src/glx/glxcurrent.c

   1 /*
   2  * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
   3  * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice including the dates of first publication and
  13  * either this permission notice or a reference to
  14  * http://oss.sgi.com/projects/FreeB/
  15  * shall be included 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  * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  21  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
  22  * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE.
  24  *
  25  * Except as contained in this notice, the name of Silicon Graphics, Inc.
  26  * shall not be used in advertising or otherwise to promote the sale, use or
  27  * other dealings in this Software without prior written authorization from
  28  * Silicon Graphics, Inc.
  29  */
  30
  31 /**
  32  * \file glxcurrent.c
  33  * Client-side GLX interface for current context management.
  34  */
  35
  36 #ifdef HAVE_PTHREAD
  37 #include <pthread.h>
  38 #endif
  39
  40 #include "glxclient.h"
  41
  42 #include "glapi.h"
  43
  44 /*
  45 ** We setup some dummy structures here so that the API can be used
  46 ** even if no context is current.
  47 */
  48
  49 static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];
  50 static struct glx_context_vtable dummyVtable;
  51 /*
  52 ** Dummy context used by small commands when there is no current context.
  53 ** All the
  54 ** gl and glx entry points are designed to operate as nop's when using
  55 ** the dummy context structure.
  56 */
  57 struct glx_context dummyContext = {
  58    &dummyBuffer[0],
  59    &dummyBuffer[0],
  60    &dummyBuffer[0],
  61    &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
  62    sizeof(dummyBuffer),
  63    &dummyVtable
  64 };
  65
  66 /*
  67  * Current context management and locking
  68  */
  69
  70 #if defined( HAVE_PTHREAD )
  71
  72 _X_HIDDEN pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;
  73
  74 # if defined( GLX_USE_TLS )
  75
  76 /**
  77  * Per-thread GLX context pointer.
  78  *
  79  * \c __glXSetCurrentContext is written is such a way that this pointer can
  80  * \b never be \c NULL.  This is important!  Because of this
  81  * \c __glXGetCurrentContext can be implemented as trivial macro.
  82  */
  83 __thread void *__glX_tls_Context __attribute__ ((tls_model("initial-exec")))
  84    = &dummyContext;
  85
  86 _X_HIDDEN void
  87 __glXSetCurrentContext(struct glx_context * c)
  88 {
  89    __glX_tls_Context = (c != NULL) ? c : &dummyContext;
  90 }
  91
  92 # else
  93
  94 static pthread_once_t once_control = PTHREAD_ONCE_INIT;
  95
  96 /**
  97  * Per-thread data key.
  98  *
  99  * Once \c init_thread_data has been called, the per-thread data key will
 100  * take a value of \c NULL.  As each new thread is created the default
 101  * value, in that thread, will be \c NULL.
 102  */
 103 static pthread_key_t ContextTSD;
 104
 105 /**
 106  * Initialize the per-thread data key.
 107  *
 108  * This function is called \b exactly once per-process (not per-thread!) to
 109  * initialize the per-thread data key.  This is ideally done using the
 110  * \c pthread_once mechanism.
 111  */
 112 static void
 113 init_thread_data(void)
 114 {
 115    if (pthread_key_create(&ContextTSD, NULL) != 0) {
 116       perror("pthread_key_create");
 117       exit(-1);
 118    }
 119 }
 120
 121 _X_HIDDEN void
 122 __glXSetCurrentContext(struct glx_context * c)
 123 {
 124    pthread_once(&once_control, init_thread_data);
 125    pthread_setspecific(ContextTSD, c);
 126 }
 127
 128 _X_HIDDEN struct glx_context *
 129 __glXGetCurrentContext(void)
 130 {
 131    void *v;
 132
 133    pthread_once(&once_control, init_thread_data);
 134
 135    v = pthread_getspecific(ContextTSD);
 136    return (v == NULL) ? &dummyContext : (struct glx_context *) v;
 137 }
 138
 139 # endif /* defined( GLX_USE_TLS ) */
 140
 141 #else
 142
 143 /* not thread safe */
 144 _X_HIDDEN struct glx_context *__glXcurrentContext = &dummyContext;
 145
 146 #endif
 147
 148
 149 _X_HIDDEN void
 150 __glXSetCurrentContextNull(void)
 151 {
 152    __glXSetCurrentContext(&dummyContext);
 153 #if defined(GLX_DIRECT_RENDERING)
 154    _glapi_set_dispatch(NULL);   /* no-op functions */
 155    _glapi_set_context(NULL);
 156 #endif
 157 }
 158
 159 _X_EXPORT GLXContext
 160 glXGetCurrentContext(void)
 161 {
 162    struct glx_context *cx = __glXGetCurrentContext();
 163
 164    if (cx == &dummyContext) {
 165       return NULL;
 166    }
 167    else {
 168       return (GLXContext) cx;
 169    }
 170 }
 171
 172 _X_EXPORT GLXDrawable
 173 glXGetCurrentDrawable(void)
 174 {
 175    struct glx_context *gc = __glXGetCurrentContext();
 176    return gc->currentDrawable;
 177 }
 178
 179 static void
 180 __glXGenerateError(Display * dpy, XID resource,
 181                    BYTE errorCode, CARD16 minorCode)
 182 {
 183    xError error;
 184
 185    error.errorCode = errorCode;
 186    error.resourceID = resource;
 187    error.sequenceNumber = dpy->request;
 188    error.type = X_Error;
 189    error.majorCode = __glXSetupForCommand(dpy);
 190    error.minorCode = minorCode;
 191    _XError(dpy, &error);
 192 }
 193
 194 /**
 195  * Make a particular context current.
 196  *
 197  * \note This is in this file so that it can access dummyContext.
 198  */
 199 static Bool
 200 MakeContextCurrent(Display * dpy, GLXDrawable draw,
 201                    GLXDrawable read, GLXContext gc_user)
 202 {
 203    struct glx_context *gc = (struct glx_context *) gc_user;
 204    struct glx_context *oldGC = __glXGetCurrentContext();
 205
 206    /* Make sure that the new context has a nonzero ID.  In the request,
 207     * a zero context ID is used only to mean that we bind to no current
 208     * context.
 209     */
 210    if ((gc != NULL) && (gc->xid == None)) {
 211       return GL_FALSE;
 212    }
 213
 214    _glapi_check_multithread();
 215
 216    __glXLock();
 217    if (oldGC == gc &&
 218        gc->currentDrawable == draw && gc->currentReadable == read) {
 219       __glXUnlock();
 220       return True;
 221    }
 222
 223    if (oldGC != &dummyContext) {
 224       if (--oldGC->thread_refcount == 0) {
 225          oldGC->vtable->unbind(oldGC, gc);
 226          oldGC->currentDpy = 0;
 227       }
 228    }
 229
 230    if (gc) {
 231       /* Attempt to bind the context.  We do this before mucking with
 232        * gc and __glXSetCurrentContext to properly handle our state in
 233        * case of an error.
 234        *
 235        * If an error occurs, set the Null context since we've already
 236        * blown away our old context.  The caller is responsible for
 237        * figuring out how to handle setting a valid context.
 238        */
 239       if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
 240          __glXSetCurrentContextNull();
 241          __glXUnlock();
 242          __glXGenerateError(dpy, None, GLXBadContext, X_GLXMakeContextCurrent);
 243          return GL_FALSE;
 244       }
 245
 246       if (gc->thread_refcount == 0) {
 247          gc->currentDpy = dpy;
 248          gc->currentDrawable = draw;
 249          gc->currentReadable = read;
 250       }
 251       gc->thread_refcount++;
 252       __glXSetCurrentContext(gc);
 253    } else {
 254       __glXSetCurrentContextNull();
 255    }
 256
 257    if (oldGC->thread_refcount == 0 && oldGC != &dummyContext && oldGC->xid == None) {
 258       /* We are switching away from a context that was
 259        * previously destroyed, so we need to free the memory
 260        * for the old handle. */
 261       oldGC->vtable->destroy(oldGC);
 262    }
 263
 264    __glXUnlock();
 265
 266    return GL_TRUE;
 267 }
 268
 269
 270 _X_EXPORT Bool
 271 glXMakeCurrent(Display * dpy, GLXDrawable draw, GLXContext gc)
 272 {
 273    return MakeContextCurrent(dpy, draw, draw, gc);
 274 }
 275
 276 _X_EXPORT
 277 GLX_ALIAS(Bool, glXMakeCurrentReadSGI,
 278           (Display * dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
 279           (dpy, d, r, ctx), MakeContextCurrent)
 280
 281 _X_EXPORT
 282 GLX_ALIAS(Bool, glXMakeContextCurrent,
 283           (Display * dpy, GLXDrawable d, GLXDrawable r,
 284            GLXContext ctx), (dpy, d, r, ctx), MakeContextCurrent)