1 files changed, 71 insertions, 0 deletions
diff --git a/contrib/librdns/ref.h b/contrib/librdns/ref.h
new file mode 100644
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+++ b/contrib/librdns/ref.h
@@ -0,0 +1,71 @@
+/* Copyright (c) 2014, Vsevolod Stakhov
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *       * Redistributions of source code must retain the above copyright
+ *         notice, this list of conditions and the following disclaimer.
+ *       * Redistributions in binary form must reproduce the above copyright
+ *         notice, this list of conditions and the following disclaimer in the
+ *         documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef REF_H_
+#define REF_H_
+
+/**
+ * @file ref.h
+ * A set of macros to handle refcounts
+ */
+
+typedef void (*ref_dtor_cb_t)(void *data);
+
+typedef struct ref_entry_s {
+	unsigned int refcount;
+	ref_dtor_cb_t dtor;
+} ref_entry_t;
+
+#define REF_INIT(obj, dtor_cb) do {								\
+	(obj)->ref.refcount = 0;										\
+	(obj)->ref.dtor = (ref_dtor_cb_t)(dtor_cb);						\
+} while (0)
+
+#define REF_INIT_RETAIN(obj, dtor_cb) do {							\
+	(obj)->ref.refcount = 1;										\
+	(obj)->ref.dtor = (ref_dtor_cb_t)(dtor_cb);						\
+} while (0)
+
+#ifdef HAVE_ATOMIC_BUILTINS
+#define REF_RETAIN(obj) do {										\
+    __sync_add_and_fetch (&(obj)->ref.refcount, 1);					\
+} while (0)
+
+#define REF_RELEASE(obj) do {										\
+	unsigned int rc = __sync_sub_and_fetch (&(obj)->ref.refcount, 1); \
+	if (rc == 0 && (obj)->ref.dtor) {								\
+		(obj)->ref.dtor (obj);										\
+	}																\
+} while (0)
+#else
+#define REF_RETAIN(obj) do {										\
+	(obj)->ref.refcount ++;											\
+} while (0)
+
+#define REF_RELEASE(obj) do {										\
+	if (--(obj)->ref.refcount == 0 && (obj)->ref.dtor) {			\
+		(obj)->ref.dtor (obj);										\
+	}																\
+} while (0)
+#endif
+
+#endif /* REF_H_ */