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