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