1 /*- 2 * Copyright (c) 1990, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Margo Seltzer. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 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. 23 * 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 34 * SUCH DAMAGE. 35 * 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 $ 38 */ 39 40 /* Operations */ 41 typedef enum { 42 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 43 } ACTION; 44 45 /* Buffer Management structures */ 46 typedef struct _bufhead BUFHEAD; 47 48 struct _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 */ 54 char flags; 55 #define BUF_MOD 0x0001 56 #define BUF_DISK 0x0002 57 #define BUF_BUCKET 0x0004 58 #define BUF_PIN 0x0008 59 }; 60 61 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 62 63 typedef BUFHEAD **SEGMENT; 64 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 76 * allocated */ 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 81 * table */ 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 87 * points */ 88 int spares[NCACHED];/* spare pages for overflow */ 89 u_int16_t bitmaps[NCACHED]; /* address of overflow page 90 * bitmaps */ 91 } HASHHDR; 92 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 97 * segments */ 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 108 * compatibility */ 109 int new_file; /* Indicates if fd is backing store 110 * or no */ 111 int save_file; /* Indicates whether we need to flush 112 * file at 113 * exit */ 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 117 * allocate */ 118 BUFHEAD bufhead; /* Header of buffer lru list */ 119 SEGMENT *dir; /* Hash Bucket directory */ 120 } HTAB; 121 122 /* 123 * Constants 124 */ 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 4 136 #define SPLTMAX 8 137 #define CHARKEY "%$sniglet^&" 138 #define NUMKEY 1038583 139 #define BYTE_SHIFT 3 140 #define INT_TO_BYTE 2 141 #define INT_BYTE_SHIFT 5 142 #define ALL_SET ((u_int32_t)0xFFFFFFFF) 143 #define ALL_CLEAR 0 144 145 #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)) 150 151 #define BITS_PER_MAP 32 152 153 /* 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))) 157 158 /* Overflow management */ 159 /* 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). 165 */ 166 167 #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)) 172 173 #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)); 177 178 /* 179 * page.h contains a detailed description of the page format. 180 * 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 184 * the following: 185 * 186 * 187 * OVFLPAGE Rather than a key data pair, this pair contains 188 * the address of an overflow page. The format of 189 * the pair is: 190 * OVERFLOW_PAGE_NUMBER OVFLPAGE 191 * 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 198 * 199 * KEY_OFF -- offset of the beginning of the key 200 * PARTIAL_KEY -- 1 201 * OVFL_PAGENO - page number of the next overflow page 202 * OVFLPAGE -- 0 203 * 204 * FULL_KEY This must be the first key/data pair on the page. It 205 * is used in two cases. 206 * 207 * Case 1: 208 * There is a complete key on the page but no data 209 * (because it wouldn't fit). The next page contains 210 * the data. 211 * 212 * Page format it: 213 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 214 * 215 * KEY_OFF -- offset of the beginning of the key 216 * FULL_KEY -- 2 217 * OVFL_PAGENO - page number of the next overflow page 218 * OVFLPAGE -- 0 219 * 220 * Case 2: 221 * This page contains no key, but part of a large 222 * data field, which is continued on the next page. 223 * 224 * Page format it: 225 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 226 * 227 * KEY_OFF -- offset of the beginning of the data on 228 * this page 229 * FULL_KEY -- 2 230 * OVFL_PAGENO - page number of the next overflow page 231 * OVFLPAGE -- 0 232 * 233 * FULL_KEY_DATA 234 * This must be the first key/data pair on the page. 235 * There are two cases: 236 * 237 * Case 1: 238 * This page contains a key and the beginning of the 239 * data field, but the data field is continued on the 240 * next page. 241 * 242 * Page format is: 243 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 244 * 245 * KEY_OFF -- offset of the beginning of the key 246 * FULL_KEY_DATA -- 3 247 * OVFL_PAGENO - page number of the next overflow page 248 * DATA_OFF -- offset of the beginning of the data 249 * 250 * Case 2: 251 * This page contains the last page of a big data pair. 252 * There is no key, only the tail end of the data 253 * on this page. 254 * 255 * Page format is: 256 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 257 * 258 * DATA_OFF -- offset of the beginning of the data on 259 * this page 260 * FULL_KEY_DATA -- 3 261 * OVFL_PAGENO - page number of the next overflow page 262 * OVFLPAGE -- 0 263 * 264 * OVFL_PAGENO and OVFLPAGE are optional (they are 265 * not present if there is no next page). 266 */ 267 268 #define OVFLPAGE 0 269 #define PARTIAL_KEY 1 270 #define FULL_KEY 2 271 #define FULL_KEY_DATA 3 272 #define REAL_KEY 4 273 274 /* 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 295