2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2008 Brian Paul All Rights Reserved.
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
21 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
27 * This file manages the OpenGL API dispatch layer.
28 * The dispatch table (struct _glapi_table) is basically just a list
29 * of function pointers.
30 * There are functions to set/get the current dispatch table for the
31 * current thread and to manage registration/dispatch of dynamically
32 * added extension functions.
34 * It's intended that this file and the other glapi*.[ch] files are
35 * flexible enough to be reused in several places: XFree86, DRI-
36 * based libGL.so, and perhaps the SGI SI.
38 * NOTE: There are no dependencies on Mesa in this code.
40 * Versions (API changes):
41 * 2000/02/23 - original version for Mesa 3.3 and XFree86 4.0
42 * 2001/01/16 - added dispatch override feature for Mesa 3.5
43 * 2002/06/28 - added _glapi_set_warning_func(), Mesa 4.1.
44 * 2002/10/01 - _glapi_get_proc_address() will now generate new entrypoints
45 * itself (using offset ~0). _glapi_add_entrypoint() can be
46 * called afterward and it'll fill in the correct dispatch
47 * offset. This allows DRI libGL to avoid probing for DRI
48 * drivers! No changes to the public glapi interface.
53 #ifdef HAVE_DIX_CONFIG_H
54 #include <dix-config.h>
55 #include "glapi/mesa.h"
57 #include "main/glheader.h"
58 #include "main/compiler.h"
61 #include "glapi/glapi.h"
62 #include "glapi/glapi_priv.h"
64 extern _glapi_proc __glapi_noop_table
[];
68 * \name Current dispatch and current context control variables
70 * Depending on whether or not multithreading is support, and the type of
71 * support available, several variables are used to store the current context
72 * pointer and the current dispatch table pointer. In the non-threaded case,
73 * the variables \c _glapi_Dispatch and \c _glapi_Context are used for this
76 * In the "normal" threaded case, the variables \c _glapi_Dispatch and
77 * \c _glapi_Context will be \c NULL if an application is detected as being
78 * multithreaded. Single-threaded applications will use \c _glapi_Dispatch
79 * and \c _glapi_Context just like the case without any threading support.
80 * When \c _glapi_Dispatch and \c _glapi_Context are \c NULL, the thread state
81 * data \c _gl_DispatchTSD and \c ContextTSD are used. Drivers and the
82 * static dispatch functions access these variables via \c _glapi_get_dispatch
83 * and \c _glapi_get_context.
85 * There is a race condition in setting \c _glapi_Dispatch to \c NULL. It is
86 * possible for the original thread to be setting it at the same instant a new
87 * thread, perhaps running on a different processor, is clearing it. Because
88 * of that, \c ThreadSafe, which can only ever be changed to \c GL_TRUE, is
89 * used to determine whether or not the application is multithreaded.
91 * In the TLS case, the variables \c _glapi_Dispatch and \c _glapi_Context are
92 * hardcoded to \c NULL. Instead the TLS variables \c _glapi_tls_Dispatch and
93 * \c _glapi_tls_Context are used. Having \c _glapi_Dispatch and
94 * \c _glapi_Context be hardcoded to \c NULL maintains binary compatability
95 * between TLS enabled loaders and non-TLS DRI drivers.
98 #if defined(GLX_USE_TLS)
100 PUBLIC __thread
struct _glapi_table
* _glapi_tls_Dispatch
101 __attribute__((tls_model("initial-exec")))
102 = (struct _glapi_table
*) __glapi_noop_table
;
104 PUBLIC __thread
void * _glapi_tls_Context
105 __attribute__((tls_model("initial-exec")));
107 PUBLIC
const struct _glapi_table
*_glapi_Dispatch
= NULL
;
109 PUBLIC
const void *_glapi_Context
= NULL
;
115 static GLboolean ThreadSafe
= GL_FALSE
; /**< In thread-safe mode? */
117 _glthread_TSD _gl_DispatchTSD
; /**< Per-thread dispatch pointer */
119 static _glthread_TSD ContextTSD
; /**< Per-thread context pointer */
121 #endif /* defined(THREADS) */
123 PUBLIC
struct _glapi_table
*_glapi_Dispatch
= (struct _glapi_table
*) __glapi_noop_table
;
125 PUBLIC
void *_glapi_Context
= NULL
;
127 #endif /* defined(GLX_USE_TLS) */
132 #if defined(THREADS) && !defined(GLX_USE_TLS)
135 _glapi_init_multithread(void)
137 _glthread_InitTSD(&_gl_DispatchTSD
);
138 _glthread_InitTSD(&ContextTSD
);
142 _glapi_destroy_multithread(void)
145 _glthread_DestroyTSD(&_gl_DispatchTSD
);
146 _glthread_DestroyTSD(&ContextTSD
);
151 * Mutex for multithread check.
154 /* _glthread_DECLARE_STATIC_MUTEX is broken on windows. There will be race! */
155 #define CHECK_MULTITHREAD_LOCK()
156 #define CHECK_MULTITHREAD_UNLOCK()
158 _glthread_DECLARE_STATIC_MUTEX(ThreadCheckMutex
);
159 #define CHECK_MULTITHREAD_LOCK() _glthread_LOCK_MUTEX(ThreadCheckMutex)
160 #define CHECK_MULTITHREAD_UNLOCK() _glthread_UNLOCK_MUTEX(ThreadCheckMutex)
164 * We should call this periodically from a function such as glXMakeCurrent
165 * in order to test if multiple threads are being used.
168 _glapi_check_multithread(void)
170 static unsigned long knownID
;
171 static GLboolean firstCall
= GL_TRUE
;
176 CHECK_MULTITHREAD_LOCK();
178 _glapi_init_multithread();
180 knownID
= _glthread_GetID();
181 firstCall
= GL_FALSE
;
183 else if (knownID
!= _glthread_GetID()) {
184 ThreadSafe
= GL_TRUE
;
185 _glapi_set_dispatch(NULL
);
186 _glapi_set_context(NULL
);
188 CHECK_MULTITHREAD_UNLOCK();
194 _glapi_init_multithread(void) { }
197 _glapi_destroy_multithread(void) { }
200 _glapi_check_multithread(void) { }
207 * Set the current context pointer for this thread.
208 * The context pointer is an opaque type which should be cast to
209 * void from the real context pointer type.
212 _glapi_set_context(void *context
)
214 #if defined(GLX_USE_TLS)
215 _glapi_tls_Context
= context
;
216 #elif defined(THREADS)
217 _glthread_SetTSD(&ContextTSD
, context
);
218 _glapi_Context
= (ThreadSafe
) ? NULL
: context
;
220 _glapi_Context
= context
;
227 * Get the current context pointer for this thread.
228 * The context pointer is an opaque type which should be cast from
229 * void to the real context pointer type.
232 _glapi_get_context(void)
234 #if defined(GLX_USE_TLS)
235 return _glapi_tls_Context
;
236 #elif defined(THREADS)
237 return (ThreadSafe
) ? _glthread_GetTSD(&ContextTSD
) : _glapi_Context
;
239 return _glapi_Context
;
246 * Set the global or per-thread dispatch table pointer.
247 * If the dispatch parameter is NULL we'll plug in the no-op dispatch
248 * table (__glapi_noop_table).
251 _glapi_set_dispatch(struct _glapi_table
*dispatch
)
253 init_glapi_relocs_once();
255 if (dispatch
== NULL
) {
256 /* use the no-op functions */
257 dispatch
= (struct _glapi_table
*) __glapi_noop_table
;
261 _glapi_check_table_not_null(dispatch
);
262 _glapi_check_table(dispatch
);
266 #if defined(GLX_USE_TLS)
267 _glapi_tls_Dispatch
= dispatch
;
268 #elif defined(THREADS)
269 _glthread_SetTSD(&_gl_DispatchTSD
, (void *) dispatch
);
270 _glapi_Dispatch
= (ThreadSafe
) ? NULL
: dispatch
;
272 _glapi_Dispatch
= dispatch
;
279 * Return pointer to current dispatch table for calling thread.
281 PUBLIC
struct _glapi_table
*
282 _glapi_get_dispatch(void)
284 #if defined(GLX_USE_TLS)
285 return _glapi_tls_Dispatch
;
286 #elif defined(THREADS)
288 ? (struct _glapi_table
*) _glthread_GetTSD(&_gl_DispatchTSD
)
291 return _glapi_Dispatch
;