1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Olson. 7 * 8 * %sccs.include.redist.c% 9 * 10 * @(#)btree.h 5.3 (Berkeley) 09/04/91 11 */ 12 13 #include <mpool.h> 14 15 #define DEFMAXKEYPAGE (0) /* Maximum keys per page */ 16 #define DEFMINKEYPAGE (2) /* Minimum keys per page */ 17 #define MINCACHE (5) /* Minimum cached pages */ 18 #define MINPSIZE (512) /* Minimum page size */ 19 20 /* 21 * Page 0 of a btree file contains a BTMETA structure. The rest of the first 22 * page is empty, so that all disk operations are page-aligned. This page is 23 * also used as an out-of-band page, i.e. page pointers that point to nowhere 24 * point to page 0. The m_nrecs field is used only the RECNO code. This is 25 * because the btree doesn't really need it and it requires that put or delete 26 * calls modify the meta data. 27 */ 28 #define P_INVALID 0 /* Invalid tree page number. */ 29 #define P_META 0 /* Tree meta-info page number. */ 30 #define P_ROOT 1 /* Tree root page number. */ 31 32 typedef struct BTMETA { 33 u_long m_magic; /* magic number */ 34 u_long m_version; /* version */ 35 u_long m_psize; /* page size */ 36 u_long m_free; /* page number of first free page */ 37 u_long m_nrecs; /* R: number of records */ 38 #define SAVEMETA (BTF_NODUPS | BTF_RECNO) 39 u_long m_flags; /* bt_flags & SAVEMETA */ 40 u_long m_lorder; /* byte order */ 41 } BTMETA; 42 43 /* 44 * There are five page layouts in the btree: btree internal pages, btree leaf 45 * pages, recno internal pages, recno leaf pages and overflow pages. Each type 46 * of page starts with a page header as typed by PAGE. 47 */ 48 typedef struct PAGE { 49 pgno_t pgno; /* this page's page number */ 50 pgno_t prevpg; /* left sibling */ 51 pgno_t nextpg; /* right sibling */ 52 53 #define P_BINTERNAL 0x01 /* btree internal page */ 54 #define P_BLEAF 0x02 /* leaf page */ 55 #define P_OVERFLOW 0x04 /* overflow page */ 56 #define P_RINTERNAL 0x08 /* recno internal page */ 57 #define P_RLEAF 0x10 /* leaf page */ 58 #define P_TYPE 0x1f /* type mask */ 59 60 #define P_PRESERVE 0x20 /* never delete this chain of pages */ 61 u_long flags; 62 63 index_t lower; /* lower bound of free space on page */ 64 index_t upper; /* upper bound of free space on page */ 65 index_t linp[1]; /* long-aligned VARIABLE LENGTH DATA */ 66 } PAGE; 67 68 /* First and next index. */ 69 #define BTDATAOFF (sizeof(PAGE) - sizeof(index_t)) 70 #define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(index_t)) 71 72 /* 73 * For pages other than overflow pages, there is an array of offsets into the 74 * rest of the page immediately following the page header. Each offset is to 75 * an item which is unique to the type of page. The h_lower offset is just 76 * past the last filled-in index. The h_upper offset is the first item on the 77 * page. Offsets are from the beginning of the page. 78 * 79 * If an item is too big to store on a single page, a flag is set and the item 80 * is a { page, size } pair such that the page is the first page of an overflow 81 * chain with size bytes of item. Overflow pages are simply bytes without any 82 * external structure. 83 * 84 * The size and page number fields in the items are long aligned so they can be 85 * manipulated without copying. 86 */ 87 #define LALIGN(l) (((l) + sizeof(u_long) - 1) & ~(sizeof(u_long) - 1)) 88 #define NOVFLSIZE (sizeof(pgno_t) + sizeof(size_t)) 89 90 /* 91 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno} 92 * pairs, such that the key compares less than or equal to all of the records 93 * on that page. For a tree without duplicate keys, an internal page with two 94 * consecutive keys, a and b, will have all records greater than or equal to a 95 * and less than b stored on the page associated with a. Duplicate keys are 96 * somewhat special and can cause duplicate internal and leaf page records and 97 * some minor modifications of the above rule. 98 */ 99 typedef struct BINTERNAL { 100 size_t ksize; /* key size */ 101 pgno_t pgno; /* page number stored on */ 102 #define P_BIGDATA 0x01 /* overflow data */ 103 #define P_BIGKEY 0x02 /* overflow key */ 104 u_char flags; 105 char bytes[1]; /* data */ 106 } BINTERNAL; 107 108 /* Get the page's BINTERNAL structure at index indx. */ 109 #define GETBINTERNAL(pg, indx) \ 110 ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 111 112 /* Get the number of bytes in the entry. */ 113 #define NBINTERNAL(len) \ 114 LALIGN(sizeof(size_t) + sizeof(pgno_t) + sizeof(u_char) + (len)) 115 116 /* Copy a BINTERNAL entry to the page. */ 117 #define WR_BINTERNAL(p, size, pgno, flags) { \ 118 *(size_t *)p = size; \ 119 p += sizeof(size_t); \ 120 *(pgno_t *)p = pgno; \ 121 p += sizeof(pgno_t); \ 122 *(u_char *)p = flags; \ 123 p += sizeof(u_char); \ 124 } 125 126 /* 127 * For the recno internal pages, the item is a page number with the number of 128 * keys found on that page and below. 129 */ 130 typedef struct RINTERNAL { 131 recno_t nrecs; /* number of records */ 132 pgno_t pgno; /* page number stored below */ 133 } RINTERNAL; 134 135 /* Get the page's RINTERNAL structure at index indx. */ 136 #define GETRINTERNAL(pg, indx) \ 137 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 138 139 /* Get the number of bytes in the entry. */ 140 #define NRINTERNAL \ 141 LALIGN(sizeof(recno_t) + sizeof(pgno_t)) 142 143 /* Copy a RINTERAL entry to the page. */ 144 #define WR_RINTERNAL(p, nrecs, pgno) { \ 145 *(size_t *)p = nrecs; \ 146 p += sizeof(recno_t); \ 147 *(pgno_t *)p = pgno; \ 148 } 149 150 /* For the btree leaf pages, the item is a key and data pair. */ 151 typedef struct BLEAF { 152 size_t ksize; /* size of key */ 153 size_t dsize; /* size of data */ 154 u_char flags; /* P_BIGDATA, P_BIGKEY */ 155 char bytes[1]; /* data */ 156 } BLEAF; 157 158 /* Get the page's BLEAF structure at index indx. */ 159 #define GETBLEAF(pg, indx) \ 160 ((BLEAF *)((char *)(pg) + (pg)->linp[indx])) 161 162 /* Get the number of bytes in the entry. */ 163 #define NBLEAF(p) \ 164 LALIGN(sizeof(size_t) + sizeof(size_t) + sizeof(u_char) + \ 165 (p)->ksize + (p)->dsize) 166 167 /* Get the number of bytes in the user's key/data pair. */ 168 #define NBLEAFDBT(ksize, dsize) \ 169 LALIGN(sizeof(size_t) + sizeof(size_t) + sizeof(u_char) + \ 170 (ksize) + (dsize)) 171 172 /* Copy a BLEAF entry to the page. */ 173 #define WR_BLEAF(p, key, data, flags) { \ 174 *(size_t *)p = key->size; \ 175 p += sizeof(size_t); \ 176 *(size_t *)p = data->size; \ 177 p += sizeof(size_t); \ 178 *(u_char *)p = flags; \ 179 p += sizeof(u_char); \ 180 bcopy(key->data, p, key->size); \ 181 p += key->size; \ 182 bcopy(data->data, p, data->size); \ 183 } 184 185 /* For the recno leaf pages, the item is a data entry. */ 186 typedef struct RLEAF { 187 size_t dsize; /* size of data */ 188 u_char flags; /* P_BIGDATA */ 189 char bytes[1]; 190 } RLEAF; 191 192 /* Get the page's RLEAF structure at index indx. */ 193 #define GETRLEAF(pg, indx) \ 194 ((RLEAF *)((char *)(pg) + (pg)->linp[indx])) 195 196 /* Get the number of bytes in the entry. */ 197 #define NRLEAF(p) \ 198 LALIGN(sizeof(size_t) + sizeof(u_char) + (p)->dsize) 199 200 /* Get the number of bytes from the user's data. */ 201 #define NRLEAFDBT(dsize) \ 202 LALIGN(sizeof(size_t) + sizeof(u_char) + (dsize)) 203 204 /* Copy a RLEAF entry to the page. */ 205 #define WR_RLEAF(p, data, flags) { \ 206 *(size_t *)p = data->size; \ 207 p += sizeof(size_t); \ 208 *(u_char *)p = flags; \ 209 p += sizeof(u_char); \ 210 bcopy(data->data, p, data->size); \ 211 } 212 213 /* 214 * A record in the tree is either a pointer to a page and an index in the page 215 * or a page number and an index. These structures are used as a cursor, stack 216 * entry and search returns as well as to pass records to other routines. 217 * 218 * One comment about searches. Internal page searches must find the largest 219 * record less than key in the tree so that descents work. Leaf page searches 220 * must find the smallest record greater than key so that the returned index 221 * is the record's correct position for insertion. 222 */ 223 typedef struct EPGNO { 224 pgno_t pgno; /* the page number */ 225 index_t index; /* the index on the page */ 226 } EPGNO; 227 228 typedef struct EPG { 229 PAGE *page; /* the (pinned) page */ 230 index_t index; /* the index on the page */ 231 } EPG; 232 233 /* The in-memory btree/recno data structure. */ 234 typedef struct BTREE { 235 MPOOL *bt_mp; /* memory pool cookie */ 236 237 DB *bt_dbp; /* pointer to enclosing DB */ 238 239 EPGNO bt_bcursor; /* btree cursor */ 240 recno_t bt_rcursor; /* R: recno cursor */ 241 242 #define BT_POP(t) (t->bt_sp ? t->bt_stack + --t->bt_sp : NULL) 243 #define BT_CLR(t) (t->bt_sp = 0) 244 EPGNO *bt_stack; /* stack of parent pages */ 245 u_int bt_sp; /* current stack pointer */ 246 u_int bt_maxstack; /* largest stack */ 247 248 char *bt_kbuf; /* key buffer */ 249 size_t bt_kbufsz; /* key buffer size */ 250 char *bt_dbuf; /* data buffer */ 251 size_t bt_dbufsz; /* data buffer size */ 252 253 int bt_fd; /* tree file descriptor */ 254 FILE *bt_rfp; /* R: record FILE pointer */ 255 int bt_rfd; /* R: record file descriptor */ 256 257 pgno_t bt_free; /* next free page */ 258 size_t bt_psize; /* page size */ 259 int bt_maxkeypage; /* maximum keys per page */ 260 size_t bt_minkeypage; /* minimum keys per page */ 261 int bt_lorder; /* byte order */ 262 263 /* sorted order */ 264 enum { NOT, BACK, FORWARD, } bt_order; 265 EPGNO bt_last; /* last insert */ 266 267 /* B: key comparison function */ 268 int (*bt_cmp) __P((const DBT *, const DBT *)); 269 /* B: prefix comparison function */ 270 int (*bt_pfx) __P((const DBT *, const DBT *)); 271 272 /* R: recno input function */ 273 int (*bt_irec) __P((struct BTREE *, recno_t)); 274 recno_t bt_nrecs; /* R: number of records in the tree */ 275 caddr_t bt_smap; /* R: start of mapped space */ 276 caddr_t bt_emap; /* R: end of mapped space */ 277 size_t bt_reclen; /* R: fixed record length */ 278 u_char bt_bval; /* R: delimiting byte/pad character */ 279 280 #define BTF_DELCRSR 0x001 /* B: delete cursor when closes/moves */ 281 #define BTF_FIXEDLEN 0x002 /* fixed length records */ 282 #define BTF_INMEM 0x004 /* in-memory tree */ 283 #define BTF_METADIRTY 0x008 /* B: need to write meta-data */ 284 #define BTF_MODIFIED 0x010 /* tree modified */ 285 #define BTF_NODUPS 0x020 /* no duplicate keys permitted */ 286 #define BTF_RDONLY 0x040 /* read-only tree */ 287 #define BTF_RECNO 0x080 /* record oriented tree */ 288 #define BTF_SEQINIT 0x100 /* sequential scan initialized */ 289 u_long bt_flags; /* btree state */ 290 } BTREE; 291 292 #define ISSET(t, f) ((t)->bt_flags & (f)) 293 #define NOTSET(t, f) (!((t)->bt_flags & (f))) 294 #define SET(t, f) ((t)->bt_flags |= (f)) 295 #define UNSET(t, f) ((t)->bt_flags &= ~(f)) 296 297 #include "extern.h" 298