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 * 4. 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 * $FreeBSD$ 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 u_int32_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(u_int32_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(u_int32_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 u_int32_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 u_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(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len)) 133 134 /* Copy a BINTERNAL entry to the page. */ 135 #define WR_BINTERNAL(p, size, pgno, flags) { \ 136 *(u_int32_t *)p = size; \ 137 p += sizeof(u_int32_t); \ 138 *(pgno_t *)p = pgno; \ 139 p += sizeof(pgno_t); \ 140 *(u_char *)p = flags; \ 141 p += sizeof(u_char); \ 142 } 143 144 /* 145 * For the recno internal pages, the item is a page number with the number of 146 * keys found on that page and below. 147 */ 148 typedef struct _rinternal { 149 recno_t nrecs; /* number of records */ 150 pgno_t pgno; /* page number stored below */ 151 } RINTERNAL; 152 153 /* Get the page's RINTERNAL structure at index indx. */ 154 #define GETRINTERNAL(pg, indx) \ 155 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx])) 156 157 /* Get the number of bytes in the entry. */ 158 #define NRINTERNAL \ 159 LALIGN(sizeof(recno_t) + sizeof(pgno_t)) 160 161 /* Copy a RINTERAL entry to the page. */ 162 #define WR_RINTERNAL(p, nrecs, pgno) { \ 163 *(recno_t *)p = nrecs; \ 164 p += sizeof(recno_t); \ 165 *(pgno_t *)p = pgno; \ 166 } 167 168 /* For the btree leaf pages, the item is a key and data pair. */ 169 typedef struct _bleaf { 170 u_int32_t ksize; /* size of key */ 171 u_int32_t dsize; /* size of data */ 172 u_char flags; /* P_BIGDATA, P_BIGKEY */ 173 char bytes[1]; /* data */ 174 } BLEAF; 175 176 /* Get the page's BLEAF structure at index indx. */ 177 #define GETBLEAF(pg, indx) \ 178 ((BLEAF *)((char *)(pg) + (pg)->linp[indx])) 179 180 /* Get the number of bytes in the entry. */ 181 #define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize) 182 183 /* Get the number of bytes in the user's key/data pair. */ 184 #define NBLEAFDBT(ksize, dsize) \ 185 LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \ 186 (ksize) + (dsize)) 187 188 /* Copy a BLEAF entry to the page. */ 189 #define WR_BLEAF(p, key, data, flags) { \ 190 *(u_int32_t *)p = key->size; \ 191 p += sizeof(u_int32_t); \ 192 *(u_int32_t *)p = data->size; \ 193 p += sizeof(u_int32_t); \ 194 *(u_char *)p = flags; \ 195 p += sizeof(u_char); \ 196 memmove(p, key->data, key->size); \ 197 p += key->size; \ 198 memmove(p, data->data, data->size); \ 199 } 200 201 /* For the recno leaf pages, the item is a data entry. */ 202 typedef struct _rleaf { 203 u_int32_t dsize; /* size of data */ 204 u_char flags; /* P_BIGDATA */ 205 char bytes[1]; 206 } RLEAF; 207 208 /* Get the page's RLEAF structure at index indx. */ 209 #define GETRLEAF(pg, indx) \ 210 ((RLEAF *)((char *)(pg) + (pg)->linp[indx])) 211 212 /* Get the number of bytes in the entry. */ 213 #define NRLEAF(p) NRLEAFDBT((p)->dsize) 214 215 /* Get the number of bytes from the user's data. */ 216 #define NRLEAFDBT(dsize) \ 217 LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize)) 218 219 /* Copy a RLEAF entry to the page. */ 220 #define WR_RLEAF(p, data, flags) { \ 221 *(u_int32_t *)p = data->size; \ 222 p += sizeof(u_int32_t); \ 223 *(u_char *)p = flags; \ 224 p += sizeof(u_char); \ 225 memmove(p, data->data, data->size); \ 226 } 227 228 /* 229 * A record in the tree is either a pointer to a page and an index in the page 230 * or a page number and an index. These structures are used as a cursor, stack 231 * entry and search returns as well as to pass records to other routines. 232 * 233 * One comment about searches. Internal page searches must find the largest 234 * record less than key in the tree so that descents work. Leaf page searches 235 * must find the smallest record greater than key so that the returned index 236 * is the record's correct position for insertion. 237 */ 238 typedef struct _epgno { 239 pgno_t pgno; /* the page number */ 240 indx_t index; /* the index on the page */ 241 } EPGNO; 242 243 typedef struct _epg { 244 PAGE *page; /* the (pinned) page */ 245 indx_t index; /* the index on the page */ 246 } EPG; 247 248 /* 249 * About cursors. The cursor (and the page that contained the key/data pair 250 * that it referenced) can be deleted, which makes things a bit tricky. If 251 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set 252 * or there simply aren't any duplicates of the key) we copy the key that it 253 * referenced when it's deleted, and reacquire a new cursor key if the cursor 254 * is used again. If there are duplicates keys, we move to the next/previous 255 * key, and set a flag so that we know what happened. NOTE: if duplicate (to 256 * the cursor) keys are added to the tree during this process, it is undefined 257 * if they will be returned or not in a cursor scan. 258 * 259 * The flags determine the possible states of the cursor: 260 * 261 * CURS_INIT The cursor references *something*. 262 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that 263 * we can reacquire the right position in the tree. 264 * CURS_AFTER, CURS_BEFORE 265 * The cursor was deleted, and now references a key/data pair 266 * that has not yet been returned, either before or after the 267 * deleted key/data pair. 268 * XXX 269 * This structure is broken out so that we can eventually offer multiple 270 * cursors as part of the DB interface. 271 */ 272 typedef struct _cursor { 273 EPGNO pg; /* B: Saved tree reference. */ 274 DBT key; /* B: Saved key, or key.data == NULL. */ 275 recno_t rcursor; /* R: recno cursor (1-based) */ 276 277 #define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */ 278 #define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */ 279 #define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */ 280 #define CURS_INIT 0x08 /* RB: Cursor initialized. */ 281 u_int8_t flags; 282 } CURSOR; 283 284 /* 285 * The metadata of the tree. The nrecs field is used only by the RECNO code. 286 * This is because the btree doesn't really need it and it requires that every 287 * put or delete call modify the metadata. 288 */ 289 typedef struct _btmeta { 290 u_int32_t magic; /* magic number */ 291 u_int32_t version; /* version */ 292 u_int32_t psize; /* page size */ 293 u_int32_t free; /* page number of first free page */ 294 u_int32_t nrecs; /* R: number of records */ 295 296 #define SAVEMETA (B_NODUPS | R_RECNO) 297 u_int32_t flags; /* bt_flags & SAVEMETA */ 298 } BTMETA; 299 300 /* The in-memory btree/recno data structure. */ 301 typedef struct _btree { 302 MPOOL *bt_mp; /* memory pool cookie */ 303 304 DB *bt_dbp; /* pointer to enclosing DB */ 305 306 EPG bt_cur; /* current (pinned) page */ 307 PAGE *bt_pinned; /* page pinned across calls */ 308 309 CURSOR bt_cursor; /* cursor */ 310 311 #define BT_PUSH(t, p, i) { \ 312 t->bt_sp->pgno = p; \ 313 t->bt_sp->index = i; \ 314 ++t->bt_sp; \ 315 } 316 #define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp) 317 #define BT_CLR(t) (t->bt_sp = t->bt_stack) 318 EPGNO bt_stack[50]; /* stack of parent pages */ 319 EPGNO *bt_sp; /* current stack pointer */ 320 321 DBT bt_rkey; /* returned key */ 322 DBT bt_rdata; /* returned data */ 323 324 int bt_fd; /* tree file descriptor */ 325 326 pgno_t bt_free; /* next free page */ 327 u_int32_t bt_psize; /* page size */ 328 indx_t bt_ovflsize; /* cut-off for key/data overflow */ 329 int bt_lorder; /* byte order */ 330 /* sorted order */ 331 enum { NOT, BACK, FORWARD } bt_order; 332 EPGNO bt_last; /* last insert */ 333 334 /* B: key comparison function */ 335 int (*bt_cmp)(const DBT *, const DBT *); 336 /* B: prefix comparison function */ 337 size_t (*bt_pfx)(const DBT *, const DBT *); 338 /* R: recno input function */ 339 int (*bt_irec)(struct _btree *, recno_t); 340 341 FILE *bt_rfp; /* R: record FILE pointer */ 342 int bt_rfd; /* R: record file descriptor */ 343 344 caddr_t bt_cmap; /* R: current point in mapped space */ 345 caddr_t bt_smap; /* R: start of mapped space */ 346 caddr_t bt_emap; /* R: end of mapped space */ 347 size_t bt_msize; /* R: size of mapped region. */ 348 349 recno_t bt_nrecs; /* R: number of records */ 350 size_t bt_reclen; /* R: fixed record length */ 351 u_char bt_bval; /* R: delimiting byte/pad character */ 352 353 /* 354 * NB: 355 * B_NODUPS and R_RECNO are stored on disk, and may not be changed. 356 */ 357 #define B_INMEM 0x00001 /* in-memory tree */ 358 #define B_METADIRTY 0x00002 /* need to write metadata */ 359 #define B_MODIFIED 0x00004 /* tree modified */ 360 #define B_NEEDSWAP 0x00008 /* if byte order requires swapping */ 361 #define B_RDONLY 0x00010 /* read-only tree */ 362 363 #define B_NODUPS 0x00020 /* no duplicate keys permitted */ 364 #define R_RECNO 0x00080 /* record oriented tree */ 365 366 #define R_CLOSEFP 0x00040 /* opened a file pointer */ 367 #define R_EOF 0x00100 /* end of input file reached. */ 368 #define R_FIXLEN 0x00200 /* fixed length records */ 369 #define R_MEMMAPPED 0x00400 /* memory mapped file. */ 370 #define R_INMEM 0x00800 /* in-memory file */ 371 #define R_MODIFIED 0x01000 /* modified file */ 372 #define R_RDONLY 0x02000 /* read-only file */ 373 374 #define B_DB_LOCK 0x04000 /* DB_LOCK specified. */ 375 #define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */ 376 #define B_DB_TXN 0x10000 /* DB_TXN specified. */ 377 u_int32_t flags; 378 } BTREE; 379 380 #include "extern.h" 381