1 /*- 2 * Copyright (c) 1991, 1993, 1994 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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)btree.h 8.11 (Berkeley) 8/17/94 33 * $FreeBSD: head/lib/libc/db/btree/btree.h 189327 2009-03-04 00:58:04Z delphij $ 34 */ 35 36 /* Macros to set/clear/test flags. */ 37 #define F_SET(p, f) (p)->flags |= (f) 38 #define F_CLR(p, f) (p)->flags &= ~(f) 39 #define F_ISSET(p, f) ((p)->flags & (f)) 40 41 #include <mpool.h> 42 43 #define DEFMINKEYPAGE (2) /* Minimum keys per page */ 44 #define MINCACHE (5) /* Minimum cached pages */ 45 #define MINPSIZE (512) /* Minimum page size */ 46 #define NOMPSIZE 16384 /* Nominal page size */ 47 48 /* 49 * Page 0 of a btree file contains a copy of the meta-data. This page is also 50 * used as an out-of-band page, i.e. page pointers that point to nowhere point 51 * to page 0. Page 1 is the root of the btree. 52 */ 53 #define P_INVALID 0 /* Invalid tree page number. */ 54 #define P_META 0 /* Tree metadata page number. */ 55 #define P_ROOT 1 /* Tree root page number. */ 56 57 /* 58 * There are five page layouts in the btree: btree internal pages (BINTERNAL), 59 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages 60 * (RLEAF) and overflow pages. All five page types have a page header (PAGE). 61 * This implementation requires that values within structures NOT be padded. 62 * (ANSI C permits random padding.) If your compiler pads randomly you'll have 63 * to do some work to get this package to run. 64 */ 65 typedef struct _page { 66 pgno_t pgno; /* this page's page number */ 67 pgno_t prevpg; /* left sibling */ 68 pgno_t nextpg; /* right sibling */ 69 70 #define P_BINTERNAL 0x01 /* btree internal page */ 71 #define P_BLEAF 0x02 /* leaf page */ 72 #define P_OVERFLOW 0x04 /* overflow page */ 73 #define P_RINTERNAL 0x08 /* recno internal page */ 74 #define P_RLEAF 0x10 /* leaf page */ 75 #define P_TYPE 0x1f /* type mask */ 76 #define P_PRESERVE 0x20 /* never delete this chain of pages */ 77 uint32_t flags; 78 79 indx_t lower; /* lower bound of free space on page */ 80 indx_t upper; /* upper bound of free space on page */ 81 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */ 82 } PAGE; 83 84 /* First and next index. */ 85 #define BTDATAOFF \ 86 (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \ 87 sizeof(uint32_t) + sizeof(indx_t) + sizeof(indx_t)) 88 #define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t)) 89 90 /* 91 * For pages other than overflow pages, there is an array of offsets into the 92 * rest of the page immediately following the page header. Each offset is to 93 * an item which is unique to the type of page. The h_lower offset is just 94 * past the last filled-in index. The h_upper offset is the first item on the 95 * page. Offsets are from the beginning of the page. 96 * 97 * If an item is too big to store on a single page, a flag is set and the item 98 * is a { page, size } pair such that the page is the first page of an overflow 99 * chain with size bytes of item. Overflow pages are simply bytes without any 100 * external structure. 101 * 102 * The page number and size fields in the items are pgno_t-aligned so they can 103 * be manipulated without copying. (This presumes that 32 bit items can be 104 * manipulated on this system.) 105 */ 106 #define LALIGN(n) roundup2(n, sizeof(pgno_t)) 107 #define NOVFLSIZE (sizeof(pgno_t) + sizeof(uint32_t)) 108 109 /* 110 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno} 111 * pairs, such that the key compares less than or equal to all of the records 112 * on that page. For a tree without duplicate keys, an internal page with two 113 * consecutive keys, a and b, will have all records greater than or equal to a 114 * and less than b stored on the page associated with a. Duplicate keys are 115 * somewhat special and can cause duplicate internal and leaf page records and 116 * some minor modifications of the above rule. 117 */ 118 typedef struct _binternal { 119 uint32_t ksize; /* key size */ 120 pgno_t pgno; /* page number stored on */ 121 #define P_BIGDATA 0x01 /* overflow data */ 122 #define P_BIGKEY 0x02 /* overflow key */ 123 unsigned char flags; 124 char bytes[1]; /* data */ 125 } BINTERNAL; 126 127 /* Get the page's BINTERNAL structure at index indx. */ 128 #define GETBINTERNAL(pg, indx) \ 129 ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 130 131 /* Get the number of bytes in the entry. */ 132 #define NBINTERNAL(len) \ 133 LALIGN(sizeof(uint32_t) + sizeof(pgno_t) + \ 134 sizeof(unsigned char) + (len)) 135 136 /* Copy a BINTERNAL entry to the page. */ 137 #define WR_BINTERNAL(p, size, pgno, flags) { \ 138 *(uint32_t *)p = size; \ 139 p += sizeof(uint32_t); \ 140 *(pgno_t *)p = pgno; \ 141 p += sizeof(pgno_t); \ 142 *(unsigned char *)p = flags; \ 143 p += sizeof(unsigned char); \ 144 } 145 146 /* 147 * For the recno internal pages, the item is a page number with the number of 148 * keys found on that page and below. 149 */ 150 typedef struct _rinternal { 151 recno_t nrecs; /* number of records */ 152 pgno_t pgno; /* page number stored below */ 153 } RINTERNAL; 154 155 /* Get the page's RINTERNAL structure at index indx. */ 156 #define GETRINTERNAL(pg, indx) \ 157 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 158 159 /* Get the number of bytes in the entry. */ 160 #define NRINTERNAL \ 161 LALIGN(sizeof(recno_t) + sizeof(pgno_t)) 162 163 /* Copy a RINTERAL entry to the page. */ 164 #define WR_RINTERNAL(p, nrecs, pgno) { \ 165 *(recno_t *)p = nrecs; \ 166 p += sizeof(recno_t); \ 167 *(pgno_t *)p = pgno; \ 168 } 169 170 /* For the btree leaf pages, the item is a key and data pair. */ 171 typedef struct _bleaf { 172 uint32_t ksize; /* size of key */ 173 uint32_t dsize; /* size of data */ 174 unsigned char flags; /* P_BIGDATA, P_BIGKEY */ 175 char bytes[1]; /* data */ 176 } BLEAF; 177 178 /* Get the page's BLEAF structure at index indx. */ 179 #define GETBLEAF(pg, indx) \ 180 ((BLEAF *)((char *)(pg) + (pg)->linp[indx])) 181 182 /* Get the number of bytes in the entry. */ 183 #define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize) 184 185 /* Get the number of bytes in the user's key/data pair. */ 186 #define NBLEAFDBT(ksize, dsize) \ 187 LALIGN(sizeof(uint32_t) + sizeof(uint32_t) + \ 188 sizeof(unsigned char) + (ksize) + (dsize)) 189 190 /* Copy a BLEAF entry to the page. */ 191 #define WR_BLEAF(p, key, data, flags) { \ 192 *(uint32_t *)p = key->size; \ 193 p += sizeof(uint32_t); \ 194 *(uint32_t *)p = data->size; \ 195 p += sizeof(uint32_t); \ 196 *(unsigned char *)p = flags; \ 197 p += sizeof(unsigned char); \ 198 memmove(p, key->data, key->size); \ 199 p += key->size; \ 200 memmove(p, data->data, data->size); \ 201 } 202 203 /* For the recno leaf pages, the item is a data entry. */ 204 typedef struct _rleaf { 205 uint32_t dsize; /* size of data */ 206 unsigned char flags; /* P_BIGDATA */ 207 char bytes[1]; 208 } RLEAF; 209 210 /* Get the page's RLEAF structure at index indx. */ 211 #define GETRLEAF(pg, indx) \ 212 ((RLEAF *)((char *)(pg) + (pg)->linp[indx])) 213 214 /* Get the number of bytes in the entry. */ 215 #define NRLEAF(p) NRLEAFDBT((p)->dsize) 216 217 /* Get the number of bytes from the user's data. */ 218 #define NRLEAFDBT(dsize) \ 219 LALIGN(sizeof(uint32_t) + sizeof(unsigned char) + (dsize)) 220 221 /* Copy a RLEAF entry to the page. */ 222 #define WR_RLEAF(p, data, flags) { \ 223 *(uint32_t *)p = data->size; \ 224 p += sizeof(uint32_t); \ 225 *(unsigned char *)p = flags; \ 226 p += sizeof(unsigned char); \ 227 memmove(p, data->data, data->size); \ 228 } 229 230 /* 231 * A record in the tree is either a pointer to a page and an index in the page 232 * or a page number and an index. These structures are used as a cursor, stack 233 * entry and search returns as well as to pass records to other routines. 234 * 235 * One comment about searches. Internal page searches must find the largest 236 * record less than key in the tree so that descents work. Leaf page searches 237 * must find the smallest record greater than key so that the returned index 238 * is the record's correct position for insertion. 239 */ 240 typedef struct _epgno { 241 pgno_t pgno; /* the page number */ 242 indx_t index; /* the index on the page */ 243 } EPGNO; 244 245 typedef struct _epg { 246 PAGE *page; /* the (pinned) page */ 247 indx_t index; /* the index on the page */ 248 } EPG; 249 250 /* 251 * About cursors. The cursor (and the page that contained the key/data pair 252 * that it referenced) can be deleted, which makes things a bit tricky. If 253 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set 254 * or there simply aren't any duplicates of the key) we copy the key that it 255 * referenced when it's deleted, and reacquire a new cursor key if the cursor 256 * is used again. If there are duplicates keys, we move to the next/previous 257 * key, and set a flag so that we know what happened. NOTE: if duplicate (to 258 * the cursor) keys are added to the tree during this process, it is undefined 259 * if they will be returned or not in a cursor scan. 260 * 261 * The flags determine the possible states of the cursor: 262 * 263 * CURS_INIT The cursor references *something*. 264 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that 265 * we can reacquire the right position in the tree. 266 * CURS_AFTER, CURS_BEFORE 267 * The cursor was deleted, and now references a key/data pair 268 * that has not yet been returned, either before or after the 269 * deleted key/data pair. 270 * XXX 271 * This structure is broken out so that we can eventually offer multiple 272 * cursors as part of the DB interface. 273 */ 274 typedef struct _cursor { 275 EPGNO pg; /* B: Saved tree reference. */ 276 DBT key; /* B: Saved key, or key.data == NULL. */ 277 recno_t rcursor; /* R: recno cursor (1-based) */ 278 279 #define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */ 280 #define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */ 281 #define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */ 282 #define CURS_INIT 0x08 /* RB: Cursor initialized. */ 283 uint8_t flags; 284 } CURSOR; 285 286 /* 287 * The metadata of the tree. The nrecs field is used only by the RECNO code. 288 * This is because the btree doesn't really need it and it requires that every 289 * put or delete call modify the metadata. 290 */ 291 typedef struct _btmeta { 292 uint32_t magic; /* magic number */ 293 uint32_t version; /* version */ 294 uint32_t psize; /* page size */ 295 uint32_t free; /* page number of first free page */ 296 uint32_t nrecs; /* R: number of records */ 297 298 #define SAVEMETA (B_NODUPS | R_RECNO) 299 uint32_t flags; /* bt_flags & SAVEMETA */ 300 } BTMETA; 301 302 /* The in-memory btree/recno data structure. */ 303 typedef struct _btree { 304 MPOOL *bt_mp; /* memory pool cookie */ 305 306 DB *bt_dbp; /* pointer to enclosing DB */ 307 308 EPG bt_cur; /* current (pinned) page */ 309 PAGE *bt_pinned; /* page pinned across calls */ 310 311 CURSOR bt_cursor; /* cursor */ 312 313 #define BT_PUSH(t, p, i) { \ 314 t->bt_sp->pgno = p; \ 315 t->bt_sp->index = i; \ 316 ++t->bt_sp; \ 317 } 318 #define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp) 319 #define BT_CLR(t) (t->bt_sp = t->bt_stack) 320 EPGNO bt_stack[50]; /* stack of parent pages */ 321 EPGNO *bt_sp; /* current stack pointer */ 322 323 DBT bt_rkey; /* returned key */ 324 DBT bt_rdata; /* returned data */ 325 326 int bt_fd; /* tree file descriptor */ 327 328 pgno_t bt_free; /* next free page */ 329 uint32_t bt_psize; /* page size */ 330 indx_t bt_ovflsize; /* cut-off for key/data overflow */ 331 int bt_lorder; /* byte order */ 332 /* sorted order */ 333 enum { NOT, BACK, FORWARD } bt_order; 334 EPGNO bt_last; /* last insert */ 335 336 /* B: key comparison function */ 337 int (*bt_cmp)(const DBT *, const DBT *); 338 /* B: prefix comparison function */ 339 size_t (*bt_pfx)(const DBT *, const DBT *); 340 /* R: recno input function */ 341 int (*bt_irec)(struct _btree *, recno_t); 342 343 FILE *bt_rfp; /* R: record FILE pointer */ 344 int bt_rfd; /* R: record file descriptor */ 345 346 caddr_t bt_cmap; /* R: current point in mapped space */ 347 caddr_t bt_smap; /* R: start of mapped space */ 348 caddr_t bt_emap; /* R: end of mapped space */ 349 size_t bt_msize; /* R: size of mapped region. */ 350 351 recno_t bt_nrecs; /* R: number of records */ 352 size_t bt_reclen; /* R: fixed record length */ 353 unsigned char bt_bval; /* R: delimiting byte/pad character */ 354 355 /* 356 * NB: 357 * B_NODUPS and R_RECNO are stored on disk, and may not be changed. 358 */ 359 #define B_INMEM 0x00001 /* in-memory tree */ 360 #define B_METADIRTY 0x00002 /* need to write metadata */ 361 #define B_MODIFIED 0x00004 /* tree modified */ 362 #define B_NEEDSWAP 0x00008 /* if byte order requires swapping */ 363 #define B_RDONLY 0x00010 /* read-only tree */ 364 365 #define B_NODUPS 0x00020 /* no duplicate keys permitted */ 366 #define R_RECNO 0x00080 /* record oriented tree */ 367 368 #define R_CLOSEFP 0x00040 /* opened a file pointer */ 369 #define R_EOF 0x00100 /* end of input file reached. */ 370 #define R_FIXLEN 0x00200 /* fixed length records */ 371 #define R_MEMMAPPED 0x00400 /* memory mapped file. */ 372 #define R_INMEM 0x00800 /* in-memory file */ 373 #define R_MODIFIED 0x01000 /* modified file */ 374 #define R_RDONLY 0x02000 /* read-only file */ 375 376 #define B_DB_LOCK 0x04000 /* DB_LOCK specified. */ 377 #define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */ 378 #define B_DB_TXN 0x10000 /* DB_TXN specified. */ 379 uint32_t flags; 380 } BTREE; 381 382 #include "extern.h" 383