Add refcounter inmplementation.

diff --git a/src/libutil/ref.h b/src/libutil/ref.h
new file mode 100644 (file)
index 0000000..a8016b1
--- /dev/null
+++ b/src/libutil/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_ */