use IPC subscription for caffeinated status

1 files changed, 61 insertions, 31 deletions

diff --git a/scripts/desktop/i3status-wrapper b/scripts/desktop/i3status-wrapper
index e9df86c8..5c4a25c8 100755
--- a/scripts/desktop/i3status-wrapper
+++ b/scripts/desktop/i3status-wrapper
@@ -1,7 +1,21 @@
-#!/usr/bin/env perl
+#!/usr/bin/perl
 
-# originally based on Michael Stapelberg's i3status-wrapper; added forking
-# i3status ourselves, user@host, and scanning for caffeinated mark
+# i3status-wrapper -- wrapper for i3status(1), plus other monitoring
+#
+# Copyright (C) 2019, 2021-2022 Sean Whitton
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or (at
+# your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 use 5.032;
 use strict;
@@ -11,11 +25,13 @@ use lib "$ENV{HOME}/src/dotfiles/perl5";
 use JSON;
 use Local::Desktop;
 use IO::Pipe;
+use IPC::Shareable;
 use Sys::Hostname;
 
 $| = 1;
 
 my $pipe = IO::Pipe->new;
+
 my $i3status = fork // die "couldn't fork()!";
 unless ($i3status) {
     $pipe->writer;
@@ -23,43 +39,57 @@ unless ($i3status) {
       or die "couldn't open child's STDOUT";
     exec "i3status";
 }
-$pipe->reader;
 
-# Skip the first line which contains the version header.
-print scalar <$pipe>;
+tie my %info, "IPC::Shareable", undef, { destroy => 1 };
 
-# The second line contains the start of the infinite array.
-print scalar <$pipe>;
+unless (fork // die "couldn't fork()!") {
+    $pipe->reader;
+    open STDIN, "<&=", $pipe->fileno
+      or die "couldn't reopen child's STDIN!";
 
-my $caffeinated;
-my $username = $ENV{LOGNAME} || $ENV{USER} || getpwuid($<);
-my $hostname = hostname;
+    # Following based on Michael Stapelberg's sample i3status-wrapper script.
 
-expensive();
-$SIG{USR1} = sub { kill USR1 => $i3status; expensive() };
+    my $hostname = hostname;
+    my $username = $ENV{LOGNAME} || $ENV{USER} || getpwuid($<);
 
-# Read lines forever, ignore a comma at the beginning if it exists.
-while (my ($statusline) = (<$pipe> =~ /^,?(.*)/)) {
-    my @blocks = @{ decode_json $statusline };
+    # Skip the first line which contains the version header.
+    print scalar <>;
 
-    unshift @blocks,
-      { full_text => "Caffeinated: $caffeinated", name => "caffeinated" }
-      if $caffeinated;
+    # The second line contains the start of the infinite array.
+    print scalar <>;
 
-    unshift @blocks,
-      { full_text => $username . "@" . $hostname, name => "hostinfo" };
+    # Read lines forever, ignore a comma at the beginning if it exists.
+    while (my ($statusline) = (<> =~ /^,?(.*)/)) {
+        my @blocks = @{ decode_json $statusline };
 
-    print encode_json(\@blocks) . ",\n";
-}
+        unshift @blocks,
+          {
+            name      => "caffeinated",
+            full_text => "Caffeinated: " . $info{caffeinated_name} }
+          if $info{caffeinated_name};
+
+        unshift @blocks,
+          { name => "hostinfo", full_text => $username . "@" . $hostname };
 
-sub expensive {
-    my %marks;
-    walk_tree(\%marks, decode_json `$wmipc -t get_tree`);
-    $caffeinated = exists $marks{caffeinated} ? $marks{caffeinated} : undef;
+        print encode_json(\@blocks) . ",\n";
+    }
 }
 
-sub walk_tree {
-    my ($marks, $tree) = @_;
-    $marks->{$_} = $tree->{name} for $tree->{marks}->@*;
-    walk_tree($marks, $_) for $tree->{nodes}->@*;
+my $caffeinated_id;
+
+open my $events, "-|",
+  $wmipc, "-t", "subscribe", "-m", '[ "window" ]';
+
+while (my $event = decode_json <$events>) {
+    if ($event->{change} eq "mark") {
+        if (grep $_ eq "caffeinated", $event->{container}{marks}->@*) {
+            $caffeinated_id = $event->{container}{id};
+            $info{caffeinated_name} = $event->{container}{name};
+            kill USR1 => $i3status;
+        } elsif ($caffeinated_id
+            and $caffeinated_id == $event->{container}{id}) {
+            undef $caffeinated_id, undef $info{caffeinated_name};
+            kill USR1 => $i3status;
+        }
+    }
 }