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/*
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.
*/
#ifndef _REFCOUNT_H
#define _REFCOUNT_H
/* check for compiler support for __sync_*_and_fetch()
*
* a more comprehensive feature test is shown at
* http://lists.iptel.org/pipermail/semsdev/2010-October/005075.html
* this is sufficient for RHEL5 i386 builds
*/
#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)) && \
!defined(__i386__)
#undef REFCOUNT_NEEDS_LOCK
#else
#define REFCOUNT_NEEDS_LOCK
#include "glusterfs/locking.h"
#endif /* compiler support for __sync_*_and_fetch() */
typedef void (*gf_ref_release_t)(void *data);
struct _gf_ref {
#ifdef REFCOUNT_NEEDS_LOCK
gf_lock_t lk; /* lock for atomically adjust cnt */
#endif
unsigned int cnt; /* number of users, free on 0 */
gf_ref_release_t release; /* cleanup when cnt == 0 */
void *data; /* parameter passed to release() */
};
typedef struct _gf_ref gf_ref_t;
/* _gf_ref_get -- increase the refcount
*
* @return: greater then 0 when a reference was taken, 0 when not
*/
void *
_gf_ref_get(gf_ref_t *ref);
/* _gf_ref_put -- decrease the refcount
*
* @return: greater then 0 when there are still references, 0 when cleanup
* should be done, gf_ref_release_t is called on cleanup
*/
unsigned int
_gf_ref_put(gf_ref_t *ref);
/* _gf_ref_init -- initialize an embedded refcount object
*
* @release: function to call when the refcount == 0
* @data: parameter to be passed to @release
*/
void
_gf_ref_init(gf_ref_t *ref, gf_ref_release_t release, void *data);
/*
* Strong suggestion to use the simplified GF_REF_* API.
*/
/* GF_REF_DECL -- declaration to put inside your structure
*
* Example:
* struct my_struct {
* GF_REF_DECL;
*
* ... // additional members
* };
*/
#define GF_REF_DECL gf_ref_t _ref
/* GF_REF_INIT -- initialize a GF_REF_DECL structure
*
* @p: allocated structure with GF_REF_DECL
* @d: destructor to call once refcounting reaches 0
*
* Sets the refcount to 1.
*/
#define GF_REF_INIT(p, d) _gf_ref_init(&(p)->_ref, (gf_ref_release_t)d, p)
/* GF_REF_GET -- increase the refcount of a GF_REF_DECL structure
*
* @return: greater then 0 when a reference was taken, 0 when not
*/
#define GF_REF_GET(p) _gf_ref_get(&(p)->_ref)
/* GF_REF_PUT -- decrease the refcount of a GF_REF_DECL structure
*
* @return: greater then 0 when there are still references, 0 when cleanup
* should be done, gf_ref_release_t is called on cleanup
*/
#define GF_REF_PUT(p) _gf_ref_put(&(p)->_ref)
#endif /* _REFCOUNT_H */
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