include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Tue, 23 Apr 2019 07:59:31 -0700
changeset 12714 9b7633bd0aa0
parent 12503 806492103856
permissions -rw-r--r--
Use _Exit() when available
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/*
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  Simple DirectMedia Layer
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  Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
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  This software is provided 'as-is', without any express or implied
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  warranty.  In no event will the authors be held liable for any damages
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  arising from the use of this software.
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  Permission is granted to anyone to use this software for any purpose,
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  including commercial applications, and to alter it and redistribute it
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  freely, subject to the following restrictions:
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  1. The origin of this software must not be misrepresented; you must not
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     claim that you wrote the original software. If you use this software
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     in a product, an acknowledgment in the product documentation would be
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     appreciated but is not required.
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  2. Altered source versions must be plainly marked as such, and must not be
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     misrepresented as being the original software.
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  3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef SDL_thread_h_
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#define SDL_thread_h_
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/**
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 *  \file SDL_thread.h
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 *
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 *  Header for the SDL thread management routines.
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 */
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#include "SDL_stdinc.h"
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#include "SDL_error.h"
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/* Thread synchronization primitives */
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#include "SDL_atomic.h"
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#include "SDL_mutex.h"
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#include "begin_code.h"
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/* Set up for C function definitions, even when using C++ */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* The SDL thread structure, defined in SDL_thread.c */
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struct SDL_Thread;
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typedef struct SDL_Thread SDL_Thread;
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/* The SDL thread ID */
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typedef unsigned long SDL_threadID;
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/* Thread local storage ID, 0 is the invalid ID */
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typedef unsigned int SDL_TLSID;
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/**
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 *  The SDL thread priority.
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 *
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 *  \note On many systems you require special privileges to set high or time critical priority.
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 */
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typedef enum {
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    SDL_THREAD_PRIORITY_LOW,
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    SDL_THREAD_PRIORITY_NORMAL,
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    SDL_THREAD_PRIORITY_HIGH,
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    SDL_THREAD_PRIORITY_TIME_CRITICAL
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} SDL_ThreadPriority;
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/**
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 *  The function passed to SDL_CreateThread().
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 *  It is passed a void* user context parameter and returns an int.
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 */
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typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
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#if defined(__WIN32__) && !defined(HAVE_LIBC)
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/**
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 *  \file SDL_thread.h
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 *
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 *  We compile SDL into a DLL. This means, that it's the DLL which
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 *  creates a new thread for the calling process with the SDL_CreateThread()
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 *  API. There is a problem with this, that only the RTL of the SDL2.DLL will
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 *  be initialized for those threads, and not the RTL of the calling
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 *  application!
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 *
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 *  To solve this, we make a little hack here.
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 *
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 *  We'll always use the caller's _beginthread() and _endthread() APIs to
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 *  start a new thread. This way, if it's the SDL2.DLL which uses this API,
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 *  then the RTL of SDL2.DLL will be used to create the new thread, and if it's
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 *  the application, then the RTL of the application will be used.
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 *
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 *  So, in short:
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 *  Always use the _beginthread() and _endthread() of the calling runtime
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 *  library!
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 */
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#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
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#include <process.h> /* _beginthreadex() and _endthreadex() */
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typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread)
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                   (void *, unsigned, unsigned (__stdcall *func)(void *),
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                    void * /*arg*/, unsigned, unsigned * /* threadID */);
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typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
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/**
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 *  Create a thread.
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 */
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
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                 pfnSDL_CurrentBeginThread pfnBeginThread,
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                 pfnSDL_CurrentEndThread pfnEndThread);
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *),
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                 const char *name, const size_t stacksize, void *data,
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                 pfnSDL_CurrentBeginThread pfnBeginThread,
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                 pfnSDL_CurrentEndThread pfnEndThread);
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/**
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 *  Create a thread.
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 */
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#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
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#undef SDL_CreateThread
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
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#undef SDL_CreateThreadWithStackSize
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
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#else
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)_endthreadex)
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#endif
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#elif defined(__OS2__)
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/*
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 * just like the windows case above:  We compile SDL2
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 * into a dll with Watcom's runtime statically linked.
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 */
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#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
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#ifndef __EMX__
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#include <process.h>
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#else
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#include <stdlib.h>
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#endif
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typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
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typedef void (*pfnSDL_CurrentEndThread)(void);
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
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                 pfnSDL_CurrentBeginThread pfnBeginThread,
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                 pfnSDL_CurrentEndThread pfnEndThread);
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
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                 pfnSDL_CurrentBeginThread pfnBeginThread,
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                 pfnSDL_CurrentEndThread pfnEndThread);
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#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
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#undef SDL_CreateThread
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
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#undef SDL_CreateThreadWithStackSize
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
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#else
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)_beginthread, (pfnSDL_CurrentEndThread)_endthread)
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#endif
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#else
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/**
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 *  Create a thread with a default stack size.
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 *
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 *  This is equivalent to calling:
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 *  SDL_CreateThreadWithStackSize(fn, name, 0, data);
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 */
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
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/**
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 *  Create a thread.
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 *
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 *   Thread naming is a little complicated: Most systems have very small
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 *    limits for the string length (Haiku has 32 bytes, Linux currently has 16,
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 *    Visual C++ 6.0 has nine!), and possibly other arbitrary rules. You'll
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 *    have to see what happens with your system's debugger. The name should be
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 *    UTF-8 (but using the naming limits of C identifiers is a better bet).
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 *   There are no requirements for thread naming conventions, so long as the
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 *    string is null-terminated UTF-8, but these guidelines are helpful in
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 *    choosing a name:
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 *
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 *    http://stackoverflow.com/questions/149932/naming-conventions-for-threads
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 *
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 *   If a system imposes requirements, SDL will try to munge the string for
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 *    it (truncate, etc), but the original string contents will be available
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 *    from SDL_GetThreadName().
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 *
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 *   The size (in bytes) of the new stack can be specified. Zero means "use
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 *    the system default" which might be wildly different between platforms
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 *    (x86 Linux generally defaults to eight megabytes, an embedded device
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 *    might be a few kilobytes instead).
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 *
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 *   In SDL 2.1, stacksize will be folded into the original SDL_CreateThread
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 *    function.
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 */
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
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#endif
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/**
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 * Get the thread name, as it was specified in SDL_CreateThread().
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 *  This function returns a pointer to a UTF-8 string that names the
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 *  specified thread, or NULL if it doesn't have a name. This is internal
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 *  memory, not to be free()'d by the caller, and remains valid until the
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 *  specified thread is cleaned up by SDL_WaitThread().
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 */
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extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
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/**
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 *  Get the thread identifier for the current thread.
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 */
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extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
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/**
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 *  Get the thread identifier for the specified thread.
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 *
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 *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
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 */
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extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
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/**
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 *  Set the priority for the current thread
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 */
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extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
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/**
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 *  Wait for a thread to finish. Threads that haven't been detached will
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 *  remain (as a "zombie") until this function cleans them up. Not doing so
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 *  is a resource leak.
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 *
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 *  Once a thread has been cleaned up through this function, the SDL_Thread
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 *  that references it becomes invalid and should not be referenced again.
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 *  As such, only one thread may call SDL_WaitThread() on another.
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 *
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 *  The return code for the thread function is placed in the area
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 *  pointed to by \c status, if \c status is not NULL.
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 *
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 *  You may not wait on a thread that has been used in a call to
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 *  SDL_DetachThread(). Use either that function or this one, but not
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 *  both, or behavior is undefined.
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 *
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 *  It is safe to pass NULL to this function; it is a no-op.
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 */
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extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
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/**
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 *  A thread may be "detached" to signify that it should not remain until
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 *  another thread has called SDL_WaitThread() on it. Detaching a thread
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 *  is useful for long-running threads that nothing needs to synchronize
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 *  with or further manage. When a detached thread is done, it simply
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 *  goes away.
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 *
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 *  There is no way to recover the return code of a detached thread. If you
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 *  need this, don't detach the thread and instead use SDL_WaitThread().
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 *
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 *  Once a thread is detached, you should usually assume the SDL_Thread isn't
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 *  safe to reference again, as it will become invalid immediately upon
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 *  the detached thread's exit, instead of remaining until someone has called
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 *  SDL_WaitThread() to finally clean it up. As such, don't detach the same
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 *  thread more than once.
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 *
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 *  If a thread has already exited when passed to SDL_DetachThread(), it will
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 *  stop waiting for a call to SDL_WaitThread() and clean up immediately.
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 *  It is not safe to detach a thread that might be used with SDL_WaitThread().
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 *
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 *  You may not call SDL_WaitThread() on a thread that has been detached.
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 *  Use either that function or this one, but not both, or behavior is
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 *  undefined.
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 *
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 *  It is safe to pass NULL to this function; it is a no-op.
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 */
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extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
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/**
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 *  \brief Create an identifier that is globally visible to all threads but refers to data that is thread-specific.
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 *
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 *  \return The newly created thread local storage identifier, or 0 on error
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 *
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 *  \code
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 *  static SDL_SpinLock tls_lock;
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 *  static SDL_TLSID thread_local_storage;
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 * 
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 *  void SetMyThreadData(void *value)
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 *  {
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 *      if (!thread_local_storage) {
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 *          SDL_AtomicLock(&tls_lock);
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 *          if (!thread_local_storage) {
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 *              thread_local_storage = SDL_TLSCreate();
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 *          }
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 *          SDL_AtomicUnlock(&tls_lock);
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 *      }
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 *      SDL_TLSSet(thread_local_storage, value, 0);
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 *  }
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 *  
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 *  void *GetMyThreadData(void)
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 *  {
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 *      return SDL_TLSGet(thread_local_storage);
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 *  }
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 *  \endcode
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 *
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 *  \sa SDL_TLSGet()
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 *  \sa SDL_TLSSet()
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 */
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extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
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/**
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 *  \brief Get the value associated with a thread local storage ID for the current thread.
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 *
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 *  \param id The thread local storage ID
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 *
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 *  \return The value associated with the ID for the current thread, or NULL if no value has been set.
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 *
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 *  \sa SDL_TLSCreate()
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 *  \sa SDL_TLSSet()
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 */
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extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
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/**
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 *  \brief Set the value associated with a thread local storage ID for the current thread.
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 *
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 *  \param id The thread local storage ID
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 *  \param value The value to associate with the ID for the current thread
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 *  \param destructor A function called when the thread exits, to free the value.
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 *
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 *  \return 0 on success, -1 on error
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 *
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 *  \sa SDL_TLSCreate()
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 *  \sa SDL_TLSGet()
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 */
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extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
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/* Ends C function definitions when using C++ */
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#ifdef __cplusplus
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}
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#endif
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#include "close_code.h"
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#endif /* SDL_thread_h_ */
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/* vi: set ts=4 sw=4 expandtab: */