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.
 * 3. ***REMOVED*** - see 
 *    ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change
 * 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
 */

/* Operations */

#include <stdio.h>
#include "mcom_db.h"
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 */
	uint32	 	addr;		/* Address of this page */
	char		*page;		/* Actual page data */
	char     	is_disk;
	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;

typedef int DBFILE_PTR;
#define NO_FILE -1
#ifdef macintosh
#define DBFILE_OPEN(path, flag,mode) open((path), flag)
#define EXISTS(path)
#else
#define DBFILE_OPEN(path, flag,mode) open((path), (flag), (mode))
#endif
/* Hash Table Information */
typedef struct hashhdr {		/* Disk resident portion */
	int32		magic;		/* Magic NO for hash tables */
	int32		version;	/* Version ID */
	uint32		lorder;		/* Byte Order */
	int32		bsize;		/* Bucket/Page Size */
	int32		bshift;		/* Bucket shift */
	int32		dsize;		/* Directory Size */
	int32		ssize;		/* Segment Size */
	int32		sshift;		/* Segment shift */
	int32		ovfl_point;	/* Where overflow pages are being 
					 * allocated */
	int32		last_freed;	/* Last overflow page freed */
	int32		max_bucket;	/* ID of Maximum bucket in use */
	int32		high_mask;	/* Mask to modulo into entire table */
	int32		low_mask;	/* Mask to modulo into lower half of 
					 * table */
	int32		ffactor;	/* Fill factor */
	int32		nkeys;		/* Number of keys in hash table */
	int32		hdrpages;	/* Size of table header */
	uint32		h_charkey;	/* value of hash(CHARKEY) */
#define NCACHED	32			/* number of bit maps and spare 
					 * points */
	int32		spares[NCACHED];/* spare pages for overflow */
	uint16		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 */
	uint32			/* Hash function */
	    (*hash)(const void *, size_t);
	int		flags;		/* Flag values */
	DBFILE_PTR	fp;		/* File pointer */
	char            *filename;
	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		dbmerrno;		/* Error Number -- for DBM 
					 * compatability */
	int		new_file;	/* Indicates if fd is backing store 
					 * or no */
	int		save_file;	/* Indicates whether we need to flush 
					 * file at
					 * exit */
	uint32		*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 */
	off_t		file_size;	/* in bytes */
	char		is_temp;	/* unlink file on close */
	char		updateEOF;	/* force EOF update on flush */
} HTAB;

/*
 * Constants
 */
#define DATABASE_CORRUPTED_ERROR -999   /* big ugly abort, delete database */
#define	OLD_MAX_BSIZE		65536		/* 2^16 */
#define MAX_BSIZE       	32l*1024l         /* 2^15 */
#define MIN_BUFFERS		6
#define MINHDRSIZE		512
#define DEF_BUFSIZE		65536l		/* 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		65536l
#define MIN_FFACTOR		4
#define SPLTMAX			8
#define CHARKEY			"%$sniglet^&"
#define NUMKEY			1038583l
#define BYTE_SHIFT		3
#define INT_TO_BYTE		2
#define INT_BYTE_SHIFT		5
#define ALL_SET			((uint32)0xFFFFFFFF)
#define ALL_CLEAR		0

#define PTROF(X)	((ptrdiff_t)(X) == BUF_DISK ? 0 : (X))
#define ISDISK(X)	((X) ? ((ptrdiff_t)(X) == BUF_DISK ? BUF_DISK \
				: (X)->is_disk) : 0)

#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)	(((uint32)(N)) >> SPLITSHIFT)
#define OPAGENUM(N)	((N) & SPLITMASK)
#define	OADDR_OF(S,O)	((uint32)((uint32)(S) << SPLITSHIFT) + (O))

#define BUCKET_TO_PAGE(B) \
	(B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((uint32)((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 */
#undef BSIZE
#define BSIZE		hdr.bsize
#undef BSHIFT
#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

extern uint32 (*__default_hash) (const void *, size_t);
void __buf_init(HTAB *hashp, int32 nbytes);
int __big_delete(HTAB *hashp, BUFHEAD *bufp);
BUFHEAD * __get_buf(HTAB *hashp, uint32 addr, BUFHEAD *prev_bp, int newpage);
uint32 __call_hash(HTAB *hashp, char *k, size_t len);
#include "page.h"
extern int __big_split(HTAB *hashp, BUFHEAD *op,BUFHEAD *np,
BUFHEAD *big_keyp,uint32 addr,uint32   obucket, SPLIT_RETURN *ret);
void __free_ovflpage(HTAB *hashp, BUFHEAD *obufp);
BUFHEAD * __add_ovflpage(HTAB *hashp, BUFHEAD *bufp);
int __big_insert(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT *val);
int __expand_table(HTAB *hashp);
uint32 __log2(uint32 num);
void __reclaim_buf(HTAB *hashp, BUFHEAD *bp);
int __get_page(HTAB *hashp, char * p, uint32 bucket, int is_bucket, int is_disk, int is_bitmap);
int __put_page(HTAB *hashp, char *p, uint32 bucket, int is_bucket, int is_bitmap);
int __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx);
int __buf_free(HTAB *hashp, int do_free, int to_disk);
int __find_bigpair(HTAB *hashp, BUFHEAD *bufp, int ndx, char *key, int size);
uint16 __find_last_page(HTAB *hashp, BUFHEAD **bpp);
int __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT * val);
int __big_return(HTAB *hashp, BUFHEAD *bufp, int ndx, DBT *val, int set_current);
int __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx);
int __big_keydata(HTAB *hashp, BUFHEAD *bufp, DBT *key, DBT *val, int set);
int __split_page(HTAB *hashp, uint32 obucket, uint32 nbucket);