utils: imported singleton setup from NetworkManager

1 files changed, 83 insertions, 0 deletions

diff --git a/src/mm-utils.h b/src/mm-utils.h
new file mode 100644
index 00000000..2b0a9340
--- /dev/null
+++ b/src/mm-utils.h
@@ -0,0 +1,83 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details:
+ *
+ * Singleton support imported from NetworkManager.
+ *     (C) Copyright 2014 Red Hat, Inc.
+ */
+
+#ifndef MM_UTILS_H
+#define MM_UTILS_H
+
+#include <glib.h>
+#include <glib-object.h>
+
+#include "mm-log.h"
+
+/*****************************************************************************/
+
+#define MM_DEFINE_SINGLETON_INSTANCE(TYPE)      \
+    static TYPE *singleton_instance
+
+#define MM_DEFINE_SINGLETON_WEAK_REF(TYPE)                              \
+    MM_DEFINE_SINGLETON_INSTANCE (TYPE);                                \
+    static void                                                         \
+    _singleton_instance_weak_ref_cb (gpointer data,                     \
+                                     GObject *where_the_object_was)     \
+    {                                                                   \
+        mm_dbg ("disposing %s singleton (%p)", G_STRINGIFY (TYPE), singleton_instance); \
+        singleton_instance = NULL;                                      \
+    }                                                                   \
+    static inline void                                                  \
+    mm_singleton_instance_weak_ref_register (void)                      \
+    {                                                                   \
+        g_object_weak_ref (G_OBJECT (singleton_instance), _singleton_instance_weak_ref_cb, NULL); \
+    }
+
+#define MM_DEFINE_SINGLETON_DESTRUCTOR(TYPE)                            \
+    MM_DEFINE_SINGLETON_INSTANCE (TYPE);                                \
+    static void __attribute__((destructor))                             \
+    _singleton_destructor (void)                                        \
+    {                                                                   \
+        if (singleton_instance) {                                       \
+            if (G_OBJECT (singleton_instance)->ref_count > 1)           \
+                mm_dbg ("disown %s singleton (%p)", G_STRINGIFY (TYPE), singleton_instance); \
+            g_object_unref (singleton_instance);                        \
+        }                                                               \
+    }
+
+/* By default, the getter will assert that the singleton will be created only once. You can
+ * change this by redefining MM_DEFINE_SINGLETON_ALLOW_MULTIPLE. */
+#ifndef MM_DEFINE_SINGLETON_ALLOW_MULTIPLE
+#define MM_DEFINE_SINGLETON_ALLOW_MULTIPLE     FALSE
+#endif
+
+#define MM_DEFINE_SINGLETON_GETTER(TYPE, GETTER, GTYPE, ...)            \
+    MM_DEFINE_SINGLETON_INSTANCE (TYPE);                                \
+    MM_DEFINE_SINGLETON_WEAK_REF (TYPE);                                \
+    TYPE *                                                              \
+    GETTER (void)                                                       \
+    {                                                                   \
+        if (G_UNLIKELY (!singleton_instance)) {                         \
+            static char _already_created = FALSE;                       \
+                                                                        \
+            g_assert (!_already_created || (MM_DEFINE_SINGLETON_ALLOW_MULTIPLE));        \
+            _already_created = TRUE;                                                     \
+            singleton_instance = (g_object_new (GTYPE, ##__VA_ARGS__, NULL));            \
+            g_assert (singleton_instance);                                               \
+            mm_singleton_instance_weak_ref_register ();                                  \
+            mm_dbg ("create %s singleton (%p)", G_STRINGIFY (TYPE), singleton_instance); \
+        }                                                               \
+        return singleton_instance;                                      \
+    }                                                                   \
+    MM_DEFINE_SINGLETON_DESTRUCTOR(TYPE)
+
+#endif /* MM_UTILS_H */