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Examine input files and set the openinfo hint accordingly to number of

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found records. This makes resulting db for small capability databases
much smaller - for vgrind(1), the resulting vgrindefs.db is about 24KB
instead of ~500KB.

The hint passed to dbopen() is number of records in input files
rounded up to nearest power-of-two value and multiplied by two.
Besides being a nice conservative value, termcap.db become about
70KB bigger if the hint matches the count of records (1023), probably
due to hash overflows.
This commit is contained in:
jdolecek 2001-01-28 20:01:42 +00:00
parent 26a80cb447
commit b80b95a77a
1 changed files with 49 additions and 2 deletions
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51
usr.bin/cap_mkdb/cap_mkdb.c
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@ -1,4 +1,4 @@
/* $NetBSD: cap_mkdb.c,v 1.14 2001/01/28 19:42:17 jdolecek Exp $ */
/* $NetBSD: cap_mkdb.c,v 1.15 2001/01/28 20:01:42 jdolecek Exp $ */
/*-
* Copyright (c) 1992, 1993
@ -43,7 +43,7 @@ __COPYRIGHT("@(#) Copyright (c) 1992, 1993\n\
#if 0
static char sccsid[] = "@(#)cap_mkdb.c 8.2 (Berkeley) 4/27/95";
#endif
__RCSID("$NetBSD: cap_mkdb.c,v 1.14 2001/01/28 19:42:17 jdolecek Exp $");
__RCSID("$NetBSD: cap_mkdb.c,v 1.15 2001/01/28 20:01:42 jdolecek Exp $");
#endif /* not lint */
#include <sys/param.h>
@ -56,10 +56,12 @@ __RCSID("$NetBSD: cap_mkdb.c,v 1.14 2001/01/28 19:42:17 jdolecek Exp $");
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
static void db_build (char **);
static void dounlink (void);
static void usage (void);
static int count_records(char **);
DB *capdbp;
int verbose;
@ -116,6 +118,11 @@ main(int argc, char *argv[])
/* Set byte order */
openinfo.lorder = byteorder;
/*
* Set nelem to twice the value returned by count_record().
*/
openinfo.nelem = count_records(argv) << 1;
/*
* The database file is the first argument if no name is specified.
* Make arrangements to unlink it if exit badly.
@ -267,3 +274,43 @@ usage(void)
"usage: cap_mkdb [-b|-l] [-v] [-f outfile] file1 [file2 ...]\n");
exit(1);
}
/*
* Count number of records in input files. This does not need
* to be really accurate (the result is used only as a hint).
* It seems to match number of records should a cgetnext() be used, though.
*/
static int
count_records(char **list)
{
FILE *fp;
char *line;
size_t len;
int nelem, slash;
/* scan input files and count individual records */
for(nelem = 0, slash = 0; *list && (fp = fopen(*list++, "r")); ) {
while((line = fgetln(fp, &len))) {
if (len < 2)
continue;
if (!isspace((unsigned char) *line) && *line != ':'
&& *line != '#' && !slash)
nelem++;
slash = (line[len - 2] == '\\');
}
fclose(fp);
}
if (nelem == 0) {
/* no records found; pass default size hint */
nelem = 1;
} else if (!powerof2(nelem)) {
/* set nelem to nearest bigger power-of-two number */
int bt = 1;
while(bt < nelem) bt <<= 1;
nelem = bt;
}
return nelem;
}