1 /*- 2 * Copyright (c) 1990, 1993 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 8.2 (Berkeley) 2/21/94 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_int 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 long 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 allocated */ 75 int last_freed; /* Last overflow page freed */ 76 int max_bucket; /* ID of Maximum bucket in use */ 77 int high_mask; /* Mask to modulo into entire table */ 78 int low_mask; /* Mask to modulo into lower half of table */ 79 int ffactor; /* Fill factor */ 80 int nkeys; /* Number of keys in hash table */ 81 int hdrpages; /* Size of table header */ 82 int h_charkey; /* value of hash(CHARKEY) */ 83 #define NCACHED 32 /* number of bit maps and spare points */ 84 int spares[NCACHED];/* spare pages for overflow */ 85 u_short bitmaps[NCACHED]; /* address of overflow page 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 segments */ 92 u_int32_t /* Hash function */ 93 (*hash)__P((const void *, size_t)); 94 int flags; /* Flag values */ 95 int fp; /* File pointer */ 96 char *tmp_buf; /* Temporary Buffer for BIG data */ 97 char *tmp_key; /* Temporary Buffer for BIG keys */ 98 BUFHEAD *cpage; /* Current page */ 99 int cbucket; /* Current bucket */ 100 int cndx; /* Index of next item on cpage */ 101 int errno; /* Error Number -- for DBM compatability */ 102 int new_file; /* Indicates if fd is backing store or no */ 103 int save_file; /* Indicates whether we need to flush file at 104 * exit */ 105 u_long *mapp[NCACHED]; /* Pointers to page maps */ 106 int nmaps; /* Initial number of bitmaps */ 107 int nbufs; /* Number of buffers left to allocate */ 108 BUFHEAD bufhead; /* Header of buffer lru list */ 109 SEGMENT *dir; /* Hash Bucket directory */ 110 } HTAB; 111 112 /* 113 * Constants 114 */ 115 #define MAX_BSIZE 65536 /* 2^16 */ 116 #define MIN_BUFFERS 6 117 #define MINHDRSIZE 512 118 #define DEF_BUFSIZE 65536 /* 64 K */ 119 #define DEF_BUCKET_SIZE 4096 120 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */ 121 #define DEF_SEGSIZE 256 122 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ 123 #define DEF_DIRSIZE 256 124 #define DEF_FFACTOR 65536 125 #define MIN_FFACTOR 4 126 #define SPLTMAX 8 127 #define CHARKEY "%$sniglet^&" 128 #define NUMKEY 1038583 129 #define BYTE_SHIFT 3 130 #define INT_TO_BYTE 2 131 #define INT_BYTE_SHIFT 5 132 #define ALL_SET ((u_int)0xFFFFFFFF) 133 #define ALL_CLEAR 0 134 135 #define PTROF(X) ((BUFHEAD *)((u_int)(X)&~0x3)) 136 #define ISMOD(X) ((u_int)(X)&0x1) 137 #define DOMOD(X) ((X) = (char *)((u_int)(X)|0x1)) 138 #define ISDISK(X) ((u_int)(X)&0x2) 139 #define DODISK(X) ((X) = (char *)((u_int)(X)|0x2)) 140 141 #define BITS_PER_MAP 32 142 143 /* Given the address of the beginning of a big map, clear/set the nth bit */ 144 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) 145 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) 146 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) 147 148 /* Overflow management */ 149 /* 150 * Overflow page numbers are allocated per split point. At each doubling of 151 * the table, we can allocate extra pages. So, an overflow page number has 152 * the top 5 bits indicate which split point and the lower 11 bits indicate 153 * which page at that split point is indicated (pages within split points are 154 * numberered starting with 1). 155 */ 156 157 #define SPLITSHIFT 11 158 #define SPLITMASK 0x7FF 159 #define SPLITNUM(N) (((u_int)(N)) >> SPLITSHIFT) 160 #define OPAGENUM(N) ((N) & SPLITMASK) 161 #define OADDR_OF(S,O) ((u_int)((u_int)(S) << SPLITSHIFT) + (O)) 162 163 #define BUCKET_TO_PAGE(B) \ 164 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) 165 #define OADDR_TO_PAGE(B) \ 166 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); 167 168 /* 169 * page.h contains a detailed description of the page format. 170 * 171 * Normally, keys and data are accessed from offset tables in the top of 172 * each page which point to the beginning of the key and data. There are 173 * four flag values which may be stored in these offset tables which indicate 174 * the following: 175 * 176 * 177 * OVFLPAGE Rather than a key data pair, this pair contains 178 * the address of an overflow page. The format of 179 * the pair is: 180 * OVERFLOW_PAGE_NUMBER OVFLPAGE 181 * 182 * PARTIAL_KEY This must be the first key/data pair on a page 183 * and implies that page contains only a partial key. 184 * That is, the key is too big to fit on a single page 185 * so it starts on this page and continues on the next. 186 * The format of the page is: 187 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE 188 * 189 * KEY_OFF -- offset of the beginning of the key 190 * PARTIAL_KEY -- 1 191 * OVFL_PAGENO - page number of the next overflow page 192 * OVFLPAGE -- 0 193 * 194 * FULL_KEY This must be the first key/data pair on the page. It 195 * is used in two cases. 196 * 197 * Case 1: 198 * There is a complete key on the page but no data 199 * (because it wouldn't fit). The next page contains 200 * the data. 201 * 202 * Page format it: 203 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 204 * 205 * KEY_OFF -- offset of the beginning of the key 206 * FULL_KEY -- 2 207 * OVFL_PAGENO - page number of the next overflow page 208 * OVFLPAGE -- 0 209 * 210 * Case 2: 211 * This page contains no key, but part of a large 212 * data field, which is continued on the next page. 213 * 214 * Page format it: 215 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 216 * 217 * KEY_OFF -- offset of the beginning of the data on 218 * this page 219 * FULL_KEY -- 2 220 * OVFL_PAGENO - page number of the next overflow page 221 * OVFLPAGE -- 0 222 * 223 * FULL_KEY_DATA 224 * This must be the first key/data pair on the page. 225 * There are two cases: 226 * 227 * Case 1: 228 * This page contains a key and the beginning of the 229 * data field, but the data field is continued on the 230 * next page. 231 * 232 * Page format is: 233 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 234 * 235 * KEY_OFF -- offset of the beginning of the key 236 * FULL_KEY_DATA -- 3 237 * OVFL_PAGENO - page number of the next overflow page 238 * DATA_OFF -- offset of the beginning of the data 239 * 240 * Case 2: 241 * This page contains the last page of a big data pair. 242 * There is no key, only the tail end of the data 243 * on this page. 244 * 245 * Page format is: 246 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 247 * 248 * DATA_OFF -- offset of the beginning of the data on 249 * this page 250 * FULL_KEY_DATA -- 3 251 * OVFL_PAGENO - page number of the next overflow page 252 * OVFLPAGE -- 0 253 * 254 * OVFL_PAGENO and OVFLPAGE are optional (they are 255 * not present if there is no next page). 256 */ 257 258 #define OVFLPAGE 0 259 #define PARTIAL_KEY 1 260 #define FULL_KEY 2 261 #define FULL_KEY_DATA 3 262 #define REAL_KEY 4 263 264 /* Short hands for accessing structure */ 265 #define BSIZE hdr.bsize 266 #define BSHIFT hdr.bshift 267 #define DSIZE hdr.dsize 268 #define SGSIZE hdr.ssize 269 #define SSHIFT hdr.sshift 270 #define LORDER hdr.lorder 271 #define OVFL_POINT hdr.ovfl_point 272 #define LAST_FREED hdr.last_freed 273 #define MAX_BUCKET hdr.max_bucket 274 #define FFACTOR hdr.ffactor 275 #define HIGH_MASK hdr.high_mask 276 #define LOW_MASK hdr.low_mask 277 #define NKEYS hdr.nkeys 278 #define HDRPAGES hdr.hdrpages 279 #define SPARES hdr.spares 280 #define BITMAPS hdr.bitmaps 281 #define VERSION hdr.version 282 #define MAGIC hdr.magic 283 #define NEXT_FREE hdr.next_free 284 #define H_CHARKEY hdr.h_charkey 285