1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 35 /* Operations */ 36 typedef enum { 37 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 38 } ACTION; 39 40 /* Buffer Management structures */ 41 typedef struct _bufhead BUFHEAD; 42 43 struct _bufhead { 44 BUFHEAD *prev; /* LRU links */ 45 BUFHEAD *next; /* LRU links */ 46 BUFHEAD *ovfl; /* Overflow page buffer header */ 47 u_int32_t addr; /* Address of this page */ 48 char *page; /* Actual page data */ 49 char flags; 50 #define BUF_MOD 0x0001 51 #define BUF_DISK 0x0002 52 #define BUF_BUCKET 0x0004 53 #define BUF_PIN 0x0008 54 }; 55 56 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 57 58 typedef BUFHEAD **SEGMENT; 59 60 /* Hash Table Information */ 61 typedef struct hashhdr { /* Disk resident portion */ 62 int32_t magic; /* Magic NO for hash tables */ 63 int32_t version; /* Version ID */ 64 u_int32_t lorder; /* Byte Order */ 65 int32_t bsize; /* Bucket/Page Size */ 66 int32_t bshift; /* Bucket shift */ 67 int32_t dsize; /* Directory Size */ 68 int32_t ssize; /* Segment Size */ 69 int32_t sshift; /* Segment shift */ 70 int32_t ovfl_point; /* Where overflow pages are being 71 * allocated */ 72 int32_t last_freed; /* Last overflow page freed */ 73 u_int32_t max_bucket; /* ID of Maximum bucket in use */ 74 u_int32_t high_mask; /* Mask to modulo into entire table */ 75 u_int32_t low_mask; /* Mask to modulo into lower half of 76 * table */ 77 u_int32_t ffactor; /* Fill factor */ 78 int32_t nkeys; /* Number of keys in hash table */ 79 int32_t hdrpages; /* Size of table header */ 80 int32_t h_charkey; /* value of hash(CHARKEY) */ 81 #define NCACHED 32 /* number of bit maps and spare 82 * points */ 83 int32_t spares[NCACHED];/* spare pages for overflow */ 84 u_int16_t bitmaps[NCACHED]; /* address of overflow page 85 * bitmaps */ 86 } HASHHDR; 87 88 typedef struct htab { /* Memory resident data structure */ 89 HASHHDR hdr; /* Header */ 90 int nsegs; /* Number of allocated segments */ 91 int exsegs; /* Number of extra allocated 92 * segments */ 93 u_int32_t /* Hash function */ 94 (*hash)(const void *, size_t); 95 int flags; /* Flag values */ 96 int fp; /* File pointer */ 97 char *tmp_buf; /* Temporary Buffer for BIG data */ 98 char *tmp_key; /* Temporary Buffer for BIG keys */ 99 BUFHEAD *cpage; /* Current page */ 100 int cbucket; /* Current bucket */ 101 int cndx; /* Index of next item on cpage */ 102 int error; /* Error Number -- for DBM 103 * compatibility */ 104 int new_file; /* Indicates if fd is backing store 105 * or no */ 106 int save_file; /* Indicates whether we need to flush 107 * file at 108 * exit */ 109 u_int32_t *mapp[NCACHED]; /* Pointers to page maps */ 110 int nmaps; /* Initial number of bitmaps */ 111 int nbufs; /* Number of buffers left to 112 * allocate */ 113 BUFHEAD bufhead; /* Header of buffer lru list */ 114 SEGMENT *dir; /* Hash Bucket directory */ 115 } HTAB; 116 117 /* 118 * Constants 119 */ 120 #define MAX_BSIZE 32768 /* 2^15 but should be 65536 */ 121 #define MIN_BUFFERS 6 122 #define MINHDRSIZE 512 123 #define DEF_BUFSIZE 65536 /* 64 K */ 124 #define DEF_BUCKET_SIZE 4096 125 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */ 126 #define DEF_SEGSIZE 256 127 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ 128 #define DEF_DIRSIZE 256 129 #define DEF_FFACTOR 65536 130 #define MIN_FFACTOR 4 131 #define SPLTMAX 8 132 #define CHARKEY "%$sniglet^&" 133 #define NUMKEY 1038583 134 #define BYTE_SHIFT 3 135 #define INT_TO_BYTE 2 136 #define INT_BYTE_SHIFT 5 137 #define ALL_SET ((u_int32_t)0xFFFFFFFF) 138 #define ALL_CLEAR 0 139 140 #define PTROF(X) ((BUFHEAD *)((intptr_t)(X)&~0x3)) 141 #define ISMOD(X) ((u_int32_t)(intptr_t)(X)&0x1) 142 #define DOMOD(X) ((X) = (char *)((intptr_t)(X)|0x1)) 143 #define ISDISK(X) ((u_int32_t)(intptr_t)(X)&0x2) 144 #define DODISK(X) ((X) = (char *)((intptr_t)(X)|0x2)) 145 146 #define BITS_PER_MAP 32 147 148 /* Given the address of the beginning of a big map, clear/set the nth bit */ 149 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) 150 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) 151 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) 152 153 /* Overflow management */ 154 /* 155 * Overflow page numbers are allocated per split point. At each doubling of 156 * the table, we can allocate extra pages. So, an overflow page number has 157 * the top 5 bits indicate which split point and the lower 11 bits indicate 158 * which page at that split point is indicated (pages within split points are 159 * numberered starting with 1). 160 */ 161 162 #define SPLITSHIFT 11 163 #define SPLITMASK 0x7FF 164 #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT) 165 #define OPAGENUM(N) ((N) & SPLITMASK) 166 #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O)) 167 168 #define BUCKET_TO_PAGE(B) \ 169 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) 170 #define OADDR_TO_PAGE(B) \ 171 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); 172 173 /* 174 * page.h contains a detailed description of the page format. 175 * 176 * Normally, keys and data are accessed from offset tables in the top of 177 * each page which point to the beginning of the key and data. There are 178 * four flag values which may be stored in these offset tables which indicate 179 * the following: 180 * 181 * 182 * OVFLPAGE Rather than a key data pair, this pair contains 183 * the address of an overflow page. The format of 184 * the pair is: 185 * OVERFLOW_PAGE_NUMBER OVFLPAGE 186 * 187 * PARTIAL_KEY This must be the first key/data pair on a page 188 * and implies that page contains only a partial key. 189 * That is, the key is too big to fit on a single page 190 * so it starts on this page and continues on the next. 191 * The format of the page is: 192 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE 193 * 194 * KEY_OFF -- offset of the beginning of the key 195 * PARTIAL_KEY -- 1 196 * OVFL_PAGENO - page number of the next overflow page 197 * OVFLPAGE -- 0 198 * 199 * FULL_KEY This must be the first key/data pair on the page. It 200 * is used in two cases. 201 * 202 * Case 1: 203 * There is a complete key on the page but no data 204 * (because it wouldn't fit). The next page contains 205 * the data. 206 * 207 * Page format it: 208 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 209 * 210 * KEY_OFF -- offset of the beginning of the key 211 * FULL_KEY -- 2 212 * OVFL_PAGENO - page number of the next overflow page 213 * OVFLPAGE -- 0 214 * 215 * Case 2: 216 * This page contains no key, but part of a large 217 * data field, which is continued on the next page. 218 * 219 * Page format it: 220 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 221 * 222 * KEY_OFF -- offset of the beginning of the data on 223 * this page 224 * FULL_KEY -- 2 225 * OVFL_PAGENO - page number of the next overflow page 226 * OVFLPAGE -- 0 227 * 228 * FULL_KEY_DATA 229 * This must be the first key/data pair on the page. 230 * There are two cases: 231 * 232 * Case 1: 233 * This page contains a key and the beginning of the 234 * data field, but the data field is continued on the 235 * next page. 236 * 237 * Page format is: 238 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 239 * 240 * KEY_OFF -- offset of the beginning of the key 241 * FULL_KEY_DATA -- 3 242 * OVFL_PAGENO - page number of the next overflow page 243 * DATA_OFF -- offset of the beginning of the data 244 * 245 * Case 2: 246 * This page contains the last page of a big data pair. 247 * There is no key, only the tail end of the data 248 * on this page. 249 * 250 * Page format is: 251 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 252 * 253 * DATA_OFF -- offset of the beginning of the data on 254 * this page 255 * FULL_KEY_DATA -- 3 256 * OVFL_PAGENO - page number of the next overflow page 257 * OVFLPAGE -- 0 258 * 259 * OVFL_PAGENO and OVFLPAGE are optional (they are 260 * not present if there is no next page). 261 */ 262 263 #define OVFLPAGE 0 264 #define PARTIAL_KEY 1 265 #define FULL_KEY 2 266 #define FULL_KEY_DATA 3 267 #define REAL_KEY 4 268 269 /* Short hands for accessing structure */ 270 #define BSIZE hdr.bsize 271 #define BSHIFT hdr.bshift 272 #define DSIZE hdr.dsize 273 #define SGSIZE hdr.ssize 274 #define SSHIFT hdr.sshift 275 #define LORDER hdr.lorder 276 #define OVFL_POINT hdr.ovfl_point 277 #define LAST_FREED hdr.last_freed 278 #define MAX_BUCKET hdr.max_bucket 279 #define FFACTOR hdr.ffactor 280 #define HIGH_MASK hdr.high_mask 281 #define LOW_MASK hdr.low_mask 282 #define NKEYS hdr.nkeys 283 #define HDRPAGES hdr.hdrpages 284 #define SPARES hdr.spares 285 #define BITMAPS hdr.bitmaps 286 #define VERSION hdr.version 287 #define MAGIC hdr.magic 288 #define NEXT_FREE hdr.next_free 289 #define H_CHARKEY hdr.h_charkey 290