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         $time = int $time / 1000000000;
  26 } else {
  27         die "Unsupported query-fsmonitor hook version '$version'.\n" .
  28             "Falling back to scanning...\n";
  29 }
  30
  31 # Convert unix style paths to escaped Windows style paths when running
  32 # in Windows command prompt
  33
  34 my $system = `uname -s`;
  35 $system =~ s/[\r\n]+//g;
  36 my $git_work_tree;
  37
  38 if ($system =~ m/^MSYS_NT/ || $system =~ m/^MINGW/) {
  39         $git_work_tree = `cygpath -aw "\$PWD"`;
  40         $git_work_tree =~ s/[\r\n]+//g;
  41         $git_work_tree =~ s,\\,/,g;
  42 } else {
  43         $git_work_tree = $ENV{'PWD'};
  44 }
  45
  46 my $retry = 1;
  47
  48 launch_watchman();
  49
  50 sub launch_watchman {
  51
  52         # Set input record separator
  53         local $/ = 0666;
  54
  55         my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j')
  56             or die "open2() failed: $!\n" .
  57             "Falling back to scanning...\n";
  58
  59         # In the query expression below we're asking for names of files that
  60         # changed since $time but were not transient (ie created after
  61         # $time but no longer exist).
  62         #
  63         # To accomplish this, we're using the "since" generator to use the
  64         # recency index to select candidate nodes and "fields" to limit the
  65         # output to file names only. Then we're using the "expression" term to
  66         # further constrain the results.
  67         #
  68         # The category of transient files that we want to ignore will have a
  69         # creation clock (cclock) newer than $time_t value and will also not
  70         # currently exist.
  71
  72         my $query = <<" END";
  73                 ["query", "$git_work_tree", {
  74                         "since": $time,
  75                         "fields": ["name"],
  76                         "expression": ["not", ["allof", ["since", $time, "cclock"], ["not", "exists"]]]
  77                 }]
  78         END
  79
  80         print CHLD_IN $query;
  81         my $response = <CHLD_OUT>;
  82
  83         die "Watchman: command returned no output.\n" .
  84             "Falling back to scanning...\n" if $response eq "";
  85         die "Watchman: command returned invalid output: $response\n" .
  86             "Falling back to scanning...\n" unless $response =~ /^\{/;
  87
  88         my $json_pkg;
  89         eval {
  90                 require JSON::XS;
  91                 $json_pkg = "JSON::XS";
  92                 1;
  93         } or do {
  94                 require JSON::PP;
  95                 $json_pkg = "JSON::PP";
  96         };
  97
  98         my $o = $json_pkg->new->utf8->decode($response);
  99
 100         if ($retry > 0 and $o->{error} and $o->{error} =~ m/unable to resolve root .* directory (.*) is not watched/) {
 101                 print STDERR "Adding '$git_work_tree' to watchman's watch list.\n";
 102                 $retry--;
 103                 qx/watchman watch "$git_work_tree"/;
 104                 die "Failed to make watchman watch '$git_work_tree'.\n" .
 105                     "Falling back to scanning...\n" if $? != 0;
 106
 107                 # Watchman will always return all files on the first query so
 108                 # return the fast "everything is dirty" flag to git and do the
 109                 # Watchman query just to get it over with now so we won't pay
 110                 # the cost in git to look up each individual file.
 111                 print "/\0";
 112                 eval { launch_watchman() };
 113                 exit 0;
 114         }
 115
 116         die "Watchman: $o->{error}.\n" .
 117             "Falling back to scanning...\n" if $o->{error};
 118
 119         binmode STDOUT, ":utf8";
 120         local $, = "\0";
 121         print @{$o->{files}};
 122 }