Subject: Re: [PATCH] grep: do not do external grep on skip-worktree entries

From: Nguyen Thai Ngoc Duy <[email-masked]>
Date: Sat, 2 Jan 2010 18:50:42 +0700

On Wed, Dec 30, 2009 at 11:09:52PM -0800, Junio C Hamano wrote:
> Junio C Hamano <[email-masked]> writes:
> 
> > This looks a bit wrong for a couple of reasons:
> >
> >  - external_grep() is designed to return negative without running external
> >    grep when it shouldn't be used (see the beginning of the function for
> >    how it refuses to run when opt->extended is set and other conditions).
> >    The new logic seems to belong there, i.e. "in addition to the existing
> >    case we decline, if ce_skip_worktree() entry exists in the cache, we
> >    decline";
> 
> IOW, something like this instead of your patch.  You would want to tests
> to demonstrate the original breakage, perhaps?

Your patch works great. By the way I think we should move "cached"
check from grep_cache() into external_grep() too, for consistency.

I thought of tests when I wrote the patch, but it was hard to find a
reliable way to detect if a git build supports external grep. Perhaps
this on top of yours? The way to check for external grep support isn't
nice, but it works.

diff --git a/builtin-grep.c b/builtin-grep.c
index f093b60..bc4500a 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -222,6 +222,7 @@ static int exec_grep(int argc, const char **argv)
 	int status;
 
 	argv[argc] = NULL;
+	trace_argv_printf(argv, "trace: grep:");
 	pid = fork();
 	if (pid < 0)
 		return pid;
@@ -371,7 +372,7 @@ static int external_grep(struct grep_opt *opt, const char **paths, int cached)
 	struct grep_pat *p;
 
 	if (opt->extended || (opt->relative && opt->prefix_length)
-	    || has_skip_worktree_entry(opt, paths))
+	    || cached || has_skip_worktree_entry(opt, paths))
 		return -1;
 	len = nr = 0;
 	push_arg("grep");
@@ -509,7 +510,7 @@ static int grep_cache(struct grep_opt *opt, const char **paths, int cached,
 	 * we grep through the checked-out files. It tends to
 	 * be a lot more optimized
 	 */
-	if (!cached && external_grep_allowed) {
+	if (external_grep_allowed) {
 		hit = external_grep(opt, paths, cached);
 		if (hit >= 0)
 			return hit;
diff --git a/t/t7002-grep.sh b/t/t7002-grep.sh
index abd14bf..f77970c 100755
--- a/t/t7002-grep.sh
+++ b/t/t7002-grep.sh
@@ -8,6 +8,14 @@ test_description='git grep various.
 
 . ./test-lib.sh
 
+support_external_grep() {
+	case "$(git grep -h 2>&1 >/dev/null|grep -e --ext-grep)" in
+	*"(default)"*)  return 0;;
+	*"(ignored by this build)"*) return 1;;
+	*) test_expect_success 'External grep check is broken' 'false';;
+	esac
+}
+
 cat >hello.c <<EOF
 #include <stdio.h>
 int main(int argc, const char **argv)
@@ -426,4 +434,20 @@ test_expect_success 'grep -Fi' '
 	test_cmp expected actual
 '
 
+if support_external_grep; then
+
+test_expect_success 'external grep' '
+	GIT_TRACE=2 git grep foo >/dev/null 2>actual &&
+	grep "trace: grep:.*foo" actual >/dev/null
+'
+test_expect_success 'no external grep when skip-worktree entries exist' '
+	git update-index --skip-worktree file &&
+	GIT_TRACE=2 git grep foo >/dev/null 2>actual &&
+	! grep "trace: grep:" actual >/dev/null &&
+	git update-index --no-skip-worktree file
+'
+
+else
+	say "External grep tests skipped"
+fi
 test_done

-- 
Duy