1 /* $OpenBSD: hash.h,v 1.9 2004/06/21 23:13:22 marc Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Margo Seltzer. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)hash.h 8.3 (Berkeley) 5/31/94 35 */ 36 37 /* Operations */ 38 typedef enum { 39 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 40 } ACTION; 41 42 /* Buffer Management structures */ 43 typedef struct _bufhead BUFHEAD; 44 45 struct _bufhead { 46 BUFHEAD *prev; /* LRU links */ 47 BUFHEAD *next; /* LRU links */ 48 BUFHEAD *ovfl; /* Overflow page buffer header */ 49 u_int32_t addr; /* Address of this page */ 50 char *page; /* Actual page data */ 51 char flags; 52 #define BUF_MOD 0x0001 53 #define BUF_DISK 0x0002 54 #define BUF_BUCKET 0x0004 55 #define BUF_PIN 0x0008 56 }; 57 58 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 59 60 typedef BUFHEAD **SEGMENT; 61 62 /* Hash Table Information */ 63 typedef struct hashhdr { /* Disk resident portion */ 64 int32_t magic; /* Magic NO for hash tables */ 65 int32_t version; /* Version ID */ 66 u_int32_t lorder; /* Byte Order */ 67 int32_t bsize; /* Bucket/Page Size */ 68 int32_t bshift; /* Bucket shift */ 69 int32_t dsize; /* Directory Size */ 70 int32_t ssize; /* Segment Size */ 71 int32_t sshift; /* Segment shift */ 72 int32_t ovfl_point; /* Where overflow pages are being 73 * allocated */ 74 int32_t last_freed; /* Last overflow page freed */ 75 int32_t max_bucket; /* ID of Maximum bucket in use */ 76 int32_t high_mask; /* Mask to modulo into entire table */ 77 int32_t low_mask; /* Mask to modulo into lower half of 78 * table */ 79 int32_t ffactor; /* Fill factor */ 80 int32_t nkeys; /* Number of keys in hash table */ 81 int32_t hdrpages; /* Size of table header */ 82 int32_t h_charkey; /* value of hash(CHARKEY) */ 83 #define NCACHED 32 /* number of bit maps and spare 84 * points */ 85 int32_t spares[NCACHED];/* spare pages for overflow */ 86 u_int16_t bitmaps[NCACHED]; /* address of overflow page 87 * bitmaps */ 88 } HASHHDR; 89 90 typedef struct htab { /* Memory resident data structure */ 91 HASHHDR hdr; /* Header */ 92 int nsegs; /* Number of allocated segments */ 93 int exsegs; /* Number of extra allocated 94 * segments */ 95 u_int32_t /* Hash function */ 96 (*hash)(const void *, size_t); 97 int flags; /* Flag values */ 98 int fp; /* File pointer */ 99 char *tmp_buf; /* Temporary Buffer for BIG data */ 100 char *tmp_key; /* Temporary Buffer for BIG keys */ 101 BUFHEAD *cpage; /* Current page */ 102 int cbucket; /* Current bucket */ 103 int cndx; /* Index of next item on cpage */ 104 int err; /* Error Number -- for DBM 105 * compatibility */ 106 int new_file; /* Indicates if fd is backing store 107 * or no */ 108 int save_file; /* Indicates whether we need to flush 109 * file at 110 * exit */ 111 u_int32_t *mapp[NCACHED]; /* Pointers to page maps */ 112 int nmaps; /* Initial number of bitmaps */ 113 int nbufs; /* Number of buffers left to 114 * allocate */ 115 BUFHEAD bufhead; /* Header of buffer lru list */ 116 SEGMENT *dir; /* Hash Bucket directory */ 117 } HTAB; 118 119 /* 120 * Constants 121 */ 122 #define MAX_BSIZE 65536 /* 2^16 */ 123 #define MIN_BUFFERS 6 124 #define MINHDRSIZE 512 125 #define DEF_BUFSIZE 65536 /* 64 K */ 126 #define DEF_BUCKET_SIZE 4096 127 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */ 128 #define DEF_SEGSIZE 256 129 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ 130 #define DEF_DIRSIZE 256 131 #define DEF_FFACTOR 65536 132 #define MIN_FFACTOR 4 133 #define SPLTMAX 8 134 #define CHARKEY "%$sniglet^&" 135 #define NUMKEY 1038583 136 #define BYTE_SHIFT 3 137 #define INT_TO_BYTE 2 138 #define INT_BYTE_SHIFT 5 139 #define ALL_SET ((u_int32_t)0xFFFFFFFF) 140 #define ALL_CLEAR 0 141 142 #define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3)) 143 #define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1) 144 #define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1)) 145 #define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2) 146 #define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2)) 147 148 #define BITS_PER_MAP 32 149 150 /* Given the address of the beginning of a big map, clear/set the nth bit */ 151 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) 152 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) 153 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) 154 155 /* Overflow management */ 156 /* 157 * Overflow page numbers are allocated per split point. At each doubling of 158 * the table, we can allocate extra pages. So, an overflow page number has 159 * the top 5 bits indicate which split point and the lower 11 bits indicate 160 * which page at that split point is indicated (pages within split points are 161 * numberered starting with 1). 162 */ 163 164 #define SPLITSHIFT 11 165 #define SPLITMASK 0x7FF 166 #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT) 167 #define OPAGENUM(N) ((N) & SPLITMASK) 168 #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O)) 169 170 #define BUCKET_TO_PAGE(B) \ 171 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) 172 #define OADDR_TO_PAGE(B) \ 173 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); 174 175 /* 176 * page.h contains a detailed description of the page format. 177 * 178 * Normally, keys and data are accessed from offset tables in the top of 179 * each page which point to the beginning of the key and data. There are 180 * four flag values which may be stored in these offset tables which indicate 181 * the following: 182 * 183 * 184 * OVFLPAGE Rather than a key data pair, this pair contains 185 * the address of an overflow page. The format of 186 * the pair is: 187 * OVERFLOW_PAGE_NUMBER OVFLPAGE 188 * 189 * PARTIAL_KEY This must be the first key/data pair on a page 190 * and implies that page contains only a partial key. 191 * That is, the key is too big to fit on a single page 192 * so it starts on this page and continues on the next. 193 * The format of the page is: 194 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE 195 * 196 * KEY_OFF -- offset of the beginning of the key 197 * PARTIAL_KEY -- 1 198 * OVFL_PAGENO - page number of the next overflow page 199 * OVFLPAGE -- 0 200 * 201 * FULL_KEY This must be the first key/data pair on the page. It 202 * is used in two cases. 203 * 204 * Case 1: 205 * There is a complete key on the page but no data 206 * (because it wouldn't fit). The next page contains 207 * the data. 208 * 209 * Page format it: 210 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 211 * 212 * KEY_OFF -- offset of the beginning of the key 213 * FULL_KEY -- 2 214 * OVFL_PAGENO - page number of the next overflow page 215 * OVFLPAGE -- 0 216 * 217 * Case 2: 218 * This page contains no key, but part of a large 219 * data field, which is continued on the next page. 220 * 221 * Page format it: 222 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 223 * 224 * KEY_OFF -- offset of the beginning of the data on 225 * this page 226 * FULL_KEY -- 2 227 * OVFL_PAGENO - page number of the next overflow page 228 * OVFLPAGE -- 0 229 * 230 * FULL_KEY_DATA 231 * This must be the first key/data pair on the page. 232 * There are two cases: 233 * 234 * Case 1: 235 * This page contains a key and the beginning of the 236 * data field, but the data field is continued on the 237 * next page. 238 * 239 * Page format is: 240 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 241 * 242 * KEY_OFF -- offset of the beginning of the key 243 * FULL_KEY_DATA -- 3 244 * OVFL_PAGENO - page number of the next overflow page 245 * DATA_OFF -- offset of the beginning of the data 246 * 247 * Case 2: 248 * This page contains the last page of a big data pair. 249 * There is no key, only the tail end of the data 250 * on this page. 251 * 252 * Page format is: 253 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 254 * 255 * DATA_OFF -- offset of the beginning of the data on 256 * this page 257 * FULL_KEY_DATA -- 3 258 * OVFL_PAGENO - page number of the next overflow page 259 * OVFLPAGE -- 0 260 * 261 * OVFL_PAGENO and OVFLPAGE are optional (they are 262 * not present if there is no next page). 263 */ 264 265 #define OVFLPAGE 0 266 #define PARTIAL_KEY 1 267 #define FULL_KEY 2 268 #define FULL_KEY_DATA 3 269 #define REAL_KEY 4 270 271 /* Short hands for accessing structure */ 272 #define BSIZE hdr.bsize 273 #define BSHIFT hdr.bshift 274 #define DSIZE hdr.dsize 275 #define SGSIZE hdr.ssize 276 #define SSHIFT hdr.sshift 277 #define LORDER hdr.lorder 278 #define OVFL_POINT hdr.ovfl_point 279 #define LAST_FREED hdr.last_freed 280 #define MAX_BUCKET hdr.max_bucket 281 #define FFACTOR hdr.ffactor 282 #define HIGH_MASK hdr.high_mask 283 #define LOW_MASK hdr.low_mask 284 #define NKEYS hdr.nkeys 285 #define HDRPAGES hdr.hdrpages 286 #define SPARES hdr.spares 287 #define BITMAPS hdr.bitmaps 288 #define VERSION hdr.version 289 #define MAGIC hdr.magic 290 #define NEXT_FREE hdr.next_free 291 #define H_CHARKEY hdr.h_charkey 292