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