include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Mon, 18 Jun 2018 13:14:04 -0700
changeset 12025 39a92b19f99e
parent 11952 d82e6e63c632
permissions -rw-r--r--
Use a blank cursor instead of PointerIcon.TYPE_NULL since that shows the default cursor on Samsung DeX
     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 /**
   110  *  Create a thread.
   111  */
   112 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   113 #undef SDL_CreateThread
   114 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   115 #else
   116 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   117 #endif
   118 
   119 #elif defined(__OS2__)
   120 /*
   121  * just like the windows case above:  We compile SDL2
   122  * into a dll with Watcom's runtime statically linked.
   123  */
   124 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
   125 #ifndef __EMX__
   126 #include <process.h>
   127 #else
   128 #include <stdlib.h>
   129 #endif
   130 typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
   131 typedef void (*pfnSDL_CurrentEndThread)(void);
   132 extern DECLSPEC SDL_Thread *SDLCALL
   133 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
   134                  pfnSDL_CurrentBeginThread pfnBeginThread,
   135                  pfnSDL_CurrentEndThread pfnEndThread);
   136 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   137 #undef SDL_CreateThread
   138 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   139 #else
   140 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
   141 #endif
   142 
   143 #else
   144 
   145 /**
   146  *  Create a thread.
   147  *
   148  *   Thread naming is a little complicated: Most systems have very small
   149  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   150  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   151  *    have to see what happens with your system's debugger. The name should be
   152  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   153  *   There are no requirements for thread naming conventions, so long as the
   154  *    string is null-terminated UTF-8, but these guidelines are helpful in
   155  *    choosing a name:
   156  *
   157  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   158  *
   159  *   If a system imposes requirements, SDL will try to munge the string for
   160  *    it (truncate, etc), but the original string contents will be available
   161  *    from SDL_GetThreadName().
   162  */
   163 extern DECLSPEC SDL_Thread *SDLCALL
   164 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   165 
   166 #endif
   167 
   168 /**
   169  * Get the thread name, as it was specified in SDL_CreateThread().
   170  *  This function returns a pointer to a UTF-8 string that names the
   171  *  specified thread, or NULL if it doesn't have a name. This is internal
   172  *  memory, not to be free()'d by the caller, and remains valid until the
   173  *  specified thread is cleaned up by SDL_WaitThread().
   174  */
   175 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   176 
   177 /**
   178  *  Get the thread identifier for the current thread.
   179  */
   180 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   181 
   182 /**
   183  *  Get the thread identifier for the specified thread.
   184  *
   185  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   186  */
   187 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   188 
   189 /**
   190  *  Set the priority for the current thread
   191  */
   192 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   193 
   194 /**
   195  *  Wait for a thread to finish. Threads that haven't been detached will
   196  *  remain (as a "zombie") until this function cleans them up. Not doing so
   197  *  is a resource leak.
   198  *
   199  *  Once a thread has been cleaned up through this function, the SDL_Thread
   200  *  that references it becomes invalid and should not be referenced again.
   201  *  As such, only one thread may call SDL_WaitThread() on another.
   202  *
   203  *  The return code for the thread function is placed in the area
   204  *  pointed to by \c status, if \c status is not NULL.
   205  *
   206  *  You may not wait on a thread that has been used in a call to
   207  *  SDL_DetachThread(). Use either that function or this one, but not
   208  *  both, or behavior is undefined.
   209  *
   210  *  It is safe to pass NULL to this function; it is a no-op.
   211  */
   212 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   213 
   214 /**
   215  *  A thread may be "detached" to signify that it should not remain until
   216  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   217  *  is useful for long-running threads that nothing needs to synchronize
   218  *  with or further manage. When a detached thread is done, it simply
   219  *  goes away.
   220  *
   221  *  There is no way to recover the return code of a detached thread. If you
   222  *  need this, don't detach the thread and instead use SDL_WaitThread().
   223  *
   224  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   225  *  safe to reference again, as it will become invalid immediately upon
   226  *  the detached thread's exit, instead of remaining until someone has called
   227  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   228  *  thread more than once.
   229  *
   230  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   231  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   232  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   233  *
   234  *  You may not call SDL_WaitThread() on a thread that has been detached.
   235  *  Use either that function or this one, but not both, or behavior is
   236  *  undefined.
   237  *
   238  *  It is safe to pass NULL to this function; it is a no-op.
   239  */
   240 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   241 
   242 /**
   243  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   244  *
   245  *  \return The newly created thread local storage identifier, or 0 on error
   246  *
   247  *  \code
   248  *  static SDL_SpinLock tls_lock;
   249  *  static SDL_TLSID thread_local_storage;
   250  * 
   251  *  void SetMyThreadData(void *value)
   252  *  {
   253  *      if (!thread_local_storage) {
   254  *          SDL_AtomicLock(&tls_lock);
   255  *          if (!thread_local_storage) {
   256  *              thread_local_storage = SDL_TLSCreate();
   257  *          }
   258  *          SDL_AtomicUnlock(&tls_lock);
   259  *      }
   260  *      SDL_TLSSet(thread_local_storage, value, 0);
   261  *  }
   262  *  
   263  *  void *GetMyThreadData(void)
   264  *  {
   265  *      return SDL_TLSGet(thread_local_storage);
   266  *  }
   267  *  \endcode
   268  *
   269  *  \sa SDL_TLSGet()
   270  *  \sa SDL_TLSSet()
   271  */
   272 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   273 
   274 /**
   275  *  \brief Get the value associated with a thread local storage ID for the current thread.
   276  *
   277  *  \param id The thread local storage ID
   278  *
   279  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   280  *
   281  *  \sa SDL_TLSCreate()
   282  *  \sa SDL_TLSSet()
   283  */
   284 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   285 
   286 /**
   287  *  \brief Set the value associated with a thread local storage ID for the current thread.
   288  *
   289  *  \param id The thread local storage ID
   290  *  \param value The value to associate with the ID for the current thread
   291  *  \param destructor A function called when the thread exits, to free the value.
   292  *
   293  *  \return 0 on success, -1 on error
   294  *
   295  *  \sa SDL_TLSCreate()
   296  *  \sa SDL_TLSGet()
   297  */
   298 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
   299 
   300 
   301 /* Ends C function definitions when using C++ */
   302 #ifdef __cplusplus
   303 }
   304 #endif
   305 #include "close_code.h"
   306 
   307 #endif /* SDL_thread_h_ */
   308 
   309 /* vi: set ts=4 sw=4 expandtab: */