fsmonitor: add script for debugging and update script for tests

The fsmonitor script that can be used for running all the git tests
using watchman was causing some of the tests to fail because it wrote
to stderr and created some files for debugging purposes.

Add a new debug script to use with debugging and modify the other script
to remove the code that would cause tests to fail.

Signed-off-by: Kevin Willford <Kevin.Willford@microsoft.com>

t/t7519/fsmonitor-watchman

@@ -17,7 +17,6 @@ use IPC::Open2;
 # 'git config core.fsmonitor .git/hooks/query-watchman'
 #
 my ($version, $time) = @ARGV;
-#print STDERR "$0 $version $time\n";
 
 # Check the hook interface version
 
@@ -44,7 +43,7 @@ launch_watchman();
 
 sub launch_watchman {
 
-	my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j')
+	my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j --no-pretty')
 	    or die "open2() failed: $!\n" .
 	    "Falling back to scanning...\n";
 
@@ -62,19 +61,11 @@ sub launch_watchman {
 			"fields": ["name"]
 		}]
 	END
-	
-	open (my $fh, ">", ".git/watchman-query.json");
-	print $fh $query;
-	close $fh;
 
 	print CHLD_IN $query;
 	close CHLD_IN;
 	my $response = do {local $/; <CHLD_OUT>};
 
-	open ($fh, ">", ".git/watchman-response.json");
-	print $fh $response;
-	close $fh;
-
 	die "Watchman: command returned no output.\n" .
 	    "Falling back to scanning...\n" if $response eq "";
 	die "Watchman: command returned invalid output: $response\n" .
@@ -93,7 +84,6 @@ sub launch_watchman {
 	my $o = $json_pkg->new->utf8->decode($response);
 
 	if ($retry > 0 and $o->{error} and $o->{error} =~ m/unable to resolve root .* directory (.*) is not watched/) {
-		print STDERR "Adding '$git_work_tree' to watchman's watch list.\n";
 		$retry--;
 		qx/watchman watch "$git_work_tree"/;
 		die "Failed to make watchman watch '$git_work_tree'.\n" .
@@ -103,11 +93,6 @@ sub launch_watchman {
 		# return the fast "everything is dirty" flag to git and do the
 		# Watchman query just to get it over with now so we won't pay
 		# the cost in git to look up each individual file.
-
-		open ($fh, ">", ".git/watchman-output.out");
-		print "/\0";
-		close $fh;
-
 		print "/\0";
 		eval { launch_watchman() };
 		exit 0;
@@ -116,11 +101,6 @@ sub launch_watchman {
 	die "Watchman: $o->{error}.\n" .
 	    "Falling back to scanning...\n" if $o->{error};
 
-	open ($fh, ">", ".git/watchman-output.out");
-	binmode $fh, ":utf8";
-	print $fh @{$o->{files}};
-	close $fh;
-
 	binmode STDOUT, ":utf8";
 	local $, = "\0";
 	print @{$o->{files}};

t/t7519/fsmonitor-watchman-debug

@@ -0,0 +1,128 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use IPC::Open2;
+
+# An example hook script to integrate Watchman
+# (https://facebook.github.io/watchman/) with git to speed up detecting
+# new and modified files.
+#
+# The hook is passed a version (currently 1) and a time in nanoseconds
+# formatted as a string and outputs to stdout all files that have been
+# modified since the given time. Paths must be relative to the root of
+# the working tree and separated by a single NUL.
+#
+# To enable this hook, rename this file to "query-watchman" and set
+# 'git config core.fsmonitor .git/hooks/query-watchman'
+#
+my ($version, $time) = @ARGV;
+#print STDERR "$0 $version $time\n";
+
+# Check the hook interface version
+
+if ($version == 1) {
+	# convert nanoseconds to seconds
+	# subtract one second to make sure watchman will return all changes
+	$time = int ($time / 1000000000) - 1;
+} else {
+	die "Unsupported query-fsmonitor hook version '$version'.\n" .
+	    "Falling back to scanning...\n";
+}
+
+my $git_work_tree;
+if ($^O =~ 'msys' || $^O =~ 'cygwin') {
+	$git_work_tree = Win32::GetCwd();
+	$git_work_tree =~ tr/\\/\//;
+} else {
+	require Cwd;
+	$git_work_tree = Cwd::cwd();
+}
+
+my $retry = 1;
+
+launch_watchman();
+
+sub launch_watchman {
+
+	my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j')
+	    or die "open2() failed: $!\n" .
+	    "Falling back to scanning...\n";
+
+	# In the query expression below we're asking for names of files that
+	# changed since $time but were not transient (ie created after
+	# $time but no longer exist).
+	#
+	# To accomplish this, we're using the "since" generator to use the
+	# recency index to select candidate nodes and "fields" to limit the
+	# output to file names only.
+
+	my $query = <<"	END";
+		["query", "$git_work_tree", {
+			"since": $time,
+			"fields": ["name"]
+		}]
+	END
+	
+	open (my $fh, ">", ".git/watchman-query.json");
+	print $fh $query;
+	close $fh;
+
+	print CHLD_IN $query;
+	close CHLD_IN;
+	my $response = do {local $/; <CHLD_OUT>};
+
+	open ($fh, ">", ".git/watchman-response.json");
+	print $fh $response;
+	close $fh;
+
+	die "Watchman: command returned no output.\n" .
+	    "Falling back to scanning...\n" if $response eq "";
+	die "Watchman: command returned invalid output: $response\n" .
+	    "Falling back to scanning...\n" unless $response =~ /^\{/;
+
+	my $json_pkg;
+	eval {
+		require JSON::XS;
+		$json_pkg = "JSON::XS";
+		1;
+	} or do {
+		require JSON::PP;
+		$json_pkg = "JSON::PP";
+	};
+
+	my $o = $json_pkg->new->utf8->decode($response);
+
+	if ($retry > 0 and $o->{error} and $o->{error} =~ m/unable to resolve root .* directory (.*) is not watched/) {
+		print STDERR "Adding '$git_work_tree' to watchman's watch list.\n";
+		$retry--;
+		qx/watchman watch "$git_work_tree"/;
+		die "Failed to make watchman watch '$git_work_tree'.\n" .
+		    "Falling back to scanning...\n" if $? != 0;
+
+		# Watchman will always return all files on the first query so
+		# return the fast "everything is dirty" flag to git and do the
+		# Watchman query just to get it over with now so we won't pay
+		# the cost in git to look up each individual file.
+
+		open ($fh, ">", ".git/watchman-output.out");
+		print "/\0";
+		close $fh;
+
+		print "/\0";
+		eval { launch_watchman() };
+		exit 0;
+	}
+
+	die "Watchman: $o->{error}.\n" .
+	    "Falling back to scanning...\n" if $o->{error};
+
+	open ($fh, ">", ".git/watchman-output.out");
+	binmode $fh, ":utf8";
+	print $fh @{$o->{files}};
+	close $fh;
+
+	binmode STDOUT, ":utf8";
+	local $, = "\0";
+	print @{$o->{files}};
+}