1 /* $NetBSD: btree.h,v 1.18 2022/04/19 20:32:15 rillig Exp $ */
2
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 * @(#)btree.h 8.11 (Berkeley) 8/17/94
35 */
36
37 #if HAVE_NBTOOL_CONFIG_H
38 #include "nbtool_config.h"
39 #endif
40
41 /* Macros to set/clear/test flags. */
42 #define F_SET(p, f) (p)->flags |= (f)
43 #define F_CLR(p, f) (p)->flags &= ~(f)
44 #define F_ISSET(p, f) ((p)->flags & (f))
45
46 #include <mpool.h>
47
48 #define DEFMINKEYPAGE (2) /* Minimum keys per page */
49 #define MINCACHE (5) /* Minimum cached pages */
50 #define MINPSIZE (512) /* Minimum page size */
51
52 /*
53 * Page 0 of a btree file contains a copy of the meta-data. This page is also
54 * used as an out-of-band page, i.e. page pointers that point to nowhere point
55 * to page 0. Page 1 is the root of the btree.
56 */
57 #define P_INVALID 0 /* Invalid tree page number. */
58 #define P_META 0 /* Tree metadata page number. */
59 #define P_ROOT 1 /* Tree root page number. */
60
61 /*
62 * There are five page layouts in the btree: btree internal pages (BINTERNAL),
63 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
64 * (RLEAF) and overflow pages. All five page types have a page header (PAGE).
65 * This implementation requires that values within structures NOT be padded.
66 * (ANSI C permits random padding.) If your compiler pads randomly you'll have
67 * to do some work to get this package to run.
68 */
69 typedef struct _page {
70 pgno_t pgno; /* this page's page number */
71 pgno_t prevpg; /* left sibling */
72 pgno_t nextpg; /* right sibling */
73
74 #define P_BINTERNAL 0x01 /* btree internal page */
75 #define P_BLEAF 0x02 /* leaf page */
76 #define P_OVERFLOW 0x04 /* overflow page */
77 #define P_RINTERNAL 0x08 /* recno internal page */
78 #define P_RLEAF 0x10 /* leaf page */
79 #define P_TYPE 0x1f /* type mask */
80 #define P_PRESERVE 0x20 /* never delete this chain of pages */
81 uint32_t flags;
82
83 indx_t lower; /* lower bound of free space on page */
84 indx_t upper; /* upper bound of free space on page */
85 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */
86 } PAGE;
87
88 /* First and next index. */
89 #define BTDATAOFF \
90 (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \
91 sizeof(uint32_t) + sizeof(indx_t) + sizeof(indx_t))
92
93 #define _NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
94 #ifdef _DIAGNOSTIC
95 static __inline indx_t
NEXTINDEX(const PAGE * p)96 NEXTINDEX(const PAGE *p) {
97 size_t x = _NEXTINDEX(p);
98 _DBFIT(x, indx_t);
99 return (indx_t)x;
100 }
101 #else
102 #define NEXTINDEX(p) (indx_t)_NEXTINDEX(p)
103 #endif
104
105 /*
106 * For pages other than overflow pages, there is an array of offsets into the
107 * rest of the page immediately following the page header. Each offset is to
108 * an item which is unique to the type of page. The h_lower offset is just
109 * past the last filled-in index. The h_upper offset is the first item on the
110 * page. Offsets are from the beginning of the page.
111 *
112 * If an item is too big to store on a single page, a flag is set and the item
113 * is a { page, size } pair such that the page is the first page of an overflow
114 * chain with size bytes of item. Overflow pages are simply bytes without any
115 * external structure.
116 *
117 * The page number and size fields in the items are pgno_t-aligned so they can
118 * be manipulated without copying. (This presumes that 32 bit items can be
119 * manipulated on this system.)
120 */
121 #define BTLALIGN(n) (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
122 #define NOVFLSIZE (sizeof(pgno_t) + sizeof(uint32_t))
123
124 /*
125 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno}
126 * pairs, such that the key compares less than or equal to all of the records
127 * on that page. For a tree without duplicate keys, an internal page with two
128 * consecutive keys, a and b, will have all records greater than or equal to a
129 * and less than b stored on the page associated with a. Duplicate keys are
130 * somewhat special and can cause duplicate internal and leaf page records and
131 * some minor modifications of the above rule.
132 */
133 typedef struct _binternal {
134 uint32_t ksize; /* key size */
135 pgno_t pgno; /* page number stored on */
136 #define P_BIGDATA 0x01 /* overflow data */
137 #define P_BIGKEY 0x02 /* overflow key */
138 uint8_t flags;
139 char bytes[1]; /* data */
140 } BINTERNAL;
141
142 /* Get the page's BINTERNAL structure at index indx. */
143 #define GETBINTERNAL(pg, indx) \
144 ((BINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
145
146 /* Get the number of bytes in the entry. */
147 #define _NBINTERNAL(len) \
148 BTLALIGN(sizeof(uint32_t) + sizeof(pgno_t) + sizeof(uint8_t) + (len))
149 #ifdef _DIAGNOSTIC
150 static __inline uint32_t
NBINTERNAL(uint32_t len)151 NBINTERNAL(uint32_t len) {
152 size_t x = _NBINTERNAL(len);
153 _DBFIT(x, uint32_t);
154 return (uint32_t)x;
155 }
156 #else
157 #define NBINTERNAL(len) (uint32_t)_NBINTERNAL(len)
158 #endif
159
160 /* Copy a BINTERNAL entry to the page. */
161 #define WR_BINTERNAL(p, size, pgno, flags) do { \
162 _DBFIT(size, uint32_t); \
163 *(uint32_t *)(void *)p = (uint32_t)size; \
164 p += sizeof(uint32_t); \
165 *(pgno_t *)(void *)p = pgno; \
166 p += sizeof(pgno_t); \
167 *(uint8_t *)(void *)p = flags; \
168 p += sizeof(uint8_t); \
169 } while (0)
170
171 /*
172 * For the recno internal pages, the item is a page number with the number of
173 * keys found on that page and below.
174 */
175 typedef struct _rinternal {
176 recno_t nrecs; /* number of records */
177 pgno_t pgno; /* page number stored below */
178 } RINTERNAL;
179
180 /* Get the page's RINTERNAL structure at index indx. */
181 #define GETRINTERNAL(pg, indx) \
182 ((RINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
183
184 /* Get the number of bytes in the entry. */
185 #define NRINTERNAL \
186 BTLALIGN(sizeof(recno_t) + sizeof(pgno_t))
187
188 /* Copy a RINTERNAL entry to the page. */
189 #define WR_RINTERNAL(p, nrecs, pgno) do { \
190 *(recno_t *)(void *)p = nrecs; \
191 p += sizeof(recno_t); \
192 *(pgno_t *)(void *)p = pgno; \
193 } while (0)
194
195 /* For the btree leaf pages, the item is a key and data pair. */
196 typedef struct _bleaf {
197 uint32_t ksize; /* size of key */
198 uint32_t dsize; /* size of data */
199 uint8_t flags; /* P_BIGDATA, P_BIGKEY */
200 char bytes[1]; /* data */
201 } BLEAF;
202
203 /* Get the page's BLEAF structure at index indx. */
204 #define GETBLEAF(pg, indx) \
205 ((BLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
206
207
208 /* Get the number of bytes in the user's key/data pair. */
209 #define _NBLEAFDBT(ksize, dsize) \
210 BTLALIGN(sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint8_t) + \
211 (ksize) + (dsize))
212 #ifdef _DIAGNOSTIC
213 static __inline uint32_t
NBLEAFDBT(size_t k,size_t d)214 NBLEAFDBT(size_t k, size_t d) {
215 size_t x = _NBLEAFDBT(k, d);
216 _DBFIT(x, uint32_t);
217 return (uint32_t)x;
218 }
219 #else
220 #define NBLEAFDBT(p, q) (uint32_t)_NBLEAFDBT(p, q)
221 #endif
222
223 /* Get the number of bytes in the entry. */
224 #define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize)
225
226 /* Copy a BLEAF entry to the page. */
227 #define WR_BLEAF(p, key, data, flags) do { \
228 _DBFIT(key->size, uint32_t); \
229 *(uint32_t *)(void *)p = (uint32_t)key->size; \
230 p += sizeof(uint32_t); \
231 _DBFIT(data->size, uint32_t); \
232 *(uint32_t *)(void *)p = (uint32_t)data->size; \
233 p += sizeof(uint32_t); \
234 *(uint8_t *)(void *)p = flags; \
235 p += sizeof(uint8_t); \
236 (void)memmove(p, key->data, key->size); \
237 p += key->size; \
238 (void)memmove(p, data->data, data->size); \
239 } while (0)
240
241 /* For the recno leaf pages, the item is a data entry. */
242 typedef struct _rleaf {
243 uint32_t dsize; /* size of data */
244 uint8_t flags; /* P_BIGDATA */
245 char bytes[1];
246 } RLEAF;
247
248 /* Get the page's RLEAF structure at index indx. */
249 #define GETRLEAF(pg, indx) \
250 ((RLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
251
252 #define _NRLEAFDBT(dsize) \
253 BTLALIGN(sizeof(uint32_t) + sizeof(uint8_t) + (dsize))
254
255 #ifdef _DIAGNOSTIC
256 static __inline uint32_t
NRLEAFDBT(size_t d)257 NRLEAFDBT(size_t d) {
258 size_t x = _NRLEAFDBT(d);
259 _DBFIT(x, uint32_t);
260 return (uint32_t)x;
261 }
262 #else
263 #define NRLEAFDBT(d) (uint32_t)_NRLEAFDBT(d)
264 #endif
265
266 /* Get the number of bytes in the entry. */
267 #define NRLEAF(p) NRLEAFDBT((p)->dsize)
268
269 /* Get the number of bytes from the user's data. */
270
271 /* Copy a RLEAF entry to the page. */
272 #define WR_RLEAF(p, data, flags) do { \
273 _DBFIT(data->size, uint32_t); \
274 *(uint32_t *)(void *)p = (uint32_t)data->size; \
275 p += sizeof(uint32_t); \
276 *(uint8_t *)(void *)p = flags; \
277 p += sizeof(uint8_t); \
278 memmove(p, data->data, data->size); \
279 } while (0)
280
281 /*
282 * A record in the tree is either a pointer to a page and an index in the page
283 * or a page number and an index. These structures are used as a cursor, stack
284 * entry and search returns as well as to pass records to other routines.
285 *
286 * One comment about searches. Internal page searches must find the largest
287 * record less than key in the tree so that descents work. Leaf page searches
288 * must find the smallest record greater than key so that the returned index
289 * is the record's correct position for insertion.
290 */
291 typedef struct _epgno {
292 pgno_t pgno; /* the page number */
293 indx_t index; /* the index on the page */
294 } EPGNO;
295
296 typedef struct _epg {
297 PAGE *page; /* the (pinned) page */
298 indx_t index; /* the index on the page */
299 } EPG;
300
301 /*
302 * About cursors. The cursor (and the page that contained the key/data pair
303 * that it referenced) can be deleted, which makes things a bit tricky. If
304 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
305 * or there simply aren't any duplicates of the key) we copy the key that it
306 * referenced when it's deleted, and reacquire a new cursor key if the cursor
307 * is used again. If there are duplicates keys, we move to the next/previous
308 * key, and set a flag so that we know what happened. NOTE: if duplicate (to
309 * the cursor) keys are added to the tree during this process, it is undefined
310 * if they will be returned or not in a cursor scan.
311 *
312 * The flags determine the possible states of the cursor:
313 *
314 * CURS_INIT The cursor references *something*.
315 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
316 * we can reacquire the right position in the tree.
317 * CURS_AFTER, CURS_BEFORE
318 * The cursor was deleted, and now references a key/data pair
319 * that has not yet been returned, either before or after the
320 * deleted key/data pair.
321 * XXX
322 * This structure is broken out so that we can eventually offer multiple
323 * cursors as part of the DB interface.
324 */
325 typedef struct _cursor {
326 EPGNO pg; /* B: Saved tree reference. */
327 DBT key; /* B: Saved key, or key.data == NULL. */
328 recno_t rcursor; /* R: recno cursor (1-based) */
329
330 #define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */
331 #define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */
332 #define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */
333 #define CURS_INIT 0x08 /* RB: Cursor initialized. */
334 uint8_t flags;
335 } CURSOR;
336
337 /*
338 * The metadata of the tree. The nrecs field is used only by the RECNO code.
339 * This is because the btree doesn't really need it and it requires that every
340 * put or delete call modify the metadata.
341 */
342 typedef struct _btmeta {
343 uint32_t magic; /* magic number */
344 uint32_t version; /* version */
345 uint32_t psize; /* page size */
346 uint32_t free; /* page number of first free page */
347 uint32_t nrecs; /* R: number of records */
348
349 #define SAVEMETA (B_NODUPS | R_RECNO)
350 uint32_t flags; /* bt_flags & SAVEMETA */
351 } BTMETA;
352
353 /* The in-memory btree/recno data structure. */
354 typedef struct _btree {
355 MPOOL *bt_mp; /* memory pool cookie */
356
357 DB *bt_dbp; /* pointer to enclosing DB */
358
359 EPG bt_cur; /* current (pinned) page */
360 PAGE *bt_pinned; /* page pinned across calls */
361
362 CURSOR bt_cursor; /* cursor */
363
364 #define BT_PUSH(t, p, i) { \
365 t->bt_sp->pgno = p; \
366 t->bt_sp->index = i; \
367 ++t->bt_sp; \
368 }
369 #define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
370 #define BT_CLR(t) (t->bt_sp = t->bt_stack)
371 EPGNO bt_stack[50]; /* stack of parent pages */
372 EPGNO *bt_sp; /* current stack pointer */
373
374 DBT bt_rkey; /* returned key */
375 DBT bt_rdata; /* returned data */
376
377 int bt_fd; /* tree file descriptor */
378
379 pgno_t bt_free; /* next free page */
380 uint32_t bt_psize; /* page size */
381 indx_t bt_ovflsize; /* cut-off for key/data overflow */
382 int bt_lorder; /* byte order */
383 /* sorted order */
384 enum { NOT, BACK, FORWARD } bt_order;
385 EPGNO bt_last; /* last insert */
386
387 /* B: key comparison function */
388 int (*bt_cmp)(const DBT *, const DBT *);
389 /* B: prefix comparison function */
390 size_t (*bt_pfx)(const DBT *, const DBT *);
391 /* R: recno input function */
392 int (*bt_irec)(struct _btree *, recno_t);
393
394 FILE *bt_rfp; /* R: record FILE pointer */
395 int bt_rfd; /* R: record file descriptor */
396
397 caddr_t bt_cmap; /* R: current point in mapped space */
398 caddr_t bt_smap; /* R: start of mapped space */
399 caddr_t bt_emap; /* R: end of mapped space */
400 size_t bt_msize; /* R: size of mapped region. */
401
402 recno_t bt_nrecs; /* R: number of records */
403 size_t bt_reclen; /* R: fixed record length */
404 uint8_t bt_bval; /* R: delimiting byte/pad character */
405
406 /*
407 * NB:
408 * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
409 */
410 #define B_INMEM 0x00001 /* in-memory tree */
411 #define B_METADIRTY 0x00002 /* need to write metadata */
412 #define B_MODIFIED 0x00004 /* tree modified */
413 #define B_NEEDSWAP 0x00008 /* if byte order requires swapping */
414 #define B_RDONLY 0x00010 /* read-only tree */
415
416 #define B_NODUPS 0x00020 /* no duplicate keys permitted */
417 #define R_RECNO 0x00080 /* record oriented tree */
418
419 #define R_CLOSEFP 0x00040 /* opened a file pointer */
420 #define R_EOF 0x00100 /* end of input file reached. */
421 #define R_FIXLEN 0x00200 /* fixed length records */
422 #define R_MEMMAPPED 0x00400 /* memory mapped file. */
423 #define R_INMEM 0x00800 /* in-memory file */
424 #define R_MODIFIED 0x01000 /* modified file */
425 #define R_RDONLY 0x02000 /* read-only file */
426
427 #define B_DB_LOCK 0x04000 /* DB_LOCK specified. */
428 #define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */
429 #define B_DB_TXN 0x10000 /* DB_TXN specified. */
430 uint32_t flags;
431 } BTREE;
432
433 #include "extern.h"
434