Repository List / webpac / openisis / current / lbt.h @ HEAD

/*
	openisis - an open implementation of the CDS/ISIS database
	Version 0.8.x (patchlevel see file Version)
	Copyright (C) 2001-2003 by Erik Grziwotz, erik@openisis.org

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public
	License as published by the Free Software Foundation; either
	version 2.1 of the License, or (at your option) any later version.

	This library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public
	License along with this library; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	see README for more information
EOH */
#ifndef LBT_H

/*
	$Id: lbt.h,v 1.12 2003/05/27 11:03:30 kripke Exp $
	package interface of the btree.
	see Lehmann/Yao or the GiST for how it works.
*/

#include "ldb.h"	/* LdbPost */


/**
	key comparision function.
	however, we still assume that two keys have to be identical
	in length and bytes to be equal.
*/
typedef int lbt_comp ( const unsigned char *a, const unsigned char *b,
	unsigned int l );

/**
	variables:
	4 bits: #bytes for value 8+(0..15)
	2 bits: blocksize 1024<<(0..3)
	max key length (4..255)
	collation (comparision function) 0..255
*/
typedef struct Idx { /* actually it's a B-L-Tree ;) */
	int             fd; /* the file */
	int            flg; /* flags: writeable, batch */
	unsigned char  typ; /* type: bsz, ifp, flags */
	unsigned char  key; /* max key length */
	unsigned char  col; /* collation */
	unsigned char  dpt; /* depth (level of root over bottom > 0) */
	lbt_comp      *cmp; /* comparision function */
	/* following members (and the depth above) are set automatically.
	they are going to stay and you may check them, if you're interested.
	*/
	unsigned       vsz; /* ifp size computed from type */
	unsigned       bsz; /* block size computed from type */
	unsigned       len; /* # blocks in index */
	/* following members are considered internal.
	if you import lbt and rely on them, don't blame me if they change.
	*/
	unsigned       hlen; /* hash length */
	unsigned       clen; /* cache length */
	struct Block  *root; /* the root */
	struct Block **hash; /* hash array */
	struct Block  *lru[4]; /* least recently used list for lowest levels */
	struct Block  *mru[4]; /* tail of lru list (most recently used) */
	struct Chunk  *mem; 
	struct Batch  *bat;
} Idx;

enum { /* btree flags */
	LBT_WRITE = 0x01 /* open for writing */
};
enum { /* btree type */
	LBT_BLK1K = 0x00, /* 1K blocks */
	LBT_BLK2K = 0x10, /* 2K blocks */
	LBT_BLK4K = 0x20, /* 4K blocks */
	LBT_BLK8K = 0x30, /* 8K blocks */
	LBT_CMPRS = 0x80  /* compressed keys */
};



/**
	initialise from an already open fd.
*/
extern int lbt_init ( Idx *bt );

/**
	flush and release any cache, close fd.
*/
extern void lbt_close ( Idx *bt );

extern int lbt_batch ( Idx *bt, unsigned char pctfree );
extern int lbt_batchval ( Idx *bt, Key *key );

extern int lbt_add ( Idx *bt, Key *key );
extern int lbt_del ( Idx *bt, Key *key );

extern int lbt_loop ( Idx *bt, DXLoop *l );
extern int lbt_search ( Idx *bt, Key *key, LdbPost *post, Rec *rec );

/* half public ... ??? */
extern void cXMkVal ( Idx *bt, Val *val, Hit *hit );

#define LBT_H
#endif /* LBT_H */