glusterfs

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/*
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  Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
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  This file is part of GlusterFS.
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  This file is licensed to you under your choice of the GNU Lesser
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  General Public License, version 3 or any later version (LGPLv3 or
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  later), or the GNU General Public License, version 2 (GPLv2), in all
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  cases as published by the Free Software Foundation.
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*/
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#include "glusterfs/common-utils.h"
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#include "glusterfs/refcount.h"
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void *
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_gf_ref_get(gf_ref_t *ref)
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{
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    unsigned int cnt = GF_ATOMIC_FETCH_ADD(ref->cnt, 1);
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    /* if cnt == 0, we're in a fatal position, the object will be free'd
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     *
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     * There is a race when two threads do a _gf_ref_get(). Only one of
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     * them may get a 0 returned. That is acceptable, because one
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     * _gf_ref_get() returning 0 should be handled as a fatal problem and
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     * when correct usage/locking is used, it should never happen.
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     */
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    GF_ASSERT(cnt != 0);
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    return cnt ? ref->data : NULL;
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}
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unsigned int
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_gf_ref_put(gf_ref_t *ref)
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{
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    unsigned int cnt = GF_ATOMIC_FETCH_SUB(ref->cnt, 1);
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    /* if cnt == 1, the last user just did a _gf_ref_put()
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     *
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     * When cnt == 0, one _gf_ref_put() was done too much and there has
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     * been a thread using the refcounted structure when it was not
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     * supposed to.
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     */
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    GF_ASSERT(cnt != 0);
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    if (cnt == 1 && ref->release)
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        ref->release(ref->data);
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    return (cnt != 1);
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}
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void
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_gf_ref_init(gf_ref_t *ref, gf_ref_release_t release, void *data)
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{
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    GF_ASSERT(ref);
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    GF_ATOMIC_INIT(ref->cnt, 1);
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    ref->release = release;
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    ref->data = data;
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}
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