2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)hash.h 8.3 (Berkeley) 5/31/94
37 * $FreeBSD: src/lib/libc/db/hash/hash.h,v 1.4.8.1 2001/03/05 03:50:02 kris Exp $
42 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT
45 /* Buffer Management structures */
46 typedef struct _bufhead BUFHEAD;
49 BUFHEAD *prev; /* LRU links */
50 BUFHEAD *next; /* LRU links */
51 BUFHEAD *ovfl; /* Overflow page buffer header */
52 u_int32_t addr; /* Address of this page */
53 char *page; /* Actual page data */
55 #define BUF_MOD 0x0001
56 #define BUF_DISK 0x0002
57 #define BUF_BUCKET 0x0004
58 #define BUF_PIN 0x0008
61 #define IS_BUCKET(X) ((X) & BUF_BUCKET)
63 typedef BUFHEAD **SEGMENT;
65 /* Hash Table Information */
66 typedef struct hashhdr { /* Disk resident portion */
67 int magic; /* Magic NO for hash tables */
68 int version; /* Version ID */
69 u_int32_t lorder; /* Byte Order */
70 int bsize; /* Bucket/Page Size */
71 int bshift; /* Bucket shift */
72 int dsize; /* Directory Size */
73 int ssize; /* Segment Size */
74 int sshift; /* Segment shift */
75 int ovfl_point; /* Where overflow pages are being
77 int last_freed; /* Last overflow page freed */
78 int max_bucket; /* ID of Maximum bucket in use */
79 int high_mask; /* Mask to modulo into entire table */
80 int low_mask; /* Mask to modulo into lower half of
82 int ffactor; /* Fill factor */
83 int nkeys; /* Number of keys in hash table */
84 int hdrpages; /* Size of table header */
85 int h_charkey; /* value of hash(CHARKEY) */
86 #define NCACHED 32 /* number of bit maps and spare
88 int spares[NCACHED];/* spare pages for overflow */
89 u_int16_t bitmaps[NCACHED]; /* address of overflow page
93 typedef struct htab { /* Memory resident data structure */
94 HASHHDR hdr; /* Header */
95 int nsegs; /* Number of allocated segments */
96 int exsegs; /* Number of extra allocated
98 u_int32_t /* Hash function */
99 (*hash)__P((const void *, size_t));
100 int flags; /* Flag values */
101 int fp; /* File pointer */
102 char *tmp_buf; /* Temporary Buffer for BIG data */
103 char *tmp_key; /* Temporary Buffer for BIG keys */
104 BUFHEAD *cpage; /* Current page */
105 int cbucket; /* Current bucket */
106 int cndx; /* Index of next item on cpage */
107 int error; /* Error Number -- for DBM
109 int new_file; /* Indicates if fd is backing store
111 int save_file; /* Indicates whether we need to flush
114 u_int32_t *mapp[NCACHED]; /* Pointers to page maps */
115 int nmaps; /* Initial number of bitmaps */
116 int nbufs; /* Number of buffers left to
118 BUFHEAD bufhead; /* Header of buffer lru list */
119 SEGMENT *dir; /* Hash Bucket directory */
125 #define MAX_BSIZE 65536 /* 2^16 */
126 #define MIN_BUFFERS 6
127 #define MINHDRSIZE 512
128 #define DEF_BUFSIZE 65536 /* 64 K */
129 #define DEF_BUCKET_SIZE 4096
130 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */
131 #define DEF_SEGSIZE 256
132 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */
133 #define DEF_DIRSIZE 256
134 #define DEF_FFACTOR 65536
135 #define MIN_FFACTOR 4
137 #define CHARKEY "%$sniglet^&"
138 #define NUMKEY 1038583
140 #define INT_TO_BYTE 2
141 #define INT_BYTE_SHIFT 5
142 #define ALL_SET ((u_int32_t)0xFFFFFFFF)
145 #define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
146 #define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1)
147 #define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1))
148 #define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2)
149 #define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2))
151 #define BITS_PER_MAP 32
153 /* Given the address of the beginning of a big map, clear/set the nth bit */
154 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
155 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
156 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
158 /* Overflow management */
160 * Overflow page numbers are allocated per split point. At each doubling of
161 * the table, we can allocate extra pages. So, an overflow page number has
162 * the top 5 bits indicate which split point and the lower 11 bits indicate
163 * which page at that split point is indicated (pages within split points are
164 * numberered starting with 1).
167 #define SPLITSHIFT 11
168 #define SPLITMASK 0x7FF
169 #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT)
170 #define OPAGENUM(N) ((N) & SPLITMASK)
171 #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
173 #define BUCKET_TO_PAGE(B) \
174 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0)
175 #define OADDR_TO_PAGE(B) \
176 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
179 * page.h contains a detailed description of the page format.
181 * Normally, keys and data are accessed from offset tables in the top of
182 * each page which point to the beginning of the key and data. There are
183 * four flag values which may be stored in these offset tables which indicate
187 * OVFLPAGE Rather than a key data pair, this pair contains
188 * the address of an overflow page. The format of
190 * OVERFLOW_PAGE_NUMBER OVFLPAGE
192 * PARTIAL_KEY This must be the first key/data pair on a page
193 * and implies that page contains only a partial key.
194 * That is, the key is too big to fit on a single page
195 * so it starts on this page and continues on the next.
196 * The format of the page is:
197 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
199 * KEY_OFF -- offset of the beginning of the key
201 * OVFL_PAGENO - page number of the next overflow page
204 * FULL_KEY This must be the first key/data pair on the page. It
205 * is used in two cases.
208 * There is a complete key on the page but no data
209 * (because it wouldn't fit). The next page contains
213 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
215 * KEY_OFF -- offset of the beginning of the key
217 * OVFL_PAGENO - page number of the next overflow page
221 * This page contains no key, but part of a large
222 * data field, which is continued on the next page.
225 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
227 * KEY_OFF -- offset of the beginning of the data on
230 * OVFL_PAGENO - page number of the next overflow page
234 * This must be the first key/data pair on the page.
235 * There are two cases:
238 * This page contains a key and the beginning of the
239 * data field, but the data field is continued on the
243 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
245 * KEY_OFF -- offset of the beginning of the key
247 * OVFL_PAGENO - page number of the next overflow page
248 * DATA_OFF -- offset of the beginning of the data
251 * This page contains the last page of a big data pair.
252 * There is no key, only the tail end of the data
256 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
258 * DATA_OFF -- offset of the beginning of the data on
261 * OVFL_PAGENO - page number of the next overflow page
264 * OVFL_PAGENO and OVFLPAGE are optional (they are
265 * not present if there is no next page).
269 #define PARTIAL_KEY 1
271 #define FULL_KEY_DATA 3
274 /* Short hands for accessing structure */
275 #define BSIZE hdr.bsize
276 #define BSHIFT hdr.bshift
277 #define DSIZE hdr.dsize
278 #define SGSIZE hdr.ssize
279 #define SSHIFT hdr.sshift
280 #define LORDER hdr.lorder
281 #define OVFL_POINT hdr.ovfl_point
282 #define LAST_FREED hdr.last_freed
283 #define MAX_BUCKET hdr.max_bucket
284 #define FFACTOR hdr.ffactor
285 #define HIGH_MASK hdr.high_mask
286 #define LOW_MASK hdr.low_mask
287 #define NKEYS hdr.nkeys
288 #define HDRPAGES hdr.hdrpages
289 #define SPARES hdr.spares
290 #define BITMAPS hdr.bitmaps
291 #define VERSION hdr.version
292 #define MAGIC hdr.magic
293 #define NEXT_FREE hdr.next_free
294 #define H_CHARKEY hdr.h_charkey