Re: [RFC/PATCH 0/1] cygwin: Remove the Win32 l/stat() functions

From

Jeff King <peff@peff.net>

Date

Jun 26, 2013, 22:43 UTC

Message-ID

<20130626224336.GA22486@sigill.intra.peff.net>

In-Reply-To

<20130626223552.GA12785@sigill.intra.peff.net>

On Wed, Jun 26, 2013 at 06:35:52PM -0400, Jeff King wrote:

> I am curious how often Cygwin gives us the false positive. If it is
> every time, then the check is not doing much good at all. Is it possible
> for you to instrument stat_validity_check to report how often it does or
> does not do anything useful?

Maybe like this:

diff --git a/read-cache.c b/read-cache.c
index d5201f9..19dcb69 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1958,6 +1958,14 @@ void stat_validity_clear(struct stat_validity *sv)
 	sv->sd = NULL;
 }
 
+static int unchanged;
+static int attempts;
+static void print_stats(void)
+{
+	fprintf(stderr, "stat data was unchanged %d/%d\n",
+		unchanged, attempts);
+}
+
 int stat_validity_check(struct stat_validity *sv, const char *path)
 {
 	struct stat st;
@@ -1966,7 +1974,16 @@ int stat_validity_check(struct stat_validity *sv, const char *path)
 		return sv->sd == NULL;
 	if (!sv->sd)
 		return 0;
-	return S_ISREG(st.st_mode) && !match_stat_data(sv->sd, &st);
+	if (!S_ISREG(st.st_mode))
+		return 0;
+	if (!attempts++)
+		atexit(print_stats);
+	if (!match_stat_data(sv->sd, &st)) {
+		unchanged++;
+		return 1;
+	}
+	else
+		return 0;
 }
 
 void stat_validity_update(struct stat_validity *sv, int fd)

Running "t3211 -v", I see things like:

  stat data was unchanged 3/3
  stat data was unchanged 20/20
  stat data was unchanged 2/2
  Deleted branch yadda (was d1ff1c9).
  stat data was unchanged 8/8
  ok 8 - peeled refs survive deletion of packed ref

I am curious if you will see 0/20 or 19/20 there on Cygwin.

-Peff