1 | /*- |
---|
2 | * Copyright (c) 1990, 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 | * Margo Seltzer. |
---|
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 | * @(#)page.h 8.2 (Berkeley) 5/31/94 |
---|
37 | * $FreeBSD: src/lib/libc/db/hash/page.h,v 1.2 2002/03/22 23:41:40 obrien Exp $ |
---|
38 | */ |
---|
39 | |
---|
40 | /* |
---|
41 | * Definitions for hashing page file format. |
---|
42 | */ |
---|
43 | |
---|
44 | /* |
---|
45 | * routines dealing with a data page |
---|
46 | * |
---|
47 | * page format: |
---|
48 | * +------------------------------+ |
---|
49 | * p | n | keyoff | datoff | keyoff | |
---|
50 | * +------------+--------+--------+ |
---|
51 | * | datoff | free | ptr | --> | |
---|
52 | * +--------+---------------------+ |
---|
53 | * | F R E E A R E A | |
---|
54 | * +--------------+---------------+ |
---|
55 | * | <---- - - - | data | |
---|
56 | * +--------+-----+----+----------+ |
---|
57 | * | key | data | key | |
---|
58 | * +--------+----------+----------+ |
---|
59 | * |
---|
60 | * Pointer to the free space is always: p[p[0] + 2] |
---|
61 | * Amount of free space on the page is: p[p[0] + 1] |
---|
62 | */ |
---|
63 | |
---|
64 | /* |
---|
65 | * How many bytes required for this pair? |
---|
66 | * 2 shorts in the table at the top of the page + room for the |
---|
67 | * key and room for the data |
---|
68 | * |
---|
69 | * We prohibit entering a pair on a page unless there is also room to append |
---|
70 | * an overflow page. The reason for this it that you can get in a situation |
---|
71 | * where a single key/data pair fits on a page, but you can't append an |
---|
72 | * overflow page and later you'd have to split the key/data and handle like |
---|
73 | * a big pair. |
---|
74 | * You might as well do this up front. |
---|
75 | */ |
---|
76 | |
---|
77 | #define PAIRSIZE(K,D) (2*sizeof(__uint16_t) + (K)->size + (D)->size) |
---|
78 | #define BIGOVERHEAD (4*sizeof(__uint16_t)) |
---|
79 | #define KEYSIZE(K) (4*sizeof(__uint16_t) + (K)->size); |
---|
80 | #define OVFLSIZE (2*sizeof(__uint16_t)) |
---|
81 | #define FREESPACE(P) ((P)[(P)[0]+1]) |
---|
82 | #define OFFSET(P) ((P)[(P)[0]+2]) |
---|
83 | #define PAIRFITS(P,K,D) \ |
---|
84 | (((P)[2] >= REAL_KEY) && \ |
---|
85 | (PAIRSIZE((K),(D)) + OVFLSIZE) <= FREESPACE((P))) |
---|
86 | #define PAGE_META(N) (((N)+3) * sizeof(__uint16_t)) |
---|
87 | |
---|
88 | typedef struct { |
---|
89 | BUFHEAD *newp; |
---|
90 | BUFHEAD *oldp; |
---|
91 | BUFHEAD *nextp; |
---|
92 | __uint16_t next_addr; |
---|
93 | } SPLIT_RETURN; |
---|