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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)hash.h 8.3 (Berkeley) 5/31/94 33 * $FreeBSD$ 34 */ 35 36 /* Operations */ 37 typedef enum { 38 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 39 } ACTION; 40 41 /* Buffer Management structures */ 42 typedef struct _bufhead BUFHEAD; 43 44 struct _bufhead { 45 BUFHEAD *prev; /* LRU links */ 46 BUFHEAD *next; /* LRU links */ 47 BUFHEAD *ovfl; /* Overflow page buffer header */ 48 u_int32_t addr; /* Address of this page */ 49 char *page; /* Actual page data */ 50 char flags; 51 #define BUF_MOD 0x0001 52 #define BUF_DISK 0x0002 53 #define BUF_BUCKET 0x0004 54 #define BUF_PIN 0x0008 55 }; 56 57 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 58 59 typedef BUFHEAD **SEGMENT; 60 61 /* Hash Table Information */ 62 typedef struct hashhdr { /* Disk resident portion */ 63 int32_t magic; /* Magic NO for hash tables */ 64 int32_t version; /* Version ID */ 65 u_int32_t lorder; /* Byte Order */ 66 int32_t bsize; /* Bucket/Page Size */ 67 int32_t bshift; /* Bucket shift */ 68 int32_t dsize; /* Directory Size */ 69 int32_t ssize; /* Segment Size */ 70 int32_t sshift; /* Segment shift */ 71 int32_t ovfl_point; /* Where overflow pages are being 72 * allocated */ 73 int32_t last_freed; /* Last overflow page freed */ 74 u_int32_t max_bucket; /* ID of Maximum bucket in use */ 75 u_int32_t high_mask; /* Mask to modulo into entire table */ 76 u_int32_t low_mask; /* Mask to modulo into lower half of 77 * table */ 78 u_int32_t ffactor; /* Fill factor */ 79 int32_t nkeys; /* Number of keys in hash table */ 80 int32_t hdrpages; /* Size of table header */ 81 int32_t h_charkey; /* value of hash(CHARKEY) */ 82 #define NCACHED 32 /* number of bit maps and spare 83 * points */ 84 int32_t spares[NCACHED];/* spare pages for overflow */ 85 u_int16_t bitmaps[NCACHED]; /* address of overflow page 86 * bitmaps */ 87 } HASHHDR; 88 89 typedef struct htab { /* Memory resident data structure */ 90 HASHHDR hdr; /* Header */ 91 int nsegs; /* Number of allocated segments */ 92 int exsegs; /* Number of extra allocated 93 * segments */ 94 u_int32_t /* Hash function */ 95 (*hash)(const void *, size_t); 96 int flags; /* Flag values */ 97 int fp; /* File pointer */ 98 char *tmp_buf; /* Temporary Buffer for BIG data */ 99 char *tmp_key; /* Temporary Buffer for BIG keys */ 100 BUFHEAD *cpage; /* Current page */ 101 int cbucket; /* Current bucket */ 102 int cndx; /* Index of next item on cpage */ 103 int error; /* Error Number -- for DBM 104 * compatibility */ 105 int new_file; /* Indicates if fd is backing store 106 * or no */ 107 int save_file; /* Indicates whether we need to flush 108 * file at 109 * exit */ 110 u_int32_t *mapp[NCACHED]; /* Pointers to page maps */ 111 int nmaps; /* Initial number of bitmaps */ 112 int nbufs; /* Number of buffers left to 113 * allocate */ 114 BUFHEAD bufhead; /* Header of buffer lru list */ 115 SEGMENT *dir; /* Hash Bucket directory */ 116 } HTAB; 117 118 /* 119 * Constants 120 */ 121 #define MAX_BSIZE 32768 /* 2^15 but should be 65536 */ 122 #define MIN_BUFFERS 6 123 #define MINHDRSIZE 512 124 #define DEF_BUFSIZE 65536 /* 64 K */ 125 #define DEF_BUCKET_SIZE 4096 126 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */ 127 #define DEF_SEGSIZE 256 128 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ 129 #define DEF_DIRSIZE 256 130 #define DEF_FFACTOR 65536 131 #define MIN_FFACTOR 4 132 #define SPLTMAX 8 133 #define CHARKEY "%$sniglet^&" 134 #define NUMKEY 1038583 135 #define BYTE_SHIFT 3 136 #define INT_TO_BYTE 2 137 #define INT_BYTE_SHIFT 5 138 #define ALL_SET ((u_int32_t)0xFFFFFFFF) 139 #define ALL_CLEAR 0 140 141 #define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3)) 142 #define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1) 143 #define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1)) 144 #define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2) 145 #define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2)) 146 147 #define BITS_PER_MAP 32 148 149 /* Given the address of the beginning of a big map, clear/set the nth bit */ 150 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) 151 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) 152 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) 153 154 /* Overflow management */ 155 /* 156 * Overflow page numbers are allocated per split point. At each doubling of 157 * the table, we can allocate extra pages. So, an overflow page number has 158 * the top 5 bits indicate which split point and the lower 11 bits indicate 159 * which page at that split point is indicated (pages within split points are 160 * numberered starting with 1). 161 */ 162 163 #define SPLITSHIFT 11 164 #define SPLITMASK 0x7FF 165 #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT) 166 #define OPAGENUM(N) ((N) & SPLITMASK) 167 #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O)) 168 169 #define BUCKET_TO_PAGE(B) \ 170 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) 171 #define OADDR_TO_PAGE(B) \ 172 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); 173 174 /* 175 * page.h contains a detailed description of the page format. 176 * 177 * Normally, keys and data are accessed from offset tables in the top of 178 * each page which point to the beginning of the key and data. There are 179 * four flag values which may be stored in these offset tables which indicate 180 * the following: 181 * 182 * 183 * OVFLPAGE Rather than a key data pair, this pair contains 184 * the address of an overflow page. The format of 185 * the pair is: 186 * OVERFLOW_PAGE_NUMBER OVFLPAGE 187 * 188 * PARTIAL_KEY This must be the first key/data pair on a page 189 * and implies that page contains only a partial key. 190 * That is, the key is too big to fit on a single page 191 * so it starts on this page and continues on the next. 192 * The format of the page is: 193 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE 194 * 195 * KEY_OFF -- offset of the beginning of the key 196 * PARTIAL_KEY -- 1 197 * OVFL_PAGENO - page number of the next overflow page 198 * OVFLPAGE -- 0 199 * 200 * FULL_KEY This must be the first key/data pair on the page. It 201 * is used in two cases. 202 * 203 * Case 1: 204 * There is a complete key on the page but no data 205 * (because it wouldn't fit). The next page contains 206 * the data. 207 * 208 * Page format it: 209 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 210 * 211 * KEY_OFF -- offset of the beginning of the key 212 * FULL_KEY -- 2 213 * OVFL_PAGENO - page number of the next overflow page 214 * OVFLPAGE -- 0 215 * 216 * Case 2: 217 * This page contains no key, but part of a large 218 * data field, which is continued on the next page. 219 * 220 * Page format it: 221 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 222 * 223 * KEY_OFF -- offset of the beginning of the data on 224 * this page 225 * FULL_KEY -- 2 226 * OVFL_PAGENO - page number of the next overflow page 227 * OVFLPAGE -- 0 228 * 229 * FULL_KEY_DATA 230 * This must be the first key/data pair on the page. 231 * There are two cases: 232 * 233 * Case 1: 234 * This page contains a key and the beginning of the 235 * data field, but the data field is continued on the 236 * next page. 237 * 238 * Page format is: 239 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 240 * 241 * KEY_OFF -- offset of the beginning of the key 242 * FULL_KEY_DATA -- 3 243 * OVFL_PAGENO - page number of the next overflow page 244 * DATA_OFF -- offset of the beginning of the data 245 * 246 * Case 2: 247 * This page contains the last page of a big data pair. 248 * There is no key, only the tail end of the data 249 * on this page. 250 * 251 * Page format is: 252 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 253 * 254 * DATA_OFF -- offset of the beginning of the data on 255 * this page 256 * FULL_KEY_DATA -- 3 257 * OVFL_PAGENO - page number of the next overflow page 258 * OVFLPAGE -- 0 259 * 260 * OVFL_PAGENO and OVFLPAGE are optional (they are 261 * not present if there is no next page). 262 */ 263 264 #define OVFLPAGE 0 265 #define PARTIAL_KEY 1 266 #define FULL_KEY 2 267 #define FULL_KEY_DATA 3 268 #define REAL_KEY 4 269 270 /* Short hands for accessing structure */ 271 #define BSIZE hdr.bsize 272 #define BSHIFT hdr.bshift 273 #define DSIZE hdr.dsize 274 #define SGSIZE hdr.ssize 275 #define SSHIFT hdr.sshift 276 #define LORDER hdr.lorder 277 #define OVFL_POINT hdr.ovfl_point 278 #define LAST_FREED hdr.last_freed 279 #define MAX_BUCKET hdr.max_bucket 280 #define FFACTOR hdr.ffactor 281 #define HIGH_MASK hdr.high_mask 282 #define LOW_MASK hdr.low_mask 283 #define NKEYS hdr.nkeys 284 #define HDRPAGES hdr.hdrpages 285 #define SPARES hdr.spares 286 #define BITMAPS hdr.bitmaps 287 #define VERSION hdr.version 288 #define MAGIC hdr.magic 289 #define NEXT_FREE hdr.next_free 290 #define H_CHARKEY hdr.h_charkey 291