1 /*- 2 * Copyright (c) 1991, 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 * Mike Olson. 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 * @(#)btree.h 8.5 (Berkeley) 2/21/94 37 */ 38 39 #include <mpool.h> 40 41 #define DEFMINKEYPAGE (2) /* Minimum keys per page */ 42 #define MINCACHE (5) /* Minimum cached pages */ 43 #define MINPSIZE (512) /* Minimum page size */ 44 45 /* 46 * Page 0 of a btree file contains a copy of the meta-data. This page is also 47 * used as an out-of-band page, i.e. page pointers that point to nowhere point 48 * to page 0. Page 1 is the root of the btree. 49 */ 50 #define P_INVALID 0 /* Invalid tree page number. */ 51 #define P_META 0 /* Tree metadata page number. */ 52 #define P_ROOT 1 /* Tree root page number. */ 53 54 /* 55 * There are five page layouts in the btree: btree internal pages (BINTERNAL), 56 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages 57 * (RLEAF) and overflow pages. All five page types have a page header (PAGE). 58 * This implementation requires that values within structures NOT be padded. 59 * (ANSI C permits random padding.) If your compiler pads randomly you'll have 60 * to do some work to get this package to run. 61 */ 62 typedef struct _page { 63 pgno_t pgno; /* this page's page number */ 64 pgno_t prevpg; /* left sibling */ 65 pgno_t nextpg; /* right sibling */ 66 67 #define P_BINTERNAL 0x01 /* btree internal page */ 68 #define P_BLEAF 0x02 /* leaf page */ 69 #define P_OVERFLOW 0x04 /* overflow page */ 70 #define P_RINTERNAL 0x08 /* recno internal page */ 71 #define P_RLEAF 0x10 /* leaf page */ 72 #define P_TYPE 0x1f /* type mask */ 73 #define P_PRESERVE 0x20 /* never delete this chain of pages */ 74 u_int32_t flags; 75 76 indx_t lower; /* lower bound of free space on page */ 77 indx_t upper; /* upper bound of free space on page */ 78 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */ 79 } PAGE; 80 81 /* First and next index. */ 82 #define BTDATAOFF (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \ 83 sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t)) 84 #define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t)) 85 86 /* 87 * For pages other than overflow pages, there is an array of offsets into the 88 * rest of the page immediately following the page header. Each offset is to 89 * an item which is unique to the type of page. The h_lower offset is just 90 * past the last filled-in index. The h_upper offset is the first item on the 91 * page. Offsets are from the beginning of the page. 92 * 93 * If an item is too big to store on a single page, a flag is set and the item 94 * is a { page, size } pair such that the page is the first page of an overflow 95 * chain with size bytes of item. Overflow pages are simply bytes without any 96 * external structure. 97 * 98 * The page number and size fields in the items are pgno_t-aligned so they can 99 * be manipulated without copying. (This presumes that 32 bit items can be 100 * manipulated on this system.) 101 */ 102 #define LALIGN(n) \ 103 (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1)) 104 #define NOVFLSIZE (sizeof(pgno_t) + sizeof(size_t)) 105 106 /* 107 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno} 108 * pairs, such that the key compares less than or equal to all of the records 109 * on that page. For a tree without duplicate keys, an internal page with two 110 * consecutive keys, a and b, will have all records greater than or equal to a 111 * and less than b stored on the page associated with a. Duplicate keys are 112 * somewhat special and can cause duplicate internal and leaf page records and 113 * some minor modifications of the above rule. 114 */ 115 typedef struct _binternal { 116 size_t ksize; /* key size */ 117 pgno_t pgno; /* page number stored on */ 118 #define P_BIGDATA 0x01 /* overflow data */ 119 #define P_BIGKEY 0x02 /* overflow key */ 120 u_char flags; 121 char bytes[1]; /* data */ 122 } BINTERNAL; 123 124 /* Get the page's BINTERNAL structure at index indx. */ 125 #define GETBINTERNAL(pg, indx) \ 126 ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 127 128 /* Get the number of bytes in the entry. */ 129 #define NBINTERNAL(len) \ 130 LALIGN(sizeof(size_t) + sizeof(pgno_t) + sizeof(u_char) + (len)) 131 132 /* Copy a BINTERNAL entry to the page. */ 133 #define WR_BINTERNAL(p, size, pgno, flags) { \ 134 *(size_t *)p = size; \ 135 p += sizeof(size_t); \ 136 *(pgno_t *)p = pgno; \ 137 p += sizeof(pgno_t); \ 138 *(u_char *)p = flags; \ 139 p += sizeof(u_char); \ 140 } 141 142 /* 143 * For the recno internal pages, the item is a page number with the number of 144 * keys found on that page and below. 145 */ 146 typedef struct _rinternal { 147 recno_t nrecs; /* number of records */ 148 pgno_t pgno; /* page number stored below */ 149 } RINTERNAL; 150 151 /* Get the page's RINTERNAL structure at index indx. */ 152 #define GETRINTERNAL(pg, indx) \ 153 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 154 155 /* Get the number of bytes in the entry. */ 156 #define NRINTERNAL \ 157 LALIGN(sizeof(recno_t) + sizeof(pgno_t)) 158 159 /* Copy a RINTERAL entry to the page. */ 160 #define WR_RINTERNAL(p, nrecs, pgno) { \ 161 *(recno_t *)p = nrecs; \ 162 p += sizeof(recno_t); \ 163 *(pgno_t *)p = pgno; \ 164 } 165 166 /* For the btree leaf pages, the item is a key and data pair. */ 167 typedef struct _bleaf { 168 size_t ksize; /* size of key */ 169 size_t dsize; /* size of data */ 170 u_char flags; /* P_BIGDATA, P_BIGKEY */ 171 char bytes[1]; /* data */ 172 } BLEAF; 173 174 /* Get the page's BLEAF structure at index indx. */ 175 #define GETBLEAF(pg, indx) \ 176 ((BLEAF *)((char *)(pg) + (pg)->linp[indx])) 177 178 /* Get the number of bytes in the entry. */ 179 #define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize) 180 181 /* Get the number of bytes in the user's key/data pair. */ 182 #define NBLEAFDBT(ksize, dsize) \ 183 LALIGN(sizeof(size_t) + sizeof(size_t) + sizeof(u_char) + \ 184 (ksize) + (dsize)) 185 186 /* Copy a BLEAF entry to the page. */ 187 #define WR_BLEAF(p, key, data, flags) { \ 188 *(size_t *)p = key->size; \ 189 p += sizeof(size_t); \ 190 *(size_t *)p = data->size; \ 191 p += sizeof(size_t); \ 192 *(u_char *)p = flags; \ 193 p += sizeof(u_char); \ 194 memmove(p, key->data, key->size); \ 195 p += key->size; \ 196 memmove(p, data->data, data->size); \ 197 } 198 199 /* For the recno leaf pages, the item is a data entry. */ 200 typedef struct _rleaf { 201 size_t dsize; /* size of data */ 202 u_char flags; /* P_BIGDATA */ 203 char bytes[1]; 204 } RLEAF; 205 206 /* Get the page's RLEAF structure at index indx. */ 207 #define GETRLEAF(pg, indx) \ 208 ((RLEAF *)((char *)(pg) + (pg)->linp[indx])) 209 210 /* Get the number of bytes in the entry. */ 211 #define NRLEAF(p) NRLEAFDBT((p)->dsize) 212 213 /* Get the number of bytes from the user's data. */ 214 #define NRLEAFDBT(dsize) \ 215 LALIGN(sizeof(size_t) + sizeof(u_char) + (dsize)) 216 217 /* Copy a RLEAF entry to the page. */ 218 #define WR_RLEAF(p, data, flags) { \ 219 *(size_t *)p = data->size; \ 220 p += sizeof(size_t); \ 221 *(u_char *)p = flags; \ 222 p += sizeof(u_char); \ 223 memmove(p, data->data, data->size); \ 224 } 225 226 /* 227 * A record in the tree is either a pointer to a page and an index in the page 228 * or a page number and an index. These structures are used as a cursor, stack 229 * entry and search returns as well as to pass records to other routines. 230 * 231 * One comment about searches. Internal page searches must find the largest 232 * record less than key in the tree so that descents work. Leaf page searches 233 * must find the smallest record greater than key so that the returned index 234 * is the record's correct position for insertion. 235 * 236 * One comment about cursors. The cursor key is never removed from the tree, 237 * even if deleted. This is because it is quite difficult to decide where the 238 * cursor should be when other keys have been inserted/deleted in the tree; 239 * duplicate keys make it impossible. This scheme does require extra work 240 * though, to make sure that we don't perform an operation on a deleted key. 241 */ 242 typedef struct _epgno { 243 pgno_t pgno; /* the page number */ 244 indx_t index; /* the index on the page */ 245 } EPGNO; 246 247 typedef struct _epg { 248 PAGE *page; /* the (pinned) page */ 249 indx_t index; /* the index on the page */ 250 } EPG; 251 252 /* 253 * The metadata of the tree. The m_nrecs field is used only by the RECNO code. 254 * This is because the btree doesn't really need it and it requires that every 255 * put or delete call modify the metadata. 256 */ 257 typedef struct _btmeta { 258 u_int32_t m_magic; /* magic number */ 259 u_int32_t m_version; /* version */ 260 u_int32_t m_psize; /* page size */ 261 u_int32_t m_free; /* page number of first free page */ 262 u_int32_t m_nrecs; /* R: number of records */ 263 #define SAVEMETA (B_NODUPS | R_RECNO) 264 u_int32_t m_flags; /* bt_flags & SAVEMETA */ 265 u_int32_t m_unused; /* unused */ 266 } BTMETA; 267 268 /* The in-memory btree/recno data structure. */ 269 typedef struct _btree { 270 MPOOL *bt_mp; /* memory pool cookie */ 271 272 DB *bt_dbp; /* pointer to enclosing DB */ 273 274 EPG bt_cur; /* current (pinned) page */ 275 PAGE *bt_pinned; /* page pinned across calls */ 276 277 EPGNO bt_bcursor; /* B: btree cursor */ 278 recno_t bt_rcursor; /* R: recno cursor (1-based) */ 279 280 #define BT_POP(t) (t->bt_sp ? t->bt_stack + --t->bt_sp : NULL) 281 #define BT_CLR(t) (t->bt_sp = 0) 282 EPGNO *bt_stack; /* stack of parent pages */ 283 u_int bt_sp; /* current stack pointer */ 284 u_int bt_maxstack; /* largest stack */ 285 286 char *bt_kbuf; /* key buffer */ 287 size_t bt_kbufsz; /* key buffer size */ 288 char *bt_dbuf; /* data buffer */ 289 size_t bt_dbufsz; /* data buffer size */ 290 291 int bt_fd; /* tree file descriptor */ 292 293 pgno_t bt_free; /* next free page */ 294 u_int32_t bt_psize; /* page size */ 295 indx_t bt_ovflsize; /* cut-off for key/data overflow */ 296 int bt_lorder; /* byte order */ 297 /* sorted order */ 298 enum { NOT, BACK, FORWARD } bt_order; 299 EPGNO bt_last; /* last insert */ 300 301 /* B: key comparison function */ 302 int (*bt_cmp) __P((const DBT *, const DBT *)); 303 /* B: prefix comparison function */ 304 size_t (*bt_pfx) __P((const DBT *, const DBT *)); 305 /* R: recno input function */ 306 int (*bt_irec) __P((struct _btree *, recno_t)); 307 308 FILE *bt_rfp; /* R: record FILE pointer */ 309 int bt_rfd; /* R: record file descriptor */ 310 311 caddr_t bt_cmap; /* R: current point in mapped space */ 312 caddr_t bt_smap; /* R: start of mapped space */ 313 caddr_t bt_emap; /* R: end of mapped space */ 314 size_t bt_msize; /* R: size of mapped region. */ 315 316 recno_t bt_nrecs; /* R: number of records */ 317 size_t bt_reclen; /* R: fixed record length */ 318 u_char bt_bval; /* R: delimiting byte/pad character */ 319 320 /* 321 * NB: 322 * B_NODUPS and R_RECNO are stored on disk, and may not be changed. 323 */ 324 #define B_DELCRSR 0x00001 /* cursor has been deleted */ 325 #define B_INMEM 0x00002 /* in-memory tree */ 326 #define B_METADIRTY 0x00004 /* need to write metadata */ 327 #define B_MODIFIED 0x00008 /* tree modified */ 328 #define B_NEEDSWAP 0x00010 /* if byte order requires swapping */ 329 #define B_NODUPS 0x00020 /* no duplicate keys permitted */ 330 #define B_RDONLY 0x00040 /* read-only tree */ 331 #define R_RECNO 0x00080 /* record oriented tree */ 332 #define B_SEQINIT 0x00100 /* sequential scan initialized */ 333 334 #define R_CLOSEFP 0x00200 /* opened a file pointer */ 335 #define R_EOF 0x00400 /* end of input file reached. */ 336 #define R_FIXLEN 0x00800 /* fixed length records */ 337 #define R_MEMMAPPED 0x01000 /* memory mapped file. */ 338 #define R_INMEM 0x02000 /* in-memory file */ 339 #define R_MODIFIED 0x04000 /* modified file */ 340 #define R_RDONLY 0x08000 /* read-only file */ 341 342 #define B_DB_LOCK 0x10000 /* DB_LOCK specified. */ 343 #define B_DB_SHMEM 0x20000 /* DB_SHMEM specified. */ 344 #define B_DB_TXN 0x40000 /* DB_TXN specified. */ 345 346 u_int32_t bt_flags; /* btree state */ 347 } BTREE; 348 349 #define SET(t, f) ((t)->bt_flags |= (f)) 350 #define CLR(t, f) ((t)->bt_flags &= ~(f)) 351 #define ISSET(t, f) ((t)->bt_flags & (f)) 352 353 #include "extern.h" 354