]> git.ktnx.net Git - mpd-feeder.git/commitdiff
split-out App::MPD::Feeder -- the main application module
authorDamyan Ivanov <dmn@debian.org>
Fri, 12 Nov 2021 06:22:54 +0000 (06:22 +0000)
committerDamyan Ivanov <dmn@debian.org>
Fri, 12 Nov 2021 06:22:54 +0000 (06:22 +0000)
bin/mpd-feeder
lib/App/MPD/Feeder.pm [new file with mode: 0644]

index bbddefd4844f689e7bdfbdbfb75e3ff3035cacc8..53c826578840f3900e08e14472539117a4ba6073 100755 (executable)
 #!/usr/bin/perl
 
-use v5.32;
+use strict;
+use warnings;
+use utf8;
 
+use App::MPD::Feeder;
 use App::MPD::Feeder::Options;
-use Getopt::Long ();
 use Log::Any qw($log);
 use Log::Any::Adapter Stderr => log_level => 'error';
-use Object::Pad;
-use Syntax::Keyword::Try;
-
-class Feeder {
-    has $cfg_file :reader;
-    has $opt :reader;
-    has $db;
-    has $db_generation;
-    has $db_needs_update :writer = 1;
-    has $mpd :reader;
-
-use constant DEFAULT_CONFIG_FILE => '/etc/mpd-feeder/mpd-feeder.conf';
-
-use DBD::Pg;
-use DBI;
-use Log::Any qw($log);
-use IO::Async::Signal;
-use Net::Async::MPD;
-
-    ADJUST {
-        Getopt::Long::Configure('pass_through');
-        Getopt::Long::GetOptions('cfg|config=s' => \$cfg_file);
-        Getopt::Long::Configure('no_pass_through');
-
-        $cfg_file //= DEFAULT_CONFIG_FILE if -e DEFAULT_CONFIG_FILE;
-
-        $self->configure;
-
-        $db_needs_update = 0 if $opt->skip_db_update;
-    }
-
-    method configure {
-        my $new_opt = App::MPD::Feeder::Options->new;
-
-        $new_opt->parse_config_file($cfg_file) if $cfg_file;
-
-        $new_opt->parse_command_line;
-
-        Log::Any::Adapter->set( Stderr => log_level => $new_opt->log_level );
-
-        $opt = $new_opt;
-    }
-
-    method connect_mpd {
-        return if $mpd;
-
-        my %conn = ( auto_connect => 1 );
-        $conn{host} = $opt->mpd_host if $opt->mpd_host;
-        $conn{port} = $opt->mpd_port if $opt->mpd_port;
-
-        $mpd = Net::Async::MPD->new(%conn);
-
-        $mpd->loop->add(
-            IO::Async::Signal->new(
-                name       => 'HUP',
-                on_receipt => sub {
-                    $log->debug("SIGHUP received. Stopping loop");
-                    $mpd->loop->stop('reload');
-                },
-            )
-        );
-
-        $mpd->loop->add(
-            IO::Async::Signal->new(
-                name       => 'USR1',
-                on_receipt => sub {
-                    $log->debug("SIGUSR1 received. Dumping configuration to STDERR");
-                    my $old = select \*STDERR;
-                    try {
-                        $opt->dump;
-                    }
-                    finally {
-                        select $old;
-                    }
-                },
-            )
-        );
-    }
-
-    method connect_db {
-        return if $db;
-
-        $db = DBI->connect( "dbi:Pg:dbname=" . $opt->db_path,
-            $opt->db_user, $opt->db_password,
-            { RaiseError => 1, PrintError => 0, AutoCommit => 1 } );
-
-        $log->info( "Connected to database " . $opt->db_path );
-        $db_generation = $self->db_get_option('generation');
-        $log->debug("DB generation is $db_generation");
-        $self->update_db;
-    }
-
-    method db_get_option($name) {
-        my $sth = $db->prepare_cached("select $name from options");
-        $sth->execute;
-        my @result = $sth->fetchrow_array;
-        $sth->finish;
-        undef $sth;
-
-        return $result[0];
-    }
-
-    method db_set_option( $name, $value ) {
-        my $sth = $db->prepare_cached("update options set $name = ?");
-        $sth->execute($value);
-    }
-
-    method db_store_song($song, $artist, $album) {
-        return unless length($song) and length($artist) and length($album);
-
-        $db->prepare_cached(
-            <<'SQL')->execute( $song, $artist, $album, $db_generation );
-INSERT INTO songs(path, artist, album, generation)
-VALUES($1, $2, $3, $4)
-ON CONFLICT ON CONSTRAINT songs_pkey DO
-UPDATE SET artist = $2
-         , album = $3
-         , generation = $4
-SQL
-        $db->prepare_cached(<<'SQL')->execute( $artist, $album, $db_generation );
-INSERT INTO albums(artist, album, generation)
-VALUES($1, $2, $3)
-ON CONFLICT ON CONSTRAINT albums_pkey DO
-UPDATE SET generation = $3
-SQL
-        $db->prepare_cached(<<'SQL')->execute( $artist, $db_generation );
-INSERT INTO artists(artist, generation)
-VALUES($1, $2)
-ON CONFLICT ON CONSTRAINT artists_pkey DO
-UPDATE SET generation = $2
-SQL
-    }
-
-    method db_remove_stale_entries {
-        my $sth =
-            $db->prepare_cached('DELETE FROM songs WHERE generation <> ?');
-        $sth->execute($db_generation);
-        $log->debug( sprintf( "Deleted %d stale songs", $sth->rows ) );
-
-        $sth = $db->prepare_cached('DELETE FROM albums WHERE generation <> ?');
-        $sth->execute($db_generation);
-        $log->debug( sprintf( "Deleted %d stale albums", $sth->rows ) );
-
-        $sth =
-            $db->prepare_cached('DELETE FROM artists WHERE generation <> ?');
-        $sth->execute($db_generation);
-        $log->debug( sprintf( "Deleted %d stale artists", $sth->rows ) );
-    }
-
-    method db_note_song_qeued($item) {
-        $db->prepare_cached(
-            'UPDATE songs SET last_queued=current_timestamp WHERE path=?')
-            ->execute( $item->{song} );
-        $db->prepare_cached(
-            'UPDATE artists SET last_queued=CURRENT_TIMESTAMP WHERE artist=?')
-            ->execute( $item->{artist} );
-        $db->prepare_cached(
-            'UPDATE albums SET last_queued=CURRENT_TIMESTAMP WHERE artist=? AND album=?'
-        )->execute( $item->{artist}, $item->{album} );
-    }
-
-    method update_db($force = undef) {
-        if (!$db_needs_update and !$force) {
-            $log->debug("Skipping DB update");
-            return;
-        }
-
-        $log->info('Updating song database');
-        $self->connect_mpd;
-        $self->connect_db;
-
-        my $rows = $mpd->send('listallinfo')->get;
-        try {
-            $db->begin_work;
-
-            $db_generation++;
-
-            my $song_count;
-
-            foreach my $entry (@$rows) {
-                next unless exists $entry->{file};
-                $self->db_store_song( $entry->{file},
-                    $entry->{AlbumArtist} // $entry->{Artist},
-                    $entry->{Album} );
-                $song_count++;
-            }
-
-            $log->info("Updated data about $song_count songs");
-
-            $self->db_remove_stale_entries;
-
-            $self->db_set_option( generation => $db_generation );
-
-            $db->commit;
-
-            $db_needs_update = 0;
-        }
-        catch {
-            my $err = $@;
-
-            $db_generation--;
-
-            $db->rollback;
-
-            die $err;
-        }
-    }
-
-    method db_find_suitable_songs($num) {
-        $self->connect_db;
-        $self->update_db;
-
-        my @result;
-        my $sql = <<SQL;
-SELECT s.path, s.artist, s.album
-FROM songs s
-JOIN artists ar ON ar.artist=s.artist
-JOIN albums al ON al.album=s.album AND al.artist=s.artist
-WHERE (s.last_queued IS NULL OR s.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-  AND (ar.last_queued IS NULL OR ar.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-  AND (al.last_queued IS NULL OR al.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-  AND NOT EXISTS (SELECT 1 FROM unwanted_artists uar WHERE uar.artist = s.artist)
-  AND NOT EXISTS (SELECT 1 FROM unwanted_albums  ual WHERE ual.album  = s.album)
-ORDER BY random()
-LIMIT ?
-SQL
-        my @params = (
-            $opt->min_song_interval,  $opt->min_artist_interval,
-            $opt->min_album_interval, $num,
-        );
-        my $sth = $db->prepare_cached($sql);
-        $sth->execute(@params);
-        while ( my @row = $sth->fetchrow_array ) {
-            push @result,
-                { song => $row[0], artist => $row[1], album => $row[2] };
-        }
-        undef $sth;
-
-        if (scalar(@result) == $num and  $log->is_debug) {
-            $sql =~ s/^SELECT .+$/SELECT COUNT(DISTINCT s.path)/m;
-            $sql =~ s/^ORDER BY .+$//m;
-            $sql =~ s/^LIMIT .+$//m;
-            $log->debug($sql);
-            my $sth = $db->prepare_cached($sql);
-            pop @params;
-            $sth->execute(@params);
-            my $count = ($sth->fetchrow_array)[0];
-            $sth->finish;
-
-            $sth = $db->prepare_cached('SELECT COUNT(*) FROM songs');
-            $sth->execute;
-            my $total = ($sth->fetchrow_array)[0];
-            $log->debug(
-                sprintf(
-                    "Number of songs meeting the criteria: %d out of total %d (%5.2f%%)",
-                    $count, $total, 100.0 * $count / $total
-                )
-            );
-            $sth->finish;
-
-            $sql = <<SQL;
-SELECT COUNT(*)
-FROM songs s
-WHERE (s.last_queued IS NULL OR s.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-UNION
-SELECT COUNT(*)
-FROM songs
-SQL
-            $sth = $db->prepare_cached($sql);
-            $sth->execute($opt->min_song_interval);
-            $count = ($sth->fetchrow_array)[0];
-            $total = ($sth->fetchrow_array)[0];
-            $sth->finish;
-
-            $log->debug(
-                sprintf(
-                    "Number of songs not queued soon: %d out of total %d (%5.2f%%)",
-                    $count, $total, 100.0 * $count / $total
-                )
-            );
-            $sth->finish;
-
-            $sql = <<SQL;
-SELECT COUNT(*)
-FROM artists ar
-WHERE (ar.last_queued IS NULL OR ar.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-UNION
-SELECT COUNT(*)
-FROM artists
-SQL
-            $sth = $db->prepare_cached($sql);
-            $sth->execute($opt->min_artist_interval);
-            $count = ($sth->fetchrow_array)[0];
-            $total = ($sth->fetchrow_array)[0];
-            $log->debug(
-                sprintf(
-                    "Number of artists not queued soon: %d out of total %d (%5.2f%%)",
-                    $count, $total, 100.0 * $count / $total
-                )
-            );
-            $sth->finish;
-
-            $sql = <<SQL;
-SELECT COUNT(*)
-FROM albums al
-WHERE (al.last_queued IS NULL OR al.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
-UNION
-SELECT COUNT(*)
-FROM albums
-SQL
-            $sth = $db->prepare_cached($sql);
-            $sth->execute($opt->min_album_interval);
-            $count = ($sth->fetchrow_array)[0];
-            $total = ($sth->fetchrow_array)[0];
-            $log->debug(
-                sprintf(
-                    "Number of albums not queued soon: %d out of total %d (%5.2f%%)",
-                    $count, $total, 100.0 * $count / $total
-                )
-            );
-            $sth->finish;
-
-            undef $sth;
-        }
-
-        return @result;
-    }
-
-    method db_add_unwanted_artist($artist) {
-        $self->connect_db;
-
-        try {
-            $db->do(
-                <<'SQL',
-INSERT INTO unwanted_artists(artist, generation)
-VALUES($1, $2)
-SQL
-                undef, $artist, $db_generation
-            );
-            return 1;
-        }
-        catch {
-            my $err = $@;
-
-            $log->debug("PostgreSQL error: $err");
-            $log->debug( "SQLSTATE = " . $db->state );
-            return 0 if $db->state eq '23505';
-
-            die $err;
-        }
-    }
-
-    method db_del_unwanted_artist($artist) {
-        $self->connect_db;
-
-        return 1 == $db->do(
-            <<'SQL',
-DELETE FROM unwanted_artists
-WHERE artist = $1
-SQL
-            undef, $artist
-        );
-    }
-
-    method queue_songs($num = undef, $callback = undef) {
-        if (!defined $num) {
-            $self->connect_mpd;
-            $mpd->send('playlist')->on_done(
-                sub {
-                    my $present = scalar @{ $_[0] };
-
-                    $log->notice( "Playlist contains $present songs. Wanted: "
-                            . $opt->target_queue_length );
-                    if ( $present < $opt->target_queue_length ) {
-                        $self->queue_songs(
-                            $opt->target_queue_length - $present, $callback );
-                    }
-                    else {
-                        $callback->() if $callback;
-                    }
-                }
-            );
-
-            return;
-        }
-
-        my @list = $self->db_find_suitable_songs($num);
-
-        die "Found no suitable songs" unless @list;
-
-        if ( @list < $num ) {
-            $log->warn(
-                sprintf(
-                    'Found only %d suitable songs instead of %d',
-                    scalar(@list), $num
-                )
-            );
-        }
-
-        $log->info("About to add $num songs to the playlist");
-
-        my @paths;
-        for my $song (@list) {
-            my $path = $song->{song};
-            $path =~ s/"/\\"/g;
-            push @paths, $path;
-        }
-
-        $log->debug( "Adding " . join( ', ', map {"«$_»"} @paths ) );
-        my @commands;
-        for (@paths) {
-            push @commands, [ add => "\"$_\"" ];
-        }
-        $self->connect_mpd;
-        my $f = $mpd->send( \@commands );
-        $f->on_fail( sub { die @_ } );
-        $f->on_done(
-            sub {
-                $self->db_note_song_qeued($_) for @list;
-                $callback->(@_) if $callback;
-            }
-        );
-    }
-
-    method prepare_to_wait_idle {
-        $log->trace('declaring idle mode');
-        $mpd->send('idle database playlist')->on_done(
-            sub {
-                my $result = shift;
-
-                if ( $result->{changed} eq 'database' ) {
-                    $db_needs_update = 1;
-                    $self->prepare_to_wait_idle;
-                }
-                elsif ( $result->{changed} eq 'playlist' ) {
-                    $self->queue_songs( undef,
-                        sub { $self->prepare_to_wait_idle } );
-                }
-                else {
-                    use JSON;
-                    $log->warn(
-                        "Unknown result from idle: " . to_json($result) );
-                    $self->prepare_to_wait_idle;
-                }
-            }
-        );
-    }
-
-    method run {
-        $mpd->on(
-            close => sub {
-                die "Connection to MPD lost";
-            }
-        );
-
-        $self->prepare_to_wait_idle;
-    }
-
-    method stop {
-        undef $mpd;
-
-        if ($db) {
-            if ($db->{ActiveKids}) {
-                $log->warn("$db->{ActiveKids} active DB statements");
-                for my $st ( @{ $db->{ChildHandles} } ) {
-                    next unless $st->{Active};
-                    while(my($k,$v) = each %$st) {
-                        $log->debug("$k = ".($v//'<NULL>'));
-                    }
-                }
-            }
-
-            $db->disconnect;
-            undef $db;
-        }
-    }
-}
 
 my $feeder = Feeder->new();
 
diff --git a/lib/App/MPD/Feeder.pm b/lib/App/MPD/Feeder.pm
new file mode 100644 (file)
index 0000000..dbdcafb
--- /dev/null
@@ -0,0 +1,486 @@
+package App::MPD::Feeder;
+
+use strict;
+use warnings;
+use utf8;
+
+use App::MPD::Feeder::Options;
+use DBD::Pg;
+use DBI;
+use Getopt::Long;
+use IO::Async::Signal;
+use Log::Any qw($log);
+use Net::Async::MPD;
+use Object::Pad;
+use Syntax::Keyword::Try;
+
+
+class App::MPD::Feeder {
+    has $cfg_file :reader;
+    has $opt :reader;
+    has $db;
+    has $db_generation;
+    has $db_needs_update :writer = 1;
+    has $mpd :reader;
+
+use constant DEFAULT_CONFIG_FILE => '/etc/mpd-feeder/mpd-feeder.conf';
+
+    ADJUST {
+        Getopt::Long::Configure('pass_through');
+        Getopt::Long::GetOptions('cfg|config=s' => \$cfg_file);
+        Getopt::Long::Configure('no_pass_through');
+
+        $cfg_file //= DEFAULT_CONFIG_FILE if -e DEFAULT_CONFIG_FILE;
+
+        $self->configure;
+
+        $db_needs_update = 0 if $opt->skip_db_update;
+    }
+
+    method configure {
+        my $new_opt = App::MPD::Feeder::Options->new;
+
+        $new_opt->parse_config_file($cfg_file) if $cfg_file;
+
+        $new_opt->parse_command_line;
+
+        Log::Any::Adapter->set( Stderr => log_level => $new_opt->log_level );
+
+        $opt = $new_opt;
+    }
+
+    method connect_mpd {
+        return if $mpd;
+
+        my %conn = ( auto_connect => 1 );
+        $conn{host} = $opt->mpd_host if $opt->mpd_host;
+        $conn{port} = $opt->mpd_port if $opt->mpd_port;
+
+        $mpd = Net::Async::MPD->new(%conn);
+
+        $mpd->loop->add(
+            IO::Async::Signal->new(
+                name       => 'HUP',
+                on_receipt => sub {
+                    $log->debug("SIGHUP received. Stopping loop");
+                    $mpd->loop->stop('reload');
+                },
+            )
+        );
+
+        $mpd->loop->add(
+            IO::Async::Signal->new(
+                name       => 'USR1',
+                on_receipt => sub {
+                    $log->debug("SIGUSR1 received. Dumping configuration to STDERR");
+                    my $old = select \*STDERR;
+                    try {
+                        $opt->dump;
+                    }
+                    finally {
+                        select $old;
+                    }
+                },
+            )
+        );
+    }
+
+    method connect_db {
+        return if $db;
+
+        $db = DBI->connect( "dbi:Pg:dbname=" . $opt->db_path,
+            $opt->db_user, $opt->db_password,
+            { RaiseError => 1, PrintError => 0, AutoCommit => 1 } );
+
+        $log->info( "Connected to database " . $opt->db_path );
+        $db_generation = $self->db_get_option('generation');
+        $log->debug("DB generation is $db_generation");
+        $self->update_db;
+    }
+
+    method db_get_option($name) {
+        my $sth = $db->prepare_cached("select $name from options");
+        $sth->execute;
+        my @result = $sth->fetchrow_array;
+        $sth->finish;
+        undef $sth;
+
+        return $result[0];
+    }
+
+    method db_set_option( $name, $value ) {
+        my $sth = $db->prepare_cached("update options set $name = ?");
+        $sth->execute($value);
+    }
+
+    method db_store_song($song, $artist, $album) {
+        return unless length($song) and length($artist) and length($album);
+
+        $db->prepare_cached(
+            <<'SQL')->execute( $song, $artist, $album, $db_generation );
+INSERT INTO songs(path, artist, album, generation)
+VALUES($1, $2, $3, $4)
+ON CONFLICT ON CONSTRAINT songs_pkey DO
+UPDATE SET artist = $2
+         , album = $3
+         , generation = $4
+SQL
+        $db->prepare_cached(<<'SQL')->execute( $artist, $album, $db_generation );
+INSERT INTO albums(artist, album, generation)
+VALUES($1, $2, $3)
+ON CONFLICT ON CONSTRAINT albums_pkey DO
+UPDATE SET generation = $3
+SQL
+        $db->prepare_cached(<<'SQL')->execute( $artist, $db_generation );
+INSERT INTO artists(artist, generation)
+VALUES($1, $2)
+ON CONFLICT ON CONSTRAINT artists_pkey DO
+UPDATE SET generation = $2
+SQL
+    }
+
+    method db_remove_stale_entries {
+        my $sth =
+            $db->prepare_cached('DELETE FROM songs WHERE generation <> ?');
+        $sth->execute($db_generation);
+        $log->debug( sprintf( "Deleted %d stale songs", $sth->rows ) );
+
+        $sth = $db->prepare_cached('DELETE FROM albums WHERE generation <> ?');
+        $sth->execute($db_generation);
+        $log->debug( sprintf( "Deleted %d stale albums", $sth->rows ) );
+
+        $sth =
+            $db->prepare_cached('DELETE FROM artists WHERE generation <> ?');
+        $sth->execute($db_generation);
+        $log->debug( sprintf( "Deleted %d stale artists", $sth->rows ) );
+    }
+
+    method db_note_song_qeued($item) {
+        $db->prepare_cached(
+            'UPDATE songs SET last_queued=current_timestamp WHERE path=?')
+            ->execute( $item->{song} );
+        $db->prepare_cached(
+            'UPDATE artists SET last_queued=CURRENT_TIMESTAMP WHERE artist=?')
+            ->execute( $item->{artist} );
+        $db->prepare_cached(
+            'UPDATE albums SET last_queued=CURRENT_TIMESTAMP WHERE artist=? AND album=?'
+        )->execute( $item->{artist}, $item->{album} );
+    }
+
+    method update_db($force = undef) {
+        if (!$db_needs_update and !$force) {
+            $log->debug("Skipping DB update");
+            return;
+        }
+
+        $log->info('Updating song database');
+        $self->connect_mpd;
+        $self->connect_db;
+
+        my $rows = $mpd->send('listallinfo')->get;
+        try {
+            $db->begin_work;
+
+            $db_generation++;
+
+            my $song_count;
+
+            foreach my $entry (@$rows) {
+                next unless exists $entry->{file};
+                $self->db_store_song( $entry->{file},
+                    $entry->{AlbumArtist} // $entry->{Artist},
+                    $entry->{Album} );
+                $song_count++;
+            }
+
+            $log->info("Updated data about $song_count songs");
+
+            $self->db_remove_stale_entries;
+
+            $self->db_set_option( generation => $db_generation );
+
+            $db->commit;
+
+            $db_needs_update = 0;
+        }
+        catch {
+            my $err = $@;
+
+            $db_generation--;
+
+            $db->rollback;
+
+            die $err;
+        }
+    }
+
+    method db_find_suitable_songs($num) {
+        $self->connect_db;
+        $self->update_db;
+
+        my @result;
+        my $sql = <<SQL;
+SELECT s.path, s.artist, s.album
+FROM songs s
+JOIN artists ar ON ar.artist=s.artist
+JOIN albums al ON al.album=s.album AND al.artist=s.artist
+WHERE (s.last_queued IS NULL OR s.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+  AND (ar.last_queued IS NULL OR ar.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+  AND (al.last_queued IS NULL OR al.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+  AND NOT EXISTS (SELECT 1 FROM unwanted_artists uar WHERE uar.artist = s.artist)
+  AND NOT EXISTS (SELECT 1 FROM unwanted_albums  ual WHERE ual.album  = s.album)
+ORDER BY random()
+LIMIT ?
+SQL
+        my @params = (
+            $opt->min_song_interval,  $opt->min_artist_interval,
+            $opt->min_album_interval, $num,
+        );
+        my $sth = $db->prepare_cached($sql);
+        $sth->execute(@params);
+        while ( my @row = $sth->fetchrow_array ) {
+            push @result,
+                { song => $row[0], artist => $row[1], album => $row[2] };
+        }
+        undef $sth;
+
+        if (scalar(@result) == $num and  $log->is_debug) {
+            $sql =~ s/^SELECT .+$/SELECT COUNT(DISTINCT s.path)/m;
+            $sql =~ s/^ORDER BY .+$//m;
+            $sql =~ s/^LIMIT .+$//m;
+            $log->debug($sql);
+            my $sth = $db->prepare_cached($sql);
+            pop @params;
+            $sth->execute(@params);
+            my $count = ($sth->fetchrow_array)[0];
+            $sth->finish;
+
+            $sth = $db->prepare_cached('SELECT COUNT(*) FROM songs');
+            $sth->execute;
+            my $total = ($sth->fetchrow_array)[0];
+            $log->debug(
+                sprintf(
+                    "Number of songs meeting the criteria: %d out of total %d (%5.2f%%)",
+                    $count, $total, 100.0 * $count / $total
+                )
+            );
+            $sth->finish;
+
+            $sql = <<SQL;
+SELECT COUNT(*)
+FROM songs s
+WHERE (s.last_queued IS NULL OR s.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+UNION
+SELECT COUNT(*)
+FROM songs
+SQL
+            $sth = $db->prepare_cached($sql);
+            $sth->execute($opt->min_song_interval);
+            $count = ($sth->fetchrow_array)[0];
+            $total = ($sth->fetchrow_array)[0];
+            $sth->finish;
+
+            $log->debug(
+                sprintf(
+                    "Number of songs not queued soon: %d out of total %d (%5.2f%%)",
+                    $count, $total, 100.0 * $count / $total
+                )
+            );
+            $sth->finish;
+
+            $sql = <<SQL;
+SELECT COUNT(*)
+FROM artists ar
+WHERE (ar.last_queued IS NULL OR ar.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+UNION
+SELECT COUNT(*)
+FROM artists
+SQL
+            $sth = $db->prepare_cached($sql);
+            $sth->execute($opt->min_artist_interval);
+            $count = ($sth->fetchrow_array)[0];
+            $total = ($sth->fetchrow_array)[0];
+            $log->debug(
+                sprintf(
+                    "Number of artists not queued soon: %d out of total %d (%5.2f%%)",
+                    $count, $total, 100.0 * $count / $total
+                )
+            );
+            $sth->finish;
+
+            $sql = <<SQL;
+SELECT COUNT(*)
+FROM albums al
+WHERE (al.last_queued IS NULL OR al.last_queued < CURRENT_TIMESTAMP - (? || ' seconds')::interval)
+UNION
+SELECT COUNT(*)
+FROM albums
+SQL
+            $sth = $db->prepare_cached($sql);
+            $sth->execute($opt->min_album_interval);
+            $count = ($sth->fetchrow_array)[0];
+            $total = ($sth->fetchrow_array)[0];
+            $log->debug(
+                sprintf(
+                    "Number of albums not queued soon: %d out of total %d (%5.2f%%)",
+                    $count, $total, 100.0 * $count / $total
+                )
+            );
+            $sth->finish;
+
+            undef $sth;
+        }
+
+        return @result;
+    }
+
+    method db_add_unwanted_artist($artist) {
+        $self->connect_db;
+
+        try {
+            $db->do(
+                <<'SQL',
+INSERT INTO unwanted_artists(artist, generation)
+VALUES($1, $2)
+SQL
+                undef, $artist, $db_generation
+            );
+            return 1;
+        }
+        catch {
+            my $err = $@;
+
+            $log->debug("PostgreSQL error: $err");
+            $log->debug( "SQLSTATE = " . $db->state );
+            return 0 if $db->state eq '23505';
+
+            die $err;
+        }
+    }
+
+    method db_del_unwanted_artist($artist) {
+        $self->connect_db;
+
+        return 1 == $db->do(
+            <<'SQL',
+DELETE FROM unwanted_artists
+WHERE artist = $1
+SQL
+            undef, $artist
+        );
+    }
+
+    method queue_songs($num = undef, $callback = undef) {
+        if (!defined $num) {
+            $self->connect_mpd;
+            $mpd->send('playlist')->on_done(
+                sub {
+                    my $present = scalar @{ $_[0] };
+
+                    $log->notice( "Playlist contains $present songs. Wanted: "
+                            . $opt->target_queue_length );
+                    if ( $present < $opt->target_queue_length ) {
+                        $self->queue_songs(
+                            $opt->target_queue_length - $present, $callback );
+                    }
+                    else {
+                        $callback->() if $callback;
+                    }
+                }
+            );
+
+            return;
+        }
+
+        my @list = $self->db_find_suitable_songs($num);
+
+        die "Found no suitable songs" unless @list;
+
+        if ( @list < $num ) {
+            $log->warn(
+                sprintf(
+                    'Found only %d suitable songs instead of %d',
+                    scalar(@list), $num
+                )
+            );
+        }
+
+        $log->info("About to add $num songs to the playlist");
+
+        my @paths;
+        for my $song (@list) {
+            my $path = $song->{song};
+            $path =~ s/"/\\"/g;
+            push @paths, $path;
+        }
+
+        $log->debug( "Adding " . join( ', ', map {"«$_»"} @paths ) );
+        my @commands;
+        for (@paths) {
+            push @commands, [ add => "\"$_\"" ];
+        }
+        $self->connect_mpd;
+        my $f = $mpd->send( \@commands );
+        $f->on_fail( sub { die @_ } );
+        $f->on_done(
+            sub {
+                $self->db_note_song_qeued($_) for @list;
+                $callback->(@_) if $callback;
+            }
+        );
+    }
+
+    method prepare_to_wait_idle {
+        $log->trace('declaring idle mode');
+        $mpd->send('idle database playlist')->on_done(
+            sub {
+                my $result = shift;
+
+                if ( $result->{changed} eq 'database' ) {
+                    $db_needs_update = 1;
+                    $self->prepare_to_wait_idle;
+                }
+                elsif ( $result->{changed} eq 'playlist' ) {
+                    $self->queue_songs( undef,
+                        sub { $self->prepare_to_wait_idle } );
+                }
+                else {
+                    use JSON;
+                    $log->warn(
+                        "Unknown result from idle: " . to_json($result) );
+                    $self->prepare_to_wait_idle;
+                }
+            }
+        );
+    }
+
+    method run {
+        $mpd->on(
+            close => sub {
+                die "Connection to MPD lost";
+            }
+        );
+
+        $self->prepare_to_wait_idle;
+    }
+
+    method stop {
+        undef $mpd;
+
+        if ($db) {
+            if ($db->{ActiveKids}) {
+                $log->warn("$db->{ActiveKids} active DB statements");
+                for my $st ( @{ $db->{ChildHandles} } ) {
+                    next unless $st->{Active};
+                    while(my($k,$v) = each %$st) {
+                        $log->debug("$k = ".($v//'<NULL>'));
+                    }
+                }
+            }
+
+            $db->disconnect;
+            undef $db;
+        }
+    }
+}
+