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