gmutex.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * gmutex.c: MT safety related functions
   5  * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
   6  *                Owen Taylor
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Library General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Library General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Library General Public
  19  * License along with this library; if not, write to the
  20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21  * Boston, MA 02111-1307, USA.
  22  */
  23
  24 /*
  25  * Modified by the GLib Team and others 1997-1999.  See the AUTHORS
  26  * file for a list of people on the GLib Team.  See the ChangeLog
  27  * files for a list of changes.  These files are distributed with
  28  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  29  */
  30
  31 /*
  32  * MT safe
  33  */
  34
  35 #include "glib.h"
  36
  37 typedef struct _GStaticPrivateNode GStaticPrivateNode;
  38
  39 struct _GStaticPrivateNode
  40 {
  41   gpointer       data;
  42   GDestroyNotify destroy;
  43 };
  44
  45 static void g_static_private_free_data (gpointer data);
  46 static void g_thread_fail (void);
  47
  48 /* Global variables */
  49
  50 gboolean g_thread_use_default_impl = TRUE;
  51 gboolean g_threads_got_initialized = FALSE;
  52
  53 GUTILS_C_VAR GThreadFunctions g_thread_functions_for_glib_use = {
  54   (GMutex*(*)())g_thread_fail,                 /* mutex_new */
  55   NULL,                                        /* mutex_lock */
  56   NULL,                                        /* mutex_trylock */
  57   NULL,                                        /* mutex_unlock */
  58   NULL,                                        /* mutex_free */
  59   (GCond*(*)())g_thread_fail,                  /* cond_new */
  60   NULL,                                        /* cond_signal */
  61   NULL,                                        /* cond_broadcast */
  62   NULL,                                        /* cond_wait */
  63   NULL,                                        /* cond_timed_wait  */
  64   NULL,                                        /* cond_free */
  65   (GPrivate*(*)(GDestroyNotify))g_thread_fail, /* private_new */
  66   NULL,                                        /* private_get */
  67   NULL,                                        /* private_set */
  68 };
  69
  70 /* Local data */
  71
  72 static GMutex   *g_mutex_protect_static_mutex_allocation = NULL;
  73 static GMutex   *g_thread_specific_mutex = NULL;
  74 static GPrivate *g_thread_specific_private = NULL;
  75
  76 /* This must be called only once, before any threads are created.
  77  * It will only be called from g_thread_init() in -lgthread.
  78  */
  79 void
  80 g_mutex_init (void)
  81 {
  82   /* We let the main thread (the one that calls g_thread_init) inherit
  83    * the data, that it set before calling g_thread_init
  84    */
  85   gpointer private_old = g_thread_specific_private;
  86
  87   g_thread_specific_private = g_private_new (g_static_private_free_data);
  88
  89   /* we can not use g_private_set here, as g_threads_got_initialized is not
  90    * yet set TRUE, whereas the private_set function is already set.
  91    */
  92   g_thread_functions_for_glib_use.private_set (g_thread_specific_private,
  93                                                private_old);
  94
  95   g_mutex_protect_static_mutex_allocation = g_mutex_new();
  96   g_thread_specific_mutex = g_mutex_new();
  97 }
  98
  99 GMutex *
 100 g_static_mutex_get_mutex_impl (GMutex** mutex)
 101 {
 102   if (!g_thread_supported ())
 103     return NULL;
 104
 105   g_assert (g_mutex_protect_static_mutex_allocation);
 106
 107   g_mutex_lock (g_mutex_protect_static_mutex_allocation);
 108
 109   if (!(*mutex))
 110     *mutex = g_mutex_new();
 111
 112   g_mutex_unlock (g_mutex_protect_static_mutex_allocation);
 113
 114   return *mutex;
 115 }
 116
 117 gpointer
 118 g_static_private_get (GStaticPrivate *private_key)
 119 {
 120   GArray *array;
 121
 122   array = g_private_get (g_thread_specific_private);
 123   if (!array)
 124     return NULL;
 125
 126   if (!private_key->index)
 127     return NULL;
 128   else if (private_key->index <= array->len)
 129     return g_array_index (array, GStaticPrivateNode, private_key->index - 1).data;
 130   else
 131     return NULL;
 132 }
 133
 134 void
 135 g_static_private_set (GStaticPrivate *private_key,
 136                       gpointer        data,
 137                       GDestroyNotify  notify)
 138 {
 139   GArray *array;
 140   static guint next_index = 0;
 141   GStaticPrivateNode *node;
 142
 143   array = g_private_get (g_thread_specific_private);
 144   if (!array)
 145     {
 146       array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
 147       g_private_set (g_thread_specific_private, array);
 148     }
 149
 150   if (!private_key->index)
 151     {
 152       g_mutex_lock (g_thread_specific_mutex);
 153
 154       if (!private_key->index)
 155         private_key->index = ++next_index;
 156
 157       g_mutex_unlock (g_thread_specific_mutex);
 158     }
 159
 160   if (private_key->index > array->len)
 161     g_array_set_size (array, private_key->index);
 162
 163   node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
 164   if (node->destroy)
 165     {
 166       gpointer ddata = node->data;
 167       GDestroyNotify ddestroy = node->destroy;
 168
 169       node->data = data;
 170       node->destroy = notify;
 171
 172       ddestroy (ddata);
 173     }
 174   else
 175     {
 176       node->data = data;
 177       node->destroy = notify;
 178     }
 179 }
 180
 181 static void
 182 g_static_private_free_data (gpointer data)
 183 {
 184   if (data)
 185     {
 186       GArray* array = data;
 187       guint i;
 188
 189       for (i = 0; i < array->len; i++ )
 190         {
 191           GStaticPrivateNode *node = &g_array_index (array, GStaticPrivateNode, i);
 192           if (node->destroy)
 193             node->destroy (node->data);
 194         }
 195     }
 196 }
 197
 198 static void
 199 g_thread_fail (void)
 200 {
 201   g_error ("The thread system is not yet initialized.");
 202 }