db/hash/hash.h

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1990, 1993, 1994
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Margo Seltzer.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  *      @(#)hash.h      8.3 (Berkeley) 5/31/94
  61  * $FreeBSD: src/lib/libc/db/hash/hash.h,v 1.6 2002/03/21 22:46:26 obrien Exp $
  62  */
  63
  64 /* Operations */
  65 typedef enum {
  66         HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT
  67 } ACTION;
  68
  69 /* Buffer Management structures */
  70 typedef struct _bufhead BUFHEAD;
  71
  72 struct _bufhead {
  73         BUFHEAD         *prev;          /* LRU links */
  74         BUFHEAD         *next;          /* LRU links */
  75         BUFHEAD         *ovfl;          /* Overflow page buffer header */
  76         u_int32_t        addr;          /* Address of this page */
  77         char            *page;          /* Actual page data */
  78         char            flags;
  79 #define BUF_MOD         0x0001
  80 #define BUF_DISK        0x0002
  81 #define BUF_BUCKET      0x0004
  82 #define BUF_PIN         0x0008
  83 };
  84
  85 #define IS_BUCKET(X)    ((X) & BUF_BUCKET)
  86
  87 typedef BUFHEAD **SEGMENT;
  88
  89 /* Hash Table Information */
  90 typedef struct hashhdr {                /* Disk resident portion */
  91         int             magic;          /* Magic NO for hash tables */
  92         int             version;        /* Version ID */
  93         u_int32_t       lorder;         /* Byte Order */
  94         int             bsize;          /* Bucket/Page Size */
  95         int             bshift;         /* Bucket shift */
  96         int             dsize;          /* Directory Size */
  97         int             ssize;          /* Segment Size */
  98         int             sshift;         /* Segment shift */
  99         int             ovfl_point;     /* Where overflow pages are being
 100                                          * allocated */
 101         int             last_freed;     /* Last overflow page freed */
 102         int             max_bucket;     /* ID of Maximum bucket in use */
 103         int             high_mask;      /* Mask to modulo into entire table */
 104         int             low_mask;       /* Mask to modulo into lower half of
 105                                          * table */
 106         int             ffactor;        /* Fill factor */
 107         int             nkeys;          /* Number of keys in hash table */
 108         int             hdrpages;       /* Size of table header */
 109         int             h_charkey;      /* value of hash(CHARKEY) */
 110 #define NCACHED 32                      /* number of bit maps and spare
 111                                          * points */
 112         int             spares[NCACHED];/* spare pages for overflow */
 113         u_int16_t       bitmaps[NCACHED];       /* address of overflow page
 114                                                  * bitmaps */
 115 } HASHHDR;
 116
 117 typedef struct htab      {              /* Memory resident data structure */
 118         HASHHDR         hdr;            /* Header */
 119         int             nsegs;          /* Number of allocated segments */
 120         int             exsegs;         /* Number of extra allocated
 121                                          * segments */
 122         u_int32_t                       /* Hash function */
 123             (*hash)(const void *, size_t);
 124         int             flags;          /* Flag values */
 125         int             fp;             /* File pointer */
 126         char            *tmp_buf;       /* Temporary Buffer for BIG data */
 127         char            *tmp_key;       /* Temporary Buffer for BIG keys */
 128         BUFHEAD         *cpage;         /* Current page */
 129         int             cbucket;        /* Current bucket */
 130         int             cndx;           /* Index of next item on cpage */
 131         int             error;          /* Error Number -- for DBM
 132                                          * compatibility */
 133         int             new_file;       /* Indicates if fd is backing store
 134                                          * or no */
 135         int             save_file;      /* Indicates whether we need to flush
 136                                          * file at
 137                                          * exit */
 138         u_int32_t       *mapp[NCACHED]; /* Pointers to page maps */
 139         int             nmaps;          /* Initial number of bitmaps */
 140         int             nbufs;          /* Number of buffers left to
 141                                          * allocate */
 142         BUFHEAD         bufhead;        /* Header of buffer lru list */
 143         SEGMENT         *dir;           /* Hash Bucket directory */
 144 } HTAB;
 145
 146 /*
 147  * Constants
 148  */
 149 #define MAX_BSIZE               65536           /* 2^16 */
 150 #define MIN_BUFFERS             6
 151 #define MINHDRSIZE              512
 152 #define DEF_BUFSIZE             65536           /* 64 K */
 153 #define DEF_BUCKET_SIZE         4096
 154 #define DEF_BUCKET_SHIFT        12              /* log2(BUCKET) */
 155 #define DEF_SEGSIZE             256
 156 #define DEF_SEGSIZE_SHIFT       8               /* log2(SEGSIZE)         */
 157 #define DEF_DIRSIZE             256
 158 #define DEF_FFACTOR             65536
 159 #define MIN_FFACTOR             4
 160 #define SPLTMAX                 8
 161 #define CHARKEY                 "%$sniglet^&"
 162 #define NUMKEY                  1038583
 163 #define BYTE_SHIFT              3
 164 #define INT_TO_BYTE             2
 165 #define INT_BYTE_SHIFT          5
 166 #define ALL_SET                 ((u_int32_t)0xFFFFFFFF)
 167 #define ALL_CLEAR               0
 168
 169 #define PTROF(X)        ((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
 170 #define ISMOD(X)        ((u_int32_t)(ptrdiff_t)(X)&0x1)
 171 #define DOMOD(X)        ((X) = (char *)((ptrdiff_t)(X)|0x1))
 172 #define ISDISK(X)       ((u_int32_t)(ptrdiff_t)(X)&0x2)
 173 #define DODISK(X)       ((X) = (char *)((ptrdiff_t)(X)|0x2))
 174
 175 #define BITS_PER_MAP    32
 176
 177 /* Given the address of the beginning of a big map, clear/set the nth bit */
 178 #define CLRBIT(A, N)    ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
 179 #define SETBIT(A, N)    ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
 180 #define ISSET(A, N)     ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
 181
 182 /* Overflow management */
 183 /*
 184  * Overflow page numbers are allocated per split point.  At each doubling of
 185  * the table, we can allocate extra pages.  So, an overflow page number has
 186  * the top 5 bits indicate which split point and the lower 11 bits indicate
 187  * which page at that split point is indicated (pages within split points are
 188  * numberered starting with 1).
 189  */
 190
 191 #define SPLITSHIFT      11
 192 #define SPLITMASK       0x7FF
 193 #define SPLITNUM(N)     (((u_int32_t)(N)) >> SPLITSHIFT)
 194 #define OPAGENUM(N)     ((N) & SPLITMASK)
 195 #define OADDR_OF(S,O)   ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
 196
 197 #define BUCKET_TO_PAGE(B) \
 198         (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0)
 199 #define OADDR_TO_PAGE(B)        \
 200         BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
 201
 202 /*
 203  * page.h contains a detailed description of the page format.
 204  *
 205  * Normally, keys and data are accessed from offset tables in the top of
 206  * each page which point to the beginning of the key and data.  There are
 207  * four flag values which may be stored in these offset tables which indicate
 208  * the following:
 209  *
 210  *
 211  * OVFLPAGE     Rather than a key data pair, this pair contains
 212  *              the address of an overflow page.  The format of
 213  *              the pair is:
 214  *                  OVERFLOW_PAGE_NUMBER OVFLPAGE
 215  *
 216  * PARTIAL_KEY  This must be the first key/data pair on a page
 217  *              and implies that page contains only a partial key.
 218  *              That is, the key is too big to fit on a single page
 219  *              so it starts on this page and continues on the next.
 220  *              The format of the page is:
 221  *                  KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
 222  *
 223  *                  KEY_OFF -- offset of the beginning of the key
 224  *                  PARTIAL_KEY -- 1
 225  *                  OVFL_PAGENO - page number of the next overflow page
 226  *                  OVFLPAGE -- 0
 227  *
 228  * FULL_KEY     This must be the first key/data pair on the page.  It
 229  *              is used in two cases.
 230  *
 231  *              Case 1:
 232  *                  There is a complete key on the page but no data
 233  *                  (because it wouldn't fit).  The next page contains
 234  *                  the data.
 235  *
 236  *                  Page format it:
 237  *                  KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
 238  *
 239  *                  KEY_OFF -- offset of the beginning of the key
 240  *                  FULL_KEY -- 2
 241  *                  OVFL_PAGENO - page number of the next overflow page
 242  *                  OVFLPAGE -- 0
 243  *
 244  *              Case 2:
 245  *                  This page contains no key, but part of a large
 246  *                  data field, which is continued on the next page.
 247  *
 248  *                  Page format it:
 249  *                  DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
 250  *
 251  *                  KEY_OFF -- offset of the beginning of the data on
 252  *                              this page
 253  *                  FULL_KEY -- 2
 254  *                  OVFL_PAGENO - page number of the next overflow page
 255  *                  OVFLPAGE -- 0
 256  *
 257  * FULL_KEY_DATA
 258  *              This must be the first key/data pair on the page.
 259  *              There are two cases:
 260  *
 261  *              Case 1:
 262  *                  This page contains a key and the beginning of the
 263  *                  data field, but the data field is continued on the
 264  *                  next page.
 265  *
 266  *                  Page format is:
 267  *                  KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
 268  *
 269  *                  KEY_OFF -- offset of the beginning of the key
 270  *                  FULL_KEY_DATA -- 3
 271  *                  OVFL_PAGENO - page number of the next overflow page
 272  *                  DATA_OFF -- offset of the beginning of the data
 273  *
 274  *              Case 2:
 275  *                  This page contains the last page of a big data pair.
 276  *                  There is no key, only the  tail end of the data
 277  *                  on this page.
 278  *
 279  *                  Page format is:
 280  *                  DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
 281  *
 282  *                  DATA_OFF -- offset of the beginning of the data on
 283  *                              this page
 284  *                  FULL_KEY_DATA -- 3
 285  *                  OVFL_PAGENO - page number of the next overflow page
 286  *                  OVFLPAGE -- 0
 287  *
 288  *                  OVFL_PAGENO and OVFLPAGE are optional (they are
 289  *                  not present if there is no next page).
 290  */
 291
 292 #define OVFLPAGE        0
 293 #define PARTIAL_KEY     1
 294 #define FULL_KEY        2
 295 #define FULL_KEY_DATA   3
 296 #define REAL_KEY        4
 297
 298 /* Short hands for accessing structure */
 299 #define BSIZE           hdr.bsize
 300 #define BSHIFT          hdr.bshift
 301 #define DSIZE           hdr.dsize
 302 #define SGSIZE          hdr.ssize
 303 #define SSHIFT          hdr.sshift
 304 #define LORDER          hdr.lorder
 305 #define OVFL_POINT      hdr.ovfl_point
 306 #define LAST_FREED      hdr.last_freed
 307 #define MAX_BUCKET      hdr.max_bucket
 308 #define FFACTOR         hdr.ffactor
 309 #define HIGH_MASK       hdr.high_mask
 310 #define LOW_MASK        hdr.low_mask
 311 #define NKEYS           hdr.nkeys
 312 #define HDRPAGES        hdr.hdrpages
 313 #define SPARES          hdr.spares
 314 #define BITMAPS         hdr.bitmaps
 315 #define VERSION         hdr.version
 316 #define MAGIC           hdr.magic
 317 #define NEXT_FREE       hdr.next_free
 318 #define H_CHARKEY       hdr.h_charkey