[xlib] Use an embedded doubly-linked list for the close display hooks.

Kill the allocation and linear search of the close display list on remove,
by embedding a list node into the parent structure.

Original patch by Karl Tomlinson <karlt+@karlt.net>, Mozilla Corporation.
https://bugzilla.mozilla.org/show_bug.cgi?id=453199#c5

1 files changed, 41 insertions, 49 deletions

diff --git a/src/cairo-xlib-display.c b/src/cairo-xlib-display.c
index 895258d3..ff2e08ed 100644
--- a/src/cairo-xlib-display.c
+++ b/src/cairo-xlib-display.c
@@ -29,6 +29,8 @@
  *
  * The Initial Developer of the Original Code is Chris Wilson.
  *
+ * Contributor(s):
+ *	Karl Tomlinson <karlt+@karlt.net>, Mozilla Corporation
  */
 
 #include "cairoint.h"
@@ -65,10 +67,14 @@ struct _cairo_xlib_job {
 static cairo_xlib_display_t *_cairo_xlib_display_list;
 
 static void
+_cairo_xlib_remove_close_display_hook_internal (cairo_xlib_display_t *display,
+						cairo_xlib_hook_t *hook);
+
+static void
 _cairo_xlib_call_close_display_hooks (cairo_xlib_display_t *display)
 {
     cairo_xlib_screen_info_t	    *screen;
-    cairo_xlib_hook_t		    *hooks, *list;
+    cairo_xlib_hook_t		    *hook;
 
     /* call all registered shutdown routines */
     CAIRO_MUTEX_LOCK (display->mutex);
@@ -76,28 +82,16 @@ _cairo_xlib_call_close_display_hooks (cairo_xlib_display_t *display)
     for (screen = display->screens; screen != NULL; screen = screen->next)
 	_cairo_xlib_screen_info_close_display (screen);
 
-    hooks = display->close_display_hooks;
-    while (hooks != NULL) {
-	display->close_display_hooks = NULL;
-	CAIRO_MUTEX_UNLOCK (display->mutex);
-
-	list = hooks;
-	do {
-	    cairo_xlib_hook_t *hook = list;
-	    list = hook->next;
+    while (TRUE) {
+	hook = display->close_display_hooks;
+	if (hook == NULL)
+	    break;
 
-	    hook->func (display->display, hook->data);
-	} while (list != NULL);
+	_cairo_xlib_remove_close_display_hook_internal (display, hook);
 
+	CAIRO_MUTEX_UNLOCK (display->mutex);
+	hook->func (display->display, hook);
 	CAIRO_MUTEX_LOCK (display->mutex);
-	do {
-	    cairo_xlib_hook_t *hook = hooks;
-	    hooks = hook->next;
-
-	    _cairo_freelist_free (&display->hook_freelist, hook);
-	} while (hooks != NULL);
-
-	hooks = display->close_display_hooks;
     }
     display->closed = TRUE;
 
@@ -151,7 +145,6 @@ _cairo_xlib_display_destroy (cairo_xlib_display_t *display)
 	_cairo_freelist_free (&display->wq_freelist, job);
     }
     _cairo_freelist_fini (&display->wq_freelist);
-    _cairo_freelist_fini (&display->hook_freelist);
 
     CAIRO_MUTEX_FINI (display->mutex);
 
@@ -277,7 +270,6 @@ _cairo_xlib_display_get (Display *dpy)
     XESetCloseDisplay (dpy, codes->extension, _cairo_xlib_close_display);
 
     _cairo_freelist_init (&display->wq_freelist, sizeof (cairo_xlib_job_t));
-    _cairo_freelist_init (&display->hook_freelist, sizeof (cairo_xlib_hook_t));
 
     CAIRO_REFERENCE_COUNT_INIT (&display->ref_count, 2); /* add one for the CloseDisplay */
     CAIRO_MUTEX_INIT (display->mutex);
@@ -326,56 +318,56 @@ UNLOCK:
 }
 
 cairo_bool_t
-_cairo_xlib_add_close_display_hook (Display *dpy, void (*func) (Display *, void *), void *data)
+_cairo_xlib_add_close_display_hook (Display *dpy, cairo_xlib_hook_t *hook)
 {
     cairo_xlib_display_t *display;
-    cairo_xlib_hook_t *hook;
-    cairo_bool_t ret = FALSE;
 
     display = _cairo_xlib_display_get (dpy);
     if (display == NULL)
 	return FALSE;
 
     CAIRO_MUTEX_LOCK (display->mutex);
-    if (display->closed == FALSE) {
-	hook = _cairo_freelist_alloc (&display->hook_freelist);
-	if (hook != NULL) {
-	    hook->func = func;
-	    hook->data = data;
-
-	    hook->next = display->close_display_hooks;
-	    display->close_display_hooks = hook;
-	    ret = TRUE;
-	}
-    }
+    hook->prev = NULL;
+    hook->next = display->close_display_hooks;
+    if (hook->next != NULL)
+	hook->next->prev = hook;
+    display->close_display_hooks = hook;
     CAIRO_MUTEX_UNLOCK (display->mutex);
 
     _cairo_xlib_display_destroy (display);
 
-    return ret;
+    return TRUE;
+}
+
+/* display->mutex must be held */
+static void
+_cairo_xlib_remove_close_display_hook_internal (cairo_xlib_display_t *display,
+						cairo_xlib_hook_t *hook)
+{
+    if (display->close_display_hooks == hook)
+	display->close_display_hooks = hook->next;
+    else if (hook->prev != NULL)
+	hook->prev->next = hook->next;
+
+    if (hook->next != NULL)
+	hook->next->prev = hook->prev;
+
+    hook->prev = NULL;
+    hook->next = NULL;
 }
 
 void
-_cairo_xlib_remove_close_display_hooks (Display *dpy, const void *data)
+_cairo_xlib_remove_close_display_hook (Display *dpy,
+				       cairo_xlib_hook_t *hook)
 {
     cairo_xlib_display_t *display;
-    cairo_xlib_hook_t *hook, *next, **prev;
 
     display = _cairo_xlib_display_get (dpy);
     if (display == NULL)
 	return;
 
     CAIRO_MUTEX_LOCK (display->mutex);
-    prev = &display->close_display_hooks;
-    for (hook = display->close_display_hooks; hook != NULL; hook = next) {
-	next = hook->next;
-	if (hook->data == data) {
-	    *prev = hook->next;
-	    _cairo_freelist_free (&display->hook_freelist, hook);
-	    break;
-	}
-	prev = &hook->next;
-    }
+    _cairo_xlib_remove_close_display_hook_internal (display, hook);
     CAIRO_MUTEX_UNLOCK (display->mutex);
 
     _cairo_xlib_display_destroy (display);