sys/kern/subr_hash.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * (c) UNIX System Laboratories, Inc.
   5  * All or some portions of this file are derived from material licensed
   6  * to the University of California by American Telephone and Telegraph
   7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   8  * the permission of UNIX System Laboratories, Inc.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/malloc.h>
  43
  44 /*
  45  * General routine to allocate a hash table with control of memory flags.
  46  */
  47 void *
  48 hashinit_flags(int elements, struct malloc_type *type, u_long *hashmask,
  49     int flags)
  50 {
  51         long hashsize;
  52         LIST_HEAD(generic, generic) *hashtbl;
  53         int i;
  54
  55         KASSERT(elements > 0, ("%s: bad elements", __func__));
  56         /* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
  57         KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
  58             ("Bad flags (0x%x) passed to hashinit_flags", flags));
  59
  60         for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
  61                 continue;
  62         hashsize >>= 1;
  63
  64         if (flags & HASH_NOWAIT)
  65                 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl),
  66                     type, M_NOWAIT);
  67         else
  68                 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl),
  69                     type, M_WAITOK);
  70
  71         if (hashtbl != NULL) {
  72                 for (i = 0; i < hashsize; i++)
  73                         LIST_INIT(&hashtbl[i]);
  74                 *hashmask = hashsize - 1;
  75         }
  76         return (hashtbl);
  77 }
  78
  79 /*
  80  * Allocate and initialize a hash table with default flag: may sleep.
  81  */
  82 void *
  83 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
  84 {
  85
  86         return (hashinit_flags(elements, type, hashmask, HASH_WAITOK));
  87 }
  88
  89 void
  90 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
  91 {
  92         LIST_HEAD(generic, generic) *hashtbl, *hp;
  93
  94         hashtbl = vhashtbl;
  95         for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
  96                 KASSERT(LIST_EMPTY(hp), ("%s: hash not empty", __func__));
  97         free(hashtbl, type);
  98 }
  99
 100 static const int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531,
 101                         2039, 2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143,
 102                         6653, 7159, 7673, 8191, 12281, 16381, 24571, 32749 };
 103 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
 104
 105 /*
 106  * General routine to allocate a prime number sized hash table.
 107  */
 108 void *
 109 phashinit(int elements, struct malloc_type *type, u_long *nentries)
 110 {
 111         long hashsize;
 112         LIST_HEAD(generic, generic) *hashtbl;
 113         int i;
 114
 115         KASSERT(elements > 0, ("%s: bad elements", __func__));
 116         for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
 117                 i++;
 118                 if (i == NPRIMES)
 119                         break;
 120                 hashsize = primes[i];
 121         }
 122         hashsize = primes[i - 1];
 123         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
 124         for (i = 0; i < hashsize; i++)
 125                 LIST_INIT(&hashtbl[i]);
 126         *nentries = hashsize;
 127         return (hashtbl);
 128 }