freebsd-src/lib/libpmcstat/libpmcstat_string.c

/*-
 * Copyright (c) 2003-2008 Joseph Koshy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/cpuset.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/pmc.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <pmc.h>
#include <pmclog.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>

#include "libpmcstat.h"

static LIST_HEAD(,pmcstat_string)	pmcstat_string_hash[PMCSTAT_NHASH];

/*
 * Intern a copy of string 's', and return a pointer to the
 * interned structure.
 */

pmcstat_interned_string
pmcstat_string_intern(const char *s)
{
	struct pmcstat_string *ps;
	const struct pmcstat_string *cps;
	int hash, len;

	if ((cps = pmcstat_string_lookup(s)) != NULL)
		return (cps);

	hash = pmcstat_string_compute_hash(s);
	len  = strlen(s);

	if ((ps = malloc(sizeof(*ps))) == NULL)
		err(EX_OSERR, "ERROR: Could not intern string");
	ps->ps_len = len;
	ps->ps_hash = hash;
	ps->ps_string = strdup(s);
	LIST_INSERT_HEAD(&pmcstat_string_hash[hash], ps, ps_next);
	return ((pmcstat_interned_string) ps);
}

const char *
pmcstat_string_unintern(pmcstat_interned_string str)
{
	const char *s;

	s = ((const struct pmcstat_string *) str)->ps_string;
	return (s);
}

/*
 * Compute a 'hash' value for a string.
 */

int
pmcstat_string_compute_hash(const char *s)
{
	unsigned hash;

	for (hash = 2166136261; *s; s++)
		hash = (hash ^ *s) * 16777619;

	return (hash & PMCSTAT_HASH_MASK);
}

pmcstat_interned_string
pmcstat_string_lookup(const char *s)
{
	struct pmcstat_string *ps;
	int hash, len;

	hash = pmcstat_string_compute_hash(s);
	len = strlen(s);

	LIST_FOREACH(ps, &pmcstat_string_hash[hash], ps_next)
	    if (ps->ps_len == len && ps->ps_hash == hash &&
		strcmp(ps->ps_string, s) == 0)
		    return (ps);
	return (NULL);
}

int
pmcstat_string_lookup_hash(pmcstat_interned_string s)
{
	const struct pmcstat_string *ps;

	ps = (const struct pmcstat_string *) s;
	return (ps->ps_hash);
}

/*
 * Destroy the string table, free'ing up space.
 */

void
pmcstat_string_shutdown(void)
{
	int i;
	struct pmcstat_string *ps, *pstmp;

	for (i = 0; i < PMCSTAT_NHASH; i++)
		LIST_FOREACH_SAFE(ps, &pmcstat_string_hash[i], ps_next,
		    pstmp) {
			LIST_REMOVE(ps, ps_next);
			free(ps->ps_string);
			free(ps);
		}
}

/*
 * Initialize the string interning facility.
 */

void
pmcstat_string_initialize(void)
{
	int i;

	for (i = 0; i < PMCSTAT_NHASH; i++)
		LIST_INIT(&pmcstat_string_hash[i]);
}