/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996-2002
* Sleepycat Software. All rights reserved.
*
* $Id: db_page.h,v 11.52 2002/09/13 21:24:04 bostic Exp $
*/
#ifndef _DB_PAGE_H_
#define _DB_PAGE_H_
#if defined(__cplusplus)
extern "C" {
#endif
/*
* DB page formats.
*
* !!!
* This implementation requires that values within the following structures
* NOT be padded -- note, ANSI C permits random padding within structures.
* If your compiler pads randomly you can just forget ever making DB run on
* your system. In addition, no data type can require larger alignment than
* its own size, e.g., a 4-byte data element may not require 8-byte alignment.
*
* Note that key/data lengths are often stored in db_indx_t's -- this is
* not accidental, nor does it limit the key/data size. If the key/data
* item fits on a page, it's guaranteed to be small enough to fit into a
* db_indx_t, and storing it in one saves space.
*/
#define PGNO_INVALID 0 /* Invalid page number in any database. */
#define PGNO_BASE_MD 0 /* Base database: metadata page number. */
/* Page types. */
#define P_INVALID 0 /* Invalid page type. */
#define __P_DUPLICATE 1 /* Duplicate. DEPRECATED in 3.1 */
#define P_HASH 2 /* Hash. */
#define P_IBTREE 3 /* Btree internal. */
#define P_IRECNO 4 /* Recno internal. */
#define P_LBTREE 5 /* Btree leaf. */
#define P_LRECNO 6 /* Recno leaf. */
#define P_OVERFLOW 7 /* Overflow. */
#define P_HASHMETA 8 /* Hash metadata page. */
#define P_BTREEMETA 9 /* Btree metadata page. */
#define P_QAMMETA 10 /* Queue metadata page. */
#define P_QAMDATA 11 /* Queue data page. */
#define P_LDUP 12 /* Off-page duplicate leaf. */
#define P_PAGETYPE_MAX 13
/*
* When we create pages in mpool, we ask mpool to clear some number of bytes
* in the header. This number must be at least as big as the regular page
* headers and cover enough of the btree and hash meta-data pages to obliterate
* the page type.
*/
#define DB_PAGE_DB_LEN 32
#define DB_PAGE_QUEUE_LEN 0
/************************************************************************
GENERIC METADATA PAGE HEADER
*
* !!!
* The magic and version numbers have to be in the same place in all versions
* of the metadata page as the application may not have upgraded the database.
************************************************************************/
typedef struct _dbmeta33 {
DB_LSN lsn; /* 00-07: LSN. */
db_pgno_t pgno; /* 08-11: Current page number. */
u_int32_t magic; /* 12-15: Magic number. */
u_int32_t version; /* 16-19: Version. */
u_int32_t pagesize; /* 20-23: Pagesize. */
u_int8_t encrypt_alg; /* 24: Encryption algorithm. */
u_int8_t type; /* 25: Page type. */
#define DBMETA_CHKSUM 0x01
u_int8_t metaflags; /* 26: Meta-only flags */
u_int8_t unused1; /* 27: Unused. */
u_int32_t free; /* 28-31: Free list page number. */
db_pgno_t last_pgno; /* 32-35: Page number of last page in db. */
u_int32_t unused3; /* 36-39: Unused. */
u_int32_t key_count; /* 40-43: Cached key count. */
u_int32_t record_count; /* 44-47: Cached record count. */
u_int32_t flags; /* 48-51: Flags: unique to each AM. */
/* 52-71: Unique file ID. */
u_int8_t uid[DB_FILE_ID_LEN];
} DBMETA33, DBMETA;
/************************************************************************
BTREE METADATA PAGE LAYOUT
************************************************************************/
typedef struct _btmeta33 {
#define BTM_DUP 0x001 /* Duplicates. */
#define BTM_RECNO 0x002 /* Recno tree. */
#define BTM_RECNUM 0x004 /* Btree: maintain record count. */
#define BTM_FIXEDLEN 0x008 /* Recno: fixed length records. */
#define BTM_RENUMBER 0x010 /* Recno: renumber on insert/delete. */
#define BTM_SUBDB 0x020 /* Subdatabases. */
#define BTM_DUPSORT 0x040 /* Duplicates are sorted. */
#define BTM_MASK 0x07f
DBMETA dbmeta; /* 00-71: Generic meta-data header. */
u_int32_t maxkey; /* 72-75: Btree: Maxkey. */
u_int32_t minkey; /* 76-79: Btree: Minkey. */
u_int32_t re_len; /* 80-83: Recno: fixed-length record length. */
u_int32_t re_pad; /* 84-87: Recno: fixed-length record pad. */
u_int32_t root; /* 88-91: Root page. */
u_int32_t unused[92]; /* 92-459: Unused space */
u_int32_t crypto_magic; /* 460-463: Crypto magic number */
u_int32_t trash[3]; /* 464-475: Trash space - Do not use */
u_int8_t iv[DB_IV_BYTES]; /* 476-495: Crypto IV */
u_int8_t chksum[DB_MAC_KEY]; /* 496-511: Page chksum */
/*
* Minimum page size is 512.
*/
} BTMETA33, BTMETA;
/************************************************************************
HASH METADATA PAGE LAYOUT
************************************************************************/
typedef struct _hashmeta33 {
#define DB_HASH_DUP 0x01 /* Duplicates. */
#define DB_HASH_SUBDB 0x02 /* Subdatabases. */
#define DB_HASH_DUPSORT 0x04 /* Duplicates are sorted. */
DBMETA dbmeta; /* 00-71: Generic meta-data page header. */
u_int32_t max_bucket; /* 72-75: ID of Maximum bucket in use */
u_int32_t high_mask; /* 76-79: Modulo mask into table */
u_int32_t low_mask; /* 80-83: Modulo mask into table lower half */
u_int32_t ffactor; /* 84-87: Fill factor */
u_int32_t nelem; /* 88-91: Number of keys in hash table */
u_int32_t h_charkey; /* 92-95: Value of hash(CHARKEY) */
#define NCACHED 32 /* number of spare points */
/* 96-223: Spare pages for overflow */
u_int32_t spares[NCACHED];
u_int32_t unused[59]; /* 224-459: Unused space */
u_int32_t crypto_magic; /* 460-463: Crypto magic number */
u_int32_t trash[3]; /* 464-475: Trash space - Do not use */
u_int8_t iv[DB_IV_BYTES]; /* 476-495: Crypto IV */
u_int8_t chksum[DB_MAC_KEY]; /* 496-511: Page chksum */
/*
* Minimum page size is 512.
*/
} HMETA33, HMETA;
/************************************************************************
QUEUE METADATA PAGE LAYOUT
************************************************************************/
/*
* QAM Meta data page structure
*
*/
typedef struct _qmeta33 {
DBMETA dbmeta; /* 00-71: Generic meta-data header. */
u_int32_t first_recno; /* 72-75: First not deleted record. */
u_int32_t cur_recno; /* 76-79: Next recno to be allocated. */
u_int32_t re_len; /* 80-83: Fixed-length record length. */
u_int32_t re_pad; /* 84-87: Fixed-length record pad. */
u_int32_t rec_page; /* 88-91: Records Per Page. */
u_int32_t page_ext; /* 92-95: Pages per extent */
u_int32_t unused[91]; /* 96-459: Unused space */
u_int32_t crypto_magic; /* 460-463: Crypto magic number */
u_int32_t trash[3]; /* 464-475: Trash space - Do not use */
u_int8_t iv[DB_IV_BYTES]; /* 476-495: Crypto IV */
u_int8_t chksum[DB_MAC_KEY]; /* 496-511: Page chksum */
/*
* Minimum page size is 512.
*/
} QMETA33, QMETA;
/*
* DBMETASIZE is a constant used by __db_file_setup and DB->verify
* as a buffer which is guaranteed to be larger than any possible
* metadata page size and smaller than any disk sector.
*/
#define DBMETASIZE 512
/************************************************************************
BTREE/HASH MAIN PAGE LAYOUT
************************************************************************/
/*
* +-----------------------------------+
* | lsn | pgno | prev pgno |
* +-----------------------------------+
* | next pgno | entries | hf offset |
* +-----------------------------------+
* | level | type | chksum |
* +-----------------------------------+
* | iv | index | free --> |
* +-----------+-----------------------+
* | F R E E A R E A |
* +-----------------------------------+
* | <-- free | item |
* +-----------------------------------+
* | item | item | item |
* +-----------------------------------+
*
* sizeof(PAGE) == 26 bytes + possibly 20 bytes of checksum and possibly
* 16 bytes of IV (+ 2 bytes for alignment), and the following indices
* are guaranteed to be two-byte aligned. If we aren't doing crypto or
* checksumming the bytes are reclaimed for data storage.
*
* For hash and btree leaf pages, index items are paired, e.g., inp[0] is the
* key for inp[1]'s data. All other types of pages only contain single items.
*/
typedef struct __pg_chksum {
u_int8_t unused[2]; /* 26-27: For alignment */
u_int8_t chksum[4]; /* 28-31: Checksum */
} PG_CHKSUM;
typedef struct __pg_crypto {
u_int8_t unused[2]; /* 26-27: For alignment */
u_int8_t chksum[DB_MAC_KEY]; /* 28-47: Checksum */
u_int8_t iv[DB_IV_BYTES]; /* 48-63: IV */
/* !!!
* Must be 16-byte aligned for crypto
*/
} PG_CRYPTO;
typedef struct _db_page {
DB_LSN lsn; /* 00-07: Log sequence number. */
db_pgno_t pgno; /* 08-11: Current page number. */
db_pgno_t prev_pgno; /* 12-15: Previous page number. */
db_pgno_t next_pgno; /* 16-19: Next page number. */
db_indx_t entries; /* 20-21: Number of items on the page. */
db_indx_t hf_offset; /* 22-23: High free byte page offset. */
/*
* The btree levels are numbered from the leaf to the root, starting
* with 1, so the leaf is level 1, its parent is level 2, and so on.
* We maintain this level on all btree pages, but the only place that
* we actually need it is on the root page. It would not be difficult
* to hide the byte on the root page once it becomes an internal page,
* so we could get this byte back if we needed it for something else.
*/
#define LEAFLEVEL 1
#define MAXBTREELEVEL 255
u_int8_t level; /* 24: Btree tree level. */
u_int8_t type; /* 25: Page type. */
} PAGE;
#define SIZEOF_PAGE 26
/*
* !!!
* DB_AM_ENCRYPT always implies DB_AM_CHKSUM so that must come first.
*/
#define P_INP(dbp, pg) \
((db_indx_t *)((u_int8_t *)(pg) + SIZEOF_PAGE + \
(F_ISSET((dbp), DB_AM_ENCRYPT) ? sizeof(PG_CRYPTO) : \
(F_ISSET((dbp), DB_AM_CHKSUM) ? sizeof(PG_CHKSUM) : 0))))
#define P_IV(dbp, pg) \
(F_ISSET((dbp), DB_AM_ENCRYPT) ? ((u_int8_t *)(pg) + \
SIZEOF_PAGE + SSZA(PG_CRYPTO, iv)) \
: NULL)
#define P_CHKSUM(dbp, pg) \
(F_ISSET((dbp), DB_AM_ENCRYPT) ? ((u_int8_t *)(pg) + \
SIZEOF_PAGE + SSZA(PG_CRYPTO, chksum)) : \
(F_ISSET((dbp), DB_AM_CHKSUM) ? ((u_int8_t *)(pg) + \
SIZEOF_PAGE + SSZA(PG_CHKSUM, chksum)) \
: NULL))
/* PAGE element macros. */
#define LSN(p) (((PAGE *)p)->lsn)
#define PGNO(p) (((PAGE *)p)->pgno)
#define PREV_PGNO(p) (((PAGE *)p)->prev_pgno)
#define NEXT_PGNO(p) (((PAGE *)p)->next_pgno)
#define NUM_ENT(p) (((PAGE *)p)->entries)
#define HOFFSET(p) (((PAGE *)p)->hf_offset)
#define LEVEL(p) (((PAGE *)p)->level)
#define TYPE(p) (((PAGE *)p)->type)
/************************************************************************
QUEUE MAIN PAGE LAYOUT
************************************************************************/
/*
* Sizes of page below. Used to reclaim space if not doing
* crypto or checksumming. If you change the QPAGE below you
* MUST adjust this too.
*/
#define QPAGE_NORMAL 28
#define QPAGE_CHKSUM 48
#define QPAGE_SEC 64
typedef struct _qpage {
DB_LSN lsn; /* 00-07: Log sequence number. */
db_pgno_t pgno; /* 08-11: Current page number. */
u_int32_t unused0[3]; /* 12-23: Unused. */
u_int8_t unused1[1]; /* 24: Unused. */
u_int8_t type; /* 25: Page type. */
u_int8_t unused2[2]; /* 26-27: Unused. */
u_int8_t chksum[DB_MAC_KEY]; /* 28-47: Checksum */
u_int8_t iv[DB_IV_BYTES]; /* 48-63: IV */
} QPAGE;
#define QPAGE_SZ(dbp) \
(F_ISSET((dbp), DB_AM_ENCRYPT) ? QPAGE_SEC : \
F_ISSET((dbp), DB_AM_CHKSUM) ? QPAGE_CHKSUM : QPAGE_NORMAL)
/*
* !!!
* The next_pgno and prev_pgno fields are not maintained for btree and recno
* internal pages. Doing so only provides a minor performance improvement,
* it's hard to do when deleting internal pages, and it increases the chance
* of deadlock during deletes and splits because we have to re-link pages at
* more than the leaf level.
*
* !!!
* The btree/recno access method needs db_recno_t bytes of space on the root
* page to specify how many records are stored in the tree. (The alternative
* is to store the number of records in the meta-data page, which will create
* a second hot spot in trees being actively modified, or recalculate it from
* the BINTERNAL fields on each access.) Overload the PREV_PGNO field.
*/
#define RE_NREC(p) \
((TYPE(p) == P_IBTREE || TYPE(p) == P_IRECNO) ? PREV_PGNO(p) : \
(db_pgno_t)(TYPE(p) == P_LBTREE ? NUM_ENT(p) / 2 : NUM_ENT(p)))
#define RE_NREC_ADJ(p, adj) \
PREV_PGNO(p) += adj;
#define RE_NREC_SET(p, num) \
PREV_PGNO(p) = num;
/*
* Initialize a page.
*
* !!!
* Don't modify the page's LSN, code depends on it being unchanged after a
* P_INIT call.
*/
#define P_INIT(pg, pg_size, n, pg_prev, pg_next, btl, pg_type) do { \
PGNO(pg) = n; \
PREV_PGNO(pg) = pg_prev; \
NEXT_PGNO(pg) = pg_next; \
NUM_ENT(pg) = 0; \
HOFFSET(pg) = pg_size; \
LEVEL(pg) = btl; \
TYPE(pg) = pg_type; \
} while (0)
/* Page header length (offset to first index). */
#define P_OVERHEAD(dbp) P_TO_UINT16(P_INP(dbp, 0))
/* First free byte. */
#define LOFFSET(dbp, pg) \
(P_OVERHEAD(dbp) + NUM_ENT(pg) * sizeof(db_indx_t))
/* Free space on a regular page. */
#define P_FREESPACE(dbp, pg) (HOFFSET(pg) - LOFFSET(dbp, pg))
/* Get a pointer to the bytes at a specific index. */
#define P_ENTRY(dbp, pg, indx) ((u_int8_t *)pg + P_INP(dbp, pg)[indx])
/************************************************************************
OVERFLOW PAGE LAYOUT
************************************************************************/
/*
* Overflow items are referenced by HOFFPAGE and BOVERFLOW structures, which
* store a page number (the first page of the overflow item) and a length
* (the total length of the overflow item). The overflow item consists of
* some number of overflow pages, linked by the next_pgno field of the page.
* A next_pgno field of PGNO_INVALID flags the end of the overflow item.
*
* Overflow page overloads:
* The amount of overflow data stored on each page is stored in the
* hf_offset field.
*
* The implementation reference counts overflow items as it's possible
* for them to be promoted onto btree internal pages. The reference
* count is stored in the entries field.
*/
#define OV_LEN(p) (((PAGE *)p)->hf_offset)
#define OV_REF(p) (((PAGE *)p)->entries)
/* Maximum number of bytes that you can put on an overflow page. */
#define P_MAXSPACE(dbp, psize) ((psize) - P_OVERHEAD(dbp))
/* Free space on an overflow page. */
#define P_OVFLSPACE(dbp, psize, pg) (P_MAXSPACE(dbp, psize) - HOFFSET(pg))
/************************************************************************
HASH PAGE LAYOUT
************************************************************************/
/* Each index references a group of bytes on the page. */
#define H_KEYDATA 1 /* Key/data item. */
#define H_DUPLICATE 2 /* Duplicate key/data item. */
#define H_OFFPAGE 3 /* Overflow key/data item. */
#define H_OFFDUP 4 /* Overflow page of duplicates. */
/*
* !!!
* Items on hash pages are (potentially) unaligned, so we can never cast the
* (page + offset) pointer to an HKEYDATA, HOFFPAGE or HOFFDUP structure, as
* we do with B+tree on-page structures. Because we frequently want the type
* field, it requires no alignment, and it's in the same location in all three
* structures, there's a pair of macros.
*/
#define HPAGE_PTYPE(p) (*(u_int8_t *)p)
#define HPAGE_TYPE(dbp, pg, indx) (*P_ENTRY(dbp, pg, indx))
/*
* The first and second types are H_KEYDATA and H_DUPLICATE, represented
* by the HKEYDATA structure:
*
* +-----------------------------------+
* | type | key/data ... |
* +-----------------------------------+
*
* For duplicates, the data field encodes duplicate elements in the data
* field:
*
* +---------------------------------------------------------------+
* | type | len1 | element1 | len1 | len2 | element2 | len2 |
* +---------------------------------------------------------------+
*
* Thus, by keeping track of the offset in the element, we can do both
* backward and forward traversal.
*/
typedef struct _hkeydata {
u_int8_t type; /* 00: Page type. */
u_int8_t data[1]; /* Variable length key/data item. */
} HKEYDATA;
#define HKEYDATA_DATA(p) (((u_int8_t *)p) + SSZA(HKEYDATA, data))
/*
* The length of any HKEYDATA item. Note that indx is an element index,
* not a PAIR index.
*/
#define LEN_HITEM(dbp, pg, pgsize, indx) \
(((indx) == 0 ? pgsize : \
(P_INP(dbp, pg)[indx - 1])) - (P_INP(dbp, pg)[indx]))
#define LEN_HKEYDATA(dbp, pg, psize, indx) \
(db_indx_t)(LEN_HITEM(dbp, pg, psize, indx) - HKEYDATA_SIZE(0))
/*
* Page space required to add a new HKEYDATA item to the page, with and
* without the index value.
*/
#define HKEYDATA_SIZE(len) \
((len) + SSZA(HKEYDATA, data))
#define HKEYDATA_PSIZE(len) \
(HKEYDATA_SIZE(len) + sizeof(db_indx_t))
/* Put a HKEYDATA item at the location referenced by a page entry. */
#define PUT_HKEYDATA(pe, kd, len, type) { \
((HKEYDATA *)pe)->type = type; \
memcpy((u_int8_t *)pe + sizeof(u_int8_t), kd, len); \
}
/*
* Macros the describe the page layout in terms of key-data pairs.
*/
#define H_NUMPAIRS(pg) (NUM_ENT(pg) / 2)
#define H_KEYINDEX(indx) (indx)
#define H_DATAINDEX(indx) ((indx) + 1)
#define H_PAIRKEY(dbp, pg, indx) P_ENTRY(dbp, pg, H_KEYINDEX(indx))
#define H_PAIRDATA(dbp, pg, indx) P_ENTRY(dbp, pg, H_DATAINDEX(indx))
#define H_PAIRSIZE(dbp, pg, psize, indx) \
(LEN_HITEM(dbp, pg, psize, H_KEYINDEX(indx)) + \
LEN_HITEM(dbp, pg, psize, H_DATAINDEX(indx)))
#define LEN_HDATA(dbp, p, psize, indx) \
LEN_HKEYDATA(dbp, p, psize, H_DATAINDEX(indx))
#define LEN_HKEY(dbp, p, psize, indx) \
LEN_HKEYDATA(dbp, p, psize, H_KEYINDEX(indx))
/*
* The third type is the H_OFFPAGE, represented by the HOFFPAGE structure:
*/
typedef struct _hoffpage {
u_int8_t type; /* 00: Page type and delete flag. */
u_int8_t unused[3]; /* 01-03: Padding, unused. */
db_pgno_t pgno; /* 04-07: Offpage page number. */
u_int32_t tlen; /* 08-11: Total length of item. */
} HOFFPAGE;
#define HOFFPAGE_PGNO(p) (((u_int8_t *)p) + SSZ(HOFFPAGE, pgno))
#define HOFFPAGE_TLEN(p) (((u_int8_t *)p) + SSZ(HOFFPAGE, tlen))
/*
* Page space required to add a new HOFFPAGE item to the page, with and
* without the index value.
*/
#define HOFFPAGE_SIZE (sizeof(HOFFPAGE))
#define HOFFPAGE_PSIZE (HOFFPAGE_SIZE + sizeof(db_indx_t))
/*
* The fourth type is H_OFFDUP represented by the HOFFDUP structure:
*/
typedef struct _hoffdup {
u_int8_t type; /* 00: Page type and delete flag. */
u_int8_t unused[3]; /* 01-03: Padding, unused. */
db_pgno_t pgno; /* 04-07: Offpage page number. */
} HOFFDUP;
#define HOFFDUP_PGNO(p) (((u_int8_t *)p) + SSZ(HOFFDUP, pgno))
/*
* Page space required to add a new HOFFDUP item to the page, with and
* without the index value.
*/
#define HOFFDUP_SIZE (sizeof(HOFFDUP))
/************************************************************************
BTREE PAGE LAYOUT
************************************************************************/
/* Each index references a group of bytes on the page. */
#define B_KEYDATA 1 /* Key/data item. */
#define B_DUPLICATE 2 /* Duplicate key/data item. */
#define B_OVERFLOW 3 /* Overflow key/data item. */
/*
* We have to store a deleted entry flag in the page. The reason is complex,
* but the simple version is that we can't delete on-page items referenced by
* a cursor -- the return order of subsequent insertions might be wrong. The
* delete flag is an overload of the top bit of the type byte.
*/
#define B_DELETE (0x80)
#define B_DCLR(t) (t) &= ~B_DELETE
#define B_DSET(t) (t) |= B_DELETE
#define B_DISSET(t) ((t) & B_DELETE)
#define B_TYPE(t) ((t) & ~B_DELETE)
#define B_TSET(t, type, deleted) { \
(t) = (type); \
if (deleted) \
B_DSET(t); \
}
/*
* The first type is B_KEYDATA, represented by the BKEYDATA structure:
*/
typedef struct _bkeydata {
db_indx_t len; /* 00-01: Key/data item length. */
u_int8_t type; /* 02: Page type AND DELETE FLAG. */
u_int8_t data[1]; /* Variable length key/data item. */
} BKEYDATA;
/* Get a BKEYDATA item for a specific index. */
#define GET_BKEYDATA(dbp, pg, indx) \
((BKEYDATA *)P_ENTRY(dbp, pg, indx))
/*
* Page space required to add a new BKEYDATA item to the page, with and
* without the index value.
*/
#define BKEYDATA_SIZE(len) \
ALIGN((len) + SSZA(BKEYDATA, data), sizeof(u_int32_t))
#define BKEYDATA_PSIZE(len) \
(BKEYDATA_SIZE(len) + sizeof(db_indx_t))
/*
* The second and third types are B_DUPLICATE and B_OVERFLOW, represented
* by the BOVERFLOW structure.
*/
typedef struct _boverflow {
db_indx_t unused1; /* 00-01: Padding, unused. */
u_int8_t type; /* 02: Page type AND DELETE FLAG. */
u_int8_t unused2; /* 03: Padding, unused. */
db_pgno_t pgno; /* 04-07: Next page number. */
u_int32_t tlen; /* 08-11: Total length of item. */
} BOVERFLOW;
/* Get a BOVERFLOW item for a specific index. */
#define GET_BOVERFLOW(dbp, pg, indx) \
((BOVERFLOW *)P_ENTRY(dbp, pg, indx))
/*
* Page space required to add a new BOVERFLOW item to the page, with and
* without the index value. The (u_int16_t) cast avoids warnings: ALIGN
* casts to db_align_t, the cast converts it to a small integral type so
* we don't get complaints when we assign the final result to an integral
* type smaller than db_align_t.
*/
#define BOVERFLOW_SIZE \
((u_int16_t)ALIGN(sizeof(BOVERFLOW), sizeof(u_int32_t)))
#define BOVERFLOW_PSIZE \
(BOVERFLOW_SIZE + sizeof(db_indx_t))
/*
* Btree leaf and hash page layouts group indices in sets of two, one for the
* key and one for the data. Everything else does it in sets of one to save
* space. Use the following macros so that it's real obvious what's going on.
*/
#define O_INDX 1
#define P_INDX 2
/************************************************************************
BTREE INTERNAL PAGE LAYOUT
************************************************************************/
/*
* Btree internal entry.
*/
typedef struct _binternal {
db_indx_t len; /* 00-01: Key/data item length. */
u_int8_t type; /* 02: Page type AND DELETE FLAG. */
u_int8_t unused; /* 03: Padding, unused. */
db_pgno_t pgno; /* 04-07: Page number of referenced page. */
db_recno_t nrecs; /* 08-11: Subtree record count. */
u_int8_t data[1]; /* Variable length key item. */
} BINTERNAL;
/* Get a BINTERNAL item for a specific index. */
#define GET_BINTERNAL(dbp, pg, indx) \
((BINTERNAL *)P_ENTRY(dbp, pg, indx))
/*
* Page space required to add a new BINTERNAL item to the page, with and
* without the index value.
*/
#define BINTERNAL_SIZE(len) \
ALIGN((len) + SSZA(BINTERNAL, data), sizeof(u_int32_t))
#define BINTERNAL_PSIZE(len) \
(BINTERNAL_SIZE(len) + sizeof(db_indx_t))
/************************************************************************
RECNO INTERNAL PAGE LAYOUT
************************************************************************/
/*
* The recno internal entry.
*/
typedef struct _rinternal {
db_pgno_t pgno; /* 00-03: Page number of referenced page. */
db_recno_t nrecs; /* 04-07: Subtree record count. */
} RINTERNAL;
/* Get a RINTERNAL item for a specific index. */
#define GET_RINTERNAL(dbp, pg, indx) \
((RINTERNAL *)P_ENTRY(dbp, pg, indx))
/*
* Page space required to add a new RINTERNAL item to the page, with and
* without the index value.
*/
#define RINTERNAL_SIZE \
ALIGN(sizeof(RINTERNAL), sizeof(u_int32_t))
#define RINTERNAL_PSIZE \
(RINTERNAL_SIZE + sizeof(db_indx_t))
#if defined(__cplusplus)
}
#endif
#endif /* !_DB_PAGE_H_ */
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