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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "@(#)unique.c 1.3 07/08/02 SMI"
#include <sys/zfs_context.h>
#include <sys/avl.h>
#include <sys/unique.h>
static avl_tree_t unique_avl;
static kmutex_t unique_mtx;
typedef struct unique {
avl_node_t un_link;
uint64_t un_value;
} unique_t;
#define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
static int
unique_compare(const void *a, const void *b)
{
const unique_t *una = a;
const unique_t *unb = b;
if (una->un_value < unb->un_value)
return (-1);
if (una->un_value > unb->un_value)
return (+1);
return (0);
}
void
unique_init(void)
{
avl_create(&unique_avl, unique_compare,
sizeof (unique_t), offsetof(unique_t, un_link));
mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL);
}
void
unique_fini(void)
{
avl_destroy(&unique_avl);
mutex_destroy(&unique_mtx);
}
uint64_t
unique_create(void)
{
uint64_t value = unique_insert(0);
unique_remove(value);
return (value);
}
uint64_t
unique_insert(uint64_t value)
{
avl_index_t idx;
unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
un->un_value = value;
mutex_enter(&unique_mtx);
while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
avl_find(&unique_avl, un, &idx)) {
mutex_exit(&unique_mtx);
(void) random_get_pseudo_bytes((void*)&un->un_value,
sizeof (un->un_value));
un->un_value &= UNIQUE_MASK;
mutex_enter(&unique_mtx);
}
avl_insert(&unique_avl, un, idx);
mutex_exit(&unique_mtx);
return (un->un_value);
}
void
unique_remove(uint64_t value)
{
unique_t un_tofind;
unique_t *un;
un_tofind.un_value = value;
mutex_enter(&unique_mtx);
un = avl_find(&unique_avl, &un_tofind, NULL);
if (un != NULL) {
avl_remove(&unique_avl, un);
kmem_free(un, sizeof (unique_t));
}
mutex_exit(&unique_mtx);
}
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