This is ndbz.h in view mode; [Download] [Up]
/* $Id: ndbz.h,v 5.2 1992/10/11 01:46:35 syd Exp $ */
/*******************************************************************************
* The Elm Mail System - $Revision: 5.2 $ $State: Exp $
*
* Copyright (c) 1988-1992 USENET Community Trust
* Copyright (c) 1986,1987 Dave Taylor
*******************************************************************************
* Bug reports, patches, comments, suggestions should be sent to:
*
* Syd Weinstein, Elm Coordinator
* elm@DSI.COM dsinc!elm
*
*******************************************************************************
* $Log: ndbz.h,v $
* Revision 5.2 1992/10/11 01:46:35 syd
* change dbm name to dbz to avoid conflicts with partial call
* ins from shared librarys, and from mixing code with yp code.
* From: Syd via prompt from Jess Anderson
*
* Revision 5.1 1992/10/03 22:34:39 syd
* Initial checkin as of 2.4 Release at PL0
*
*
******************************************************************************/
/** define file for ndbz for mail system. **/
/*
* Stdio buffer for .pag reads. Buffering more than about 16 does not help
* significantly at the densities we try to maintain, and the much larger
* buffers that most stdios default to are much more expensive to fill.
* With small buffers, stdio is performance-competitive with raw read(),
* and it's much more portable.
*/
#ifndef NPAGBUF
#define NPAGBUF 16
#endif
/*
* Stdio buffer for base-file reads.
*/
#ifndef SHISTBUF
#define SHISTBUF 512
#endif
/* for dbz and ndbz */
typedef struct {
char *dptr;
int dsize;
} datum;
/*
* ANSI C says an offset into a file is a long, not an off_t, for some
* reason. This actually does simplify life a bit, but it's still nice
* to have a distinctive name for it. Beware, this is just for readability,
* don't try to change this.
*/
#define of_t long
#define SOF (sizeof(of_t))
/*
* We read configuration info from the .dir file into this structure,
* so we can avoid wired-in assumptions for an existing database.
*
* Among the info is a record of recent peak usages, so that a new table
* size can be chosen intelligently when rebuilding. 10 is a good
* number of usages to keep, since news displays marked fluctuations
* in volume on a 7-day cycle.
*/
struct dbzconfig {
int olddbz; /* .dir file empty but .pag not? */
of_t tsize; /* table size */
# ifndef NMEMORY
# define NMEMORY 10 /* # days of use info to remember */
# endif
# define NUSEDS (1+NMEMORY)
of_t used[NUSEDS]; /* entries used today, yesterday, ... */
int valuesize; /* size of table values, == SOF */
int bytemap[SOF]; /* byte-order map */
char casemap; /* case-mapping algorithm (see cipoint()) */
char fieldsep; /* field separator in base file, if any */
of_t tagenb; /* unshifted tag-enable bit */
of_t tagmask; /* unshifted tag mask */
int tagshift; /* shift count for tagmask and tagenb */
};
/*
* Data structure for recording info about searches.
*/
struct searcher {
of_t place; /* current location in file */
int tabno; /* which table we're in */
int run; /* how long we'll stay in this table */
long hash; /* the key's hash code (for optimization) */
of_t tag; /* tag we are looking for */
int seen; /* have we examined current location? */
int aborted; /* has i/o error aborted search? */
};
typedef struct dbz {
FILE *dbz_basef; /* descriptor for base file */
char *dbz_basefname; /* name for not-yet-opened base file */
FILE *dbz_dirf; /* descriptor for .dir file */
int dbz_dirronly; /* dirf open read-only? */
FILE *dbz_pagf; /* descriptor for .pag file */
of_t dbz_pagpos; /* posn in pagf; only search may set != -1 */
int dbz_pagronly; /* pagf open read-only? */
of_t *dbz_corepag; /* incore version of .pag file, if any */
FILE *dbz_bufpagf; /* well-buffered pagf, for incore rewrite */
of_t dbz_tagbits; /* pre-shifted tag mask */
of_t dbz_taghere; /* pre-shifted tag-enable bit */
of_t dbz_tagboth; /* tagbits|taghere */
struct dbzconfig dbz_conf;
int dbz_incore;
of_t dbz_pagbuf[NPAGBUF];
char dbz_basebuf[SHISTBUF];
struct searcher dbz_srch;
struct searcher *dbz_prevp; /* &srch or FRESH */
int dbz_mybmap[SOF]; /* my byte order (see mybytemap()) */
int dbz_bytesame; /* is database order same as mine? */
int dbz_debug; /* controlled by dbzdebug() */
int dbz_written; /* has a store() been done? */
} DBZ;
/* standard dbz functions */
extern DBZ *dbz_open();
extern datum dbz_fetch();
extern int dbz_store();
extern int dbz_delete(); /* not in dbz */
extern datum dbz_firstkey(); /* not in dbz */
extern datum dbz_nextkey(); /* not in dbz */
extern int dbz_close(); /* in dbz, but not in old dbm */
/* new stuff for dbz */
extern DBZ *dbz_fresh();
extern DBZ *dbz_again();
extern int dbz_sync();
extern long dbz_size();
extern int dbz_incore();
extern int dbz_cancel();
extern int dbz_debug();
/*
* In principle we could handle unlimited-length keys by operating a chunk
* at a time, but it's not worth it in practice. Setting a nice large
* bound on them simplifies the code and doesn't hurt anything.
*/
#define DBZMAXKEY 255
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.