fsmonitor: don't bother pretty-printing JSON from watchman

This provides modest performance savings.  Benchmarking with the
following program, with and without `--no-pretty`, we find savings of
23% (0.316s -> 0.242s) in the git repository, and savings of 8% (5.24s
-> 4.86s) on a large repository with 580k files in the working copy.

    #!/usr/bin/perl

    use strict;
    use warnings;
    use IPC::Open2;
    use JSON::XS;

    my $pid = open2(\*CHLD_OUT, \*CHLD_IN, "watchman -j @ARGV")
        or die "open2() failed: $!\n" .
        "Falling back to scanning...\n";

    my $query = qq|["query", "$ENV{PWD}", {}]|;

    print CHLD_IN $query;
    close CHLD_IN;
    my $response = do {local $/; <CHLD_OUT>};

    JSON::XS->new->utf8->decode($response);

Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/templates/hooks--fsmonitor-watchman.sample b/templates/hooks--fsmonitor-watchman.sample
index 9eba8a740933dfa77d7155aca2ba1979e9d0fb68..9a082f278116782c3e28af6517f2b7140224de97 100755 (executable)
--- a/templates/hooks--fsmonitor-watchman.sample
+++ b/templates/hooks--fsmonitor-watchman.sample
@@ -49,7 +49,7 @@ 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";