templates/hooks--fsmonitor-watchman.sample

   1 #!/usr/bin/perl
   2
   3 use strict;
   4 use warnings;
   5 use IPC::Open2;
   6
   7 # An example hook script to integrate Watchman
   8 # (https://facebook.github.io/watchman/) with git to speed up detecting
   9 # new and modified files.
  10 #
  11 # The hook is passed a version (currently 1) and a time in nanoseconds
  12 # formatted as a string and outputs to stdout all files that have been
  13 # modified since the given time. Paths must be relative to the root of
  14 # the working tree and separated by a single NUL.
  15 #
  16 # To enable this hook, rename this file to "query-watchman" and set
  17 # 'git config core.fsmonitor .git/hooks/query-watchman'
  18 #
  19 my ($version, $time) = @ARGV;
  20
  21 # Check the hook interface version
  22
  23 if ($version == 1) {
  24         # convert nanoseconds to seconds
  25         # subtract one second to make sure watchman will return all changes
  26         $time = int ($time / 1000000000) - 1;
  27 } else {
  28         die "Unsupported query-fsmonitor hook version '$version'.\n" .
  29             "Falling back to scanning...\n";
  30 }
  31
  32 my $git_work_tree;
  33 if ($^O =~ 'msys' || $^O =~ 'cygwin') {
  34         $git_work_tree = Win32::GetCwd();
  35         $git_work_tree =~ tr/\\/\//;
  36 } else {
  37         require Cwd;
  38         $git_work_tree = Cwd::cwd();
  39 }
  40
  41 my $retry = 1;
  42
  43 launch_watchman();
  44
  45 sub launch_watchman {
  46
  47         my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j --no-pretty')
  48             or die "open2() failed: $!\n" .
  49             "Falling back to scanning...\n";
  50
  51         # In the query expression below we're asking for names of files that
  52         # changed since $time but were not transient (ie created after
  53         # $time but no longer exist).
  54         #
  55         # To accomplish this, we're using the "since" generator to use the
  56         # recency index to select candidate nodes and "fields" to limit the
  57         # output to file names only.
  58
  59         my $query = <<" END";
  60                 ["query", "$git_work_tree", {
  61                         "since": $time,
  62                         "fields": ["name"]
  63                 }]
  64         END
  65
  66         print CHLD_IN $query;
  67         close CHLD_IN;
  68         my $response = do {local $/; <CHLD_OUT>};
  69
  70         die "Watchman: command returned no output.\n" .
  71             "Falling back to scanning...\n" if $response eq "";
  72         die "Watchman: command returned invalid output: $response\n" .
  73             "Falling back to scanning...\n" unless $response =~ /^\{/;
  74
  75         my $json_pkg;
  76         eval {
  77                 require JSON::XS;
  78                 $json_pkg = "JSON::XS";
  79                 1;
  80         } or do {
  81                 require JSON::PP;
  82                 $json_pkg = "JSON::PP";
  83         };
  84
  85         my $o = $json_pkg->new->utf8->decode($response);
  86
  87         if ($retry > 0 and $o->{error} and $o->{error} =~ m/unable to resolve root .* directory (.*) is not watched/) {
  88                 print STDERR "Adding '$git_work_tree' to watchman's watch list.\n";
  89                 $retry--;
  90                 qx/watchman watch "$git_work_tree"/;
  91                 die "Failed to make watchman watch '$git_work_tree'.\n" .
  92                     "Falling back to scanning...\n" if $? != 0;
  93
  94                 # Watchman will always return all files on the first query so
  95                 # return the fast "everything is dirty" flag to git and do the
  96                 # Watchman query just to get it over with now so we won't pay
  97                 # the cost in git to look up each individual file.
  98                 print "/\0";
  99                 eval { launch_watchman() };
 100                 exit 0;
 101         }
 102
 103         die "Watchman: $o->{error}.\n" .
 104             "Falling back to scanning...\n" if $o->{error};
 105
 106         binmode STDOUT, ":utf8";
 107         local $, = "\0";
 108         print @{$o->{files}};
 109 }