386 lines
14 KiB
C
386 lines
14 KiB
C
/* $NetBSD: btree.h,v 1.14 2003/10/27 00:12:42 lukem Exp $ */
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/*-
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* Copyright (c) 1991, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Mike Olson.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)btree.h 8.11 (Berkeley) 8/17/94
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*/
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#if HAVE_NBTOOL_CONFIG_H
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#include "nbtool_config.h"
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#endif
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/* Macros to set/clear/test flags. */
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#define F_SET(p, f) (p)->flags |= (f)
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#define F_CLR(p, f) (p)->flags &= ~(f)
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#define F_ISSET(p, f) ((p)->flags & (f))
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#include <mpool.h>
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#define DEFMINKEYPAGE (2) /* Minimum keys per page */
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#define MINCACHE (5) /* Minimum cached pages */
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#define MINPSIZE (512) /* Minimum page size */
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/*
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* Page 0 of a btree file contains a copy of the meta-data. This page is also
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* used as an out-of-band page, i.e. page pointers that point to nowhere point
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* to page 0. Page 1 is the root of the btree.
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*/
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#define P_INVALID 0 /* Invalid tree page number. */
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#define P_META 0 /* Tree metadata page number. */
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#define P_ROOT 1 /* Tree root page number. */
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/*
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* There are five page layouts in the btree: btree internal pages (BINTERNAL),
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* btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
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* (RLEAF) and overflow pages. All five page types have a page header (PAGE).
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* This implementation requires that values within structures NOT be padded.
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* (ANSI C permits random padding.) If your compiler pads randomly you'll have
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* to do some work to get this package to run.
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*/
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typedef struct _page {
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pgno_t pgno; /* this page's page number */
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pgno_t prevpg; /* left sibling */
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pgno_t nextpg; /* right sibling */
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#define P_BINTERNAL 0x01 /* btree internal page */
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#define P_BLEAF 0x02 /* leaf page */
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#define P_OVERFLOW 0x04 /* overflow page */
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#define P_RINTERNAL 0x08 /* recno internal page */
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#define P_RLEAF 0x10 /* leaf page */
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#define P_TYPE 0x1f /* type mask */
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#define P_PRESERVE 0x20 /* never delete this chain of pages */
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u_int32_t flags;
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indx_t lower; /* lower bound of free space on page */
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indx_t upper; /* upper bound of free space on page */
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indx_t linp[1]; /* indx_t-aligned VAR. LENGTH DATA */
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} PAGE;
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/* First and next index. */
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#define BTDATAOFF \
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(sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \
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sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
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#define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
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/*
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* For pages other than overflow pages, there is an array of offsets into the
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* rest of the page immediately following the page header. Each offset is to
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* an item which is unique to the type of page. The h_lower offset is just
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* past the last filled-in index. The h_upper offset is the first item on the
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* page. Offsets are from the beginning of the page.
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*
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* If an item is too big to store on a single page, a flag is set and the item
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* is a { page, size } pair such that the page is the first page of an overflow
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* chain with size bytes of item. Overflow pages are simply bytes without any
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* external structure.
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*
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* The page number and size fields in the items are pgno_t-aligned so they can
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* be manipulated without copying. (This presumes that 32 bit items can be
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* manipulated on this system.)
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*/
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#define BTLALIGN(n) (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
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#define NOVFLSIZE (sizeof(pgno_t) + sizeof(u_int32_t))
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/*
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* For the btree internal pages, the item is a key. BINTERNALs are {key, pgno}
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* pairs, such that the key compares less than or equal to all of the records
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* on that page. For a tree without duplicate keys, an internal page with two
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* consecutive keys, a and b, will have all records greater than or equal to a
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* and less than b stored on the page associated with a. Duplicate keys are
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* somewhat special and can cause duplicate internal and leaf page records and
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* some minor modifications of the above rule.
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*/
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typedef struct _binternal {
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u_int32_t ksize; /* key size */
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pgno_t pgno; /* page number stored on */
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#define P_BIGDATA 0x01 /* overflow data */
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#define P_BIGKEY 0x02 /* overflow key */
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u_char flags;
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char bytes[1]; /* data */
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} BINTERNAL;
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/* Get the page's BINTERNAL structure at index indx. */
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#define GETBINTERNAL(pg, indx) \
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((BINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
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/* Get the number of bytes in the entry. */
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#define NBINTERNAL(len) \
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BTLALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
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/* Copy a BINTERNAL entry to the page. */
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#define WR_BINTERNAL(p, size, pgno, flags) { \
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*(u_int32_t *)(void *)p = size; \
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p += sizeof(u_int32_t); \
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*(pgno_t *)(void *)p = pgno; \
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p += sizeof(pgno_t); \
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*(u_char *)(void *)p = flags; \
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p += sizeof(u_char); \
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}
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/*
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* For the recno internal pages, the item is a page number with the number of
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* keys found on that page and below.
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*/
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typedef struct _rinternal {
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recno_t nrecs; /* number of records */
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pgno_t pgno; /* page number stored below */
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} RINTERNAL;
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/* Get the page's RINTERNAL structure at index indx. */
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#define GETRINTERNAL(pg, indx) \
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((RINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
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/* Get the number of bytes in the entry. */
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#define NRINTERNAL \
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BTLALIGN(sizeof(recno_t) + sizeof(pgno_t))
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/* Copy a RINTERAL entry to the page. */
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#define WR_RINTERNAL(p, nrecs, pgno) { \
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*(recno_t *)(void *)p = nrecs; \
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p += sizeof(recno_t); \
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*(pgno_t *)(void *)p = pgno; \
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}
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/* For the btree leaf pages, the item is a key and data pair. */
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typedef struct _bleaf {
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u_int32_t ksize; /* size of key */
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u_int32_t dsize; /* size of data */
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u_char flags; /* P_BIGDATA, P_BIGKEY */
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char bytes[1]; /* data */
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} BLEAF;
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/* Get the page's BLEAF structure at index indx. */
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#define GETBLEAF(pg, indx) \
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((BLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
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/* Get the number of bytes in the entry. */
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#define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize)
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/* Get the number of bytes in the user's key/data pair. */
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#define NBLEAFDBT(ksize, dsize) \
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BTLALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) + \
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(ksize) + (dsize))
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/* Copy a BLEAF entry to the page. */
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#define WR_BLEAF(p, key, data, flags) { \
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*(u_int32_t *)(void *)p = key->size; \
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p += sizeof(u_int32_t); \
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*(u_int32_t *)(void *)p = data->size; \
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p += sizeof(u_int32_t); \
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*(u_char *)(void *)p = flags; \
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p += sizeof(u_char); \
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memmove(p, key->data, key->size); \
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p += key->size; \
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memmove(p, data->data, data->size); \
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}
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/* For the recno leaf pages, the item is a data entry. */
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typedef struct _rleaf {
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u_int32_t dsize; /* size of data */
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u_char flags; /* P_BIGDATA */
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char bytes[1];
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} RLEAF;
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/* Get the page's RLEAF structure at index indx. */
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#define GETRLEAF(pg, indx) \
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((RLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
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/* Get the number of bytes in the entry. */
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#define NRLEAF(p) NRLEAFDBT((p)->dsize)
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/* Get the number of bytes from the user's data. */
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#define NRLEAFDBT(dsize) \
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BTLALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
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/* Copy a RLEAF entry to the page. */
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#define WR_RLEAF(p, data, flags) { \
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*(u_int32_t *)(void *)p = data->size; \
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p += sizeof(u_int32_t); \
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*(u_char *)(void *)p = flags; \
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p += sizeof(u_char); \
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memmove(p, data->data, data->size); \
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}
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/*
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* A record in the tree is either a pointer to a page and an index in the page
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* or a page number and an index. These structures are used as a cursor, stack
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* entry and search returns as well as to pass records to other routines.
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*
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* One comment about searches. Internal page searches must find the largest
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* record less than key in the tree so that descents work. Leaf page searches
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* must find the smallest record greater than key so that the returned index
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* is the record's correct position for insertion.
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*/
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typedef struct _epgno {
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pgno_t pgno; /* the page number */
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indx_t index; /* the index on the page */
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} EPGNO;
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typedef struct _epg {
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PAGE *page; /* the (pinned) page */
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indx_t index; /* the index on the page */
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} EPG;
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/*
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* About cursors. The cursor (and the page that contained the key/data pair
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* that it referenced) can be deleted, which makes things a bit tricky. If
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* there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
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* or there simply aren't any duplicates of the key) we copy the key that it
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* referenced when it's deleted, and reacquire a new cursor key if the cursor
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* is used again. If there are duplicates keys, we move to the next/previous
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* key, and set a flag so that we know what happened. NOTE: if duplicate (to
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* the cursor) keys are added to the tree during this process, it is undefined
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* if they will be returned or not in a cursor scan.
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*
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* The flags determine the possible states of the cursor:
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*
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* CURS_INIT The cursor references *something*.
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* CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
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* we can reacquire the right position in the tree.
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* CURS_AFTER, CURS_BEFORE
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* The cursor was deleted, and now references a key/data pair
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* that has not yet been returned, either before or after the
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* deleted key/data pair.
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* XXX
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* This structure is broken out so that we can eventually offer multiple
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* cursors as part of the DB interface.
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*/
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typedef struct _cursor {
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EPGNO pg; /* B: Saved tree reference. */
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DBT key; /* B: Saved key, or key.data == NULL. */
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recno_t rcursor; /* R: recno cursor (1-based) */
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#define CURS_ACQUIRE 0x01 /* B: Cursor needs to be reacquired. */
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#define CURS_AFTER 0x02 /* B: Unreturned cursor after key. */
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#define CURS_BEFORE 0x04 /* B: Unreturned cursor before key. */
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#define CURS_INIT 0x08 /* RB: Cursor initialized. */
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u_int8_t flags;
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} CURSOR;
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/*
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* The metadata of the tree. The nrecs field is used only by the RECNO code.
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* This is because the btree doesn't really need it and it requires that every
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* put or delete call modify the metadata.
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*/
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typedef struct _btmeta {
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u_int32_t magic; /* magic number */
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u_int32_t version; /* version */
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u_int32_t psize; /* page size */
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u_int32_t free; /* page number of first free page */
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u_int32_t nrecs; /* R: number of records */
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#define SAVEMETA (B_NODUPS | R_RECNO)
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u_int32_t flags; /* bt_flags & SAVEMETA */
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} BTMETA;
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/* The in-memory btree/recno data structure. */
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typedef struct _btree {
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MPOOL *bt_mp; /* memory pool cookie */
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DB *bt_dbp; /* pointer to enclosing DB */
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EPG bt_cur; /* current (pinned) page */
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PAGE *bt_pinned; /* page pinned across calls */
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CURSOR bt_cursor; /* cursor */
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#define BT_PUSH(t, p, i) { \
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t->bt_sp->pgno = p; \
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t->bt_sp->index = i; \
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++t->bt_sp; \
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}
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#define BT_POP(t) (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
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#define BT_CLR(t) (t->bt_sp = t->bt_stack)
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EPGNO bt_stack[50]; /* stack of parent pages */
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EPGNO *bt_sp; /* current stack pointer */
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DBT bt_rkey; /* returned key */
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DBT bt_rdata; /* returned data */
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int bt_fd; /* tree file descriptor */
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pgno_t bt_free; /* next free page */
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u_int32_t bt_psize; /* page size */
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indx_t bt_ovflsize; /* cut-off for key/data overflow */
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int bt_lorder; /* byte order */
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/* sorted order */
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enum { NOT, BACK, FORWARD } bt_order;
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EPGNO bt_last; /* last insert */
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/* B: key comparison function */
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int (*bt_cmp) __P((const DBT *, const DBT *));
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/* B: prefix comparison function */
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size_t (*bt_pfx) __P((const DBT *, const DBT *));
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/* R: recno input function */
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int (*bt_irec) __P((struct _btree *, recno_t));
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FILE *bt_rfp; /* R: record FILE pointer */
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int bt_rfd; /* R: record file descriptor */
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caddr_t bt_cmap; /* R: current point in mapped space */
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caddr_t bt_smap; /* R: start of mapped space */
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caddr_t bt_emap; /* R: end of mapped space */
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size_t bt_msize; /* R: size of mapped region. */
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recno_t bt_nrecs; /* R: number of records */
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size_t bt_reclen; /* R: fixed record length */
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u_char bt_bval; /* R: delimiting byte/pad character */
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/*
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* NB:
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* B_NODUPS and R_RECNO are stored on disk, and may not be changed.
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*/
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#define B_INMEM 0x00001 /* in-memory tree */
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#define B_METADIRTY 0x00002 /* need to write metadata */
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#define B_MODIFIED 0x00004 /* tree modified */
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#define B_NEEDSWAP 0x00008 /* if byte order requires swapping */
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#define B_RDONLY 0x00010 /* read-only tree */
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#define B_NODUPS 0x00020 /* no duplicate keys permitted */
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#define R_RECNO 0x00080 /* record oriented tree */
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#define R_CLOSEFP 0x00040 /* opened a file pointer */
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#define R_EOF 0x00100 /* end of input file reached. */
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#define R_FIXLEN 0x00200 /* fixed length records */
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#define R_MEMMAPPED 0x00400 /* memory mapped file. */
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#define R_INMEM 0x00800 /* in-memory file */
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#define R_MODIFIED 0x01000 /* modified file */
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#define R_RDONLY 0x02000 /* read-only file */
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#define B_DB_LOCK 0x04000 /* DB_LOCK specified. */
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#define B_DB_SHMEM 0x08000 /* DB_SHMEM specified. */
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#define B_DB_TXN 0x10000 /* DB_TXN specified. */
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u_int32_t flags;
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} BTREE;
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#include "extern.h"
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