lib/libc/db/btree/btree.h

   1 /*      $NetBSD: btree.h,v 1.16 2008/08/26 21:18:38 joerg Exp $ */
   2
   3 /*-
   4  * Copyright (c) 1991, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Mike Olson.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)btree.h     8.11 (Berkeley) 8/17/94
  35  */
  36
  37 #if HAVE_NBTOOL_CONFIG_H
  38 #include "nbtool_config.h"
  39 #endif
  40
  41 /* Macros to set/clear/test flags. */
  42 #define F_SET(p, f)     (p)->flags |= (f)
  43 #define F_CLR(p, f)     (p)->flags &= ~(f)
  44 #define F_ISSET(p, f)   ((p)->flags & (f))
  45
  46 #include <mpool.h>
  47
  48 #define DEFMINKEYPAGE   (2)             /* Minimum keys per page */
  49 #define MINCACHE        (5)             /* Minimum cached pages */
  50 #define MINPSIZE        (512)           /* Minimum page size */
  51
  52 /*
  53  * Page 0 of a btree file contains a copy of the meta-data.  This page is also
  54  * used as an out-of-band page, i.e. page pointers that point to nowhere point
  55  * to page 0.  Page 1 is the root of the btree.
  56  */
  57 #define P_INVALID        0              /* Invalid tree page number. */
  58 #define P_META           0              /* Tree metadata page number. */
  59 #define P_ROOT           1              /* Tree root page number. */
  60
  61 /*
  62  * There are five page layouts in the btree: btree internal pages (BINTERNAL),
  63  * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
  64  * (RLEAF) and overflow pages.  All five page types have a page header (PAGE).
  65  * This implementation requires that values within structures NOT be padded.
  66  * (ANSI C permits random padding.)  If your compiler pads randomly you'll have
  67  * to do some work to get this package to run.
  68  */
  69 typedef struct _page {
  70         pgno_t  pgno;                   /* this page's page number */
  71         pgno_t  prevpg;                 /* left sibling */
  72         pgno_t  nextpg;                 /* right sibling */
  73
  74 #define P_BINTERNAL     0x01            /* btree internal page */
  75 #define P_BLEAF         0x02            /* leaf page */
  76 #define P_OVERFLOW      0x04            /* overflow page */
  77 #define P_RINTERNAL     0x08            /* recno internal page */
  78 #define P_RLEAF         0x10            /* leaf page */
  79 #define P_TYPE          0x1f            /* type mask */
  80 #define P_PRESERVE      0x20            /* never delete this chain of pages */
  81         uint32_t flags;
  82
  83         indx_t  lower;                  /* lower bound of free space on page */
  84         indx_t  upper;                  /* upper bound of free space on page */
  85         indx_t  linp[1];                /* indx_t-aligned VAR. LENGTH DATA */
  86 } PAGE;
  87
  88 /* First and next index. */
  89 #define BTDATAOFF                                                       \
  90         (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) +             \
  91             sizeof(uint32_t) + sizeof(indx_t) + sizeof(indx_t))
  92
  93 #define _NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
  94 #ifdef _DIAGNOSTIC
  95 static __inline indx_t
  96 NEXTINDEX(const PAGE *p) {
  97         size_t x = _NEXTINDEX(p);
  98         _DBFIT(x, indx_t);
  99         return (indx_t)x;
 100 }
 101 #else
 102 #define NEXTINDEX(p) (indx_t)_NEXTINDEX(p)
 103 #endif
 104
 105 /*
 106  * For pages other than overflow pages, there is an array of offsets into the
 107  * rest of the page immediately following the page header.  Each offset is to
 108  * an item which is unique to the type of page.  The h_lower offset is just
 109  * past the last filled-in index.  The h_upper offset is the first item on the
 110  * page.  Offsets are from the beginning of the page.
 111  *
 112  * If an item is too big to store on a single page, a flag is set and the item
 113  * is a { page, size } pair such that the page is the first page of an overflow
 114  * chain with size bytes of item.  Overflow pages are simply bytes without any
 115  * external structure.
 116  *
 117  * The page number and size fields in the items are pgno_t-aligned so they can
 118  * be manipulated without copying.  (This presumes that 32 bit items can be
 119  * manipulated on this system.)
 120  */
 121 #define BTLALIGN(n)     (((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
 122 #define NOVFLSIZE       (sizeof(pgno_t) + sizeof(uint32_t))
 123
 124 /*
 125  * For the btree internal pages, the item is a key.  BINTERNALs are {key, pgno}
 126  * pairs, such that the key compares less than or equal to all of the records
 127  * on that page.  For a tree without duplicate keys, an internal page with two
 128  * consecutive keys, a and b, will have all records greater than or equal to a
 129  * and less than b stored on the page associated with a.  Duplicate keys are
 130  * somewhat special and can cause duplicate internal and leaf page records and
 131  * some minor modifications of the above rule.
 132  */
 133 typedef struct _binternal {
 134         uint32_t ksize;                 /* key size */
 135         pgno_t  pgno;                   /* page number stored on */
 136 #define P_BIGDATA       0x01            /* overflow data */
 137 #define P_BIGKEY        0x02            /* overflow key */
 138         uint8_t flags;
 139         char    bytes[1];               /* data */
 140 } BINTERNAL;
 141
 142 /* Get the page's BINTERNAL structure at index indx. */
 143 #define GETBINTERNAL(pg, indx)                                          \
 144         ((BINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
 145
 146 /* Get the number of bytes in the entry. */
 147 #define _NBINTERNAL(len)                                                \
 148     BTLALIGN(sizeof(uint32_t) + sizeof(pgno_t) + sizeof(uint8_t) + (len))
 149 #ifdef _DIAGNOSTIC
 150 static __inline uint32_t
 151 NBINTERNAL(uint32_t len) {
 152         size_t x = _NBINTERNAL(len);
 153         _DBFIT(x, uint32_t);
 154         return (uint32_t)x;
 155 }
 156 #else
 157 #define NBINTERNAL(len) (uint32_t)_NBINTERNAL(len)
 158 #endif
 159
 160 /* Copy a BINTERNAL entry to the page. */
 161 #define WR_BINTERNAL(p, size, pgno, flags) do {                         \
 162         _DBFIT(size, uint32_t);                                         \
 163         *(uint32_t *)(void *)p = (uint32_t)size;                        \
 164         p += sizeof(uint32_t);                                          \
 165         *(pgno_t *)(void *)p = pgno;                                    \
 166         p += sizeof(pgno_t);                                            \
 167         *(uint8_t *)(void *)p = flags;                                  \
 168         p += sizeof(uint8_t);                                           \
 169 } while (/*CONSTCOND*/0)
 170
 171 /*
 172  * For the recno internal pages, the item is a page number with the number of
 173  * keys found on that page and below.
 174  */
 175 typedef struct _rinternal {
 176         recno_t nrecs;                  /* number of records */
 177         pgno_t  pgno;                   /* page number stored below */
 178 } RINTERNAL;
 179
 180 /* Get the page's RINTERNAL structure at index indx. */
 181 #define GETRINTERNAL(pg, indx)                                          \
 182         ((RINTERNAL *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
 183
 184 /* Get the number of bytes in the entry. */
 185 #define NRINTERNAL                                                      \
 186         BTLALIGN(sizeof(recno_t) + sizeof(pgno_t))
 187
 188 /* Copy a RINTERAL entry to the page. */
 189 #define WR_RINTERNAL(p, nrecs, pgno) do {                               \
 190         *(recno_t *)(void *)p = nrecs;                                  \
 191         p += sizeof(recno_t);                                           \
 192         *(pgno_t *)(void *)p = pgno;                                    \
 193 } while (/*CONSTCOND*/0)
 194
 195 /* For the btree leaf pages, the item is a key and data pair. */
 196 typedef struct _bleaf {
 197         uint32_t        ksize;          /* size of key */
 198         uint32_t        dsize;          /* size of data */
 199         uint8_t flags;                  /* P_BIGDATA, P_BIGKEY */
 200         char    bytes[1];               /* data */
 201 } BLEAF;
 202
 203 /* Get the page's BLEAF structure at index indx. */
 204 #define GETBLEAF(pg, indx)                                              \
 205         ((BLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
 206
 207
 208 /* Get the number of bytes in the user's key/data pair. */
 209 #define _NBLEAFDBT(ksize, dsize)                                        \
 210     BTLALIGN(sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint8_t) +    \
 211             (ksize) + (dsize))
 212 #ifdef _DIAGNOSTIC
 213 static __inline uint32_t
 214 NBLEAFDBT(size_t k, size_t d) {
 215         size_t x = _NBLEAFDBT(k, d);
 216         _DBFIT(x, uint32_t);
 217         return (uint32_t)x;
 218 }
 219 #else
 220 #define NBLEAFDBT(p, q) (uint32_t)_NBLEAFDBT(p, q)
 221 #endif
 222
 223 /* Get the number of bytes in the entry. */
 224 #define NBLEAF(p)       NBLEAFDBT((p)->ksize, (p)->dsize)
 225
 226 /* Copy a BLEAF entry to the page. */
 227 #define WR_BLEAF(p, key, data, flags) do {                              \
 228         _DBFIT(key->size, uint32_t);                                    \
 229         *(uint32_t *)(void *)p = (uint32_t)key->size;                   \
 230         p += sizeof(uint32_t);                                          \
 231         _DBFIT(data->size, uint32_t);                                   \
 232         *(uint32_t *)(void *)p = (uint32_t)data->size;                  \
 233         p += sizeof(uint32_t);                                          \
 234         *(uint8_t *)(void *)p = flags;                                  \
 235         p += sizeof(uint8_t);                                           \
 236         (void)memmove(p, key->data, key->size);                         \
 237         p += key->size;                                                 \
 238         (void)memmove(p, data->data, data->size);                       \
 239 } while (/*CONSTCOND*/0)
 240
 241 /* For the recno leaf pages, the item is a data entry. */
 242 typedef struct _rleaf {
 243         uint32_t        dsize;          /* size of data */
 244         uint8_t flags;                  /* P_BIGDATA */
 245         char    bytes[1];
 246 } RLEAF;
 247
 248 /* Get the page's RLEAF structure at index indx. */
 249 #define GETRLEAF(pg, indx)                                              \
 250         ((RLEAF *)(void *)((char *)(void *)(pg) + (pg)->linp[indx]))
 251
 252 #define _NRLEAFDBT(dsize)                                               \
 253         BTLALIGN(sizeof(uint32_t) + sizeof(uint8_t) + (dsize))
 254
 255 #ifdef _DIAGNOSTIC
 256 static __inline uint32_t
 257 NRLEAFDBT(size_t d) {
 258         size_t x = _NRLEAFDBT(d);
 259         _DBFIT(x, uint32_t);
 260         return (uint32_t)x;
 261 }
 262 #else
 263 #define NRLEAFDBT(d)    (uint32_t)_NRLEAFDBT(d)
 264 #endif
 265
 266 /* Get the number of bytes in the entry. */
 267 #define NRLEAF(p)       NRLEAFDBT((p)->dsize)
 268
 269 /* Get the number of bytes from the user's data. */
 270
 271 /* Copy a RLEAF entry to the page. */
 272 #define WR_RLEAF(p, data, flags) do {                                   \
 273         _DBFIT(data->size, uint32_t);                                   \
 274         *(uint32_t *)(void *)p = (uint32_t)data->size;                  \
 275         p += sizeof(uint32_t);                                          \
 276         *(uint8_t *)(void *)p = flags;                                  \
 277         p += sizeof(uint8_t);                                           \
 278         memmove(p, data->data, data->size);                             \
 279 } while (/*CONSTCOND*/0)
 280
 281 /*
 282  * A record in the tree is either a pointer to a page and an index in the page
 283  * or a page number and an index.  These structures are used as a cursor, stack
 284  * entry and search returns as well as to pass records to other routines.
 285  *
 286  * One comment about searches.  Internal page searches must find the largest
 287  * record less than key in the tree so that descents work.  Leaf page searches
 288  * must find the smallest record greater than key so that the returned index
 289  * is the record's correct position for insertion.
 290  */
 291 typedef struct _epgno {
 292         pgno_t  pgno;                   /* the page number */
 293         indx_t  index;                  /* the index on the page */
 294 } EPGNO;
 295
 296 typedef struct _epg {
 297         PAGE    *page;                  /* the (pinned) page */
 298         indx_t   index;                 /* the index on the page */
 299 } EPG;
 300
 301 /*
 302  * About cursors.  The cursor (and the page that contained the key/data pair
 303  * that it referenced) can be deleted, which makes things a bit tricky.  If
 304  * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
 305  * or there simply aren't any duplicates of the key) we copy the key that it
 306  * referenced when it's deleted, and reacquire a new cursor key if the cursor
 307  * is used again.  If there are duplicates keys, we move to the next/previous
 308  * key, and set a flag so that we know what happened.  NOTE: if duplicate (to
 309  * the cursor) keys are added to the tree during this process, it is undefined
 310  * if they will be returned or not in a cursor scan.
 311  *
 312  * The flags determine the possible states of the cursor:
 313  *
 314  * CURS_INIT    The cursor references *something*.
 315  * CURS_ACQUIRE The cursor was deleted, and a key has been saved so that
 316  *              we can reacquire the right position in the tree.
 317  * CURS_AFTER, CURS_BEFORE
 318  *              The cursor was deleted, and now references a key/data pair
 319  *              that has not yet been returned, either before or after the
 320  *              deleted key/data pair.
 321  * XXX
 322  * This structure is broken out so that we can eventually offer multiple
 323  * cursors as part of the DB interface.
 324  */
 325 typedef struct _cursor {
 326         EPGNO    pg;                    /* B: Saved tree reference. */
 327         DBT      key;                   /* B: Saved key, or key.data == NULL. */
 328         recno_t  rcursor;               /* R: recno cursor (1-based) */
 329
 330 #define CURS_ACQUIRE    0x01            /*  B: Cursor needs to be reacquired. */
 331 #define CURS_AFTER      0x02            /*  B: Unreturned cursor after key. */
 332 #define CURS_BEFORE     0x04            /*  B: Unreturned cursor before key. */
 333 #define CURS_INIT       0x08            /* RB: Cursor initialized. */
 334         uint8_t flags;
 335 } CURSOR;
 336
 337 /*
 338  * The metadata of the tree.  The nrecs field is used only by the RECNO code.
 339  * This is because the btree doesn't really need it and it requires that every
 340  * put or delete call modify the metadata.
 341  */
 342 typedef struct _btmeta {
 343         uint32_t        magic;          /* magic number */
 344         uint32_t        version;        /* version */
 345         uint32_t        psize;          /* page size */
 346         uint32_t        free;           /* page number of first free page */
 347         uint32_t        nrecs;          /* R: number of records */
 348
 349 #define SAVEMETA        (B_NODUPS | R_RECNO)
 350         uint32_t        flags;          /* bt_flags & SAVEMETA */
 351 } BTMETA;
 352
 353 /* The in-memory btree/recno data structure. */
 354 typedef struct _btree {
 355         MPOOL    *bt_mp;                /* memory pool cookie */
 356
 357         DB       *bt_dbp;               /* pointer to enclosing DB */
 358
 359         EPG       bt_cur;               /* current (pinned) page */
 360         PAGE     *bt_pinned;            /* page pinned across calls */
 361
 362         CURSOR    bt_cursor;            /* cursor */
 363
 364 #define BT_PUSH(t, p, i) {                                              \
 365         t->bt_sp->pgno = p;                                             \
 366         t->bt_sp->index = i;                                            \
 367         ++t->bt_sp;                                                     \
 368 }
 369 #define BT_POP(t)       (t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
 370 #define BT_CLR(t)       (t->bt_sp = t->bt_stack)
 371         EPGNO     bt_stack[50];         /* stack of parent pages */
 372         EPGNO    *bt_sp;                /* current stack pointer */
 373
 374         DBT       bt_rkey;              /* returned key */
 375         DBT       bt_rdata;             /* returned data */
 376
 377         int       bt_fd;                /* tree file descriptor */
 378
 379         pgno_t    bt_free;              /* next free page */
 380         uint32_t bt_psize;              /* page size */
 381         indx_t    bt_ovflsize;          /* cut-off for key/data overflow */
 382         int       bt_lorder;            /* byte order */
 383                                         /* sorted order */
 384         enum { NOT, BACK, FORWARD } bt_order;
 385         EPGNO     bt_last;              /* last insert */
 386
 387                                         /* B: key comparison function */
 388         int     (*bt_cmp)(const DBT *, const DBT *);
 389                                         /* B: prefix comparison function */
 390         size_t  (*bt_pfx)(const DBT *, const DBT *);
 391                                         /* R: recno input function */
 392         int     (*bt_irec)(struct _btree *, recno_t);
 393
 394         FILE     *bt_rfp;               /* R: record FILE pointer */
 395         int       bt_rfd;               /* R: record file descriptor */
 396
 397         caddr_t   bt_cmap;              /* R: current point in mapped space */
 398         caddr_t   bt_smap;              /* R: start of mapped space */
 399         caddr_t   bt_emap;              /* R: end of mapped space */
 400         size_t    bt_msize;             /* R: size of mapped region. */
 401
 402         recno_t   bt_nrecs;             /* R: number of records */
 403         size_t    bt_reclen;            /* R: fixed record length */
 404         uint8_t   bt_bval;              /* R: delimiting byte/pad character */
 405
 406 /*
 407  * NB:
 408  * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
 409  */
 410 #define B_INMEM         0x00001         /* in-memory tree */
 411 #define B_METADIRTY     0x00002         /* need to write metadata */
 412 #define B_MODIFIED      0x00004         /* tree modified */
 413 #define B_NEEDSWAP      0x00008         /* if byte order requires swapping */
 414 #define B_RDONLY        0x00010         /* read-only tree */
 415
 416 #define B_NODUPS        0x00020         /* no duplicate keys permitted */
 417 #define R_RECNO         0x00080         /* record oriented tree */
 418
 419 #define R_CLOSEFP       0x00040         /* opened a file pointer */
 420 #define R_EOF           0x00100         /* end of input file reached. */
 421 #define R_FIXLEN        0x00200         /* fixed length records */
 422 #define R_MEMMAPPED     0x00400         /* memory mapped file. */
 423 #define R_INMEM         0x00800         /* in-memory file */
 424 #define R_MODIFIED      0x01000         /* modified file */
 425 #define R_RDONLY        0x02000         /* read-only file */
 426
 427 #define B_DB_LOCK       0x04000         /* DB_LOCK specified. */
 428 #define B_DB_SHMEM      0x08000         /* DB_SHMEM specified. */
 429 #define B_DB_TXN        0x10000         /* DB_TXN specified. */
 430         uint32_t flags;
 431 } BTREE;
 432
 433 #include "extern.h"