1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Margo Seltzer. 7 * 8 * %sccs.include.redist.c% 9 * 10 * @(#)hash.h 5.6 (Berkeley) 09/08/91 11 */ 12 13 /* Operations */ 14 typedef enum { 15 HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT 16 } ACTION; 17 18 /* Buffer Management structures */ 19 typedef struct _bufhead BUFHEAD; 20 21 struct _bufhead { 22 BUFHEAD *prev; /* LRU links */ 23 BUFHEAD *next; /* LRU links */ 24 BUFHEAD *ovfl; /* Overflow page buffer header */ 25 u_int addr; /* Address of this page */ 26 char *page; /* Actual page data */ 27 char flags; 28 #define BUF_MOD 0x0001 29 #define BUF_DISK 0x0002 30 #define BUF_BUCKET 0x0004 31 #define BUF_PIN 0x0008 32 }; 33 34 #define IS_BUCKET(X) ((X) & BUF_BUCKET) 35 36 typedef BUFHEAD **SEGMENT; 37 38 /* Hash Table Information */ 39 typedef struct hashhdr { /* Disk resident portion */ 40 int magic; /* Magic NO for hash tables */ 41 int version; /* Version ID */ 42 long lorder; /* Byte Order */ 43 int bsize; /* Bucket/Page Size */ 44 int bshift; /* Bucket shift */ 45 int dsize; /* Directory Size */ 46 int ssize; /* Segment Size */ 47 int sshift; /* Segment shift */ 48 int ovfl_point; /* Where overflow pages are being allocated */ 49 int last_freed; /* Last overflow page freed */ 50 int max_bucket; /* ID of Maximum bucket in use */ 51 int high_mask; /* Mask to modulo into entire table */ 52 int low_mask; /* Mask to modulo into lower half of table */ 53 int ffactor; /* Fill factor */ 54 int nkeys; /* Number of keys in hash table */ 55 int hdrpages; /* Size of table header */ 56 int h_charkey; /* value of hash(CHARKEY) */ 57 #define NCACHED 32 /* number of bit maps and spare points */ 58 int spares[NCACHED];/* spare pages for overflow */ 59 u_short bitmaps[NCACHED]; /* address of overflow page bitmaps */ 60 } HASHHDR; 61 62 typedef struct htab { /* Memory resident data structure */ 63 HASHHDR hdr; /* Header */ 64 int nsegs; /* Number of allocated segments */ 65 int exsegs; /* Number of extra allocated segments */ 66 int (*hash) (); /* Hash Function */ 67 int flags; /* Flag values */ 68 int fp; /* File pointer */ 69 char *tmp_buf; /* Temporary Buffer for BIG data */ 70 char *tmp_key; /* Temporary Buffer for BIG keys */ 71 BUFHEAD *cpage; /* Current page */ 72 int cbucket; /* Current bucket */ 73 int cndx; /* Index of next item on cpage */ 74 int errno; /* Error Number -- for DBM compatability */ 75 int new_file; /* Indicates if fd is backing store or no */ 76 int save_file; /* Indicates whether we need to flush file at 77 * exit */ 78 u_long *mapp[NCACHED]; /* Pointers to page maps */ 79 int nmaps; /* Initial number of bitmaps */ 80 int nbufs; /* Number of buffers left to allocate */ 81 BUFHEAD bufhead; /* Header of buffer lru list */ 82 SEGMENT *dir; /* Hash Bucket directory */ 83 } HTAB; 84 85 /* 86 * Constants 87 */ 88 #define MAX_BSIZE 65536 /* 2^16 */ 89 #define MIN_BUFFERS 6 90 #define MINHDRSIZE 512 91 #define DEF_BUFSIZE 65536 /* 64 K */ 92 #define DEF_BUCKET_SIZE 256 93 #define DEF_BUCKET_SHIFT 8 /* log2(BUCKET) */ 94 #define DEF_SEGSIZE 256 95 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ 96 #define DEF_DIRSIZE 256 97 #define DEF_FFACTOR 5 98 #define SPLTMAX 8 99 #define CHARKEY "%$sniglet^&" 100 #define NUMKEY 1038583 101 #define BYTE_SHIFT 3 102 #define INT_TO_BYTE 2 103 #define INT_BYTE_SHIFT 5 104 #define ALL_SET ((u_int)0xFFFFFFFF) 105 #define ALL_CLEAR 0 106 107 #define PTROF(X) ((BUFHEAD *)((u_int)(X)&~0x3)) 108 #define ISMOD(X) ((u_int)(X)&0x1) 109 #define DOMOD(X) ((X) = (char *)((u_int)(X)|0x1)) 110 #define ISDISK(X) ((u_int)(X)&0x2) 111 #define DODISK(X) ((X) = (char *)((u_int)(X)|0x2)) 112 113 #define BITS_PER_MAP 32 114 115 /* Given the address of the beginning of a big map, clear/set the nth bit */ 116 #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) 117 #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) 118 #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) 119 120 /* Overflow management */ 121 /* 122 * Overflow page numbers are allocated per split point. At each doubling of 123 * the table, we can allocate extra pages. So, an overflow page number has 124 * the top 5 bits indicate which split point and the lower 11 bits indicate 125 * which page at that split point is indicated (pages within split points are 126 * numberered starting with 1). 127 */ 128 129 #define SPLITSHIFT 11 130 #define SPLITMASK 0x7FF 131 #define SPLITNUM(N) (((u_int)(N)) >> SPLITSHIFT) 132 #define OPAGENUM(N) ((N) & SPLITMASK) 133 #define OADDR_OF(S,O) ((u_int)((u_int)(S) << SPLITSHIFT) + (O)) 134 135 #define BUCKET_TO_PAGE(B) \ 136 (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) 137 #define OADDR_TO_PAGE(B) \ 138 BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); 139 140 /* 141 * page.h contains a detailed description of the page format. 142 * 143 * Normally, keys and data are accessed from offset tables in the top of 144 * each page which point to the beginning of the key and data. There are 145 * four flag values which may be stored in these offset tables which indicate 146 * the following: 147 * 148 * 149 * OVFLPAGE Rather than a key data pair, this pair contains 150 * the address of an overflow page. The format of 151 * the pair is: 152 * OVERFLOW_PAGE_NUMBER OVFLPAGE 153 * 154 * PARTIAL_KEY This must be the first key/data pair on a page 155 * and implies that page contains only a partial key. 156 * That is, the key is too big to fit on a single page 157 * so it starts on this page and continues on the next. 158 * The format of the page is: 159 * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE 160 * 161 * KEY_OFF -- offset of the beginning of the key 162 * PARTIAL_KEY -- 1 163 * OVFL_PAGENO - page number of the next overflow page 164 * OVFLPAGE -- 0 165 * 166 * FULL_KEY This must be the first key/data pair on the page. It 167 * is used in two cases. 168 * 169 * Case 1: 170 * There is a complete key on the page but no data 171 * (because it wouldn't fit). The next page contains 172 * the data. 173 * 174 * Page format it: 175 * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 176 * 177 * KEY_OFF -- offset of the beginning of the key 178 * FULL_KEY -- 2 179 * OVFL_PAGENO - page number of the next overflow page 180 * OVFLPAGE -- 0 181 * 182 * Case 2: 183 * This page contains no key, but part of a large 184 * data field, which is continued on the next page. 185 * 186 * Page format it: 187 * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE 188 * 189 * KEY_OFF -- offset of the beginning of the data on 190 * this page 191 * FULL_KEY -- 2 192 * OVFL_PAGENO - page number of the next overflow page 193 * OVFLPAGE -- 0 194 * 195 * FULL_KEY_DATA 196 * This must be the first key/data pair on the page. 197 * There are two cases: 198 * 199 * Case 1: 200 * This page contains a key and the beginning of the 201 * data field, but the data field is continued on the 202 * next page. 203 * 204 * Page format is: 205 * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF 206 * 207 * KEY_OFF -- offset of the beginning of the key 208 * FULL_KEY_DATA -- 3 209 * OVFL_PAGENO - page number of the next overflow page 210 * DATA_OFF -- offset of the beginning of the data 211 * 212 * Case 2: 213 * This page contains the last page of a big data pair. 214 * There is no key, only the tail end of the data 215 * on this page. 216 * 217 * Page format is: 218 * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> 219 * 220 * DATA_OFF -- offset of the beginning of the data on 221 * this page 222 * FULL_KEY_DATA -- 3 223 * OVFL_PAGENO - page number of the next overflow page 224 * OVFLPAGE -- 0 225 * 226 * OVFL_PAGENO and OVFLPAGE are optional (they are 227 * not present if there is no next page). 228 */ 229 230 #define OVFLPAGE 0 231 #define PARTIAL_KEY 1 232 #define FULL_KEY 2 233 #define FULL_KEY_DATA 3 234 #define REAL_KEY 4 235 236 /* Short hands for accessing structure */ 237 #define BSIZE hdr.bsize 238 #define BSHIFT hdr.bshift 239 #define DSIZE hdr.dsize 240 #define SGSIZE hdr.ssize 241 #define SSHIFT hdr.sshift 242 #define LORDER hdr.lorder 243 #define OVFL_POINT hdr.ovfl_point 244 #define LAST_FREED hdr.last_freed 245 #define MAX_BUCKET hdr.max_bucket 246 #define FFACTOR hdr.ffactor 247 #define HIGH_MASK hdr.high_mask 248 #define LOW_MASK hdr.low_mask 249 #define NKEYS hdr.nkeys 250 #define HDRPAGES hdr.hdrpages 251 #define SPARES hdr.spares 252 #define BITMAPS hdr.bitmaps 253 #define VERSION hdr.version 254 #define MAGIC hdr.magic 255 #define NEXT_FREE hdr.next_free 256 #define H_CHARKEY hdr.h_charkey 257