diff options
Diffstat (limited to 'src/mesa/glapi/glapi.c')
| -rw-r--r-- | src/mesa/glapi/glapi.c | 111 |
1 files changed, 61 insertions, 50 deletions
diff --git a/src/mesa/glapi/glapi.c b/src/mesa/glapi/glapi.c index 2b105d0f17d..4bb10df1d84 100644 --- a/src/mesa/glapi/glapi.c +++ b/src/mesa/glapi/glapi.c @@ -160,26 +160,20 @@ static GLint NoOpUnused(void) * the variables \c _glapi_Dispatch and \c _glapi_Context are used for this * purpose. * - * In the "normal" threaded case, the variables \c _glapi_Dispatch and - * \c _glapi_Context will be \c NULL if an application is detected as being - * multithreaded. Single-threaded applications will use \c _glapi_Dispatch - * and \c _glapi_Context just like the case without any threading support. - * When \c _glapi_Dispatch and \c _glapi_Context are \c NULL, the thread state - * data \c _gl_DispatchTSD and \c ContextTSD are used. Drivers and the - * static dispatch functions access these variables via \c _glapi_get_dispatch - * and \c _glapi_get_context. + * In the "normal" threaded case, the variable \c _glapi_SingleThreaded will be + * \c GL_FALSE if an application is detected as being multithreaded. + * Single-threaded applications will use \c _glapi_Dispatch and \c + * _glapi_Context just like the case without any threading support. When \c + * _glapi_SingleThreaded is \c GL_FALSE, the thread state data \c + * _gl_DispatchTSD and \c ContextTSD are used. Drivers and the static dispatch + * functions access these variables via \c _glapi_get_dispatch and \c + * _glapi_get_context. * - * There is a race condition in setting \c _glapi_Dispatch to \c NULL. It is - * possible for the original thread to be setting it at the same instant a new - * thread, perhaps running on a different processor, is clearing it. Because - * of that, \c ThreadSafe, which can only ever be changed to \c GL_TRUE, is - * used to determine whether or not the application is multithreaded. - * * In the TLS case, the variables \c _glapi_Dispatch and \c _glapi_Context are * hardcoded to \c NULL. Instead the TLS variables \c _glapi_tls_Dispatch and - * \c _glapi_tls_Context are used. Having \c _glapi_Dispatch and - * \c _glapi_Context be hardcoded to \c NULL maintains binary compatability - * between TLS enabled loaders and non-TLS DRI drivers. + * \c _glapi_tls_Context are used. The variable \c _glapi_SingleThreaded, + * though not used, is defined and hardcoded to \c GL_FALSE to maintain binary + * compatability between TLS enabled loaders and non-TLS DRI drivers. */ /*@{*/ #if defined(GLX_USE_TLS) @@ -194,13 +188,26 @@ PUBLIC __thread void * _glapi_tls_Context PUBLIC const struct _glapi_table *_glapi_Dispatch = NULL; PUBLIC const void *_glapi_Context = NULL; +/* Unused, but maintain binary compatability with non-TLS DRI drivers */ +GLboolean _glapi_SingleThreaded = GL_FALSE; + #else #if defined(THREADS) -static GLboolean ThreadSafe = GL_FALSE; /**< In thread-safe mode? */ -_glthread_TSD _gl_DispatchTSD; /**< Per-thread dispatch pointer */ -static _glthread_TSD ContextTSD; /**< Per-thread context pointer */ +#ifdef WIN32_THREADS +/* _glthread_DECLARE_STATIC_MUTEX is broken on windows. There will be race! */ +#define CHECK_MULTITHREAD_LOCK() +#define CHECK_MULTITHREAD_UNLOCK() +#else +_glthread_DECLARE_STATIC_MUTEX(ThreadCheckMutex); +#define CHECK_MULTITHREAD_LOCK() _glthread_LOCK_MUTEX(ThreadCheckMutex) +#define CHECK_MULTITHREAD_UNLOCK() _glthread_UNLOCK_MUTEX(ThreadCheckMutex) +#endif + +GLboolean _glapi_SingleThreaded = GL_TRUE; /**< In single-thread mode? */ +_glthread_TSD _gl_DispatchTSD; /**< Per-thread dispatch pointer */ +static _glthread_TSD ContextTSD; /**< Per-thread context pointer */ #if defined(WIN32_THREADS) void FreeTSD(_glthread_TSD *p); @@ -231,23 +238,30 @@ void _glapi_check_multithread(void) { #if defined(THREADS) && !defined(GLX_USE_TLS) - if (!ThreadSafe) { - static unsigned long knownID; - static GLboolean firstCall = GL_TRUE; - if (firstCall) { - knownID = _glthread_GetID(); - firstCall = GL_FALSE; - } - else if (knownID != _glthread_GetID()) { - ThreadSafe = GL_TRUE; - _glapi_set_dispatch(NULL); - _glapi_set_context(NULL); - } + static unsigned long knownID; + static GLboolean firstCall = GL_TRUE; + + if (!_glapi_SingleThreaded) + return; + + CHECK_MULTITHREAD_LOCK(); + if (firstCall) { + /* initialize TSDs */ + (void) _glthread_GetTSD(&ContextTSD); + (void) _glthread_GetTSD(&_gl_DispatchTSD); + + knownID = _glthread_GetID(); + firstCall = GL_FALSE; } - else if (!_glapi_get_dispatch()) { - /* make sure that this thread's dispatch pointer isn't null */ - _glapi_set_dispatch(NULL); + else if (knownID != _glthread_GetID()) { + /* + * switch to thread-safe mode. _glapi_Context and _glapi_Dispatch are no + * longer accessed after this point, except for raced by the first + * thread. Because of the race, they cannot be reset to NULL. + */ + _glapi_SingleThreaded = GL_FALSE; } + CHECK_MULTITHREAD_UNLOCK(); #endif } @@ -265,8 +279,10 @@ _glapi_set_context(void *context) #if defined(GLX_USE_TLS) _glapi_tls_Context = context; #elif defined(THREADS) + if (_glapi_SingleThreaded) + _glapi_Context = context; + /* always update TSD because we might switch to it at any time */ _glthread_SetTSD(&ContextTSD, context); - _glapi_Context = (ThreadSafe) ? NULL : context; #else _glapi_Context = context; #endif @@ -285,12 +301,8 @@ _glapi_get_context(void) #if defined(GLX_USE_TLS) return _glapi_tls_Context; #elif defined(THREADS) - if (ThreadSafe) { - return _glthread_GetTSD(&ContextTSD); - } - else { - return _glapi_Context; - } + return (_glapi_SingleThreaded) + ? _glapi_Context : _glthread_GetTSD(&ContextTSD); #else return _glapi_Context; #endif @@ -505,8 +517,9 @@ _glapi_set_dispatch(struct _glapi_table *dispatch) #if defined(GLX_USE_TLS) _glapi_tls_Dispatch = dispatch; #elif defined(THREADS) + if (_glapi_SingleThreaded) + _glapi_Dispatch = dispatch; _glthread_SetTSD(&_gl_DispatchTSD, (void *) dispatch); - _glapi_Dispatch = (ThreadSafe) ? NULL : dispatch; #else /*THREADS*/ _glapi_Dispatch = dispatch; #endif /*THREADS*/ @@ -520,17 +533,15 @@ _glapi_set_dispatch(struct _glapi_table *dispatch) PUBLIC struct _glapi_table * _glapi_get_dispatch(void) { - struct _glapi_table * api; #if defined(GLX_USE_TLS) - api = _glapi_tls_Dispatch; + return _glapi_tls_Dispatch; #elif defined(THREADS) - api = (ThreadSafe) - ? (struct _glapi_table *) _glthread_GetTSD(&_gl_DispatchTSD) - : _glapi_Dispatch; + return (_glapi_SingleThreaded) + ? _glapi_Dispatch + : (struct _glapi_table *) _glthread_GetTSD(&_gl_DispatchTSD); #else - api = _glapi_Dispatch; + return _glapi_Dispatch; #endif - return api; } |