1 /*
2 * Mesa 3-D graphics library
3 * Version: 7.1
4 *
5 * Copyright (C) 1999-2008 Brian Paul All Rights Reserved.
6 *
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:
13 *
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
16 *
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.
23 */
24
25
26 /*
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.
33 *
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.
37 *
38 * NOTE: There are no dependencies on Mesa in this code.
39 *
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.
49 */
50
51 #include "u_current.h"
52 #include "u_thread.h"
53
54 #ifndef MAPI_MODE_UTIL
55
56 #include "table.h"
57 #include "stub.h"
58
59 #else
60
61 extern void init_glapi_relocs_once(void);
62 extern void (*__glapi_noop_table[])(void);
63
64 #define table_noop_array __glapi_noop_table
65 #define stub_init_once() init_glapi_relocs_once()
66
67 #endif
68
69 /**
70 * \name Current dispatch and current context control variables
71 *
72 * Depending on whether or not multithreading is support, and the type of
73 * support available, several variables are used to store the current context
74 * pointer and the current dispatch table pointer. In the non-threaded case,
75 * the variables \c _glapi_Dispatch and \c _glapi_Context are used for this
76 * purpose.
77 *
78 * In the "normal" threaded case, the variables \c _glapi_Dispatch and
79 * \c _glapi_Context will be \c NULL if an application is detected as being
80 * multithreaded. Single-threaded applications will use \c _glapi_Dispatch
81 * and \c _glapi_Context just like the case without any threading support.
82 * When \c _glapi_Dispatch and \c _glapi_Context are \c NULL, the thread state
83 * data \c _gl_DispatchTSD and \c ContextTSD are used. Drivers and the
84 * static dispatch functions access these variables via \c _glapi_get_dispatch
85 * and \c _glapi_get_context.
86 *
87 * There is a race condition in setting \c _glapi_Dispatch to \c NULL. It is
88 * possible for the original thread to be setting it at the same instant a new
89 * thread, perhaps running on a different processor, is clearing it. Because
90 * of that, \c ThreadSafe, which can only ever be changed to \c GL_TRUE, is
91 * used to determine whether or not the application is multithreaded.
92 *
93 * In the TLS case, the variables \c _glapi_Dispatch and \c _glapi_Context are
94 * hardcoded to \c NULL. Instead the TLS variables \c _glapi_tls_Dispatch and
95 * \c _glapi_tls_Context are used. Having \c _glapi_Dispatch and
96 * \c _glapi_Context be hardcoded to \c NULL maintains binary compatability
97 * between TLS enabled loaders and non-TLS DRI drivers.
98 */
99 /*@{*/
100 #if defined(GLX_USE_TLS)
101
102 __thread struct mapi_table *u_current_table
103 __attribute__((tls_model("initial-exec")))
104 = (struct mapi_table *) table_noop_array;
105
106 __thread void *u_current_user
107 __attribute__((tls_model("initial-exec")));
108
109 #else
110
111 struct mapi_table *u_current_table =
112 (struct mapi_table *) table_noop_array;
113 void *u_current_user;
114
115 #ifdef THREADS
116 struct u_tsd u_current_table_tsd;
117 static struct u_tsd u_current_user_tsd;
118 static int ThreadSafe;
119 #endif /* THREADS */
120
121 #endif /* defined(GLX_USE_TLS) */
122 /*@}*/
123
124
125 void
u_current_destroy(void)126 u_current_destroy(void)
127 {
128 #if defined(THREADS) && defined(WIN32)
129 u_tsd_destroy(&u_current_table_tsd);
130 u_tsd_destroy(&u_current_user_tsd);
131 #endif
132 }
133
134
135 #if defined(THREADS) && !defined(GLX_USE_TLS)
136
137 static void
u_current_init_tsd(void)138 u_current_init_tsd(void)
139 {
140 u_tsd_init(&u_current_table_tsd);
141 u_tsd_init(&u_current_user_tsd);
142 }
143
144 /**
145 * Mutex for multithread check.
146 */
147 u_mutex_declare_static(ThreadCheckMutex);
148
149 /**
150 * We should call this periodically from a function such as glXMakeCurrent
151 * in order to test if multiple threads are being used.
152 */
153 void
u_current_init(void)154 u_current_init(void)
155 {
156 static unsigned long knownID;
157 static int firstCall = 1;
158
159 if (ThreadSafe)
160 return;
161
162 u_mutex_lock(ThreadCheckMutex);
163 if (firstCall) {
164 u_current_init_tsd();
165
166 knownID = u_thread_self();
167 firstCall = 0;
168 }
169 else if (knownID != u_thread_self()) {
170 ThreadSafe = 1;
171 u_current_set(NULL);
172 u_current_set_user(NULL);
173 }
174 u_mutex_unlock(ThreadCheckMutex);
175 }
176
177 #else
178
179 void
u_current_init(void)180 u_current_init(void)
181 {
182 }
183
184 #endif
185
186
187
188 /**
189 * Set the current context pointer for this thread.
190 * The context pointer is an opaque type which should be cast to
191 * void from the real context pointer type.
192 */
193 void
u_current_set_user(const void * ptr)194 u_current_set_user(const void *ptr)
195 {
196 u_current_init();
197
198 #if defined(GLX_USE_TLS)
199 u_current_user = (void *) ptr;
200 #elif defined(THREADS)
201 u_tsd_set(&u_current_user_tsd, (void *) ptr);
202 u_current_user = (ThreadSafe) ? NULL : (void *) ptr;
203 #else
204 u_current_user = (void *) ptr;
205 #endif
206 }
207
208 /**
209 * Get the current context pointer for this thread.
210 * The context pointer is an opaque type which should be cast from
211 * void to the real context pointer type.
212 */
213 void *
u_current_get_user_internal(void)214 u_current_get_user_internal(void)
215 {
216 #if defined(GLX_USE_TLS)
217 return u_current_user;
218 #elif defined(THREADS)
219 return (ThreadSafe)
220 ? u_tsd_get(&u_current_user_tsd)
221 : u_current_user;
222 #else
223 return u_current_user;
224 #endif
225 }
226
227 /**
228 * Set the global or per-thread dispatch table pointer.
229 * If the dispatch parameter is NULL we'll plug in the no-op dispatch
230 * table (__glapi_noop_table).
231 */
232 void
u_current_set(const struct mapi_table * tbl)233 u_current_set(const struct mapi_table *tbl)
234 {
235 u_current_init();
236
237 stub_init_once();
238
239 if (!tbl)
240 tbl = (const struct mapi_table *) table_noop_array;
241
242 #if defined(GLX_USE_TLS)
243 u_current_table = (struct mapi_table *) tbl;
244 #elif defined(THREADS)
245 u_tsd_set(&u_current_table_tsd, (void *) tbl);
246 u_current_table = (ThreadSafe) ? NULL : (void *) tbl;
247 #else
248 u_current_table = (struct mapi_table *) tbl;
249 #endif
250 }
251
252 /**
253 * Return pointer to current dispatch table for calling thread.
254 */
255 struct mapi_table *
u_current_get_internal(void)256 u_current_get_internal(void)
257 {
258 #if defined(GLX_USE_TLS)
259 return u_current_table;
260 #elif defined(THREADS)
261 return (struct mapi_table *) ((ThreadSafe) ?
262 u_tsd_get(&u_current_table_tsd) : (void *) u_current_table);
263 #else
264 return u_current_table;
265 #endif
266 }
267