git/t/t7519/fsmonitor-watchman
Kevin Willford 8da2c57629 fsmonitor: handle version 2 of the hooks that will use opaque token
Some file monitors like watchman will use something other than a timestamp
to keep better track of what changes happen in between calls to query
the fsmonitor. The clockid in watchman is a string. Now that the index
is storing an opaque token for the last update the code needs to be
updated to pass that opaque token to a verion 2 of the fsmonitor hook.

Because there are repos that already have version 1 of the hook and we
want them to continue to work when git is updated, we need to handle
both version 1 and version 2 of the hook. In order to do that a
config value is being added core.fsmonitorHookVersion to force what
version of the hook should be used.  When this is not set it will default
to -1 and then the code will attempt to call version 2 of the hook first.
If that fails it will fallback to trying version 1.

Signed-off-by: Kevin Willford <Kevin.Willford@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-13 14:58:43 -08:00

127 lines
3.3 KiB
Perl
Executable file

#!/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 {
exit 1;
}
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}};
}