 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
    96                    (void *, unsigned, unsigned (__stdcall *func)(void *),
    97                     void * /*arg*/, unsigned, unsigned * /* threadID */);
    98 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
    99 
   100 /**
   101  *  Create a thread.
   102  */
   103 extern DECLSPEC SDL_Thread *SDLCALL
   104 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   105                  pfnSDL_CurrentBeginThread pfnBeginThread,
   106                  pfnSDL_CurrentEndThread pfnEndThread);
   107 
   108 /**
   109  *  Create a thread.
   110  */
   111 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   112 #undef SDL_CreateThread
   113 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   114 #else
   115 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   116 #endif
   117 
   118 #elif defined(__OS2__)
   119 /*
   120  * just like the windows case above:  We compile SDL2
   121  * into a dll with Watcom's runtime statically linked.
   122  */
   123 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   124 #ifndef __EMX__
   125 #include <process.h>
   126 #else
   127 #include <stdlib.h>
   128 #endif
   129 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
   130 typedef void (*pfnSDL_CurrentEndThread)(void);
   131 extern DECLSPEC SDL_Thread *SDLCALL
   132 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   133                  pfnSDL_CurrentBeginThread pfnBeginThread,
   134                  pfnSDL_CurrentEndThread pfnEndThread);
   135 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   136 #undef SDL_CreateThread
   137 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   138 #else
   139 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   140 #endif
   141 
   142 #else
   143 
   144 /**
   145  *  Create a thread.
   146  *
   147  *   Thread naming is a little complicated: Most systems have very small
   148  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   149  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   150  *    have to see what happens with your system's debugger. The name should be
   151  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   152  *   There are no requirements for thread naming conventions, so long as the
   153  *    string is null-terminated UTF-8, but these guidelines are helpful in
   154  *    choosing a name:
   155  *
   156  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   157  *
   158  *   If a system imposes requirements, SDL will try to munge the string for
   159  *    it (truncate, etc), but the original string contents will be available
   160  *    from SDL_GetThreadName().
   161  */
   162 extern DECLSPEC SDL_Thread *SDLCALL
   163 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   164 
   165 #endif
   166 
   167 /**
   168  * Get the thread name, as it was specified in SDL_CreateThread().
   169  *  This function returns a pointer to a UTF-8 string that names the
   170  *  specified thread, or NULL if it doesn't have a name. This is internal
   171  *  memory, not to be free()'d by the caller, and remains valid until the
   172  *  specified thread is cleaned up by SDL_WaitThread().
   173  */
   174 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   175 
   176 /**
   177  *  Get the thread identifier for the current thread.
   178  */
   179 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   180 
   181 /**
   182  *  Get the thread identifier for the specified thread.
   183  *
   184  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   185  */
   186 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   187 
   188 /**
   189  *  Set the priority for the current thread
   190  */
   191 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   192 
   193 /**
   194  *  Wait for a thread to finish. Threads that haven't been detached will
   195  *  remain (as a "zombie") until this function cleans them up. Not doing so
   196  *  is a resource leak.
   197  *
   198  *  Once a thread has been cleaned up through this function, the SDL_Thread
   199  *  that references it becomes invalid and should not be referenced again.
   200  *  As such, only one thread may call SDL_WaitThread() on another.
   201  *
   202  *  The return code for the thread function is placed in the area
   203  *  pointed to by \c status, if \c status is not NULL.
   204  *
   205  *  You may not wait on a thread that has been used in a call to
   206  *  SDL_DetachThread(). Use either that function or this one, but not
   207  *  both, or behavior is undefined.
   208  *
   209  *  It is safe to pass NULL to this function; it is a no-op.
   210  */
   211 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   212 
   213 /**
   214  *  A thread may be "detached" to signify that it should not remain until
   215  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   216  *  is useful for long-running threads that nothing needs to synchronize
   217  *  with or further manage. When a detached thread is done, it simply
   218  *  goes away.
   219  *
   220  *  There is no way to recover the return code of a detached thread. If you
   221  *  need this, don't detach the thread and instead use SDL_WaitThread().
   222  *
   223  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   224  *  safe to reference again, as it will become invalid immediately upon
   225  *  the detached thread's exit, instead of remaining until someone has called
   226  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   227  *  thread more than once.
   228  *
   229  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   230  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   231  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   232  *
   233  *  You may not call SDL_WaitThread() on a thread that has been detached.
   234  *  Use either that function or this one, but not both, or behavior is
   235  *  undefined.
   236  *
   237  *  It is safe to pass NULL to this function; it is a no-op.
   238  */
   239 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   240 
   241 /**
   242  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   243  *
   244  *  \return The newly created thread local storage identifier, or 0 on error
   245  *
   246  *  \code
   247  *  static SDL_SpinLock tls_lock;
   248  *  static SDL_TLSID thread_local_storage;
   249  * 
   250  *  void SetMyThreadData(void *value)
   251  *  {
   252  *      if (!thread_local_storage) {
   253  *          SDL_AtomicLock(&tls_lock);
   254  *          if (!thread_local_storage) {
   255  *              thread_local_storage = SDL_TLSCreate();
   256  *          }
   257  *          SDL_AtomicUnlock(&tls_lock);
   258  *      }
   259  *      SDL_TLSSet(thread_local_storage, value, 0);
   260  *  }
   261  *  
   262  *  void *GetMyThreadData(void)
   263  *  {
   264  *      return SDL_TLSGet(thread_local_storage);
   265  *  }
   266  *  \endcode
   267  *
   268  *  \sa SDL_TLSGet()
   269  *  \sa SDL_TLSSet()
   270  */
   271 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   272 
   273 /**
   274  *  \brief Get the value associated with a thread local storage ID for the current thread.
   275  *
   276  *  \param id The thread local storage ID
   277  *
   278  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   279  *
   280  *  \sa SDL_TLSCreate()
   281  *  \sa SDL_TLSSet()
   282  */
   283 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   284 
   285 /**
   286  *  \brief Set the value associated with a thread local storage ID for the current thread.
   287  *
   288  *  \param id The thread local storage ID
   289  *  \param value The value to associate with the ID for the current thread
   290  *  \param destructor A function called when the thread exits, to free the value.
   291  *
   292  *  \return 0 on success, -1 on error
   293  *
   294  *  \sa SDL_TLSCreate()
   295  *  \sa SDL_TLSGet()
   296  */
   297 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   298 
   299 
   300 /* Ends C function definitions when using C++ */
   301 #ifdef __cplusplus
   302 }
   303 #endif
   304 #include "close_code.h"
   305 
   306 #endif /* SDL_thread_h_ */
   307 
   308 /* vi: set ts=4 sw=4 expandtab: */