db.1.85/hash/hash.h

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