simple thread-safe implementation of refcount.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   This library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA  */
+
+#ifndef _MAILUTILS_REFCOUNT_H
+#define _MAILUTILS_REFCOUNT_H
+
+#include <mailutils/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* FIXME: Declaration should be hidden in mailutils/sys/refcount.h */
+struct _mu_refcount
+{
+  unsigned int ref;
+  monitor_t lock;
+};
+
+extern int  mu_refcount_create  __P ((mu_refcount_t *));
+extern void mu_refcount_destroy __P ((mu_refcount_t *));
+extern int  mu_refcount_inc     __P ((mu_refcount_t));
+extern int  mu_refcount_dec     __P ((mu_refcount_t));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _MAILUTILS_REFCOUNT_H */

@@ -59,6 +59,7 @@ struct _message;
 struct _mime;
 struct _mu_mailcap;
 struct _mu_mailcap_entry;
+struct _mu_refcount;
 struct _observable;
 struct _observer;
 struct _property;
@@ -87,6 +88,7 @@ typedef struct _message *message_t;
 typedef struct _mime *mime_t;
 typedef struct _mu_mailcap *mu_mailcap_t;
 typedef struct _mu_mailcap_entry *mu_mailcap_entry_t;
+typedef struct _mu_refcount *mu_refcount_t;
 typedef struct _observable *observable_t;
 typedef struct _observer *observer_t;
 typedef struct _property *property_t;