* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
* This code is derived from software contributed to Berkeley by
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 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
* @(#)hash.h 8.1 (Berkeley) 6/4/93
HASH_GET
, HASH_PUT
, HASH_PUTNEW
, HASH_DELETE
, HASH_FIRST
, HASH_NEXT
/* Buffer Management structures */
typedef struct _bufhead BUFHEAD
;
BUFHEAD
*prev
; /* LRU links */
BUFHEAD
*next
; /* LRU links */
BUFHEAD
*ovfl
; /* Overflow page buffer header */
u_int addr
; /* Address of this page */
char *page
; /* Actual page data */
#define BUF_BUCKET 0x0004
#define IS_BUCKET(X) ((X) & BUF_BUCKET)
typedef BUFHEAD
**SEGMENT
;
/* Hash Table Information */
typedef struct hashhdr
{ /* Disk resident portion */
int magic
; /* Magic NO for hash tables */
int version
; /* Version ID */
long lorder
; /* Byte Order */
int bsize
; /* Bucket/Page Size */
int bshift
; /* Bucket shift */
int dsize
; /* Directory Size */
int ssize
; /* Segment Size */
int sshift
; /* Segment shift */
int ovfl_point
; /* Where overflow pages are being allocated */
int last_freed
; /* Last overflow page freed */
int max_bucket
; /* ID of Maximum bucket in use */
int high_mask
; /* Mask to modulo into entire table */
int low_mask
; /* Mask to modulo into lower half of table */
int ffactor
; /* Fill factor */
int nkeys
; /* Number of keys in hash table */
int hdrpages
; /* Size of table header */
int h_charkey
; /* value of hash(CHARKEY) */
#define NCACHED 32 /* number of bit maps and spare points */
int spares
[NCACHED
];/* spare pages for overflow */
u_short bitmaps
[NCACHED
]; /* address of overflow page bitmaps */
typedef struct htab
{ /* Memory resident data structure */
HASHHDR hdr
; /* Header */
int nsegs
; /* Number of allocated segments */
int exsegs
; /* Number of extra allocated segments */
int (*hash
) (); /* Hash Function */
int flags
; /* Flag values */
int fp
; /* File pointer */
char *tmp_buf
; /* Temporary Buffer for BIG data */
char *tmp_key
; /* Temporary Buffer for BIG keys */
BUFHEAD
*cpage
; /* Current page */
int cbucket
; /* Current bucket */
int cndx
; /* Index of next item on cpage */
int errno
; /* Error Number -- for DBM compatability */
int new_file
; /* Indicates if fd is backing store or no */
int save_file
; /* Indicates whether we need to flush file at
u_long
*mapp
[NCACHED
]; /* Pointers to page maps */
int nmaps
; /* Initial number of bitmaps */
int nbufs
; /* Number of buffers left to allocate */
BUFHEAD bufhead
; /* Header of buffer lru list */
SEGMENT
*dir
; /* Hash Bucket directory */
#define MAX_BSIZE 65536 /* 2^16 */
#define DEF_BUFSIZE 65536 /* 64 K */
#define DEF_BUCKET_SIZE 4096
#define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */
#define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */
#define DEF_FFACTOR 65536
#define CHARKEY "%$sniglet^&"
#define ALL_SET ((u_int)0xFFFFFFFF)
#define PTROF(X) ((BUFHEAD *)((u_int)(X)&~0x3))
#define ISMOD(X) ((u_int)(X)&0x1)
#define DOMOD(X) ((X) = (char *)((u_int)(X)|0x1))
#define ISDISK(X) ((u_int)(X)&0x2)
#define DODISK(X) ((X) = (char *)((u_int)(X)|0x2))
/* Given the address of the beginning of a big map, clear/set the nth bit */
#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
/* Overflow management */
* Overflow page numbers are allocated per split point. At each doubling of
* the table, we can allocate extra pages. So, an overflow page number has
* the top 5 bits indicate which split point and the lower 11 bits indicate
* which page at that split point is indicated (pages within split points are
* numberered starting with 1).
#define SPLITNUM(N) (((u_int)(N)) >> SPLITSHIFT)
#define OPAGENUM(N) ((N) & SPLITMASK)
#define OADDR_OF(S,O) ((u_int)((u_int)(S) << SPLITSHIFT) + (O))
#define BUCKET_TO_PAGE(B) \
(B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0)
#define OADDR_TO_PAGE(B) \
BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
* page.h contains a detailed description of the page format.
* Normally, keys and data are accessed from offset tables in the top of
* each page which point to the beginning of the key and data. There are
* four flag values which may be stored in these offset tables which indicate
* OVFLPAGE Rather than a key data pair, this pair contains
* the address of an overflow page. The format of
* OVERFLOW_PAGE_NUMBER OVFLPAGE
* PARTIAL_KEY This must be the first key/data pair on a page
* and implies that page contains only a partial key.
* That is, the key is too big to fit on a single page
* so it starts on this page and continues on the next.
* The format of the page is:
* KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
* KEY_OFF -- offset of the beginning of the key
* OVFL_PAGENO - page number of the next overflow page
* FULL_KEY This must be the first key/data pair on the page. It
* There is a complete key on the page but no data
* (because it wouldn't fit). The next page contains
* KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
* KEY_OFF -- offset of the beginning of the key
* OVFL_PAGENO - page number of the next overflow page
* This page contains no key, but part of a large
* data field, which is continued on the next page.
* DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
* KEY_OFF -- offset of the beginning of the data on
* OVFL_PAGENO - page number of the next overflow page
* This must be the first key/data pair on the page.
* This page contains a key and the beginning of the
* data field, but the data field is continued on the
* KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
* KEY_OFF -- offset of the beginning of the key
* OVFL_PAGENO - page number of the next overflow page
* DATA_OFF -- offset of the beginning of the data
* This page contains the last page of a big data pair.
* There is no key, only the tail end of the data
* DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
* DATA_OFF -- offset of the beginning of the data on
* OVFL_PAGENO - page number of the next overflow page
* OVFL_PAGENO and OVFLPAGE are optional (they are
* not present if there is no next page).
/* Short hands for accessing structure */
#define BSHIFT hdr.bshift
#define SSHIFT hdr.sshift
#define LORDER hdr.lorder
#define OVFL_POINT hdr.ovfl_point
#define LAST_FREED hdr.last_freed
#define MAX_BUCKET hdr.max_bucket
#define FFACTOR hdr.ffactor
#define HIGH_MASK hdr.high_mask
#define LOW_MASK hdr.low_mask
#define HDRPAGES hdr.hdrpages
#define SPARES hdr.spares
#define BITMAPS hdr.bitmaps
#define VERSION hdr.version
#define NEXT_FREE hdr.next_free
#define H_CHARKEY hdr.h_charkey