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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 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*
* stable.c -- string table module
*
* simple string table module. all read-only strings are entered in
* this table, allowing us to compare pointers rather than characters
* to see if two strings are equal.
*
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include <stdio.h>
#include <strings.h>
#include "alloc.h"
#include "out.h"
#include "stats.h"
#include "stable.h"
#define MINPTR_ALIGN sizeof (char *) /* alignment boundary for pointers */
#define DEF_HASH_SIZE 11113 /* default hash table size */
#define CHUNK_SIZE 8192 /* grab more memory with this chunk size */
static char **Stable; /* the hash table */
static unsigned Stablesz;
static char *Stableblock;
static char *Stablenext;
static struct stats *Stablecount;
static struct stats *Blockcount;
static struct stats *Add0;
static struct stats *Add1;
static struct stats *Add2;
static struct stats *Add3;
static struct stats *Addn;
struct chunklst {
struct chunklst *next;
char *chunkp;
};
struct chunklst *Stablechunks;
/*
* stable_init -- initialize the stable module
*
* hash table is sized according to sz. sz of zero means pick
* reasonable default size.
*/
void
stable_init(unsigned sz)
{
/* allocate hash table */
if (sz == 0)
Stablesz = DEF_HASH_SIZE;
else
Stablesz = sz;
Stable = MALLOC(Stablesz * sizeof (*Stable));
bzero((void *)Stable, Stablesz * sizeof (*Stable));
Stablecount = stats_new_counter("stable.size", "hash table size", 1);
Blockcount = stats_new_counter("stable.blocks", "blocks allocated", 1);
Add0 = stats_new_counter("stable.add0", "adds to empty buckets", 1);
Add1 = stats_new_counter("stable.add1", "adds to 1-entry buckets", 1);
Add2 = stats_new_counter("stable.add2", "adds to 2-entry buckets", 1);
Add3 = stats_new_counter("stable.add3", "adds to 3-entry buckets", 1);
Addn = stats_new_counter("stable.addn", "adds to n-entry buckets", 1);
stats_counter_add(Stablecount, Stablesz);
}
void
stable_fini(void)
{
struct chunklst *cp, *nc;
stats_delete(Stablecount);
stats_delete(Blockcount);
stats_delete(Add0);
stats_delete(Add1);
stats_delete(Add2);
stats_delete(Add3);
stats_delete(Addn);
FREE(Stable);
cp = Stablechunks;
nc = NULL;
while (cp != NULL) {
nc = cp->next;
FREE(cp->chunkp);
FREE(cp);
cp = nc;
}
Stablechunks = NULL;
}
static char *
stable_newchunk(void)
{
struct chunklst *save = Stablechunks;
char *n;
n = MALLOC(CHUNK_SIZE);
bzero((void *)n, CHUNK_SIZE);
stats_counter_bump(Blockcount);
Stablechunks = MALLOC(sizeof (struct chunklst));
Stablechunks->next = save;
Stablechunks->chunkp = n;
return (n);
}
/*
* stable -- create/lookup a string table entry
*/
const char *
stable(const char *s)
{
unsigned slen = 0;
unsigned hash = DEF_HASH_SIZE ^ ((unsigned)*s << 2);
char **ptrp;
char *ptr;
char *eptr;
const char *sptr;
int collisions = 0;
if (Stablesz == 0)
out(O_DIE, "internal error: Stablesz not set");
for (sptr = &s[1]; *sptr; sptr++) {
slen++;
hash ^= (((unsigned)*sptr) << (slen % 3)) +
((unsigned)*(sptr - 1) << ((slen % 3 + 7)));
}
hash ^= slen;
if (slen > CHUNK_SIZE - sizeof (char *) - 1 - 4)
out(O_DIE, "too big for string table %.20s...", s);
hash %= Stablesz;
ptrp = &Stable[hash];
ptr = *ptrp;
while (ptr) {
/* hash brought us to something, see if it is the string */
sptr = s;
eptr = ptr;
while (*sptr && *eptr && *sptr++ == *eptr++)
;
if (*sptr == '\0' && *eptr == '\0')
return (ptr); /* found it */
/* strings didn't match, advance eptr to end of string */
while (*eptr)
eptr++;
eptr++; /* move past '\0' */
while ((uintptr_t)eptr % MINPTR_ALIGN)
eptr++;
/* pull in next pointer in bucket */
ptrp = (char **)(void *)eptr;
ptr = *ptrp;
collisions++;
}
/* string wasn't in table, add it and point ptr to it */
if (Stablenext == NULL || (&Stableblock[CHUNK_SIZE] - Stablenext) <
(slen + sizeof (char *) + MINPTR_ALIGN + 4)) {
/* need more room */
Stablenext = Stableblock = stable_newchunk();
}
/* current chunk has room in it */
ptr = *ptrp = Stablenext;
sptr = s;
while (*Stablenext++ = *sptr++)
;
while ((uintptr_t)Stablenext % MINPTR_ALIGN)
Stablenext++;
ptrp = (char **)(void *)Stablenext;
Stablenext += sizeof (char *);
*ptrp = NULL;
/* just did an add, update stats */
if (collisions == 0)
stats_counter_bump(Add0);
else if (collisions == 1)
stats_counter_bump(Add1);
else if (collisions == 2)
stats_counter_bump(Add2);
else if (collisions == 3)
stats_counter_bump(Add3);
else
stats_counter_bump(Addn);
return (ptr);
}
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