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| Current File : //usr/src/lib/libc/db/hash/hash.h |
/*-
* Copyright (c) 1990, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Margo Seltzer.
*
* 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.
* 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.
*
* @(#)hash.h 8.3 (Berkeley) 5/31/94
* $FreeBSD: release/9.1.0/lib/libc/db/hash/hash.h 206178 2010-04-05 10:12:21Z avg $
*/
/* Operations */
typedef enum {
HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT
} ACTION;
/* Buffer Management structures */
typedef struct _bufhead BUFHEAD;
struct _bufhead {
BUFHEAD *prev; /* LRU links */
BUFHEAD *next; /* LRU links */
BUFHEAD *ovfl; /* Overflow page buffer header */
u_int32_t addr; /* Address of this page */
char *page; /* Actual page data */
char flags;
#define BUF_MOD 0x0001
#define BUF_DISK 0x0002
#define BUF_BUCKET 0x0004
#define BUF_PIN 0x0008
};
#define IS_BUCKET(X) ((X) & BUF_BUCKET)
typedef BUFHEAD **SEGMENT;
/* Hash Table Information */
typedef struct hashhdr { /* Disk resident portion */
int32_t magic; /* Magic NO for hash tables */
int32_t version; /* Version ID */
u_int32_t lorder; /* Byte Order */
int32_t bsize; /* Bucket/Page Size */
int32_t bshift; /* Bucket shift */
int32_t dsize; /* Directory Size */
int32_t ssize; /* Segment Size */
int32_t sshift; /* Segment shift */
int32_t ovfl_point; /* Where overflow pages are being
* allocated */
int32_t last_freed; /* Last overflow page freed */
u_int32_t max_bucket; /* ID of Maximum bucket in use */
u_int32_t high_mask; /* Mask to modulo into entire table */
u_int32_t low_mask; /* Mask to modulo into lower half of
* table */
u_int32_t ffactor; /* Fill factor */
int32_t nkeys; /* Number of keys in hash table */
int32_t hdrpages; /* Size of table header */
int32_t h_charkey; /* value of hash(CHARKEY) */
#define NCACHED 32 /* number of bit maps and spare
* points */
int32_t spares[NCACHED];/* spare pages for overflow */
u_int16_t bitmaps[NCACHED]; /* address of overflow page
* bitmaps */
} HASHHDR;
typedef struct htab { /* Memory resident data structure */
HASHHDR hdr; /* Header */
int nsegs; /* Number of allocated segments */
int exsegs; /* Number of extra allocated
* segments */
u_int32_t /* Hash function */
(*hash)(const void *, size_t);
int flags; /* Flag values */
int fp; /* File pointer */
char *tmp_buf; /* Temporary Buffer for BIG data */
char *tmp_key; /* Temporary Buffer for BIG keys */
BUFHEAD *cpage; /* Current page */
int cbucket; /* Current bucket */
int cndx; /* Index of next item on cpage */
int error; /* Error Number -- for DBM
* compatibility */
int new_file; /* Indicates if fd is backing store
* or no */
int save_file; /* Indicates whether we need to flush
* file at
* exit */
u_int32_t *mapp[NCACHED]; /* Pointers to page maps */
int nmaps; /* Initial number of bitmaps */
int nbufs; /* Number of buffers left to
* allocate */
BUFHEAD bufhead; /* Header of buffer lru list */
SEGMENT *dir; /* Hash Bucket directory */
} HTAB;
/*
* Constants
*/
#define MAX_BSIZE 32768 /* 2^15 but should be 65536 */
#define MIN_BUFFERS 6
#define MINHDRSIZE 512
#define DEF_BUFSIZE 65536 /* 64 K */
#define DEF_BUCKET_SIZE 4096
#define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */
#define DEF_SEGSIZE 256
#define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */
#define DEF_DIRSIZE 256
#define DEF_FFACTOR 65536
#define MIN_FFACTOR 4
#define SPLTMAX 8
#define CHARKEY "%$sniglet^&"
#define NUMKEY 1038583
#define BYTE_SHIFT 3
#define INT_TO_BYTE 2
#define INT_BYTE_SHIFT 5
#define ALL_SET ((u_int32_t)0xFFFFFFFF)
#define ALL_CLEAR 0
#define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3))
#define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1)
#define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1))
#define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2)
#define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2))
#define BITS_PER_MAP 32
/* Given the address of the beginning of a big map, clear/set the nth bit */
#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
/* Overflow management */
/*
* Overflow page numbers are allocated per split point. At each doubling of
* the table, we can allocate extra pages. So, an overflow page number has
* the top 5 bits indicate which split point and the lower 11 bits indicate
* which page at that split point is indicated (pages within split points are
* numberered starting with 1).
*/
#define SPLITSHIFT 11
#define SPLITMASK 0x7FF
#define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT)
#define OPAGENUM(N) ((N) & SPLITMASK)
#define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O))
#define BUCKET_TO_PAGE(B) \
(B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0)
#define OADDR_TO_PAGE(B) \
BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B));
/*
* page.h contains a detailed description of the page format.
*
* Normally, keys and data are accessed from offset tables in the top of
* each page which point to the beginning of the key and data. There are
* four flag values which may be stored in these offset tables which indicate
* the following:
*
*
* OVFLPAGE Rather than a key data pair, this pair contains
* the address of an overflow page. The format of
* the pair is:
* OVERFLOW_PAGE_NUMBER OVFLPAGE
*
* PARTIAL_KEY This must be the first key/data pair on a page
* and implies that page contains only a partial key.
* That is, the key is too big to fit on a single page
* so it starts on this page and continues on the next.
* The format of the page is:
* KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE
*
* KEY_OFF -- offset of the beginning of the key
* PARTIAL_KEY -- 1
* OVFL_PAGENO - page number of the next overflow page
* OVFLPAGE -- 0
*
* FULL_KEY This must be the first key/data pair on the page. It
* is used in two cases.
*
* Case 1:
* There is a complete key on the page but no data
* (because it wouldn't fit). The next page contains
* the data.
*
* Page format it:
* KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
*
* KEY_OFF -- offset of the beginning of the key
* FULL_KEY -- 2
* OVFL_PAGENO - page number of the next overflow page
* OVFLPAGE -- 0
*
* Case 2:
* This page contains no key, but part of a large
* data field, which is continued on the next page.
*
* Page format it:
* DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE
*
* KEY_OFF -- offset of the beginning of the data on
* this page
* FULL_KEY -- 2
* OVFL_PAGENO - page number of the next overflow page
* OVFLPAGE -- 0
*
* FULL_KEY_DATA
* This must be the first key/data pair on the page.
* There are two cases:
*
* Case 1:
* This page contains a key and the beginning of the
* data field, but the data field is continued on the
* next page.
*
* Page format is:
* KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF
*
* KEY_OFF -- offset of the beginning of the key
* FULL_KEY_DATA -- 3
* OVFL_PAGENO - page number of the next overflow page
* DATA_OFF -- offset of the beginning of the data
*
* Case 2:
* This page contains the last page of a big data pair.
* There is no key, only the tail end of the data
* on this page.
*
* Page format is:
* DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE>
*
* DATA_OFF -- offset of the beginning of the data on
* this page
* FULL_KEY_DATA -- 3
* OVFL_PAGENO - page number of the next overflow page
* OVFLPAGE -- 0
*
* OVFL_PAGENO and OVFLPAGE are optional (they are
* not present if there is no next page).
*/
#define OVFLPAGE 0
#define PARTIAL_KEY 1
#define FULL_KEY 2
#define FULL_KEY_DATA 3
#define REAL_KEY 4
/* Short hands for accessing structure */
#define BSIZE hdr.bsize
#define BSHIFT hdr.bshift
#define DSIZE hdr.dsize
#define SGSIZE hdr.ssize
#define SSHIFT hdr.sshift
#define LORDER hdr.lorder
#define OVFL_POINT hdr.ovfl_point
#define LAST_FREED hdr.last_freed
#define MAX_BUCKET hdr.max_bucket
#define FFACTOR hdr.ffactor
#define HIGH_MASK hdr.high_mask
#define LOW_MASK hdr.low_mask
#define NKEYS hdr.nkeys
#define HDRPAGES hdr.hdrpages
#define SPARES hdr.spares
#define BITMAPS hdr.bitmaps
#define VERSION hdr.version
#define MAGIC hdr.magic
#define NEXT_FREE hdr.next_free
#define H_CHARKEY hdr.h_charkey