/*
* Mesa 3-D graphics library
* Version: 7.1
*
* Copyright (C) 1999-2008 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* This file manages the OpenGL API dispatch layer.
* The dispatch table (struct _glapi_table) is basically just a list
* of function pointers.
* There are functions to set/get the current dispatch table for the
* current thread and to manage registration/dispatch of dynamically
* added extension functions.
*
* It's intended that this file and the other glapi*.[ch] files are
* flexible enough to be reused in several places: XFree86, DRI-
* based libGL.so, and perhaps the SGI SI.
*
* NOTE: There are no dependencies on Mesa in this code.
*
* Versions (API changes):
* 2000/02/23 - original version for Mesa 3.3 and XFree86 4.0
* 2001/01/16 - added dispatch override feature for Mesa 3.5
* 2002/06/28 - added _glapi_set_warning_func(), Mesa 4.1.
* 2002/10/01 - _glapi_get_proc_address() will now generate new entrypoints
* itself (using offset ~0). _glapi_add_entrypoint() can be
* called afterward and it'll fill in the correct dispatch
* offset. This allows DRI libGL to avoid probing for DRI
* drivers! No changes to the public glapi interface.
*/
#include "u_current.h"
#include "u_thread.h"
#ifndef MAPI_GLAPI_CURRENT
#include "table.h"
#include "stub.h"
#else
extern void init_glapi_relocs_once(void);
extern void (*__glapi_noop_table[])(void);
#define table_noop_array __glapi_noop_table
#define stub_init_once() init_glapi_relocs_once()
#endif
/**
* \name Current dispatch and current context control variables
*
* Depending on whether or not multithreading is support, and the type of
* support available, several variables are used to store the current context
* pointer and the current dispatch table pointer. In the non-threaded case,
* 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.
*
* 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.
*/
/*@{*/
#if defined(GLX_USE_TLS)
__thread struct mapi_table *u_current_table_tls
__attribute__((tls_model("initial-exec")))
= (struct mapi_table *) table_noop_array;
__thread void *u_current_user_tls
__attribute__((tls_model("initial-exec")));
const struct mapi_table *u_current_table;
const void *u_current_user;
#else
struct mapi_table *u_current_table =
(struct mapi_table *) table_noop_array;
void *u_current_user;
#ifdef THREADS
struct u_tsd u_current_table_tsd;
static struct u_tsd u_current_user_tsd;
static int ThreadSafe;
#endif /* THREADS */
#endif /* defined(GLX_USE_TLS) */
/*@}*/
void
u_current_destroy(void)
{
#if defined(THREADS) && defined(WIN32)
u_tsd_destroy(&u_current_table_tsd);
u_tsd_destroy(&u_current_user_tsd);
#endif
}
#if defined(THREADS) && !defined(GLX_USE_TLS)
static void
u_current_init_tsd(void)
{
u_tsd_init(&u_current_table_tsd);
u_tsd_init(&u_current_user_tsd);
}
/**
* Mutex for multithread check.
*/
#ifdef WIN32
/* _glthread_DECLARE_STATIC_MUTEX is broken on windows. There will be race! */
#define CHECK_MULTITHREAD_LOCK()
#define CHECK_MULTITHREAD_UNLOCK()
#else
u_mutex_declare_static(ThreadCheckMutex);
#define CHECK_MULTITHREAD_LOCK() u_mutex_lock(ThreadCheckMutex)
#define CHECK_MULTITHREAD_UNLOCK() u_mutex_unlock(ThreadCheckMutex)
#endif
/**
* We should call this periodically from a function such as glXMakeCurrent
* in order to test if multiple threads are being used.
*/
void
u_current_init(void)
{
static unsigned long knownID;
static int firstCall = 1;
if (ThreadSafe)
return;
CHECK_MULTITHREAD_LOCK();
if (firstCall) {
u_current_init_tsd();
knownID = u_thread_self();
firstCall = 0;
}
else if (knownID != u_thread_self()) {
ThreadSafe = 1;
u_current_set_internal(NULL);
u_current_set_user_internal(NULL);
}
CHECK_MULTITHREAD_UNLOCK();
}
#else
void
u_current_init(void)
{
}
#endif
/**
* Set the current context pointer for this thread.
* The context pointer is an opaque type which should be cast to
* void from the real context pointer type.
*/
void
u_current_set_user_internal(void *ptr)
{
u_current_init();
#if defined(GLX_USE_TLS)
u_current_user_tls = ptr;
#elif defined(THREADS)
u_tsd_set(&u_current_user_tsd, ptr);
u_current_user = (ThreadSafe) ? NULL : ptr;
#else
u_current_user = ptr;
#endif
}
/**
* Get the current context pointer for this thread.
* The context pointer is an opaque type which should be cast from
* void to the real context pointer type.
*/
void *
u_current_get_user_internal(void)
{
#if defined(GLX_USE_TLS)
return u_current_user_tls;
#elif defined(THREADS)
return (ThreadSafe)
? u_tsd_get(&u_current_user_tsd)
: u_current_user;
#else
return u_current_user;
#endif
}
/**
* Set the global or per-thread dispatch table pointer.
* If the dispatch parameter is NULL we'll plug in the no-op dispatch
* table (__glapi_noop_table).
*/
void
u_current_set_internal(struct mapi_table *tbl)
{
u_current_init();
stub_init_once();
if (!tbl)
tbl = (struct mapi_table *) table_noop_array;
#if defined(GLX_USE_TLS)
u_current_table_tls = tbl;
#elif defined(THREADS)
u_tsd_set(&u_current_table_tsd, (void *) tbl);
u_current_table = (ThreadSafe) ? NULL : tbl;
#else
u_current_table = tbl;
#endif
}
/**
* Return pointer to current dispatch table for calling thread.
*/
struct mapi_table *
u_current_get_internal(void)
{
#if defined(GLX_USE_TLS)
return u_current_table_tls;
#elif defined(THREADS)
return (struct mapi_table *) ((ThreadSafe) ?
u_tsd_get(&u_current_table_tsd) : (void *) u_current_table);
#else
return u_current_table;
#endif
}