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      1 /* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
      2  *
      3  * Permission is hereby granted, free of charge, to any person obtaining a
      4  * copy of this software and associated documentation files (the "Software"),
      5  * to deal in the Software without restriction, including without limitation
      6  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      7  * and/or sell copies of the Software, and to permit persons to whom the
      8  * Software is furnished to do so, subject to the following conditions:
      9  *
     10  * The above copyright notice and this permission notice shall be included in
     11  * all copies or substantial portions of the Software.
     12  *
     13  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     14  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     15  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     16  * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
     17  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
     18  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     19  *
     20  * Except as contained in this notice, the names of the authors or their
     21  * institutions shall not be used in advertising or otherwise to promote the
     22  * sale, use or other dealings in this Software without prior written
     23  * authorization from the authors.
     24  */
     25 
     26 /* A cache for QueryExtension results. */
     27 
     28 #ifdef HAVE_CONFIG_H
     29 #include "config.h"
     30 #endif
     31 
     32 #include <stdlib.h>
     33 #include <string.h>
     34 
     35 #include "xcb.h"
     36 #include "xcbext.h"
     37 #include "xcbint.h"
     38 
     39 typedef struct lazyreply {
     40     enum lazy_reply_tag tag;
     41     union {
     42         xcb_query_extension_cookie_t cookie;
     43         xcb_query_extension_reply_t *reply;
     44     } value;
     45 } lazyreply;
     46 
     47 static lazyreply *get_index(xcb_connection_t *c, int idx)
     48 {
     49     if(idx > c->ext.extensions_size)
     50     {
     51         int new_size = idx << 1;
     52         lazyreply *new_extensions = realloc(c->ext.extensions, sizeof(lazyreply) * new_size);
     53         if(!new_extensions)
     54             return 0;
     55         memset(new_extensions + c->ext.extensions_size, 0, sizeof(lazyreply) * (new_size - c->ext.extensions_size));
     56         c->ext.extensions = new_extensions;
     57         c->ext.extensions_size = new_size;
     58     }
     59     return c->ext.extensions + idx - 1;
     60 }
     61 
     62 static lazyreply *get_lazyreply(xcb_connection_t *c, xcb_extension_t *ext)
     63 {
     64     static pthread_mutex_t global_lock = PTHREAD_MUTEX_INITIALIZER;
     65     static int next_global_id;
     66 
     67     lazyreply *data;
     68 
     69     pthread_mutex_lock(&global_lock);
     70     if(!ext->global_id)
     71         ext->global_id = ++next_global_id;
     72     pthread_mutex_unlock(&global_lock);
     73 
     74     data = get_index(c, ext->global_id);
     75     if(data && data->tag == LAZY_NONE)
     76     {
     77         /* cache miss: query the server */
     78         data->tag = LAZY_COOKIE;
     79         data->value.cookie = xcb_query_extension(c, strlen(ext->name), ext->name);
     80     }
     81     return data;
     82 }
     83 
     84 /* Public interface */
     85 
     86 /* Do not free the returned xcb_query_extension_reply_t - on return, it's aliased
     87  * from the cache. */
     88 const xcb_query_extension_reply_t *xcb_get_extension_data(xcb_connection_t *c, xcb_extension_t *ext)
     89 {
     90     lazyreply *data;
     91     if(c->has_error)
     92         return 0;
     93 
     94     pthread_mutex_lock(&c->ext.lock);
     95     data = get_lazyreply(c, ext);
     96     if(data && data->tag == LAZY_COOKIE)
     97     {
     98         data->tag = LAZY_FORCED;
     99         data->value.reply = xcb_query_extension_reply(c, data->value.cookie, 0);
    100     }
    101     pthread_mutex_unlock(&c->ext.lock);
    102 
    103     return data ? data->value.reply : 0;
    104 }
    105 
    106 void xcb_prefetch_extension_data(xcb_connection_t *c, xcb_extension_t *ext)
    107 {
    108     if(c->has_error)
    109         return;
    110     pthread_mutex_lock(&c->ext.lock);
    111     get_lazyreply(c, ext);
    112     pthread_mutex_unlock(&c->ext.lock);
    113 }
    114 
    115 /* Private interface */
    116 
    117 int _xcb_ext_init(xcb_connection_t *c)
    118 {
    119     if(pthread_mutex_init(&c->ext.lock, 0))
    120         return 0;
    121     return 1;
    122 }
    123 
    124 void _xcb_ext_destroy(xcb_connection_t *c)
    125 {
    126     pthread_mutex_destroy(&c->ext.lock);
    127     while(c->ext.extensions_size-- > 0)
    128         if(c->ext.extensions[c->ext.extensions_size].tag == LAZY_FORCED)
    129             free(c->ext.extensions[c->ext.extensions_size].value.reply);
    130     free(c->ext.extensions);
    131 }
    132