--- /dev/null
+/*
+ * 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_MODE_UTIL
+
+#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
+ __attribute__((tls_model("initial-exec")))
+ = (struct mapi_table *) table_noop_array;
+
+__thread void *u_current_user
+ __attribute__((tls_model("initial-exec")));
+
+#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.
+ */
+u_mutex_declare_static(ThreadCheckMutex);
+
+/**
+ * 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;
+
+ u_mutex_lock(ThreadCheckMutex);
+ if (firstCall) {
+ u_current_init_tsd();
+
+ knownID = u_thread_self();
+ firstCall = 0;
+ }
+ else if (knownID != u_thread_self()) {
+ ThreadSafe = 1;
+ u_current_set(NULL);
+ u_current_set_user(NULL);
+ }
+ u_mutex_unlock(ThreadCheckMutex);
+}
+
+#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(const void *ptr)
+{
+ u_current_init();
+
+#if defined(GLX_USE_TLS)
+ u_current_user = (void *) ptr;
+#elif defined(THREADS)
+ u_tsd_set(&u_current_user_tsd, (void *) ptr);
+ u_current_user = (ThreadSafe) ? NULL : (void *) ptr;
+#else
+ u_current_user = (void *) 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;
+#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(const struct mapi_table *tbl)
+{
+ u_current_init();
+
+ stub_init_once();
+
+ if (!tbl)
+ tbl = (const struct mapi_table *) table_noop_array;
+
+#if defined(GLX_USE_TLS)
+ u_current_table = (struct mapi_table *) tbl;
+#elif defined(THREADS)
+ u_tsd_set(&u_current_table_tsd, (void *) tbl);
+ u_current_table = (ThreadSafe) ? NULL : (void *) tbl;
+#else
+ u_current_table = (struct mapi_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;
+#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
+}
projects / mesa.git / blobdiff