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
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9 * modification, are permitted provided that the following conditions
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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
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29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * @(#)hash.h 8.3 (Berkeley) 5/31/94
41 HASH_GET
, HASH_PUT
, HASH_PUTNEW
, HASH_DELETE
, HASH_FIRST
, HASH_NEXT
44 /* Buffer Management structures */
45 typedef struct _bufhead BUFHEAD
;
48 BUFHEAD
*prev
; /* LRU links */
49 BUFHEAD
*next
; /* LRU links */
50 BUFHEAD
*ovfl
; /* Overflow page buffer header */
51 u_int32_t addr
; /* Address of this page */
52 char *page
; /* Actual page data */
54 #define BUF_MOD 0x0001
55 #define BUF_DISK 0x0002
56 #define BUF_BUCKET 0x0004
57 #define BUF_PIN 0x0008
60 #define IS_BUCKET(X) ((X) & BUF_BUCKET)
62 typedef BUFHEAD
**SEGMENT
;
64 /* Hash Table Information */
65 typedef struct hashhdr
{ /* Disk resident portion */
66 int magic
; /* Magic NO for hash tables */
67 int version
; /* Version ID */
68 u_int32_t lorder
; /* Byte Order */
69 int bsize
; /* Bucket/Page Size */
70 int bshift
; /* Bucket shift */
71 int dsize
; /* Directory Size */
72 int ssize
; /* Segment Size */
73 int sshift
; /* Segment shift */
74 int ovfl_point
; /* Where overflow pages are being
76 int last_freed
; /* Last overflow page freed */
77 int max_bucket
; /* ID of Maximum bucket in use */
78 int high_mask
; /* Mask to modulo into entire table */
79 int low_mask
; /* Mask to modulo into lower half of
81 int ffactor
; /* Fill factor */
82 int nkeys
; /* Number of keys in hash table */
83 int hdrpages
; /* Size of table header */
84 int h_charkey
; /* value of hash(CHARKEY) */
85 #define NCACHED 32 /* number of bit maps and spare
87 int spares
[NCACHED
];/* spare pages for overflow */
88 u_int16_t bitmaps
[NCACHED
]; /* address of overflow page
92 typedef struct htab
{ /* Memory resident data structure */
93 HASHHDR hdr
; /* Header */
94 int nsegs
; /* Number of allocated segments */
95 int exsegs
; /* Number of extra allocated
97 u_int32_t
/* Hash function */
98 (*hash
)__P((const void *, size_t));
99 int flags
; /* Flag values */
100 int fp
; /* File pointer */
101 char *tmp_buf
; /* Temporary Buffer for BIG data */
102 char *tmp_key
; /* Temporary Buffer for BIG keys */
103 BUFHEAD
*cpage
; /* Current page */
104 int cbucket
; /* Current bucket */
105 int cndx
; /* Index of next item on cpage */
106 int _errno
; /* Error Number -- for DBM
108 int new_file
; /* Indicates if fd is backing store
110 int save_file
; /* Indicates whether we need to flush
113 u_int32_t
*mapp
[NCACHED
]; /* Pointers to page maps */
114 int nmaps
; /* Initial number of bitmaps */
115 int nbufs
; /* Number of buffers left to
117 BUFHEAD bufhead
; /* Header of buffer lru list */
118 SEGMENT
*dir
; /* Hash Bucket directory */
124 #define MAX_BSIZE 65536 /* 2^16 */
125 #define MIN_BUFFERS 6
126 #define MINHDRSIZE 512
127 #define DEF_BUFSIZE 65536 /* 64 K */
128 #define DEF_BUCKET_SIZE 4096
129 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */
130 #define DEF_SEGSIZE 256
131 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */
132 #define DEF_DIRSIZE 256
133 #define DEF_FFACTOR 65536
134 #define MIN_FFACTOR 4
136 #define CHARKEY "%$sniglet^&"
137 #define NUMKEY 1038583
139 #define INT_TO_BYTE 2
140 #define INT_BYTE_SHIFT 5
141 #define ALL_SET ((u_int32_t)0xFFFFFFFF)
144 #define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
145 #define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1)
146 #define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1))
147 #define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2)
148 #define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2))
150 #define BITS_PER_MAP 32
152 /* Given the address of the beginning of a big map, clear/set the nth bit */
153 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
154 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
155 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
157 /* Overflow management */
159 * Overflow page numbers are allocated per split point. At each doubling of
160 * the table, we can allocate extra pages. So, an overflow page number has
161 * the top 5 bits indicate which split point and the lower 11 bits indicate
162 * which page at that split point is indicated (pages within split points are
163 * numberered starting with 1).
166 #define SPLITSHIFT 11
167 #define SPLITMASK 0x7FF
168 #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT)
169 #define OPAGENUM(N) ((N) & SPLITMASK)
170 #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
172 #define BUCKET_TO_PAGE(B) \
173 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0)
174 #define OADDR_TO_PAGE(B) \
175 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
178 * page.h contains a detailed description of the page format.
180 * Normally, keys and data are accessed from offset tables in the top of
181 * each page which point to the beginning of the key and data. There are
182 * four flag values which may be stored in these offset tables which indicate
186 * OVFLPAGE Rather than a key data pair, this pair contains
187 * the address of an overflow page. The format of
189 * OVERFLOW_PAGE_NUMBER OVFLPAGE
191 * PARTIAL_KEY This must be the first key/data pair on a page
192 * and implies that page contains only a partial key.
193 * That is, the key is too big to fit on a single page
194 * so it starts on this page and continues on the next.
195 * The format of the page is:
196 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
198 * KEY_OFF -- offset of the beginning of the key
200 * OVFL_PAGENO - page number of the next overflow page
203 * FULL_KEY This must be the first key/data pair on the page. It
204 * is used in two cases.
207 * There is a complete key on the page but no data
208 * (because it wouldn't fit). The next page contains
212 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
214 * KEY_OFF -- offset of the beginning of the key
216 * OVFL_PAGENO - page number of the next overflow page
220 * This page contains no key, but part of a large
221 * data field, which is continued on the next page.
224 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
226 * KEY_OFF -- offset of the beginning of the data on
229 * OVFL_PAGENO - page number of the next overflow page
233 * This must be the first key/data pair on the page.
234 * There are two cases:
237 * This page contains a key and the beginning of the
238 * data field, but the data field is continued on the
242 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
244 * KEY_OFF -- offset of the beginning of the key
246 * OVFL_PAGENO - page number of the next overflow page
247 * DATA_OFF -- offset of the beginning of the data
250 * This page contains the last page of a big data pair.
251 * There is no key, only the tail end of the data
255 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
257 * DATA_OFF -- offset of the beginning of the data on
260 * OVFL_PAGENO - page number of the next overflow page
263 * OVFL_PAGENO and OVFLPAGE are optional (they are
264 * not present if there is no next page).
268 #define PARTIAL_KEY 1
270 #define FULL_KEY_DATA 3
273 /* Short hands for accessing structure */
274 #define BSIZE hdr.bsize
275 #define BSHIFT hdr.bshift
276 #define DSIZE hdr.dsize
277 #define SGSIZE hdr.ssize
278 #define SSHIFT hdr.sshift
279 #define LORDER hdr.lorder
280 #define OVFL_POINT hdr.ovfl_point
281 #define LAST_FREED hdr.last_freed
282 #define MAX_BUCKET hdr.max_bucket
283 #define FFACTOR hdr.ffactor
284 #define HIGH_MASK hdr.high_mask
285 #define LOW_MASK hdr.low_mask
286 #define NKEYS hdr.nkeys
287 #define HDRPAGES hdr.hdrpages
288 #define SPARES hdr.spares
289 #define BITMAPS hdr.bitmaps
290 #define VERSION hdr.version
291 #define MAGIC hdr.magic
292 #define NEXT_FREE hdr.next_free
293 #define H_CHARKEY hdr.h_charkey