hash.c

asterisk 一个模拟IPPBX的源代码

/*-
 * Copyright (c) 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)hash.c	8.9 (Berkeley) 6/16/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef DEBUG
#include <assert.h>
#endif

#include "../include/db.h"
#include "hash.h"
#include "page.h"
#include "extern.h"

static int   alloc_segs __P((HTAB *, int));
static int   flush_meta __P((HTAB *));
static int   hash_access __P((HTAB *, ACTION, DBT *, DBT *));
static int   hash_close __P((DB *));
static int   hash_delete __P((const DB *, const DBT *, u_int32_t));
static int   hash_fd __P((const DB *));
static int   hash_get __P((const DB *, const DBT *, DBT *, u_int32_t));
static int   hash_put __P((const DB *, DBT *, const DBT *, u_int32_t));
static void *hash_realloc __P((SEGMENT **, int, int));
static int   hash_seq __P((const DB *, DBT *, DBT *, u_int32_t));
static int   hash_sync __P((const DB *, u_int32_t));
static int   hdestroy __P((HTAB *));
static HTAB *init_hash __P((HTAB *, const char *, const HASHINFO *));
static int   init_htab __P((HTAB *, int));
#if BYTE_ORDER == LITTLE_ENDIAN
static void  swap_header __P((HTAB *));
static void  swap_header_copy __P((HASHHDR *, HASHHDR *));
#endif

/* Fast arithmetic, relying on powers of 2, */
#define MOD(x, y)		((x) & ((y) - 1))

#define RETURN_ERROR(ERR, LOC)	{ save_errno = ERR; goto LOC; }

/* Return values */
#define	SUCCESS	 (0)
#define	ERROR	(-1)
#define	ABNORMAL (1)

#ifdef HASH_STATISTICS
int hash_accesses, hash_collisions, hash_expansions, hash_overflows;
#endif

/************************** INTERFACE ROUTINES ***************************/
/* OPEN/CLOSE */

extern DB *
__hash_open(file, flags, mode, info, dflags)
	const char *file;
	int flags, mode, dflags;
	const HASHINFO *info;	/* Special directives for create */
{
	HTAB *hashp;
	struct stat statbuf;
	DB *dbp;
	int bpages, hdrsize, new_table, nsegs, save_errno;

	if ((flags & O_ACCMODE) == O_WRONLY) {
		errno = EINVAL;
		return (NULL);
	}

	if (!(hashp = (HTAB *)calloc(1, sizeof(HTAB))))
		return (NULL);
	hashp->fp = -1;

	/*
	 * Even if user wants write only, we need to be able to read
	 * the actual file, so we need to open it read/write. But, the
	 * field in the hashp structure needs to be accurate so that
	 * we can check accesses.
	 */
	hashp->flags = flags;

	new_table = 0;
	if (!file || (flags & O_TRUNC) ||
	    (stat(file, &statbuf) && (errno == ENOENT))) {
		if (errno == ENOENT)
			errno = 0; /* Just in case someone looks at errno */
		new_table = 1;
	}
	if (file) {
		if ((hashp->fp = open(file, flags, mode)) == -1)
			RETURN_ERROR(errno, error0);
		(void)fcntl(hashp->fp, F_SETFD, 1);
	}
	if (new_table) {
		if (!(hashp = init_hash(hashp, file, info)))
			RETURN_ERROR(errno, error1);
	} else {
		/* Table already exists */
		if (info && info->hash)
			hashp->hash = info->hash;
		else
			hashp->hash = __default_hash;

		hdrsize = read(hashp->fp, &hashp->hdr, sizeof(HASHHDR));
#if BYTE_ORDER == LITTLE_ENDIAN
		swap_header(hashp);
#endif
		if (hdrsize == -1)
			RETURN_ERROR(errno, error1);
		if (hdrsize != sizeof(HASHHDR))
			RETURN_ERROR(EFTYPE, error1);
		/* Verify file type, versions and hash function */
		if (hashp->MAGIC != HASHMAGIC)
			RETURN_ERROR(EFTYPE, error1);
#define	OLDHASHVERSION	1
		if (hashp->VERSION != HASHVERSION &&
		    hashp->VERSION != OLDHASHVERSION)
			RETURN_ERROR(EFTYPE, error1);
		if (hashp->hash(CHARKEY, sizeof(CHARKEY))
		    != (u_int32_t) hashp->H_CHARKEY)
			RETURN_ERROR(EFTYPE, error1);
		/*
		 * Figure out how many segments we need.  Max_Bucket is the
		 * maximum bucket number, so the number of buckets is
		 * max_bucket + 1.
		 */
		nsegs = (hashp->MAX_BUCKET + 1 + hashp->SGSIZE - 1) /
			 hashp->SGSIZE;
		hashp->nsegs = 0;
		if (alloc_segs(hashp, nsegs))
			/*
			 * If alloc_segs fails, table will have been destroyed
			 * and errno will have been set.
			 */
			return (NULL);
		/* Read in bitmaps */
		bpages = (hashp->SPARES[hashp->OVFL_POINT] +
		    (hashp->BSIZE << BYTE_SHIFT) - 1) >>
		    (hashp->BSHIFT + BYTE_SHIFT);

		hashp->nmaps = bpages;
		(void)memset(&hashp->mapp[0], 0, bpages * sizeof(u_int32_t *));
	}

	/* Initialize Buffer Manager */
	if (info && info->cachesize)
		__buf_init(hashp, info->cachesize);
	else
		__buf_init(hashp, DEF_BUFSIZE);

	hashp->new_file = new_table;
	hashp->save_file = file && (hashp->flags & O_ACCMODE) != O_RDONLY;
	hashp->cbucket = -1;
	if (!(dbp = (DB *)malloc(sizeof(DB)))) {
		save_errno = errno;
		hdestroy(hashp);
		errno = save_errno;
		return (NULL);
	}
	dbp->internal = hashp;
	dbp->close = hash_close;
	dbp->del = hash_delete;
	dbp->fd = hash_fd;
	dbp->get = hash_get;
	dbp->put = hash_put;
	dbp->seq = hash_seq;
	dbp->sync = hash_sync;
	dbp->type = DB_HASH;

#ifdef DEBUG
	(void)fprintf(stderr,
"%s\n%s%x\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n%s%x\n%s%x\n%s%d\n%s%d\n",
	    "init_htab:",
	    "TABLE POINTER   ", hashp,
	    "BUCKET SIZE     ", hashp->BSIZE,
	    "BUCKET SHIFT    ", hashp->BSHIFT,
	    "DIRECTORY SIZE  ", hashp->DSIZE,
	    "SEGMENT SIZE    ", hashp->SGSIZE,
	    "SEGMENT SHIFT   ", hashp->SSHIFT,
	    "FILL FACTOR     ", hashp->FFACTOR,
	    "MAX BUCKET      ", hashp->MAX_BUCKET,
	    "OVFL POINT	     ", hashp->OVFL_POINT,
	    "LAST FREED      ", hashp->LAST_FREED,
	    "HIGH MASK       ", hashp->HIGH_MASK,
	    "LOW  MASK       ", hashp->LOW_MASK,
	    "NSEGS           ", hashp->nsegs,
	    "NKEYS           ", hashp->NKEYS);
#endif
#ifdef HASH_STATISTICS
	hash_overflows = hash_accesses = hash_collisions = hash_expansions = 0;
#endif
	return (dbp);

error1:
	if (hashp != NULL)
		(void)close(hashp->fp);

error0:
	free(hashp);
	errno = save_errno;
	return (NULL);
}

static int
hash_close(dbp)
	DB *dbp;
{
	HTAB *hashp;
	int retval;

	if (!dbp)
		return (ERROR);

	hashp = (HTAB *)dbp->internal;
	retval = hdestroy(hashp);
	free(dbp);
	return (retval);
}

static int
hash_fd(dbp)
	const DB *dbp;
{
	HTAB *hashp;

	if (!dbp)
		return (ERROR);

	hashp = (HTAB *)dbp->internal;
	if (hashp->fp == -1) {
		errno = ENOENT;
		return (-1);
	}
	return (hashp->fp);
}

/************************** LOCAL CREATION ROUTINES **********************/
static HTAB *
init_hash(hashp, file, info)
	HTAB *hashp;
	const char *file;
	const HASHINFO *info;
{
#ifdef _STATBUF_ST_BLKSIZE
	struct stat statbuf;
#endif
	int nelem;

	nelem = 1;
	hashp->NKEYS = 0;
	hashp->LORDER = BYTE_ORDER;
	hashp->BSIZE = DEF_BUCKET_SIZE;
	hashp->BSHIFT = DEF_BUCKET_SHIFT;
	hashp->SGSIZE = DEF_SEGSIZE;
	hashp->SSHIFT = DEF_SEGSIZE_SHIFT;
	hashp->DSIZE = DEF_DIRSIZE;
	hashp->FFACTOR = DEF_FFACTOR;
	hashp->hash = __default_hash;
	memset(hashp->SPARES, 0, sizeof(hashp->SPARES));
	memset(hashp->BITMAPS, 0, sizeof (hashp->BITMAPS));

	/* Fix bucket size to be optimal for file system */
#ifdef _STATBUF_ST_BLKSIZE
	if (file != NULL) {
		if (stat(file, &statbuf))
			return (NULL);
		hashp->BSIZE = statbuf.st_blksize;
		hashp->BSHIFT = __hash_log2(hashp->BSIZE);
	}
#endif

	if (info) {
		if (info->bsize) {
			/* Round pagesize up to power of 2 */
			hashp->BSHIFT = __hash_log2(info->bsize);
			hashp->BSIZE = 1 << hashp->BSHIFT;
			if (hashp->BSIZE > MAX_BSIZE) {
				errno = EINVAL;
				return (NULL);
			}
		}
		if (info->ffactor)
			hashp->FFACTOR = info->ffactor;
		if (info->hash)
			hashp->hash = info->hash;
		if (info->nelem)
			nelem = info->nelem;
		if (info->lorder) {
			if (info->lorder != BIG_ENDIAN &&
			    info->lorder != LITTLE_ENDIAN) {
				errno = EINVAL;
				return (NULL);
			}
			hashp->LORDER = info->lorder;
		}
	}
	/* init_htab should destroy the table and set errno if it fails */
	if (init_htab(hashp, nelem))
		return (NULL);
	else
		return (hashp);
}
/*
 * This calls alloc_segs which may run out of memory.  Alloc_segs will destroy
 * the table and set errno, so we just pass the error information along.
 *
 * Returns 0 on No Error
 */
static int
init_htab(hashp, nelem)
	HTAB *hashp;
	int nelem;
{
	register int nbuckets, nsegs;
	int l2;

	/*
	 * Divide number of elements by the fill factor and determine a
	 * desired number of buckets.  Allocate space for the next greater
	 * power of two number of buckets.
	 */
	nelem = (nelem - 1) / hashp->FFACTOR + 1;

	l2 = __hash_log2(MAX(nelem, 2));
	nbuckets = 1 << l2;

	hashp->SPARES[l2] = l2 + 1;
	hashp->SPARES[l2 + 1] = l2 + 1;
	hashp->OVFL_POINT = l2;
	hashp->LAST_FREED = 2;

	/* First bitmap page is at: splitpoint l2 page offset 1 */
	if (__ibitmap(hashp, OADDR_OF(l2, 1), l2 + 1, 0))
		return (-1);

	hashp->MAX_BUCKET = hashp->LOW_MASK = nbuckets - 1;
	hashp->HIGH_MASK = (nbuckets << 1) - 1;
	hashp->HDRPAGES = ((MAX(sizeof(HASHHDR), MINHDRSIZE) - 1) >>
	    hashp->BSHIFT) + 1;

	nsegs = (nbuckets - 1) / hashp->SGSIZE + 1;
	nsegs = 1 << __hash_log2(nsegs);

	if (nsegs > hashp->DSIZE)
		hashp->DSIZE = nsegs;
	return (alloc_segs(hashp, nsegs));
}

/********************** DESTROY/CLOSE ROUTINES ************************/

/*
 * Flushes any changes to the file if necessary and destroys the hashp
 * structure, freeing all allocated space.
 */
static int
hdestroy(hashp)
	HTAB *hashp;
{
	int i, save_errno;

	save_errno = 0;

#ifdef HASH_STATISTICS
	(void)fprintf(stderr, "hdestroy: accesses %ld collisions %ld\n",
	    hash_accesses, hash_collisions);
	(void)fprintf(stderr, "hdestroy: expansions %ld\n",
	    hash_expansions);
	(void)fprintf(stderr, "hdestroy: overflows %ld\n",
	    hash_overflows);
	(void)fprintf(stderr, "keys %ld maxp %d segmentcount %d\n",
	    hashp->NKEYS, hashp->MAX_BUCKET, hashp->nsegs);

	for (i = 0; i < NCACHED; i++)
		(void)fprintf(stderr,
		    "spares[%d] = %d\n", i, hashp->SPARES[i]);
#endif
	/*
	 * Call on buffer manager to free buffers, and if required,
	 * write them to disk.
	 */
	if (__buf_free(hashp, 1, hashp->save_file))
		save_errno = errno;
	if (hashp->dir) {
		free(*hashp->dir);	/* Free initial segments */
		/* Free extra segments */
		while (hashp->exsegs--)
			free(hashp->dir[--hashp->nsegs]);
		free(hashp->dir);
	}
	if (flush_meta(hashp) && !save_errno)
		save_errno = errno;
	/* Free Bigmaps */
	for (i = 0; i < hashp->nmaps; i++)
		if (hashp->mapp[i])
			free(hashp->mapp[i]);

	if (hashp->fp != -1)
		(void)close(hashp->fp);

	free(hashp);

	if (save_errno) {
		errno = save_errno;
		return (ERROR);
	}
	return (SUCCESS);
}
/*
 * Write modified pages to disk
 *
 * Returns:
 *	 0 == OK
 *	-1 ERROR
 */
static int
hash_sync(dbp, flags)
	const DB *dbp;
	u_int32_t flags;
{
	HTAB *hashp;

	if (flags != 0) {
		errno = EINVAL;
		return (ERROR);
	}

	if (!dbp)
		return (ERROR);

	hashp = (HTAB *)dbp->internal;
	if (!hashp->save_file)
		return (0);
	if (__buf_free(hashp, 0, 1) || flush_meta(hashp))
		return (ERROR);
	hashp->new_file = 0;
	return (0);
}

/*
 * Returns:
 *	 0 == OK
 *	-1 indicates that errno should be set
 */
static int
flush_meta(hashp)
	HTAB *hashp;
{
	HASHHDR *whdrp;
#if BYTE_ORDER == LITTLE_ENDIAN
	HASHHDR whdr;
#endif
	int fp, i, wsize;

	if (!hashp->save_file)
		return (0);
	hashp->MAGIC = HASHMAGIC;
	hashp->VERSION = HASHVERSION;
	hashp->H_CHARKEY = hashp->hash(CHARKEY, sizeof(CHARKEY));