[src/trunk]: src/usr.bin/make make(1): document inefficient cache lookup in D...

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

details:   https://anonhg.NetBSD.org/src/rev/7dc00c5f07b9
branches:  trunk
changeset: 1016097:7dc00c5f07b9
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Nov 08 11:57:49 2020 +0000

description:
make(1): document inefficient cache lookup in DirMatchFiles

diffstat:

 usr.bin/make/dir.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (28 lines):

diff -r 908f406ecd54 -r 7dc00c5f07b9 usr.bin/make/dir.c
--- a/usr.bin/make/dir.c        Sun Nov 08 11:37:46 2020 +0000
+++ b/usr.bin/make/dir.c        Sun Nov 08 11:57:49 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dir.c,v 1.201 2020/11/08 09:34:55 rillig Exp $ */
+/*     $NetBSD: dir.c,v 1.202 2020/11/08 11:57:49 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -134,7 +134,7 @@
 #include "job.h"
 
 /*     "@(#)dir.c      8.2 (Berkeley) 1/2/94"  */
-MAKE_RCSID("$NetBSD: dir.c,v 1.201 2020/11/08 09:34:55 rillig Exp $");
+MAKE_RCSID("$NetBSD: dir.c,v 1.202 2020/11/08 11:57:49 rillig Exp $");
 
 #define DIR_DEBUG0(text) DEBUG0(DIR, text)
 #define DIR_DEBUG1(fmt, arg1) DEBUG1(DIR, fmt, arg1)
@@ -589,6 +589,9 @@
     Boolean isDot = dirName[0] == '.' && dirName[1] == '\0';
     HashIter hi;
 
+    /* XXX: Iterating over all hash entries is inefficient.  If the pattern
+     * is a plain string without any wildcards, a direct lookup is faster. */
+
     HashIter_Init(&hi, &dir->files);
     while (HashIter_Next(&hi) != NULL) {
        const char *base = hi.entry->key;