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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  */
75 typedef 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 */
92 } PAGE;
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  */
128 typedef 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 */
135 } BINTERNAL;
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  */
159 typedef struct _rinternal {
160  recno_t nrecs; /* number of records */
161  pgno_t pgno; /* page number stored below */
162 } RINTERNAL;
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. */
180 typedef 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 */
185 } BLEAF;
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. */
213 typedef struct _rleaf {
214  u_int32_t dsize; /* size of data */
215  u_char flags; /* P_BIGDATA */
216  char bytes[1];
217 } RLEAF;
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  */
249 typedef struct _epgno {
250  pgno_t pgno; /* the page number */
251  indx_t index; /* the index on the page */
252 } EPGNO;
253 
254 typedef struct _epg {
255  PAGE *page; /* the (pinned) page */
256  indx_t index; /* the index on the page */
257 } EPG;
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  */
283 typedef 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. */
293 } CURSOR;
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  */
300 typedef 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 */
309 } BTMETA;
310 
311 /* The in-memory btree/recno data structure. */
312 typedef 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 */
342  enum { NOT, BACK, FORWARD } bt_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. */
389 } BTREE;
390 
391 #include "extern.h"
int bt_rfd
Definition: btree.h:353
Definition: btree.h:75
EPGNO pg
Definition: btree.h:284
Definition: mpool.h:66
recno_t nrecs
Definition: btree.h:160
pgno_t pgno
Definition: btree.h:76
u_char flags
Definition: btree.h:215
Definition: btree.h:213
caddr_t bt_smap
Definition: btree.h:356
EPG bt_cur
Definition: btree.h:317
EPGNO * bt_sp
Definition: btree.h:330
pgno_t pgno
Definition: btree.h:130
u_int32_t dsize
Definition: btree.h:182
CURSOR bt_cursor
Definition: btree.h:320
recno_t rcursor
Definition: btree.h:286
u_char flags
Definition: btree.h:183
u_int32_t psize
Definition: btree.h:303
u_int32_t flags
Definition: btree.h:308
u_int32_t flags
Definition: btree.h:388
size_t bt_msize
Definition: btree.h:358
u_int32_t dsize
Definition: btree.h:214
Definition: btree.h:254
indx_t index
Definition: btree.h:251
Definition: db.h:85
DBT bt_rkey
Definition: btree.h:332
indx_t lower
Definition: btree.h:89
u_int32_t magic
Definition: btree.h:301
u_int16_t indx_t
Definition: db.h:80
indx_t upper
Definition: btree.h:90
Definition: btree.h:249
recno_t bt_nrecs
Definition: btree.h:360
Definition: btree.h:312
u_char bt_bval
Definition: btree.h:362
struct _epg EPG
u_int32_t flags
Definition: btree.h:87
u_char flags
Definition: btree.h:133
PAGE * bt_pinned
Definition: btree.h:318
int bt_lorder
Definition: btree.h:340
DBT bt_rdata
Definition: btree.h:333
pgno_t pgno
Definition: btree.h:161
PAGE * page
Definition: btree.h:255
FILE * bt_rfp
Definition: btree.h:352
indx_t linp[1]
Definition: btree.h:91
MPOOL * bt_mp
Definition: btree.h:313
DBT key
Definition: btree.h:285
struct _btree BTREE
struct _rinternal RINTERNAL
u_int32_t pgno_t
Definition: db.h:78
Definition: btree.h:283
u_int32_t nrecs
Definition: btree.h:305
pgno_t nextpg
Definition: btree.h:78
#define __P(p)
indx_t index
Definition: btree.h:256
pgno_t prevpg
Definition: btree.h:77
u_int32_t free
Definition: btree.h:304
u_int32_t bt_psize
Definition: btree.h:338
struct _bleaf BLEAF
u_int8_t flags
Definition: btree.h:292
struct _cursor CURSOR
unsigned int u_int32_t
u_int32_t version
Definition: btree.h:302
struct _btmeta BTMETA
size_t bt_reclen
Definition: btree.h:361
EPGNO bt_last
Definition: btree.h:343
struct _epgno EPGNO
pgno_t pgno
Definition: btree.h:250
unsigned char u_int8_t
Definition: btree.h:180
struct _binternal BINTERNAL
int bt_fd
Definition: btree.h:335
indx_t bt_ovflsize
Definition: btree.h:339
struct _page PAGE
DB * bt_dbp
Definition: btree.h:315
caddr_t bt_cmap
Definition: btree.h:355
Definition: db.h:129
u_int32_t ksize
Definition: btree.h:181
u_int32_t recno_t
Definition: db.h:82
caddr_t bt_emap
Definition: btree.h:357
struct _rleaf RLEAF
u_int32_t ksize
Definition: btree.h:129
pgno_t bt_free
Definition: btree.h:337
Definition: btree.h:300