From 13f4e9d07015eaccbc5524b8d1513ff7c79922bd Mon Sep 17 00:00:00 2001
From: Damyan Ivanov <dmn@debian.org>
Date: Sat, 27 Nov 2021 07:36:48 +0000
Subject: [PATCH] add systemd integration (optional)

---
 dist.ini              |  3 +++
 eg/mpd-feeder.service |  2 +-
 lib/App/MPD/Feeder.pm | 37 ++++++++++++++++++++++++++++---------
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/dist.ini b/dist.ini
index 68e4b22..864a4ec 100644
--- a/dist.ini
+++ b/dist.ini
@@ -20,6 +20,9 @@ Syntax::Keyword::Try = 0
 Time::Duration = 0
 Time::Duration::Parse = 0
 utf8::all = 0
+-phase = runtime
+-relationship = recommends
+Linux::Systemd::Daemon
 
 [Test::Compile]
 ;skip      = Test$
diff --git a/eg/mpd-feeder.service b/eg/mpd-feeder.service
index d98a43d..1b762d0 100644
--- a/eg/mpd-feeder.service
+++ b/eg/mpd-feeder.service
@@ -3,7 +3,7 @@ Description=MPD playlist manager
 ConditionPathExists=/etc/mpd-feeder/mpd-feeder.conf
 
 [Service]
-Type=exec
+Type=notify
 User=mpd-feeder
 ExecStart=/usr/bin/mpd-feeder
 StandardError=journal
diff --git a/lib/App/MPD/Feeder.pm b/lib/App/MPD/Feeder.pm
index b6c8203..7211fab 100644
--- a/lib/App/MPD/Feeder.pm
+++ b/lib/App/MPD/Feeder.pm
@@ -17,6 +17,8 @@ use Object::Pad;
 use Syntax::Keyword::Try;
 use Time::Duration qw(duration_exact);
 
+use constant UNDER_SYSTEMD => eval { require Linux::Systemd::Daemon };
+
 has $cfg_file :reader;
 has $opt :reader;
 has $db :reader;
@@ -53,6 +55,9 @@ method configure {
 
     Log::Any::Adapter->set( Stderr => log_level => $new_opt->log_level );
 
+    $log->debug( "Systemd integration "
+            . ( UNDER_SYSTEMD ? "available" : "not available" ) );
+
     $opt = $new_opt;
 
     $reconnect_delay = $opt->initial_reconnect_delay;
@@ -60,6 +65,11 @@ method configure {
     $db = App::MPD::Feeder::DB->new( opt => $opt );
 }
 
+method status($text, $log_level = undef) {
+    Linux::Systemd::Daemon::sd_notify( status => $text ) if UNDER_SYSTEMD;
+    $log->$log_level($text) if $log_level;
+}
+
 method init_mpd {
     return if $mpd;
 
@@ -157,12 +167,13 @@ method update_db( $force = undef ) {
         return;
     }
 
-    $log->info('Updating song database');
+    $self->status('Updating song database', 'info');
 
     my $rows = $mpd->send('listallinfo')->get;
 
     $log->trace('got all songs from MPD');
 
+    $self->status('Updating local song database', 'debug');
     $db->start_update;
     try {
         my $song_count;
@@ -201,7 +212,7 @@ method queue_songs( $num = undef ) {
     if ( !defined $num ) {
         return unless $playlist_needs_filling;
 
-        $log->trace("Requesting playlist");
+        $self->status("Requesting playlist", 'trace');
         my $present = $mpd->send('playlist')->get // [];
         $present = scalar(@$present);
 
@@ -218,6 +229,7 @@ method queue_songs( $num = undef ) {
         return;
     }
 
+    $self->status("Looking for suitable songs to queue", 'debug');
     my @list = $self->db->find_suitable_songs($num);
 
     die "Found no suitable songs" unless @list;
@@ -241,6 +253,7 @@ method queue_songs( $num = undef ) {
     }
 
     $log->notice( "Adding " . join( ', ', map {"«$_»"} @paths ) );
+    $self->status('Adding songs to the playlist');
 
     # MPD needs raw bytes
     utf8::encode($_) for @paths;
@@ -260,7 +273,8 @@ method queue_songs( $num = undef ) {
 }
 
 method reexec {
-    $log->info("disconnecting and re-starting");
+    $self->status("disconnecting and re-starting", 'info');
+    Linux::Systemd::Daemon::sd_reloading() if UNDER_SYSTEMD;
     $db->disconnect;
     undef $mpd;
 
@@ -288,9 +302,12 @@ method break_idle {
 }
 
 method sleep_before_reconnection {
-    $log->debug( "Waiting for "
+    $self->status(
+        "Waiting for "
             . duration_exact($reconnect_delay)
-            . " before re-connecting" );
+            . " before re-connecting",
+        'debug'
+    );
 
     $mpd->loop->add(
         IO::Async::Timer::Countdown->new(
@@ -306,7 +323,7 @@ method sleep_before_reconnection {
 
 method pulse {
     unless ($mpd_connected) {
-        $log->trace("Connecting to MPD...");
+        $self->status("Connecting to MPD", 'trace');
         my $f = $mpd->connect->await;
 
         if ( $f->is_done ) {
@@ -339,7 +356,7 @@ method pulse {
         return;
     }
 
-    $log->debug("Waiting idle. PID=$$");
+    $self->status("Waiting for playlist/database changes", 'debug');
     $last_mpd_comm = time;
     $idler         = $mpd->send("idle database playlist");
     $idler->await;
@@ -391,7 +408,7 @@ method run_loop {
 
                     $log->trace(
                         "no active MPD communication for more that 5 minutes");
-                    $log->debug("forcing alive check");
+                    $self->status("checking connection", 'debug');
                     $self->break_idle;
                 }
                 else {
@@ -405,7 +422,8 @@ method run_loop {
 
     for ( ;; ) {
         if ( $quit_requested ) {
-            $log->trace("about to quit");
+            $self->status("about to quit", 'debug');
+            Linux::Systemd::Daemon::sd_stopping() if UNDER_SYSTEMD;
             undef $mpd;
             $db->disconnect;
             last;
@@ -419,6 +437,7 @@ method run_loop {
 
         $mpd->loop->later( sub { $self->pulse } );
 
+        Linux::Systemd::Daemon::sd_ready() if UNDER_SYSTEMD;
         $mpd->loop->run;
     }
 }
-- 
2.39.5