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Diffstat (limited to 'db/btree/btree.h')
| -rw-r--r-- | db/btree/btree.h | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/db/btree/btree.h b/db/btree/btree.h new file mode 100644 index 0000000000..36d35c998b --- /dev/null +++ b/db/btree/btree.h @@ -0,0 +1,383 @@ +/*- + * 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" |