1 files changed, 108 insertions, 0 deletions
diff --git a/libglusterfs/src/refcount.c b/libglusterfs/src/refcount.c
new file mode 100644
index 00000000000..d5a5a82fa0f
--- /dev/null
+++ b/libglusterfs/src/refcount.c
@@ -0,0 +1,108 @@
+/*
+  Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#include "glusterfs/common-utils.h"
+#include "glusterfs/refcount.h"
+
+#ifndef REFCOUNT_NEEDS_LOCK
+
+void *
+_gf_ref_get(gf_ref_t *ref)
+{
+    unsigned int cnt = __sync_fetch_and_add(&ref->cnt, 1);
+
+    /* if cnt == 0, we're in a fatal position, the object will be free'd
+     *
+     * There is a race when two threads do a _gf_ref_get(). Only one of
+     * them may get a 0 returned. That is acceptable, because one
+     * _gf_ref_get() returning 0 should be handled as a fatal problem and
+     * when correct usage/locking is used, it should never happen.
+     */
+    GF_ASSERT(cnt != 0);
+
+    return cnt ? ref->data : NULL;
+}
+
+unsigned int
+_gf_ref_put(gf_ref_t *ref)
+{
+    unsigned int cnt = __sync_fetch_and_sub(&ref->cnt, 1);
+
+    /* if cnt == 1, the last user just did a _gf_ref_put()
+     *
+     * When cnt == 0, one _gf_ref_put() was done too much and there has
+     * been a thread using the refcounted structure when it was not
+     * supposed to.
+     */
+    GF_ASSERT(cnt != 0);
+
+    if (cnt == 1 && ref->release)
+        ref->release(ref->data);
+
+    return (cnt != 1);
+}
+
+#else
+
+void *
+_gf_ref_get(gf_ref_t *ref)
+{
+    unsigned int cnt = 0;
+
+    LOCK(&ref->lk);
+    {
+        /* never can be 0, should have been free'd */
+        if (ref->cnt > 0)
+            cnt = ++ref->cnt;
+        else
+            GF_ASSERT(ref->cnt > 0);
+    }
+    UNLOCK(&ref->lk);
+
+    return cnt ? ref->data : NULL;
+}
+
+unsigned int
+_gf_ref_put(gf_ref_t *ref)
+{
+    unsigned int cnt = 0;
+    int release = 0;
+
+    LOCK(&ref->lk);
+    {
+        if (ref->cnt != 0) {
+            cnt = --ref->cnt;
+            /* call release() only when cnt == 0 */
+            release = (cnt == 0);
+        } else
+            GF_ASSERT(ref->cnt != 0);
+    }
+    UNLOCK(&ref->lk);
+
+    if (release && ref->release)
+        ref->release(ref->data);
+
+    return !release;
+}
+
+#endif /* REFCOUNT_NEEDS_LOCK */
+
+void
+_gf_ref_init(gf_ref_t *ref, gf_ref_release_t release, void *data)
+{
+    GF_ASSERT(ref);
+
+#ifdef REFCOUNT_NEEDS_LOCK
+    LOCK_INIT(&ref->lk);
+#endif
+    ref->cnt = 1;
+    ref->release = release;
+    ref->data = data;
+}