include/SDL_thread.h
author Ryan C. Gordon <icculus@icculus.org>
Fri, 13 Mar 2015 00:48:30 -0400
changeset 9381 812b2dabf8a4
parent 9125 e004bdb812ce
child 9619 b94b6d0bff0f
permissions -rw-r--r--
Removed an unnecessary #ifdef.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2014 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 #if defined(SDL_CreateThread) && SDL_DYNAMIC_API
   115 #undef SDL_CreateThread
   116 #define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   117 #else
   118 #define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
   119 #endif
   120 
   121 #else
   122 
   123 /**
   124  *  Create a thread.
   125  *
   126  *   Thread naming is a little complicated: Most systems have very small
   127  *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
   128  *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
   129  *    have to see what happens with your system's debugger. The name should be
   130  *    UTF-8 (but using the naming limits of C identifiers is a better bet).
   131  *   There are no requirements for thread naming conventions, so long as the
   132  *    string is null-terminated UTF-8, but these guidelines are helpful in
   133  *    choosing a name:
   134  *
   135  *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
   136  *
   137  *   If a system imposes requirements, SDL will try to munge the string for
   138  *    it (truncate, etc), but the original string contents will be available
   139  *    from SDL_GetThreadName().
   140  */
   141 extern DECLSPEC SDL_Thread *SDLCALL
   142 SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
   143 
   144 #endif
   145 
   146 /**
   147  * Get the thread name, as it was specified in SDL_CreateThread().
   148  *  This function returns a pointer to a UTF-8 string that names the
   149  *  specified thread, or NULL if it doesn't have a name. This is internal
   150  *  memory, not to be free()'d by the caller, and remains valid until the
   151  *  specified thread is cleaned up by SDL_WaitThread().
   152  */
   153 extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
   154 
   155 /**
   156  *  Get the thread identifier for the current thread.
   157  */
   158 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   159 
   160 /**
   161  *  Get the thread identifier for the specified thread.
   162  *
   163  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   164  */
   165 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   166 
   167 /**
   168  *  Set the priority for the current thread
   169  */
   170 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   171 
   172 /**
   173  *  Wait for a thread to finish. Threads that haven't been detached will
   174  *  remain (as a "zombie") until this function cleans them up. Not doing so
   175  *  is a resource leak.
   176  *
   177  *  Once a thread has been cleaned up through this function, the SDL_Thread
   178  *  that references it becomes invalid and should not be referenced again.
   179  *  As such, only one thread may call SDL_WaitThread() on another.
   180  *
   181  *  The return code for the thread function is placed in the area
   182  *  pointed to by \c status, if \c status is not NULL.
   183  *
   184  *  You may not wait on a thread that has been used in a call to
   185  *  SDL_DetachThread(). Use either that function or this one, but not
   186  *  both, or behavior is undefined.
   187  *
   188  *  It is safe to pass NULL to this function; it is a no-op.
   189  */
   190 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   191 
   192 /**
   193  *  A thread may be "detached" to signify that it should not remain until
   194  *  another thread has called SDL_WaitThread() on it. Detaching a thread
   195  *  is useful for long-running threads that nothing needs to synchronize
   196  *  with or further manage. When a detached thread is done, it simply
   197  *  goes away.
   198  *
   199  *  There is no way to recover the return code of a detached thread. If you
   200  *  need this, don't detach the thread and instead use SDL_WaitThread().
   201  *
   202  *  Once a thread is detached, you should usually assume the SDL_Thread isn't
   203  *  safe to reference again, as it will become invalid immediately upon
   204  *  the detached thread's exit, instead of remaining until someone has called
   205  *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
   206  *  thread more than once.
   207  *
   208  *  If a thread has already exited when passed to SDL_DetachThread(), it will
   209  *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
   210  *  It is not safe to detach a thread that might be used with SDL_WaitThread().
   211  *
   212  *  You may not call SDL_WaitThread() on a thread that has been detached.
   213  *  Use either that function or this one, but not both, or behavior is
   214  *  undefined.
   215  *
   216  *  It is safe to pass NULL to this function; it is a no-op.
   217  */
   218 extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
   219 
   220 /**
   221  *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
   222  *
   223  *  \return The newly created thread local storage identifier, or 0 on error
   224  *
   225  *  \code
   226  *  static SDL_SpinLock tls_lock;
   227  *  static SDL_TLSID thread_local_storage;
   228  * 
   229  *  void SetMyThreadData(void *value)
   230  *  {
   231  *      if (!thread_local_storage) {
   232  *          SDL_AtomicLock(&tls_lock);
   233  *          if (!thread_local_storage) {
   234  *              thread_local_storage = SDL_TLSCreate();
   235  *          }
   236  *          SDL_AtomicUnlock(&tls_lock);
   237  *      }
   238  *      SDL_TLSSet(thread_local_storage, value, 0);
   239  *  }
   240  *  
   241  *  void *GetMyThreadData(void)
   242  *  {
   243  *      return SDL_TLSGet(thread_local_storage);
   244  *  }
   245  *  \endcode
   246  *
   247  *  \sa SDL_TLSGet()
   248  *  \sa SDL_TLSSet()
   249  */
   250 extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
   251 
   252 /**
   253  *  \brief Get the value associated with a thread local storage ID for the current thread.
   254  *
   255  *  \param id The thread local storage ID
   256  *
   257  *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
   258  *
   259  *  \sa SDL_TLSCreate()
   260  *  \sa SDL_TLSSet()
   261  */
   262 extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
   263 
   264 /**
   265  *  \brief Set the value associated with a thread local storage ID for the current thread.
   266  *
   267  *  \param id The thread local storage ID
   268  *  \param value The value to associate with the ID for the current thread
   269  *  \param destructor A function called when the thread exits, to free the value.
   270  *
   271  *  \return 0 on success, -1 on error
   272  *
   273  *  \sa SDL_TLSCreate()
   274  *  \sa SDL_TLSGet()
   275  */
   276 extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (*destructor)(void*));
   277 
   278 
   279 /* Ends C function definitions when using C++ */
   280 #ifdef __cplusplus
   281 }
   282 #endif
   283 #include "close_code.h"
   284 
   285 #endif /* _SDL_thread_h */
   286 
   287 /* vi: set ts=4 sw=4 expandtab: */