294 lines
10 KiB
C
294 lines
10 KiB
C
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/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Margo Seltzer.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)hash.h 8.3 (Berkeley) 5/31/94
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*/
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/* Operations */
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typedef enum {
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HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT
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} ACTION;
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/* Buffer Management structures */
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typedef struct _bufhead BUFHEAD;
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struct _bufhead {
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BUFHEAD *prev; /* LRU links */
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BUFHEAD *next; /* LRU links */
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BUFHEAD *ovfl; /* Overflow page buffer header */
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u_int32_t addr; /* Address of this page */
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char *page; /* Actual page data */
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char flags;
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#define BUF_MOD 0x0001
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#define BUF_DISK 0x0002
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#define BUF_BUCKET 0x0004
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#define BUF_PIN 0x0008
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};
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#define IS_BUCKET(X) ((X) & BUF_BUCKET)
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typedef BUFHEAD **SEGMENT;
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/* Hash Table Information */
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typedef struct hashhdr { /* Disk resident portion */
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int magic; /* Magic NO for hash tables */
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int version; /* Version ID */
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u_int32_t lorder; /* Byte Order */
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int bsize; /* Bucket/Page Size */
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int bshift; /* Bucket shift */
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int dsize; /* Directory Size */
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int ssize; /* Segment Size */
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int sshift; /* Segment shift */
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int ovfl_point; /* Where overflow pages are being
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* allocated */
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int last_freed; /* Last overflow page freed */
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int max_bucket; /* ID of Maximum bucket in use */
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int high_mask; /* Mask to modulo into entire table */
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int low_mask; /* Mask to modulo into lower half of
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* table */
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int ffactor; /* Fill factor */
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int nkeys; /* Number of keys in hash table */
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int hdrpages; /* Size of table header */
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int h_charkey; /* value of hash(CHARKEY) */
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#define NCACHED 32 /* number of bit maps and spare
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* points */
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int spares[NCACHED];/* spare pages for overflow */
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u_int16_t bitmaps[NCACHED]; /* address of overflow page
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* bitmaps */
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} HASHHDR;
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typedef struct htab { /* Memory resident data structure */
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HASHHDR hdr; /* Header */
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int nsegs; /* Number of allocated segments */
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int exsegs; /* Number of extra allocated
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* segments */
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u_int32_t /* Hash function */
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(*hash)__P((const void *, size_t));
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int flags; /* Flag values */
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int fp; /* File pointer */
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char *tmp_buf; /* Temporary Buffer for BIG data */
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char *tmp_key; /* Temporary Buffer for BIG keys */
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BUFHEAD *cpage; /* Current page */
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int cbucket; /* Current bucket */
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int cndx; /* Index of next item on cpage */
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int errnum; /* Error Number -- for DBM
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* compatibility */
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int new_file; /* Indicates if fd is backing store
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* or no */
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int save_file; /* Indicates whether we need to flush
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* file at
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* exit */
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u_int32_t *mapp[NCACHED]; /* Pointers to page maps */
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int nmaps; /* Initial number of bitmaps */
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int nbufs; /* Number of buffers left to
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* allocate */
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BUFHEAD bufhead; /* Header of buffer lru list */
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SEGMENT *dir; /* Hash Bucket directory */
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} HTAB;
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/*
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* Constants
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*/
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#define MAX_BSIZE 65536 /* 2^16 */
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#define MIN_BUFFERS 6
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#define MINHDRSIZE 512
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#define DEF_BUFSIZE 65536 /* 64 K */
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#define DEF_BUCKET_SIZE 4096
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#define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */
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#define DEF_SEGSIZE 256
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#define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */
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#define DEF_DIRSIZE 256
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#define DEF_FFACTOR 65536
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#define MIN_FFACTOR 4
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#define SPLTMAX 8
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#define CHARKEY "%$sniglet^&"
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#define NUMKEY 1038583
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#define BYTE_SHIFT 3
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#define INT_TO_BYTE 2
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#define INT_BYTE_SHIFT 5
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#define ALL_SET ((u_int32_t)0xFFFFFFFF)
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#define ALL_CLEAR 0
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#define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
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#define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1)
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#define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1))
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#define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2)
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#define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2))
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#define BITS_PER_MAP 32
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/* Given the address of the beginning of a big map, clear/set the nth bit */
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#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
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#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
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#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
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/* Overflow management */
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/*
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* Overflow page numbers are allocated per split point. At each doubling of
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* the table, we can allocate extra pages. So, an overflow page number has
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* the top 5 bits indicate which split point and the lower 11 bits indicate
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* which page at that split point is indicated (pages within split points are
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* numbered starting with 1).
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*/
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#define SPLITSHIFT 11
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#define SPLITMASK 0x7FF
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#define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT)
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#define OPAGENUM(N) ((N) & SPLITMASK)
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#define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
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#define BUCKET_TO_PAGE(B) \
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(B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__hash_log2((B)+1)-1] : 0)
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#define OADDR_TO_PAGE(B) \
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BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
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/*
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* page.h contains a detailed description of the page format.
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*
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* Normally, keys and data are accessed from offset tables in the top of
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* each page which point to the beginning of the key and data. There are
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* four flag values which may be stored in these offset tables which indicate
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* the following:
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*
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*
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* OVFLPAGE Rather than a key data pair, this pair contains
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* the address of an overflow page. The format of
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* the pair is:
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* OVERFLOW_PAGE_NUMBER OVFLPAGE
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*
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* PARTIAL_KEY This must be the first key/data pair on a page
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* and implies that page contains only a partial key.
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* That is, the key is too big to fit on a single page
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* so it starts on this page and continues on the next.
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* The format of the page is:
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* KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
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*
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* KEY_OFF -- offset of the beginning of the key
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* PARTIAL_KEY -- 1
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* OVFL_PAGENO - page number of the next overflow page
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* OVFLPAGE -- 0
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*
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* FULL_KEY This must be the first key/data pair on the page. It
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* is used in two cases.
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*
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* Case 1:
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* There is a complete key on the page but no data
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* (because it wouldn't fit). The next page contains
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* the data.
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*
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* Page format it:
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* KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
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*
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* KEY_OFF -- offset of the beginning of the key
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* FULL_KEY -- 2
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* OVFL_PAGENO - page number of the next overflow page
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* OVFLPAGE -- 0
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*
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* Case 2:
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* This page contains no key, but part of a large
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* data field, which is continued on the next page.
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*
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* Page format it:
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* DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
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*
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* KEY_OFF -- offset of the beginning of the data on
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* this page
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* FULL_KEY -- 2
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* OVFL_PAGENO - page number of the next overflow page
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* OVFLPAGE -- 0
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*
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* FULL_KEY_DATA
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* This must be the first key/data pair on the page.
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* There are two cases:
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*
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* Case 1:
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* This page contains a key and the beginning of the
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* data field, but the data field is continued on the
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* next page.
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*
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* Page format is:
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* KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
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*
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* KEY_OFF -- offset of the beginning of the key
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* FULL_KEY_DATA -- 3
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* OVFL_PAGENO - page number of the next overflow page
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* DATA_OFF -- offset of the beginning of the data
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*
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* Case 2:
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* This page contains the last page of a big data pair.
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* There is no key, only the tail end of the data
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* on this page.
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*
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* Page format is:
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* DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
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*
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* DATA_OFF -- offset of the beginning of the data on
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* this page
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* FULL_KEY_DATA -- 3
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* OVFL_PAGENO - page number of the next overflow page
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* OVFLPAGE -- 0
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*
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* OVFL_PAGENO and OVFLPAGE are optional (they are
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* not present if there is no next page).
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*/
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#define OVFLPAGE 0
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#define PARTIAL_KEY 1
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#define FULL_KEY 2
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#define FULL_KEY_DATA 3
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#define REAL_KEY 4
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/* Short hands for accessing structure */
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#define BSIZE hdr.bsize
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#define BSHIFT hdr.bshift
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#define DSIZE hdr.dsize
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#define SGSIZE hdr.ssize
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#define SSHIFT hdr.sshift
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#define LORDER hdr.lorder
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#define OVFL_POINT hdr.ovfl_point
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#define LAST_FREED hdr.last_freed
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#define MAX_BUCKET hdr.max_bucket
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#define FFACTOR hdr.ffactor
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#define HIGH_MASK hdr.high_mask
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#define LOW_MASK hdr.low_mask
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#define NKEYS hdr.nkeys
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#define HDRPAGES hdr.hdrpages
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#define SPARES hdr.spares
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#define BITMAPS hdr.bitmaps
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#define VERSION hdr.version
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#define MAGIC hdr.magic
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#define NEXT_FREE hdr.next_free
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#define H_CHARKEY hdr.h_charkey
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