summaryrefslogtreecommitdiff
path: root/db/btree/btree.h
blob: 36d35c998bfd59d7ceb89d77f5333bd858b09ada (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
/*-
 * Copyright (c) 1991, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)btree.h	8.11 (Berkeley) 8/17/94
 */

/* Macros to set/clear/test flags. */
#define	F_SET(p, f)	(p)->flags |= (f)
#define	F_CLR(p, f)	(p)->flags &= ~(f)
#define	F_ISSET(p, f)	((p)->flags & (f))

#include <mpool.h>

#define	DEFMINKEYPAGE	(2)		/* Minimum keys per page */
#define	MINCACHE	(5)		/* Minimum cached pages */
#define	MINPSIZE	(512)		/* Minimum page size */

/*
 * Page 0 of a btree file contains a copy of the meta-data.  This page is also
 * used as an out-of-band page, i.e. page pointers that point to nowhere point
 * to page 0.  Page 1 is the root of the btree.
 */
#define	P_INVALID	 0		/* Invalid tree page number. */
#define	P_META		 0		/* Tree metadata page number. */
#define	P_ROOT		 1		/* Tree root page number. */

/*
 * There are five page layouts in the btree: btree internal pages (BINTERNAL),
 * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
 * (RLEAF) and overflow pages.  All five page types have a page header (PAGE).
 * This implementation requires that values within structures NOT be padded.
 * (ANSI C permits random padding.)  If your compiler pads randomly you'll have
 * to do some work to get this package to run.
 */
typedef struct _page {
	pgno_t	pgno;			/* this page's page number */
	pgno_t	prevpg;			/* left sibling */
	pgno_t	nextpg;			/* right sibling */

#define	P_BINTERNAL	0x01		/* btree internal page */
#define	P_BLEAF		0x02		/* leaf page */
#define	P_OVERFLOW	0x04		/* overflow page */
#define	P_RINTERNAL	0x08		/* recno internal page */
#define	P_RLEAF		0x10		/* leaf page */
#define P_TYPE		0x1f		/* type mask */
#define	P_PRESERVE	0x20		/* never delete this chain of pages */
	u_int32_t flags;

	indx_t	lower;			/* lower bound of free space on page */
	indx_t	upper;			/* upper bound of free space on page */
	indx_t	linp[1];		/* indx_t-aligned VAR. LENGTH DATA */
} PAGE;

/* First and next index. */
#define	BTDATAOFF							\
	(sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) +		\
	    sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
#define	NEXTINDEX(p)	(((p)->lower - BTDATAOFF) / sizeof(indx_t))

/*
 * For pages other than overflow pages, there is an array of offsets into the
 * rest of the page immediately following the page header.  Each offset is to
 * an item which is unique to the type of page.  The h_lower offset is just
 * past the last filled-in index.  The h_upper offset is the first item on the
 * page.  Offsets are from the beginning of the page.
 *
 * If an item is too big to store on a single page, a flag is set and the item
 * is a { page, size } pair such that the page is the first page of an overflow
 * chain with size bytes of item.  Overflow pages are simply bytes without any
 * external structure.
 *
 * The page number and size fields in the items are pgno_t-aligned so they can
 * be manipulated without copying.  (This presumes that 32 bit items can be
 * manipulated on this system.)
 */
#define	LALIGN(n)	(((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
#define	NOVFLSIZE	(sizeof(pgno_t) + sizeof(u_int32_t))

/*
 * For the btree internal pages, the item is a key.  BINTERNALs are {key, pgno}
 * pairs, such that the key compares less than or equal to all of the records
 * on that page.  For a tree without duplicate keys, an internal page with two
 * consecutive keys, a and b, will have all records greater than or equal to a
 * and less than b stored on the page associated with a.  Duplicate keys are
 * somewhat special and can cause duplicate internal and leaf page records and
 * some minor modifications of the above rule.
 */
typedef struct _binternal {
	u_int32_t ksize;		/* key size */
	pgno_t	pgno;			/* page number stored on */
#define	P_BIGDATA	0x01		/* overflow data */
#define	P_BIGKEY	0x02		/* overflow key */
	u_char	flags;
	char	bytes[1];		/* data */
} BINTERNAL;

/* Get the page's BINTERNAL structure at index indx. */
#define	GETBINTERNAL(pg, indx)						\
	((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))

/* Get the number of bytes in the entry. */
#define NBINTERNAL(len)							\
	LALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))

/* Copy a BINTERNAL entry to the page. */
#define	WR_BINTERNAL(p, size, pgno, flags) {				\
	*(u_int32_t *)p = size;						\
	p += sizeof(u_int32_t);						\
	*(pgno_t *)p = pgno;						\
	p += sizeof(pgno_t);						\
	*(u_char *)p = flags;						\
	p += sizeof(u_char);						\
}

/*
 * For the recno internal pages, the item is a page number with the number of
 * keys found on that page and below.
 */
typedef struct _rinternal {
	recno_t	nrecs;			/* number of records */
	pgno_t	pgno;			/* page number stored below */
} RINTERNAL;

/* Get the page's RINTERNAL structure at index indx. */
#define	GETRINTERNAL(pg, indx)						\
	((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))

/* Get the number of bytes in the entry. */
#define NRINTERNAL							\
	LALIGN(sizeof(recno_t) + sizeof(pgno_t))

/* Copy a RINTERAL entry to the page. */
#define	WR_RINTERNAL(p, nrecs, pgno) {					\
	*(recno_t *)p = nrecs;						\
	p += sizeof(recno_t);						\
	*(pgno_t *)p = pgno;						\
}

/* For the btree leaf pages, the item is a key and data pair. */
typedef struct _bleaf {
	u_int32_t	ksize;		/* size of key */
	u_int32_t	dsize;		/* size of data */
	u_char	flags;			/* P_BIGDATA, P_BIGKEY */
	char	bytes[1];		/* data */
} BLEAF;

/* Get the page's BLEAF structure at index indx. */
#define	GETBLEAF(pg, indx)						\
	((BLEAF *)((char *)(pg) + (pg)->linp[indx]))

/* Get the number of bytes in the entry. */
#define NBLEAF(p)	NBLEAFDBT((p)->ksize, (p)->dsize)

/* Get the number of bytes in the user's key/data pair. */
#define NBLEAFDBT(ksize, dsize)						\
	LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) +	\
	    (ksize) + (dsize))

/* Copy a BLEAF entry to the page. */
#define	WR_BLEAF(p, key, data, flags) {					\
	*(u_int32_t *)p = key->size;					\
	p += sizeof(u_int32_t);						\
	*(u_int32_t *)p = data->size;					\
	p += sizeof(u_int32_t);						\
	*(u_char *)p = flags;						\
	p += sizeof(u_char);						\
	memmove(p, key->data, key->size);				\
	p += key->size;							\
	memmove(p, data->data, data->size);				\
}

/* For the recno leaf pages, the item is a data entry. */
typedef struct _rleaf {
	u_int32_t	dsize;		/* size of data */
	u_char	flags;			/* P_BIGDATA */
	char	bytes[1];
} RLEAF;

/* Get the page's RLEAF structure at index indx. */
#define	GETRLEAF(pg, indx)						\
	((RLEAF *)((char *)(pg) + (pg)->linp[indx]))

/* Get the number of bytes in the entry. */
#define NRLEAF(p)	NRLEAFDBT((p)->dsize)

/* Get the number of bytes from the user's data. */
#define	NRLEAFDBT(dsize)						\
	LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))

/* Copy a RLEAF entry to the page. */
#define	WR_RLEAF(p, data, flags) {					\
	*(u_int32_t *)p = data->size;					\
	p += sizeof(u_int32_t);						\
	*(u_char *)p = flags;						\
	p += sizeof(u_char);						\
	memmove(p, data->data, data->size);				\
}

/*
 * A record in the tree is either a pointer to a page and an index in the page
 * or a page number and an index.  These structures are used as a cursor, stack
 * entry and search returns as well as to pass records to other routines.
 *
 * One comment about searches.  Internal page searches must find the largest
 * record less than key in the tree so that descents work.  Leaf page searches
 * must find the smallest record greater than key so that the returned index
 * is the record's correct position for insertion.
 */
typedef struct _epgno {
	pgno_t	pgno;			/* the page number */
	indx_t	index;			/* the index on the page */
} EPGNO;

typedef struct _epg {
	PAGE	*page;			/* the (pinned) page */
	indx_t	 index;			/* the index on the page */
} EPG;

/*
 * About cursors.  The cursor (and the page that contained the key/data pair
 * that it referenced) can be deleted, which makes things a bit tricky.  If
 * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
 * or there simply aren't any duplicates of the key) we copy the key that it
 * referenced when it's deleted, and reacquire a new cursor key if the cursor
 * is used again.  If there are duplicates keys, we move to the next/previous
 * key, and set a flag so that we know what happened.  NOTE: if duplicate (to
 * the cursor) keys are added to the tree during this process, it is undefined
 * if they will be returned or not in a cursor scan.
 *
 * The flags determine the possible states of the cursor:
 *
 * CURS_INIT	The cursor references *something*.
 * CURS_ACQUIRE	The cursor was deleted, and a key has been saved so that
 *		we can reacquire the right position in the tree.
 * CURS_AFTER, CURS_BEFORE
 *		The cursor was deleted, and now references a key/data pair
 *		that has not yet been returned, either before or after the
 *		deleted key/data pair.
 * XXX
 * This structure is broken out so that we can eventually offer multiple
 * cursors as part of the DB interface.
 */
typedef struct _cursor {
	EPGNO	 pg;			/* B: Saved tree reference. */
	DBT	 key;			/* B: Saved key, or key.data == NULL. */
	recno_t	 rcursor;		/* R: recno cursor (1-based) */

#define	CURS_ACQUIRE	0x01		/*  B: Cursor needs to be reacquired. */
#define	CURS_AFTER	0x02		/*  B: Unreturned cursor after key. */
#define	CURS_BEFORE	0x04		/*  B: Unreturned cursor before key. */
#define	CURS_INIT	0x08		/* RB: Cursor initialized. */
	u_int8_t flags;
} CURSOR;

/*
 * The metadata of the tree.  The nrecs field is used only by the RECNO code.
 * This is because the btree doesn't really need it and it requires that every
 * put or delete call modify the metadata.
 */
typedef struct _btmeta {
	u_int32_t	magic;		/* magic number */
	u_int32_t	version;	/* version */
	u_int32_t	psize;		/* page size */
	u_int32_t	free;		/* page number of first free page */
	u_int32_t	nrecs;		/* R: number of records */

#define	SAVEMETA	(B_NODUPS | R_RECNO)
	u_int32_t	flags;		/* bt_flags & SAVEMETA */
} BTMETA;

/* The in-memory btree/recno data structure. */
typedef struct _btree {
	MPOOL	 *bt_mp;		/* memory pool cookie */

	DB	 *bt_dbp;		/* pointer to enclosing DB */

	EPG	  bt_cur;		/* current (pinned) page */
	PAGE	 *bt_pinned;		/* page pinned across calls */

	CURSOR	  bt_cursor;		/* cursor */

#define	BT_PUSH(t, p, i) {						\
	t->bt_sp->pgno = p; 						\
	t->bt_sp->index = i; 						\
	++t->bt_sp;							\
}
#define	BT_POP(t)	(t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
#define	BT_CLR(t)	(t->bt_sp = t->bt_stack)
	EPGNO	  bt_stack[50];		/* stack of parent pages */
	EPGNO	 *bt_sp;		/* current stack pointer */

	DBT	  bt_rkey;		/* returned key */
	DBT	  bt_rdata;		/* returned data */

	int	  bt_fd;		/* tree file descriptor */

	pgno_t	  bt_free;		/* next free page */
	u_int32_t bt_psize;		/* page size */
	indx_t	  bt_ovflsize;		/* cut-off for key/data overflow */
	int	  bt_lorder;		/* byte order */
					/* sorted order */
	enum { NOT, BACK, FORWARD } bt_order;
	EPGNO	  bt_last;		/* last insert */

					/* B: key comparison function */
	int	(*bt_cmp) __P((const DBT *, const DBT *));
					/* B: prefix comparison function */
	size_t	(*bt_pfx) __P((const DBT *, const DBT *));
					/* R: recno input function */
	int	(*bt_irec) __P((struct _btree *, recno_t));

	FILE	 *bt_rfp;		/* R: record FILE pointer */
	int	  bt_rfd;		/* R: record file descriptor */

	caddr_t	  bt_cmap;		/* R: current point in mapped space */
	caddr_t	  bt_smap;		/* R: start of mapped space */
	caddr_t   bt_emap;		/* R: end of mapped space */
	size_t	  bt_msize;		/* R: size of mapped region. */

	recno_t	  bt_nrecs;		/* R: number of records */
	size_t	  bt_reclen;		/* R: fixed record length */
	u_char	  bt_bval;		/* R: delimiting byte/pad character */

/*
 * NB:
 * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
 */
#define	B_INMEM		0x00001		/* in-memory tree */
#define	B_METADIRTY	0x00002		/* need to write metadata */
#define	B_MODIFIED	0x00004		/* tree modified */
#define	B_NEEDSWAP	0x00008		/* if byte order requires swapping */
#define	B_RDONLY	0x00010		/* read-only tree */

#define	B_NODUPS	0x00020		/* no duplicate keys permitted */
#define	R_RECNO		0x00080		/* record oriented tree */

#define	R_CLOSEFP	0x00040		/* opened a file pointer */
#define	R_EOF		0x00100		/* end of input file reached. */
#define	R_FIXLEN	0x00200		/* fixed length records */
#define	R_MEMMAPPED	0x00400		/* memory mapped file. */
#define	R_INMEM		0x00800		/* in-memory file */
#define	R_MODIFIED	0x01000		/* modified file */
#define	R_RDONLY	0x02000		/* read-only file */

#define	B_DB_LOCK	0x04000		/* DB_LOCK specified. */
#define	B_DB_SHMEM	0x08000		/* DB_SHMEM specified. */
#define	B_DB_TXN	0x10000		/* DB_TXN specified. */
	u_int32_t flags;
} BTREE;

#include "extern.h"