Add support for generic notifier lists

Notifiers are data-less callbacks and a notifier list is a list of registered
notifiers that all are interested in a particular event.

We'll use this in a few patches to implement mouse change notification.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
v1 -> v2
 - Do not do memory allocations by placing list nodes in notifier

1 files changed, 43 insertions, 0 deletions

diff --git a/notify.h b/notify.h
new file mode 100644
index 0000000000..b40522f582
--- /dev/null
+++ b/notify.h
@@ -0,0 +1,43 @@
+/*
+ * Notifier lists
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_NOTIFY_H
+#define QEMU_NOTIFY_H
+
+#include "qemu-queue.h"
+
+typedef struct Notifier Notifier;
+
+struct Notifier
+{
+    void (*notify)(Notifier *notifier);
+    QTAILQ_ENTRY(Notifier) node;
+};
+
+typedef struct NotifierList
+{
+    QTAILQ_HEAD(, Notifier) notifiers;
+} NotifierList;
+
+#define NOTIFIER_LIST_INITIALIZER(head) \
+    { QTAILQ_HEAD_INITIALIZER((head).notifiers) }
+
+void notifier_list_init(NotifierList *list);
+
+void notifier_list_add(NotifierList *list, Notifier *notifier);
+
+void notifier_list_remove(NotifierList *list, Notifier *notifier);
+
+void notifier_list_notify(NotifierList *list);
+
+#endif