hash.c

asterisk 一个模拟IPPBX的源代码

	fp = hashp->fp;
	whdrp = &hashp->hdr;
#if BYTE_ORDER == LITTLE_ENDIAN
	whdrp = &whdr;
	swap_header_copy(&hashp->hdr, whdrp);
#endif
	if ((lseek(fp, (off_t)0, SEEK_SET) == -1) ||
	    ((wsize = write(fp, whdrp, sizeof(HASHHDR))) == -1))
		return (-1);
	else
		if (wsize != sizeof(HASHHDR)) {
			errno = EFTYPE;
			hashp->errnum = errno;
			return (-1);
		}
	for (i = 0; i < NCACHED; i++)
		if (hashp->mapp[i])
			if (__put_page(hashp, (char *)hashp->mapp[i],
				hashp->BITMAPS[i], 0, 1))
				return (-1);
	return (0);
}

/*******************************SEARCH ROUTINES *****************************/
/*
 * All the access routines return
 *
 * Returns:
 *	 0 on SUCCESS
 *	 1 to indicate an external ERROR (i.e. key not found, etc)
 *	-1 to indicate an internal ERROR (i.e. out of memory, etc)
 */
static int
hash_get(dbp, key, data, flag)
	const DB *dbp;
	const DBT *key;
	DBT *data;
	u_int32_t flag;
{
	HTAB *hashp;

	hashp = (HTAB *)dbp->internal;
	if (flag) {
		hashp->errnum = errno = EINVAL;
		return (ERROR);
	}
	return (hash_access(hashp, HASH_GET, (DBT *)key, data));
}

static int
hash_put(dbp, key, data, flag)
	const DB *dbp;
	DBT *key;
	const DBT *data;
	u_int32_t flag;
{
	HTAB *hashp;

	hashp = (HTAB *)dbp->internal;
	if (flag && flag != R_NOOVERWRITE) {
		hashp->errnum = errno = EINVAL;
		return (ERROR);
	}
	if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
		hashp->errnum = errno = EPERM;
		return (ERROR);
	}
	return (hash_access(hashp, flag == R_NOOVERWRITE ?
	    HASH_PUTNEW : HASH_PUT, (DBT *)key, (DBT *)data));
}

static int
hash_delete(dbp, key, flag)
	const DB *dbp;
	const DBT *key;
	u_int32_t flag;		/* Ignored */
{
	HTAB *hashp;

	hashp = (HTAB *)dbp->internal;
	if (flag && flag != R_CURSOR) {
		hashp->errnum = errno = EINVAL;
		return (ERROR);
	}
	if ((hashp->flags & O_ACCMODE) == O_RDONLY) {
		hashp->errnum = errno = EPERM;
		return (ERROR);
	}
	return (hash_access(hashp, HASH_DELETE, (DBT *)key, NULL));
}

/*
 * Assume that hashp has been set in wrapper routine.
 */
static int
hash_access(hashp, action, key, val)
	HTAB *hashp;
	ACTION action;
	DBT *key, *val;
{
	register BUFHEAD *rbufp;
	BUFHEAD *bufp, *save_bufp;
	register u_int16_t *bp;
	register int n, ndx, off, size;
	register char *kp;
	u_int16_t pageno;

#ifdef HASH_STATISTICS
	hash_accesses++;
#endif

	off = hashp->BSIZE;
	size = key->size;
	kp = (char *)key->data;
	rbufp = __get_buf(hashp, __call_hash(hashp, kp, size), NULL, 0);
	if (!rbufp)
		return (ERROR);
	save_bufp = rbufp;

	/* Pin the bucket chain */
	rbufp->flags |= BUF_PIN;
	for (bp = (u_int16_t *)rbufp->page, n = *bp++, ndx = 1; ndx < n;)
		if (bp[1] >= REAL_KEY) {
			/* Real key/data pair */
			if (size == off - *bp &&
			    memcmp(kp, rbufp->page + *bp, size) == 0)
				goto found;
			off = bp[1];
#ifdef HASH_STATISTICS
			hash_collisions++;
#endif
			bp += 2;
			ndx += 2;
		} else if (bp[1] == OVFLPAGE) {
			rbufp = __get_buf(hashp, *bp, rbufp, 0);
			if (!rbufp) {
				save_bufp->flags &= ~BUF_PIN;
				return (ERROR);
			}
			/* FOR LOOP INIT */
			bp = (u_int16_t *)rbufp->page;
			n = *bp++;
			ndx = 1;
			off = hashp->BSIZE;
		} else if (bp[1] < REAL_KEY) {
			if ((ndx =
			    __find_bigpair(hashp, rbufp, ndx, kp, size)) > 0)
				goto found;
			if (ndx == -2) {
				bufp = rbufp;
				if (!(pageno =
				    __find_last_page(hashp, &bufp))) {
					ndx = 0;
					rbufp = bufp;
					break;	/* FOR */
				}
				rbufp = __get_buf(hashp, pageno, bufp, 0);
				if (!rbufp) {
					save_bufp->flags &= ~BUF_PIN;
					return (ERROR);
				}
				/* FOR LOOP INIT */
				bp = (u_int16_t *)rbufp->page;
				n = *bp++;
				ndx = 1;
				off = hashp->BSIZE;
			} else {
				save_bufp->flags &= ~BUF_PIN;
				return (ERROR);
			}
		}

	/* Not found */
	switch (action) {
	case HASH_PUT:
	case HASH_PUTNEW:
		if (__addel(hashp, rbufp, key, val)) {
			save_bufp->flags &= ~BUF_PIN;
			return (ERROR);
		} else {
			save_bufp->flags &= ~BUF_PIN;
			return (SUCCESS);
		}
	case HASH_GET:
	case HASH_DELETE:
	default:
		save_bufp->flags &= ~BUF_PIN;
		return (ABNORMAL);
	}

found:
	switch (action) {
	case HASH_PUTNEW:
		save_bufp->flags &= ~BUF_PIN;
		return (ABNORMAL);
	case HASH_GET:
		bp = (u_int16_t *)rbufp->page;
		if (bp[ndx + 1] < REAL_KEY) {
			if (__big_return(hashp, rbufp, ndx, val, 0))
				return (ERROR);
		} else {
			val->data = (u_char *)rbufp->page + (int)bp[ndx + 1];
			val->size = bp[ndx] - bp[ndx + 1];
		}
		break;
	case HASH_PUT:
		if ((__delpair(hashp, rbufp, ndx)) ||
		    (__addel(hashp, rbufp, key, val))) {
			save_bufp->flags &= ~BUF_PIN;
			return (ERROR);
		}
		break;
	case HASH_DELETE:
		if (__delpair(hashp, rbufp, ndx))
			return (ERROR);
		break;
	default:
		abort();
	}
	save_bufp->flags &= ~BUF_PIN;
	return (SUCCESS);
}

static int
hash_seq(dbp, key, data, flag)
	const DB *dbp;
	DBT *key, *data;
	u_int32_t flag;
{
	register u_int32_t bucket;
	register BUFHEAD *bufp = NULL;
	HTAB *hashp;
	u_int16_t *bp, ndx;

	hashp = (HTAB *)dbp->internal;
	if (flag && flag != R_FIRST && flag != R_NEXT) {
		hashp->errnum = errno = EINVAL;
		return (ERROR);
	}
#ifdef HASH_STATISTICS
	hash_accesses++;
#endif
	if ((hashp->cbucket < 0) || (flag == R_FIRST)) {
		hashp->cbucket = 0;
		hashp->cndx = 1;
		hashp->cpage = NULL;
	}

	for (bp = NULL; !bp || !bp[0]; ) {
		if (!(bufp = hashp->cpage)) {
			for (bucket = hashp->cbucket;
			    bucket <= (u_int32_t) hashp->MAX_BUCKET;
			    bucket++, hashp->cndx = 1) {
				bufp = __get_buf(hashp, bucket, NULL, 0);
				if (!bufp)
					return (ERROR);
				hashp->cpage = bufp;
				bp = (u_int16_t *)bufp->page;
				if (bp[0])
					break;
			}
			hashp->cbucket = bucket;
			if (hashp->cbucket > hashp->MAX_BUCKET) {
				hashp->cbucket = -1;
				return (ABNORMAL);
			}
		} else
			bp = (u_int16_t *)hashp->cpage->page;

#ifdef DEBUG
		assert(bp);
		assert(bufp);
#endif
		while (bp[hashp->cndx + 1] == OVFLPAGE) {
			bufp = hashp->cpage =
			    __get_buf(hashp, bp[hashp->cndx], bufp, 0);
			if (!bufp)
				return (ERROR);
			bp = (u_int16_t *)(bufp->page);
			hashp->cndx = 1;
		}
		if (!bp[0]) {
			hashp->cpage = NULL;
			++hashp->cbucket;
		}
	}
	ndx = hashp->cndx;
	if (bp[ndx + 1] < REAL_KEY) {
		if (__big_keydata(hashp, bufp, key, data, 1))
			return (ERROR);
	} else {
		key->data = (u_char *)hashp->cpage->page + bp[ndx];
		key->size = (ndx > 1 ? bp[ndx - 1] : hashp->BSIZE) - bp[ndx];
		data->data = (u_char *)hashp->cpage->page + bp[ndx + 1];
		data->size = bp[ndx] - bp[ndx + 1];
		ndx += 2;
		if (ndx > bp[0]) {
			hashp->cpage = NULL;
			hashp->cbucket++;
			hashp->cndx = 1;
		} else
			hashp->cndx = ndx;
	}
	return (SUCCESS);
}

/********************************* UTILITIES ************************/

/*
 * Returns:
 *	 0 ==> OK
 *	-1 ==> Error
 */
extern int
__expand_table(hashp)
	HTAB *hashp;
{
	u_int32_t old_bucket, new_bucket;
	int dirsize, new_segnum, spare_ndx;

#ifdef HASH_STATISTICS
	hash_expansions++;
#endif
	new_bucket = ++hashp->MAX_BUCKET;
	old_bucket = (hashp->MAX_BUCKET & hashp->LOW_MASK);

	new_segnum = new_bucket >> hashp->SSHIFT;

	/* Check if we need a new segment */
	if (new_segnum >= hashp->nsegs) {
		/* Check if we need to expand directory */
		if (new_segnum >= hashp->DSIZE) {
			/* Reallocate directory */
			dirsize = hashp->DSIZE * sizeof(SEGMENT *);
			if (!hash_realloc(&hashp->dir, dirsize, dirsize << 1))
				return (-1);
			hashp->DSIZE = dirsize << 1;
		}
		if ((hashp->dir[new_segnum] =
		    (SEGMENT)calloc(hashp->SGSIZE, sizeof(SEGMENT))) == NULL)
			return (-1);
		hashp->exsegs++;
		hashp->nsegs++;
	}
	/*
	 * If the split point is increasing (MAX_BUCKET's log base 2
	 * * increases), we need to copy the current contents of the spare
	 * split bucket to the next bucket.
	 */
	spare_ndx = __hash_log2(hashp->MAX_BUCKET + 1);
	if (spare_ndx > hashp->OVFL_POINT) {
		hashp->SPARES[spare_ndx] = hashp->SPARES[hashp->OVFL_POINT];
		hashp->OVFL_POINT = spare_ndx;
	}

	if (new_bucket > (u_int32_t) hashp->HIGH_MASK) {
		/* Starting a new doubling */
		hashp->LOW_MASK = hashp->HIGH_MASK;
		hashp->HIGH_MASK = new_bucket | hashp->LOW_MASK;
	}
	/* Relocate records to the new bucket */
	return (__split_page(hashp, old_bucket, new_bucket));
}

/*
 * If realloc guarantees that the pointer is not destroyed if the realloc
 * fails, then this routine can go away.
 */
static void *
hash_realloc(p_ptr, oldsize, newsize)
	SEGMENT **p_ptr;
	int oldsize, newsize;
{
	register void *p;

	if ((p = malloc(newsize))) {
		memmove(p, *p_ptr, oldsize);
		memset((char *)p + oldsize, 0, newsize - oldsize);
		free(*p_ptr);
		*p_ptr = p;
	}
	return (p);
}

extern u_int32_t
__call_hash(hashp, k, len)
	HTAB *hashp;
	char *k;
	int len;
{
	int n, bucket;

	n = hashp->hash(k, len);
	bucket = n & hashp->HIGH_MASK;
	if (bucket > hashp->MAX_BUCKET)
		bucket = bucket & hashp->LOW_MASK;
	return (bucket);
}

/*
 * Allocate segment table.  On error, destroy the table and set errno.
 *
 * Returns 0 on success
 */
static int
alloc_segs(hashp, nsegs)
	HTAB *hashp;
	int nsegs;
{
	register int i;
	register SEGMENT store;

	int save_errno;

	if ((hashp->dir =
	    (SEGMENT *)calloc(hashp->DSIZE, sizeof(SEGMENT *))) == NULL) {
		save_errno = errno;
		(void)hdestroy(hashp);
		errno = save_errno;
		return (-1);
	}
	/* Allocate segments */
	if ((store =
	    (SEGMENT)calloc(nsegs << hashp->SSHIFT, sizeof(SEGMENT))) == NULL) {
		save_errno = errno;
		(void)hdestroy(hashp);
		errno = save_errno;
		return (-1);
	}
	for (i = 0; i < nsegs; i++, hashp->nsegs++)
		hashp->dir[i] = &store[i << hashp->SSHIFT];
	return (0);
}

#if BYTE_ORDER == LITTLE_ENDIAN
/*
 * Hashp->hdr needs to be byteswapped.
 */
static void
swap_header_copy(srcp, destp)
	HASHHDR *srcp, *destp;
{
	int i;

	P_32_COPY(srcp->magic, destp->magic);
	P_32_COPY(srcp->version, destp->version);
	P_32_COPY(srcp->lorder, destp->lorder);
	P_32_COPY(srcp->bsize, destp->bsize);
	P_32_COPY(srcp->bshift, destp->bshift);
	P_32_COPY(srcp->dsize, destp->dsize);
	P_32_COPY(srcp->ssize, destp->ssize);
	P_32_COPY(srcp->sshift, destp->sshift);
	P_32_COPY(srcp->ovfl_point, destp->ovfl_point);
	P_32_COPY(srcp->last_freed, destp->last_freed);
	P_32_COPY(srcp->max_bucket, destp->max_bucket);
	P_32_COPY(srcp->high_mask, destp->high_mask);
	P_32_COPY(srcp->low_mask, destp->low_mask);
	P_32_COPY(srcp->ffactor, destp->ffactor);
	P_32_COPY(srcp->nkeys, destp->nkeys);
	P_32_COPY(srcp->hdrpages, destp->hdrpages);
	P_32_COPY(srcp->h_charkey, destp->h_charkey);
	for (i = 0; i < NCACHED; i++) {
		P_32_COPY(srcp->spares[i], destp->spares[i]);
		P_16_COPY(srcp->bitmaps[i], destp->bitmaps[i]);
	}
}

static void
swap_header(hashp)
	HTAB *hashp;
{
	HASHHDR *hdrp;
	int i;

	hdrp = &hashp->hdr;

	M_32_SWAP(hdrp->magic);
	M_32_SWAP(hdrp->version);
	M_32_SWAP(hdrp->lorder);
	M_32_SWAP(hdrp->bsize);
	M_32_SWAP(hdrp->bshift);
	M_32_SWAP(hdrp->dsize);
	M_32_SWAP(hdrp->ssize);
	M_32_SWAP(hdrp->sshift);
	M_32_SWAP(hdrp->ovfl_point);
	M_32_SWAP(hdrp->last_freed);
	M_32_SWAP(hdrp->max_bucket);
	M_32_SWAP(hdrp->high_mask);
	M_32_SWAP(hdrp->low_mask);
	M_32_SWAP(hdrp->ffactor);
	M_32_SWAP(hdrp->nkeys);
	M_32_SWAP(hdrp->hdrpages);
	M_32_SWAP(hdrp->h_charkey);
	for (i = 0; i < NCACHED; i++) {
		M_32_SWAP(hdrp->spares[i]);
		M_16_SWAP(hdrp->bitmaps[i]);
	}
}
#endif