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#ifndef MINCACHE
48#define MINCACHE (5) /* Minimum cached pages */
49#endif
50#define MINPSIZE (512) /* Minimum page size */
51#ifndef DEFPSIZE
52#define DEFPSIZE (4096) /* Default page size */
53#endif
54
55/*
56 * Page 0 of a btree file contains a copy of the meta-data. This page is also
57 * used as an out-of-band page, i.e. page pointers that point to nowhere point
58 * to page 0. Page 1 is the root of the btree.
59 */
60#define P_INVALID 0 /* Invalid tree page number. */
61#define P_META 0 /* Tree metadata page number. */
62#define P_ROOT 1 /* Tree root page number. */
63
64/*
65 * There are five page layouts in the btree: btree internal pages (BINTERNAL),
66 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
67 * (RLEAF) and overflow pages. All five page types have a page header (PAGE).
68 * This implementation requires that values within structures NOT be padded.
69 * (ANSI C permits random padding.) If your compiler pads randomly you'll have
70 * to do some work to get this package to run.
71 */
72typedef struct _page {
73 pgno_t pgno; /* this page's page number */
74 pgno_t prevpg; /* left sibling */
75 pgno_t nextpg; /* right sibling */
76
77#define P_BINTERNAL 0x01 /* btree internal page */
78#define P_BLEAF 0x02 /* leaf page */
79#define P_OVERFLOW 0x04 /* overflow page */
80#define P_RINTERNAL 0x08 /* recno internal page */
81#define P_RLEAF 0x10 /* leaf page */
82#define P_TYPE 0x1f /* type mask */
83#define P_PRESERVE 0x20 /* never delete this chain of pages */
84 u_int32_t flags;
85
86 indx_t lower; /* lower bound of free space on page */
87 indx_t upper; /* upper bound of free space on page */
88 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */
89} PAGE;
90
91/* First and next index. */
92#define BTDATAOFF \
93 (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \
94 sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
95#define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
96
97/*
98 * For pages other than overflow pages, there is an array of offsets into the
99 * rest of the page immediately following the page header. Each offset is to
100 * an item which is unique to the type of page. The h_lower offset is just
101 * past the last filled-in index. The h_upper offset is the first item on the
102 * page. Offsets are from the beginning of the page.
103 *
104 * If an item is too big to store on a single page, a flag is set and the item
105 * is a { page, size } pair such that the page is the first page of an overflow
106 * chain with size bytes of item. Overflow pages are simply bytes without any
107 * external structure.
108 *
109 * The page number and size fields in the items are pgno_t-aligned so they can
110 * be manipulated without copying. (This presumes that 32 bit items can be
111 * manipulated on this system.)
112 */
113#define LALIGN(n) (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
114#define NOVFLSIZE (sizeof(pgno_t) + sizeof(u_int32_t))
115
116/*
117 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno}
118 * pairs, such that the key compares less than or equal to all of the records
119 * on that page. For a tree without duplicate keys, an internal page with two
120 * consecutive keys, a and b, will have all records greater than or equal to a
121 * and less than b stored on the page associated with a. Duplicate keys are
122 * somewhat special and can cause duplicate internal and leaf page records and
123 * some minor modifications of the above rule.
124 */
125typedef struct _binternal {
126 u_int32_t ksize; /* key size */
127 pgno_t pgno; /* page number stored on */
128#define P_BIGDATA 0x01 /* overflow data */
129#define P_BIGKEY 0x02 /* overflow key */
130 u_char flags;
131 char bytes[1]; /* data */
132} BINTERNAL;
133
134/* Get the page's BINTERNAL structure at index indx. */
135#define GETBINTERNAL(pg, indx) \
136 ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
137
138/* Get the number of bytes in the entry. */
139#define NBINTERNAL(len) \
140 LALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
141
142/* Copy a BINTERNAL entry to the page. */
143#define WR_BINTERNAL(p, size, pgno, flags) { \
144 *(u_int32_t *)p = size; \
145 p += sizeof(u_int32_t); \
146 *(pgno_t *)p = pgno; \
147 p += sizeof(pgno_t); \
148 *(u_char *)p = flags; \
149 p += sizeof(u_char); \
150}
151
152/*
153 * For the recno internal pages, the item is a page number with the number of
154 * keys found on that page and below.
155 */
156typedef struct _rinternal {
157 recno_t nrecs; /* number of records */
158 pgno_t pgno; /* page number stored below */
159} RINTERNAL;
160
161/* Get the page's RINTERNAL structure at index indx. */
162#define GETRINTERNAL(pg, indx) \
163 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
164
165/* Get the number of bytes in the entry. */
166#define NRINTERNAL \
167 LALIGN(sizeof(recno_t) + sizeof(pgno_t))
168
169/* Copy a RINTERAL entry to the page. */
170#define WR_RINTERNAL(p, nrecs, pgno) { \
171 *(recno_t *)p = nrecs; \
172 p += sizeof(recno_t); \
173 *(pgno_t *)p = pgno; \
174}
175
176/* For the btree leaf pages, the item is a key and data pair. */
177typedef struct _bleaf {
178 u_int32_t ksize; /* size of key */
179 u_int32_t dsize; /* size of data */
180 u_char flags; /* P_BIGDATA, P_BIGKEY */
181 char bytes[1]; /* data */
182} BLEAF;
183
184/* Get the page's BLEAF structure at index indx. */
185#define GETBLEAF(pg, indx) \
186 ((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
187
188/* Get the number of bytes in the entry. */
189#define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize)
190
191/* Get the number of bytes in the user's key/data pair. */
192#define NBLEAFDBT(ksize, dsize) \
193 LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \
194 (ksize) + (dsize))
195
196/* Copy a BLEAF entry to the page. */
197#define WR_BLEAF(p, key, data, flags) { \
198 *(u_int32_t *)p = key->size; \
199 p += sizeof(u_int32_t); \
200 *(u_int32_t *)p = data->size; \
201 p += sizeof(u_int32_t); \
202 *(u_char *)p = flags; \
203 p += sizeof(u_char); \
204 memmove(p, key->data, key->size); \
205 p += key->size; \
206 memmove(p, data->data, data->size); \
207}
208
209/* For the recno leaf pages, the item is a data entry. */
210typedef struct _rleaf {
211 u_int32_t dsize; /* size of data */
212 u_char flags; /* P_BIGDATA */
213 char bytes[1];
214} RLEAF;
215
216/* Get the page's RLEAF structure at index indx. */
217#define GETRLEAF(pg, indx) \
218 ((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
219
220/* Get the number of bytes in the entry. */
221#define NRLEAF(p) NRLEAFDBT((p)->dsize)
222
223/* Get the number of bytes from the user's data. */
224#define NRLEAFDBT(dsize) \
225 LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
226
227/* Copy a RLEAF entry to the page. */
228#define WR_RLEAF(p, data, flags) { \
229 *(u_int32_t *)p = data->size; \
230 p += sizeof(u_int32_t); \
231 *(u_char *)p = flags; \
232 p += sizeof(u_char); \
233 memmove(p, data->data, data->size); \
234}
235
236/*
237 * A record in the tree is either a pointer to a page and an index in the page
238 * or a page number and an index. These structures are used as a cursor, stack
239 * entry and search returns as well as to pass records to other routines.
240 *
241 * One comment about searches. Internal page searches must find the largest
242 * record less than key in the tree so that descents work. Leaf page searches
243 * must find the smallest record greater than key so that the returned index
244 * is the record's correct position for insertion.
245 */
246typedef struct _epgno {
247 pgno_t pgno; /* the page number */
248 indx_t index; /* the index on the page */
249} EPGNO;
250
251typedef struct _epg {
252 PAGE *page; /* the (pinned) page */
253 indx_t index; /* the index on the page */
254} EPG;
255
256/*
257 * About cursors. The cursor (and the page that contained the key/data pair
258 * that it referenced) can be deleted, which makes things a bit tricky. If
259 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
260 * or there simply aren't any duplicates of the key) we copy the key that it
261 * referenced when it's deleted, and reacquire a new cursor key if the cursor
262 * is used again. If there are duplicates keys, we move to the next/previous
263 * key, and set a flag so that we know what happened. NOTE: if duplicate (to
264 * the cursor) keys are added to the tree during this process, it is undefined
265 * if they will be returned or not in a cursor scan.
266 *
267 * The flags determine the possible states of the cursor:
268 *
269 * CURS_INIT The cursor references *something*.
270 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
271 * we can reacquire the right position in the tree.
272 * CURS_AFTER, CURS_BEFORE
273 * The cursor was deleted, and now references a key/data pair
274 * that has not yet been returned, either before or after the
275 * deleted key/data pair.
276 * XXX
277 * This structure is broken out so that we can eventually offer multiple
278 * cursors as part of the DB interface.
279 */
280typedef struct _cursor {
281 EPGNO pg; /* B: Saved tree reference. */
282 DBT key; /* B: Saved key, or key.data == NULL. */
283 recno_t rcursor; /* R: recno cursor (1-based) */
284
285#define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */
286#define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */
287#define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */
288#define CURS_INIT 0x08 /* RB: Cursor initialized. */
289 u_int8_t flags;
290} CURSOR;
291
292/*
293 * The metadata of the tree. The nrecs field is used only by the RECNO code.
294 * This is because the btree doesn't really need it and it requires that every
295 * put or delete call modify the metadata.
296 */
297typedef struct _btmeta {
298 u_int32_t magic; /* magic number */
299 u_int32_t version; /* version */
300 u_int32_t psize; /* page size */
301 u_int32_t free; /* page number of first free page */
302 u_int32_t nrecs; /* R: number of records */
303
304#define SAVEMETA (B_NODUPS | R_RECNO)
305 u_int32_t flags; /* bt_flags & SAVEMETA */
306} BTMETA;
307
308/* The in-memory btree/recno data structure. */
309typedef struct _btree {
310 MPOOL *bt_mp; /* memory pool cookie */
311
312 DB *bt_dbp; /* pointer to enclosing DB */
313
314 EPG bt_cur; /* current (pinned) page */
315 PAGE *bt_pinned; /* page pinned across calls */
316
317 CURSOR bt_cursor; /* cursor */
318
319#define BT_PUSH(t, p, i) { \
320 t->bt_sp->pgno = p; \
321 t->bt_sp->index = i; \
322 ++t->bt_sp; \
323}
324#define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
325#define BT_CLR(t) (t->bt_sp = t->bt_stack)
326 EPGNO bt_stack[50]; /* stack of parent pages */
327 EPGNO *bt_sp; /* current stack pointer */
328
329 DBT bt_rkey; /* returned key */
330 DBT bt_rdata; /* returned data */
331
332 virt_fd_t bt_fd; /* tree virtual file descriptor */
333
334 pgno_t bt_free; /* next free page */
335 u_int32_t bt_psize; /* page size */
336 indx_t bt_ovflsize; /* cut-off for key/data overflow */
337 int bt_lorder; /* byte order */
338 /* sorted order */
339 enum { NOT, BACK, FORWARD } bt_order;
340 EPGNO bt_last; /* last insert */
341
342 /* B: key comparison function */
343 int (*bt_cmp) __P((const DBT *, const DBT *));
344 /* B: prefix comparison function */
345 size_t (*bt_pfx) __P((const DBT *, const DBT *));
346 /* R: recno input function */
347 int (*bt_irec) __P((struct _btree *, recno_t));
348
349 FILE *bt_rfp; /* R: record FILE pointer */
350 int bt_rfd; /* R: record file descriptor */
351
352 caddr_t bt_cmap; /* R: current point in mapped space */
353 caddr_t bt_smap; /* R: start of mapped space */
354 caddr_t bt_emap; /* R: end of mapped space */
355 size_t bt_msize; /* R: size of mapped region. */
356
357 recno_t bt_nrecs; /* R: number of records */
358 size_t bt_reclen; /* R: fixed record length */
359 u_char bt_bval; /* R: delimiting byte/pad character */
360
361/*
362 * NB:
363 * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
364 */
365#define B_INMEM 0x00001 /* in-memory tree */
366#define B_METADIRTY 0x00002 /* need to write metadata */
367#define B_MODIFIED 0x00004 /* tree modified */
368#define B_NEEDSWAP 0x00008 /* if byte order requires swapping */
369#define B_RDONLY 0x00010 /* read-only tree */
370
371#define B_NODUPS 0x00020 /* no duplicate keys permitted */
372#define R_RECNO 0x00080 /* record oriented tree */
373
374#define R_CLOSEFP 0x00040 /* opened a file pointer */
375#define R_EOF 0x00100 /* end of input file reached. */
376#define R_FIXLEN 0x00200 /* fixed length records */
377#define R_MEMMAPPED 0x00400 /* memory mapped file. */
378#define R_INMEM 0x00800 /* in-memory file */
379#define R_MODIFIED 0x01000 /* modified file */
380#define R_RDONLY 0x02000 /* read-only file */
381
382#define B_DB_LOCK 0x04000 /* DB_LOCK specified. */
383#define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */
384#define B_DB_TXN 0x10000 /* DB_TXN specified. */
385 u_int32_t flags;
386} BTREE;
387
388#include "extern.h"
389