1 /* $NetBSD: btree.h,v 1.12 2002/01/21 21:33:42 tv Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Mike Olson. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)btree.h 8.11 (Berkeley) 8/17/94 39 */ 40 41 #if HAVE_CONFIG_H 42 #include "config.h" 43 #endif 44 45 /* Macros to set/clear/test flags. */ 46 #define F_SET(p, f) (p)->flags |= (f) 47 #define F_CLR(p, f) (p)->flags &= ~(f) 48 #define F_ISSET(p, f) ((p)->flags & (f)) 49 50 #include <mpool.h> 51 52 #define DEFMINKEYPAGE (2) /* Minimum keys per page */ 53 #define MINCACHE (5) /* Minimum cached pages */ 54 #define MINPSIZE (512) /* Minimum page size */ 55 56 /* 57 * Page 0 of a btree file contains a copy of the meta-data. This page is also 58 * used as an out-of-band page, i.e. page pointers that point to nowhere point 59 * to page 0. Page 1 is the root of the btree. 60 */ 61 #define P_INVALID 0 /* Invalid tree page number. */ 62 #define P_META 0 /* Tree metadata page number. */ 63 #define P_ROOT 1 /* Tree root page number. */ 64 65 /* 66 * There are five page layouts in the btree: btree internal pages (BINTERNAL), 67 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages 68 * (RLEAF) and overflow pages. All five page types have a page header (PAGE). 69 * This implementation requires that values within structures NOT be padded. 70 * (ANSI C permits random padding.) If your compiler pads randomly you'll have 71 * to do some work to get this package to run. 72 */ 73 typedef struct _page { 74 pgno_t pgno; /* this page's page number */ 75 pgno_t prevpg; /* left sibling */ 76 pgno_t nextpg; /* right sibling */ 77 78 #define P_BINTERNAL 0x01 /* btree internal page */ 79 #define P_BLEAF 0x02 /* leaf page */ 80 #define P_OVERFLOW 0x04 /* overflow page */ 81 #define P_RINTERNAL 0x08 /* recno internal page */ 82 #define P_RLEAF 0x10 /* leaf page */ 83 #define P_TYPE 0x1f /* type mask */ 84 #define P_PRESERVE 0x20 /* never delete this chain of pages */ 85 u_int32_t flags; 86 87 indx_t lower; /* lower bound of free space on page */ 88 indx_t upper; /* upper bound of free space on page */ 89 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */ 90 } PAGE; 91 92 /* First and next index. */ 93 #define BTDATAOFF \ 94 (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \ 95 sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t)) 96 #define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t)) 97 98 /* 99 * For pages other than overflow pages, there is an array of offsets into the 100 * rest of the page immediately following the page header. Each offset is to 101 * an item which is unique to the type of page. The h_lower offset is just 102 * past the last filled-in index. The h_upper offset is the first item on the 103 * page. Offsets are from the beginning of the page. 104 * 105 * If an item is too big to store on a single page, a flag is set and the item 106 * is a { page, size } pair such that the page is the first page of an overflow 107 * chain with size bytes of item. Overflow pages are simply bytes without any 108 * external structure. 109 * 110 * The page number and size fields in the items are pgno_t-aligned so they can 111 * be manipulated without copying. (This presumes that 32 bit items can be 112 * manipulated on this system.) 113 */ 114 #define BTLALIGN(n) (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1)) 115 #define NOVFLSIZE (sizeof(pgno_t) + sizeof(u_int32_t)) 116 117 /* 118 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno} 119 * pairs, such that the key compares less than or equal to all of the records 120 * on that page. For a tree without duplicate keys, an internal page with two 121 * consecutive keys, a and b, will have all records greater than or equal to a 122 * and less than b stored on the page associated with a. Duplicate keys are 123 * somewhat special and can cause duplicate internal and leaf page records and 124 * some minor modifications of the above rule. 125 */ 126 typedef struct _binternal { 127 u_int32_t ksize; /* key size */ 128 pgno_t pgno; /* page number stored on */ 129 #define P_BIGDATA 0x01 /* overflow data */ 130 #define P_BIGKEY 0x02 /* overflow key */ 131 u_char flags; 132 char bytes[1]; /* data */ 133 } BINTERNAL; 134 135 /* Get the page's BINTERNAL structure at index indx. */ 136 #define GETBINTERNAL(pg, indx) \ 137 ((BINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx])) 138 139 /* Get the number of bytes in the entry. */ 140 #define NBINTERNAL(len) \ 141 BTLALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len)) 142 143 /* Copy a BINTERNAL entry to the page. */ 144 #define WR_BINTERNAL(p, size, pgno, flags) { \ 145 *(u_int32_t *)(void *)p = size; \ 146 p += sizeof(u_int32_t); \ 147 *(pgno_t *)(void *)p = pgno; \ 148 p += sizeof(pgno_t); \ 149 *(u_char *)(void *)p = flags; \ 150 p += sizeof(u_char); \ 151 } 152 153 /* 154 * For the recno internal pages, the item is a page number with the number of 155 * keys found on that page and below. 156 */ 157 typedef struct _rinternal { 158 recno_t nrecs; /* number of records */ 159 pgno_t pgno; /* page number stored below */ 160 } RINTERNAL; 161 162 /* Get the page's RINTERNAL structure at index indx. */ 163 #define GETRINTERNAL(pg, indx) \ 164 ((RINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx])) 165 166 /* Get the number of bytes in the entry. */ 167 #define NRINTERNAL \ 168 BTLALIGN(sizeof(recno_t) + sizeof(pgno_t)) 169 170 /* Copy a RINTERAL entry to the page. */ 171 #define WR_RINTERNAL(p, nrecs, pgno) { \ 172 *(recno_t *)(void *)p = nrecs; \ 173 p += sizeof(recno_t); \ 174 *(pgno_t *)(void *)p = pgno; \ 175 } 176 177 /* For the btree leaf pages, the item is a key and data pair. */ 178 typedef struct _bleaf { 179 u_int32_t ksize; /* size of key */ 180 u_int32_t dsize; /* size of data */ 181 u_char flags; /* P_BIGDATA, P_BIGKEY */ 182 char bytes[1]; /* data */ 183 } BLEAF; 184 185 /* Get the page's BLEAF structure at index indx. */ 186 #define GETBLEAF(pg, indx) \ 187 ((BLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx])) 188 189 /* Get the number of bytes in the entry. */ 190 #define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize) 191 192 /* Get the number of bytes in the user's key/data pair. */ 193 #define NBLEAFDBT(ksize, dsize) \ 194 BTLALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \ 195 (ksize) + (dsize)) 196 197 /* Copy a BLEAF entry to the page. */ 198 #define WR_BLEAF(p, key, data, flags) { \ 199 *(u_int32_t *)(void *)p = key->size; \ 200 p += sizeof(u_int32_t); \ 201 *(u_int32_t *)(void *)p = data->size; \ 202 p += sizeof(u_int32_t); \ 203 *(u_char *)(void *)p = flags; \ 204 p += sizeof(u_char); \ 205 memmove(p, key->data, key->size); \ 206 p += key->size; \ 207 memmove(p, data->data, data->size); \ 208 } 209 210 /* For the recno leaf pages, the item is a data entry. */ 211 typedef struct _rleaf { 212 u_int32_t dsize; /* size of data */ 213 u_char flags; /* P_BIGDATA */ 214 char bytes[1]; 215 } RLEAF; 216 217 /* Get the page's RLEAF structure at index indx. */ 218 #define GETRLEAF(pg, indx) \ 219 ((RLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx])) 220 221 /* Get the number of bytes in the entry. */ 222 #define NRLEAF(p) NRLEAFDBT((p)->dsize) 223 224 /* Get the number of bytes from the user's data. */ 225 #define NRLEAFDBT(dsize) \ 226 BTLALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize)) 227 228 /* Copy a RLEAF entry to the page. */ 229 #define WR_RLEAF(p, data, flags) { \ 230 *(u_int32_t *)(void *)p = data->size; \ 231 p += sizeof(u_int32_t); \ 232 *(u_char *)(void *)p = flags; \ 233 p += sizeof(u_char); \ 234 memmove(p, data->data, data->size); \ 235 } 236 237 /* 238 * A record in the tree is either a pointer to a page and an index in the page 239 * or a page number and an index. These structures are used as a cursor, stack 240 * entry and search returns as well as to pass records to other routines. 241 * 242 * One comment about searches. Internal page searches must find the largest 243 * record less than key in the tree so that descents work. Leaf page searches 244 * must find the smallest record greater than key so that the returned index 245 * is the record's correct position for insertion. 246 */ 247 typedef struct _epgno { 248 pgno_t pgno; /* the page number */ 249 indx_t index; /* the index on the page */ 250 } EPGNO; 251 252 typedef struct _epg { 253 PAGE *page; /* the (pinned) page */ 254 indx_t index; /* the index on the page */ 255 } EPG; 256 257 /* 258 * About cursors. The cursor (and the page that contained the key/data pair 259 * that it referenced) can be deleted, which makes things a bit tricky. If 260 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set 261 * or there simply aren't any duplicates of the key) we copy the key that it 262 * referenced when it's deleted, and reacquire a new cursor key if the cursor 263 * is used again. If there are duplicates keys, we move to the next/previous 264 * key, and set a flag so that we know what happened. NOTE: if duplicate (to 265 * the cursor) keys are added to the tree during this process, it is undefined 266 * if they will be returned or not in a cursor scan. 267 * 268 * The flags determine the possible states of the cursor: 269 * 270 * CURS_INIT The cursor references *something*. 271 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that 272 * we can reacquire the right position in the tree. 273 * CURS_AFTER, CURS_BEFORE 274 * The cursor was deleted, and now references a key/data pair 275 * that has not yet been returned, either before or after the 276 * deleted key/data pair. 277 * XXX 278 * This structure is broken out so that we can eventually offer multiple 279 * cursors as part of the DB interface. 280 */ 281 typedef struct _cursor { 282 EPGNO pg; /* B: Saved tree reference. */ 283 DBT key; /* B: Saved key, or key.data == NULL. */ 284 recno_t rcursor; /* R: recno cursor (1-based) */ 285 286 #define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */ 287 #define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */ 288 #define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */ 289 #define CURS_INIT 0x08 /* RB: Cursor initialized. */ 290 u_int8_t flags; 291 } CURSOR; 292 293 /* 294 * The metadata of the tree. The nrecs field is used only by the RECNO code. 295 * This is because the btree doesn't really need it and it requires that every 296 * put or delete call modify the metadata. 297 */ 298 typedef struct _btmeta { 299 u_int32_t magic; /* magic number */ 300 u_int32_t version; /* version */ 301 u_int32_t psize; /* page size */ 302 u_int32_t free; /* page number of first free page */ 303 u_int32_t nrecs; /* R: number of records */ 304 305 #define SAVEMETA (B_NODUPS | R_RECNO) 306 u_int32_t flags; /* bt_flags & SAVEMETA */ 307 } BTMETA; 308 309 /* The in-memory btree/recno data structure. */ 310 typedef struct _btree { 311 MPOOL *bt_mp; /* memory pool cookie */ 312 313 DB *bt_dbp; /* pointer to enclosing DB */ 314 315 EPG bt_cur; /* current (pinned) page */ 316 PAGE *bt_pinned; /* page pinned across calls */ 317 318 CURSOR bt_cursor; /* cursor */ 319 320 #define BT_PUSH(t, p, i) { \ 321 t->bt_sp->pgno = p; \ 322 t->bt_sp->index = i; \ 323 ++t->bt_sp; \ 324 } 325 #define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp) 326 #define BT_CLR(t) (t->bt_sp = t->bt_stack) 327 EPGNO bt_stack[50]; /* stack of parent pages */ 328 EPGNO *bt_sp; /* current stack pointer */ 329 330 DBT bt_rkey; /* returned key */ 331 DBT bt_rdata; /* returned data */ 332 333 int bt_fd; /* tree file descriptor */ 334 335 pgno_t bt_free; /* next free page */ 336 u_int32_t bt_psize; /* page size */ 337 indx_t bt_ovflsize; /* cut-off for key/data overflow */ 338 int bt_lorder; /* byte order */ 339 /* sorted order */ 340 enum { NOT, BACK, FORWARD } bt_order; 341 EPGNO bt_last; /* last insert */ 342 343 /* B: key comparison function */ 344 int (*bt_cmp) __P((const DBT *, const DBT *)); 345 /* B: prefix comparison function */ 346 size_t (*bt_pfx) __P((const DBT *, const DBT *)); 347 /* R: recno input function */ 348 int (*bt_irec) __P((struct _btree *, recno_t)); 349 350 FILE *bt_rfp; /* R: record FILE pointer */ 351 int bt_rfd; /* R: record file descriptor */ 352 353 caddr_t bt_cmap; /* R: current point in mapped space */ 354 caddr_t bt_smap; /* R: start of mapped space */ 355 caddr_t bt_emap; /* R: end of mapped space */ 356 size_t bt_msize; /* R: size of mapped region. */ 357 358 recno_t bt_nrecs; /* R: number of records */ 359 size_t bt_reclen; /* R: fixed record length */ 360 u_char bt_bval; /* R: delimiting byte/pad character */ 361 362 /* 363 * NB: 364 * B_NODUPS and R_RECNO are stored on disk, and may not be changed. 365 */ 366 #define B_INMEM 0x00001 /* in-memory tree */ 367 #define B_METADIRTY 0x00002 /* need to write metadata */ 368 #define B_MODIFIED 0x00004 /* tree modified */ 369 #define B_NEEDSWAP 0x00008 /* if byte order requires swapping */ 370 #define B_RDONLY 0x00010 /* read-only tree */ 371 372 #define B_NODUPS 0x00020 /* no duplicate keys permitted */ 373 #define R_RECNO 0x00080 /* record oriented tree */ 374 375 #define R_CLOSEFP 0x00040 /* opened a file pointer */ 376 #define R_EOF 0x00100 /* end of input file reached. */ 377 #define R_FIXLEN 0x00200 /* fixed length records */ 378 #define R_MEMMAPPED 0x00400 /* memory mapped file. */ 379 #define R_INMEM 0x00800 /* in-memory file */ 380 #define R_MODIFIED 0x01000 /* modified file */ 381 #define R_RDONLY 0x02000 /* read-only file */ 382 383 #define B_DB_LOCK 0x04000 /* DB_LOCK specified. */ 384 #define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */ 385 #define B_DB_TXN 0x10000 /* DB_TXN specified. */ 386 u_int32_t flags; 387 } BTREE; 388 389 #include "extern.h" 390