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btree.h
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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 mpool_open __mpool_open
47#define mpool_filter __mpool_filter
48#define mpool_new __mpool_new
49#define mpool_get __mpool_get
50#define mpool_put __mpool_put
51#define mpool_sync __mpool_sync
52#define mpool_close __mpool_close
53
54#define DEFMINKEYPAGE (2) /* Minimum keys per page */
55#define MINCACHE (5) /* Minimum cached pages */
56#define MINPSIZE (512) /* Minimum page size */
57
58/*
59 * Page 0 of a btree file contains a copy of the meta-data. This page is also
60 * used as an out-of-band page, i.e. page pointers that point to nowhere point
61 * to page 0. Page 1 is the root of the btree.
62 */
63#define P_INVALID 0 /* Invalid tree page number. */
64#define P_META 0 /* Tree metadata page number. */
65#define P_ROOT 1 /* Tree root page number. */
66
67/*
68 * There are five page layouts in the btree: btree internal pages (BINTERNAL),
69 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
70 * (RLEAF) and overflow pages. All five page types have a page header (PAGE).
71 * This implementation requires that values within structures NOT be padded.
72 * (ANSI C permits random padding.) If your compiler pads randomly you'll have
73 * to do some work to get this package to run.
74 */
75typedef struct _page {
76 pgno_t pgno; /* this page's page number */
77 pgno_t prevpg; /* left sibling */
78 pgno_t nextpg; /* right sibling */
79
80#define P_BINTERNAL 0x01 /* btree internal page */
81#define P_BLEAF 0x02 /* leaf page */
82#define P_OVERFLOW 0x04 /* overflow page */
83#define P_RINTERNAL 0x08 /* recno internal page */
84#define P_RLEAF 0x10 /* leaf page */
85#define P_TYPE 0x1f /* type mask */
86#define P_PRESERVE 0x20 /* never delete this chain of pages */
88
89 indx_t lower; /* lower bound of free space on page */
90 indx_t upper; /* upper bound of free space on page */
91 indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */
93
94/* First and next index. */
95#define BTDATAOFF \
96 (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \
97 sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
98#define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
99
100/*
101 * For pages other than overflow pages, there is an array of offsets into the
102 * rest of the page immediately following the page header. Each offset is to
103 * an item which is unique to the type of page. The h_lower offset is just
104 * past the last filled-in index. The h_upper offset is the first item on the
105 * page. Offsets are from the beginning of the page.
106 *
107 * If an item is too big to store on a single page, a flag is set and the item
108 * is a { page, size } pair such that the page is the first page of an overflow
109 * chain with size bytes of item. Overflow pages are simply bytes without any
110 * external structure.
111 *
112 * The page number and size fields in the items are pgno_t-aligned so they can
113 * be manipulated without copying. (This presumes that 32 bit items can be
114 * manipulated on this system.)
115 */
116#define LALIGN(n) (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
117#define NOVFLSIZE (sizeof(pgno_t) + sizeof(u_int32_t))
118
119/*
120 * For the btree internal pages, the item is a key. BINTERNALs are {key, pgno}
121 * pairs, such that the key compares less than or equal to all of the records
122 * on that page. For a tree without duplicate keys, an internal page with two
123 * consecutive keys, a and b, will have all records greater than or equal to a
124 * and less than b stored on the page associated with a. Duplicate keys are
125 * somewhat special and can cause duplicate internal and leaf page records and
126 * some minor modifications of the above rule.
127 */
128typedef struct _binternal {
129 u_int32_t ksize; /* key size */
130 pgno_t pgno; /* page number stored on */
131#define P_BIGDATA 0x01 /* overflow data */
132#define P_BIGKEY 0x02 /* overflow key */
133 u_char flags;
134 char bytes[1]; /* data */
136
137/* Get the page's BINTERNAL structure at index indx. */
138#define GETBINTERNAL(pg, indx) \
139 ((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
140
141/* Get the number of bytes in the entry. */
142#define NBINTERNAL(len) \
143 LALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
144
145/* Copy a BINTERNAL entry to the page. */
146#define WR_BINTERNAL(p, size, pgno, flags) { \
147 *(u_int32_t *)p = size; \
148 p += sizeof(u_int32_t); \
149 *(pgno_t *)p = pgno; \
150 p += sizeof(pgno_t); \
151 *(u_char *)p = flags; \
152 p += sizeof(u_char); \
153}
154
155/*
156 * For the recno internal pages, the item is a page number with the number of
157 * keys found on that page and below.
158 */
159typedef struct _rinternal {
160 recno_t nrecs; /* number of records */
161 pgno_t pgno; /* page number stored below */
163
164/* Get the page's RINTERNAL structure at index indx. */
165#define GETRINTERNAL(pg, indx) \
166 ((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
167
168/* Get the number of bytes in the entry. */
169#define NRINTERNAL \
170 LALIGN(sizeof(recno_t) + sizeof(pgno_t))
171
172/* Copy a RINTERNAL entry to the page. */
173#define WR_RINTERNAL(p, nrecs, pgno) { \
174 *(recno_t *)p = nrecs; \
175 p += sizeof(recno_t); \
176 *(pgno_t *)p = pgno; \
177}
178
179/* For the btree leaf pages, the item is a key and data pair. */
180typedef struct _bleaf {
181 u_int32_t ksize; /* size of key */
182 u_int32_t dsize; /* size of data */
183 u_char flags; /* P_BIGDATA, P_BIGKEY */
184 char bytes[1]; /* data */
186
187/* Get the page's BLEAF structure at index indx. */
188#define GETBLEAF(pg, indx) \
189 ((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
190
191/* Get the number of bytes in the entry. */
192#define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize)
193
194/* Get the number of bytes in the user's key/data pair. */
195#define NBLEAFDBT(ksize, dsize) \
196 LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \
197 (ksize) + (dsize))
198
199/* Copy a BLEAF entry to the page. */
200#define WR_BLEAF(p, key, data, flags) { \
201 *(u_int32_t *)p = key->size; \
202 p += sizeof(u_int32_t); \
203 *(u_int32_t *)p = data->size; \
204 p += sizeof(u_int32_t); \
205 *(u_char *)p = flags; \
206 p += sizeof(u_char); \
207 memmove(p, key->data, key->size); \
208 p += key->size; \
209 memmove(p, data->data, data->size); \
210}
211
212/* For the recno leaf pages, the item is a data entry. */
213typedef struct _rleaf {
214 u_int32_t dsize; /* size of data */
215 u_char flags; /* P_BIGDATA */
216 char bytes[1];
218
219/* Get the page's RLEAF structure at index indx. */
220#define GETRLEAF(pg, indx) \
221 ((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
222
223/* Get the number of bytes in the entry. */
224#define NRLEAF(p) NRLEAFDBT((p)->dsize)
225
226/* Get the number of bytes from the user's data. */
227#define NRLEAFDBT(dsize) \
228 LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
229
230/* Copy a RLEAF entry to the page. */
231#define WR_RLEAF(p, data, flags) { \
232 *(u_int32_t *)p = data->size; \
233 p += sizeof(u_int32_t); \
234 *(u_char *)p = flags; \
235 p += sizeof(u_char); \
236 memmove(p, data->data, data->size); \
237}
238
239/*
240 * A record in the tree is either a pointer to a page and an index in the page
241 * or a page number and an index. These structures are used as a cursor, stack
242 * entry and search returns as well as to pass records to other routines.
243 *
244 * One comment about searches. Internal page searches must find the largest
245 * record less than key in the tree so that descents work. Leaf page searches
246 * must find the smallest record greater than key so that the returned index
247 * is the record's correct position for insertion.
248 */
249typedef struct _epgno {
250 pgno_t pgno; /* the page number */
251 indx_t index; /* the index on the page */
253
254typedef struct _epg {
255 PAGE *page; /* the (pinned) page */
256 indx_t index; /* the index on the page */
258
259/*
260 * About cursors. The cursor (and the page that contained the key/data pair
261 * that it referenced) can be deleted, which makes things a bit tricky. If
262 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
263 * or there simply aren't any duplicates of the key) we copy the key that it
264 * referenced when it's deleted, and reacquire a new cursor key if the cursor
265 * is used again. If there are duplicates keys, we move to the next/previous
266 * key, and set a flag so that we know what happened. NOTE: if duplicate (to
267 * the cursor) keys are added to the tree during this process, it is undefined
268 * if they will be returned or not in a cursor scan.
269 *
270 * The flags determine the possible states of the cursor:
271 *
272 * CURS_INIT The cursor references *something*.
273 * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
274 * we can reacquire the right position in the tree.
275 * CURS_AFTER, CURS_BEFORE
276 * The cursor was deleted, and now references a key/data pair
277 * that has not yet been returned, either before or after the
278 * deleted key/data pair.
279 * XXX
280 * This structure is broken out so that we can eventually offer multiple
281 * cursors as part of the DB interface.
282 */
283typedef struct _cursor {
284 EPGNO pg; /* B: Saved tree reference. */
285 DBT key; /* B: Saved key, or key.data == NULL. */
286 recno_t rcursor; /* R: recno cursor (1-based) */
287
288#define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */
289#define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */
290#define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */
291#define CURS_INIT 0x08 /* RB: Cursor initialized. */
294
295/*
296 * The metadata of the tree. The nrecs field is used only by the RECNO code.
297 * This is because the btree doesn't really need it and it requires that every
298 * put or delete call modify the metadata.
299 */
300typedef struct _btmeta {
301 u_int32_t magic; /* magic number */
302 u_int32_t version; /* version */
303 u_int32_t psize; /* page size */
304 u_int32_t free; /* page number of first free page */
305 u_int32_t nrecs; /* R: number of records */
306
307#define SAVEMETA (B_NODUPS | R_RECNO)
308 u_int32_t flags; /* bt_flags & SAVEMETA */
310
311/* The in-memory btree/recno data structure. */
312typedef struct _btree {
313 MPOOL *bt_mp; /* memory pool cookie */
314
315 DB *bt_dbp; /* pointer to enclosing DB */
316
317 EPG bt_cur; /* current (pinned) page */
318 PAGE *bt_pinned; /* page pinned across calls */
319
320 CURSOR bt_cursor; /* cursor */
321
322#define BT_PUSH(t, p, i) { \
323 t->bt_sp->pgno = p; \
324 t->bt_sp->index = i; \
325 ++t->bt_sp; \
326}
327#define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
328#define BT_CLR(t) (t->bt_sp = t->bt_stack)
329 EPGNO bt_stack[50]; /* stack of parent pages */
330 EPGNO *bt_sp; /* current stack pointer */
331
332 DBT bt_rkey; /* returned key */
333 DBT bt_rdata; /* returned data */
334
335 int bt_fd; /* tree file descriptor */
336
337 pgno_t bt_free; /* next free page */
338 u_int32_t bt_psize; /* page size */
339 indx_t bt_ovflsize; /* cut-off for key/data overflow */
340 int bt_lorder; /* byte order */
341 /* sorted order */
343 EPGNO bt_last; /* last insert */
344
345 /* B: key comparison function */
346 int (*bt_cmp) __P((const DBT *, const DBT *));
347 /* B: prefix comparison function */
348 size_t (*bt_pfx) __P((const DBT *, const DBT *));
349 /* R: recno input function */
350 int (*bt_irec) __P((struct _btree *, recno_t));
351
352 FILE *bt_rfp; /* R: record FILE pointer */
353 int bt_rfd; /* R: record file descriptor */
354
355 caddr_t bt_cmap; /* R: current point in mapped space */
356 caddr_t bt_smap; /* R: start of mapped space */
357 caddr_t bt_emap; /* R: end of mapped space */
358 size_t bt_msize; /* R: size of mapped region. */
359
360 recno_t bt_nrecs; /* R: number of records */
361 size_t bt_reclen; /* R: fixed record length */
362 u_char bt_bval; /* R: delimiting byte/pad character */
363
364/*
365 * NB:
366 * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
367 */
368#define B_INMEM 0x00001 /* in-memory tree */
369#define B_METADIRTY 0x00002 /* need to write metadata */
370#define B_MODIFIED 0x00004 /* tree modified */
371#define B_NEEDSWAP 0x00008 /* if byte order requires swapping */
372#define B_RDONLY 0x00010 /* read-only tree */
373
374#define B_NODUPS 0x00020 /* no duplicate keys permitted */
375#define R_RECNO 0x00080 /* record oriented tree */
376
377#define R_CLOSEFP 0x00040 /* opened a file pointer */
378#define R_EOF 0x00100 /* end of input file reached. */
379#define R_FIXLEN 0x00200 /* fixed length records */
380#define R_MEMMAPPED 0x00400 /* memory mapped file. */
381#define R_INMEM 0x00800 /* in-memory file */
382#define R_MODIFIED 0x01000 /* modified file */
383#define R_RDONLY 0x02000 /* read-only file */
384
385#define B_DB_LOCK 0x04000 /* DB_LOCK specified. */
386#define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */
387#define B_DB_TXN 0x10000 /* DB_TXN specified. */
390
391#include "extern.h"
struct _binternal BINTERNAL
struct _rinternal RINTERNAL
struct _btree BTREE
struct _cursor CURSOR
struct _rleaf RLEAF
struct _epg EPG
struct _page PAGE
struct _epgno EPGNO
struct _btmeta BTMETA
struct _bleaf BLEAF
u_int16_t indx_t
Definition: db.h:80
u_int32_t recno_t
Definition: db.h:82
u_int32_t pgno_t
Definition: db.h:78
unsigned int u_int32_t
unsigned char u_int8_t
Definition: db.h:85
Definition: mpool.h:66
Definition: db.h:129
u_char flags
Definition: btree.h:133
pgno_t pgno
Definition: btree.h:130
char bytes[1]
Definition: btree.h:134
u_int32_t ksize
Definition: btree.h:129
Definition: btree.h:180
u_char flags
Definition: btree.h:183
char bytes[1]
Definition: btree.h:184
u_int32_t dsize
Definition: btree.h:182
u_int32_t ksize
Definition: btree.h:181
Definition: btree.h:300
u_int32_t flags
Definition: btree.h:308
u_int32_t magic
Definition: btree.h:301
u_int32_t nrecs
Definition: btree.h:305
u_int32_t free
Definition: btree.h:304
u_int32_t version
Definition: btree.h:302
u_int32_t psize
Definition: btree.h:303
Definition: btree.h:312
CURSOR bt_cursor
Definition: btree.h:320
int bt_fd
Definition: btree.h:335
u_int32_t bt_psize
Definition: btree.h:338
caddr_t bt_cmap
Definition: btree.h:355
DBT bt_rkey
Definition: btree.h:332
u_int32_t flags
Definition: btree.h:388
MPOOL * bt_mp
Definition: btree.h:313
caddr_t bt_emap
Definition: btree.h:357
PAGE * bt_pinned
Definition: btree.h:318
indx_t bt_ovflsize
Definition: btree.h:339
int bt_cmp __P((const DBT *, const DBT *))
u_char bt_bval
Definition: btree.h:362
@ NOT
Definition: btree.h:342
@ FORWARD
Definition: btree.h:342
@ BACK
Definition: btree.h:342
EPGNO * bt_sp
Definition: btree.h:330
int bt_lorder
Definition: btree.h:340
EPG bt_cur
Definition: btree.h:317
size_t bt_pfx __P((const DBT *, const DBT *))
size_t bt_msize
Definition: btree.h:358
int bt_irec __P((struct _btree *, recno_t))
size_t bt_reclen
Definition: btree.h:361
enum _btree::@506 bt_order
FILE * bt_rfp
Definition: btree.h:352
pgno_t bt_free
Definition: btree.h:337
caddr_t bt_smap
Definition: btree.h:356
DB * bt_dbp
Definition: btree.h:315
EPGNO bt_stack[50]
Definition: btree.h:329
recno_t bt_nrecs
Definition: btree.h:360
EPGNO bt_last
Definition: btree.h:343
DBT bt_rdata
Definition: btree.h:333
int bt_rfd
Definition: btree.h:353
Definition: btree.h:283
recno_t rcursor
Definition: btree.h:286
EPGNO pg
Definition: btree.h:284
DBT key
Definition: btree.h:285
u_int8_t flags
Definition: btree.h:292
Definition: btree.h:254
indx_t index
Definition: btree.h:256
PAGE * page
Definition: btree.h:255
Definition: btree.h:249
pgno_t pgno
Definition: btree.h:250
indx_t index
Definition: btree.h:251
Definition: btree.h:75
pgno_t prevpg
Definition: btree.h:77
indx_t lower
Definition: btree.h:89
indx_t upper
Definition: btree.h:90
u_int32_t flags
Definition: btree.h:87
pgno_t pgno
Definition: btree.h:76
indx_t linp[1]
Definition: btree.h:91
pgno_t nextpg
Definition: btree.h:78
pgno_t pgno
Definition: btree.h:161
recno_t nrecs
Definition: btree.h:160
Definition: btree.h:213
u_char flags
Definition: btree.h:215
char bytes[1]
Definition: btree.h:216
u_int32_t dsize
Definition: btree.h:214