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 /*-

  * 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);