[src/trunk]: src/usr.bin/cap_mkdb Examine input files and set the openinfo hi...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2fab1e17885d
branches:  trunk
changeset: 503007:2fab1e17885d
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Sun Jan 28 20:01:42 2001 +0000

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

diffstat:

 usr.bin/cap_mkdb/cap_mkdb.c |  51 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 49 insertions(+), 2 deletions(-)

diffs (87 lines):

diff -r c75a6f46a664 -r 2fab1e17885d usr.bin/cap_mkdb/cap_mkdb.c
--- a/usr.bin/cap_mkdb/cap_mkdb.c       Sun Jan 28 19:42:17 2001 +0000
+++ b/usr.bin/cap_mkdb/cap_mkdb.c       Sun Jan 28 20:01:42 2001 +0000
@@ -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 @@
 #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 @@
 #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;
@@ -117,6 +119,11 @@
        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: 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;
+}