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 */ 38 39 /* Operations */ 40 typedef enum { 41 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 42 } ACTION; 43 44 /* Buffer Management structures */ 45 typedef struct _bufhead BUFHEAD; 46 47 struct _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 */ 53 char flags; 54 #define BUF_MOD 0x0001 55 #define BUF_DISK 0x0002 56 #define BUF_BUCKET 0x0004 57 #define BUF_PIN 0x0008 58 }; 59 60 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 61 62 typedef BUFHEAD **SEGMENT; 63 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 75 * allocated */ 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 80 * table */ 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 86 * points */ 87 int spares[NCACHED];/* spare pages for overflow */ 88 u_int16_t bitmaps[NCACHED]; /* address of overflow page 89 * bitmaps */ 90 } HASHHDR; 91 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 96 * segments */ 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 error; /* Error Number -- for DBM 107 * compatability */ 108 int new_file; /* Indicates if fd is backing store 109 * or no */ 110 int save_file; /* Indicates whether we need to flush 111 * file at 112 * exit */ 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 116 * allocate */ 117 BUFHEAD bufhead; /* Header of buffer lru list */ 118 SEGMENT *dir; /* Hash Bucket directory */ 119 } HTAB; 120 121 /* 122 * Constants 123 */ 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 4 135 #define SPLTMAX 8 136 #define CHARKEY "%$sniglet^&" 137 #define NUMKEY 1038583 138 #define BYTE_SHIFT 3 139 #define INT_TO_BYTE 2 140 #define INT_BYTE_SHIFT 5 141 #define ALL_SET ((u_int32_t)0xFFFFFFFF) 142 #define ALL_CLEAR 0 143 144 #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)) 149 150 #define BITS_PER_MAP 32 151 152 /* 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))) 156 157 /* Overflow management */ 158 /* 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). 164 */ 165 166 #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)) 171 172 #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)); 176 177 /* 178 * page.h contains a detailed description of the page format. 179 * 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 183 * the following: 184 * 185 * 186 * OVFLPAGE Rather than a key data pair, this pair contains 187 * the address of an overflow page. The format of 188 * the pair is: 189 * OVERFLOW_PAGE_NUMBER OVFLPAGE 190 * 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 197 * 198 * KEY_OFF -- offset of the beginning of the key 199 * PARTIAL_KEY -- 1 200 * OVFL_PAGENO - page number of the next overflow page 201 * OVFLPAGE -- 0 202 * 203 * FULL_KEY This must be the first key/data pair on the page. It 204 * is used in two cases. 205 * 206 * Case 1: 207 * There is a complete key on the page but no data 208 * (because it wouldn't fit). The next page contains 209 * the data. 210 * 211 * Page format it: 212 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 213 * 214 * KEY_OFF -- offset of the beginning of the key 215 * FULL_KEY -- 2 216 * OVFL_PAGENO - page number of the next overflow page 217 * OVFLPAGE -- 0 218 * 219 * Case 2: 220 * This page contains no key, but part of a large 221 * data field, which is continued on the next page. 222 * 223 * Page format it: 224 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 225 * 226 * KEY_OFF -- offset of the beginning of the data on 227 * this page 228 * FULL_KEY -- 2 229 * OVFL_PAGENO - page number of the next overflow page 230 * OVFLPAGE -- 0 231 * 232 * FULL_KEY_DATA 233 * This must be the first key/data pair on the page. 234 * There are two cases: 235 * 236 * Case 1: 237 * This page contains a key and the beginning of the 238 * data field, but the data field is continued on the 239 * next page. 240 * 241 * Page format is: 242 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 243 * 244 * KEY_OFF -- offset of the beginning of the key 245 * FULL_KEY_DATA -- 3 246 * OVFL_PAGENO - page number of the next overflow page 247 * DATA_OFF -- offset of the beginning of the data 248 * 249 * Case 2: 250 * This page contains the last page of a big data pair. 251 * There is no key, only the tail end of the data 252 * on this page. 253 * 254 * Page format is: 255 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 256 * 257 * DATA_OFF -- offset of the beginning of the data on 258 * this page 259 * FULL_KEY_DATA -- 3 260 * OVFL_PAGENO - page number of the next overflow page 261 * OVFLPAGE -- 0 262 * 263 * OVFL_PAGENO and OVFLPAGE are optional (they are 264 * not present if there is no next page). 265 */ 266 267 #define OVFLPAGE 0 268 #define PARTIAL_KEY 1 269 #define FULL_KEY 2 270 #define FULL_KEY_DATA 3 271 #define REAL_KEY 4 272 273 /* 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 294