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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.
*/
#include "common-utils.h"
#include "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;
}
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