1 files changed, 127 insertions, 0 deletions
diff --git a/libxcb/src/xcb_ext.c b/libxcb/src/xcb_ext.c
new file mode 100644
index 000000000..12cb16463
--- /dev/null
+++ b/libxcb/src/xcb_ext.c
@@ -0,0 +1,127 @@
+/* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
+ *
+ * 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 THE
+ * AUTHORS 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.
+ * 
+ * Except as contained in this notice, the names of the authors or their
+ * institutions shall not be used in advertising or otherwise to promote the
+ * sale, use or other dealings in this Software without prior written
+ * authorization from the authors.
+ */
+
+/* A cache for QueryExtension results. */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "xcb.h"
+#include "xcbext.h"
+#include "xcbint.h"
+
+typedef struct lazyreply {
+    enum lazy_reply_tag tag;
+    union {
+        xcb_query_extension_cookie_t cookie;
+        xcb_query_extension_reply_t *reply;
+    } value;
+} lazyreply;
+
+static lazyreply *get_index(xcb_connection_t *c, int index)
+{
+    if(index > c->ext.extensions_size)
+    {
+        int new_size = index << 1;
+        lazyreply *new_extensions = realloc(c->ext.extensions, sizeof(lazyreply) * new_size);
+        if(!new_extensions)
+            return 0;
+        memset(new_extensions + c->ext.extensions_size, 0, sizeof(lazyreply) * (new_size - c->ext.extensions_size));
+        c->ext.extensions = new_extensions;
+        c->ext.extensions_size = new_size;
+    }
+    return c->ext.extensions + index - 1;
+}
+
+static lazyreply *get_lazyreply(xcb_connection_t *c, xcb_extension_t *ext)
+{
+    static pthread_mutex_t global_lock = PTHREAD_MUTEX_INITIALIZER;
+    static int next_global_id;
+
+    lazyreply *data;
+
+    pthread_mutex_lock(&global_lock);
+    if(!ext->global_id)
+        ext->global_id = ++next_global_id;
+    pthread_mutex_unlock(&global_lock);
+
+    data = get_index(c, ext->global_id);
+    if(data && data->tag == LAZY_NONE)
+    {
+        /* cache miss: query the server */
+        data->tag = LAZY_COOKIE;
+        data->value.cookie = xcb_query_extension(c, strlen(ext->name), ext->name);
+    }
+    return data;
+}
+
+/* Public interface */
+
+/* Do not free the returned xcb_query_extension_reply_t - on return, it's aliased
+ * from the cache. */
+const xcb_query_extension_reply_t *xcb_get_extension_data(xcb_connection_t *c, xcb_extension_t *ext)
+{
+    lazyreply *data;
+    if(c->has_error)
+        return 0;
+
+    pthread_mutex_lock(&c->ext.lock);
+    data = get_lazyreply(c, ext);
+    if(data && data->tag == LAZY_COOKIE)
+    {
+        data->tag = LAZY_FORCED;
+        data->value.reply = xcb_query_extension_reply(c, data->value.cookie, 0);
+    }
+    pthread_mutex_unlock(&c->ext.lock);
+
+    return data ? data->value.reply : 0;
+}
+
+void xcb_prefetch_extension_data(xcb_connection_t *c, xcb_extension_t *ext)
+{
+    if(c->has_error)
+        return;
+    pthread_mutex_lock(&c->ext.lock);
+    get_lazyreply(c, ext);
+    pthread_mutex_unlock(&c->ext.lock);
+}
+
+/* Private interface */
+
+int _xcb_ext_init(xcb_connection_t *c)
+{
+    if(pthread_mutex_init(&c->ext.lock, 0))
+        return 0;
+    return 1;
+}
+
+void _xcb_ext_destroy(xcb_connection_t *c)
+{
+    pthread_mutex_destroy(&c->ext.lock);
+    while(c->ext.extensions_size-- > 0)
+        if(c->ext.extensions[c->ext.extensions_size].tag == LAZY_FORCED)
+            free(c->ext.extensions[c->ext.extensions_size].value.reply);
+    free(c->ext.extensions);
+}