Add asynchronous song download

bot/track.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/RichardNysater/mumbledj/interfaces"
+	"sync"
 )
 
 // Track stores all metadata related to an audio track.
@@ -27,6 +28,7 @@ type Track struct {
 	Duration       time.Duration
 	PlaybackOffset time.Duration
 	Playlist       interfaces.Playlist
+	WaitGroup      sync.WaitGroup
 }
 
 // GetID returns the ID of the track.
@@ -92,3 +94,8 @@ func (t Track) GetPlaybackOffset() time.Duration {
 func (t Track) GetPlaylist() interfaces.Playlist {
 	return t.Playlist
 }
+
+// GetWaitGroup returns the WaitGroup the track is associated with.
+func(t Track) GetWaitGroup() sync.WaitGroup {
+	return t.WaitGroup
+}

bot/youtube_dl.go

@@ -42,13 +42,16 @@ func (yt *YouTubeDL) Download(t interfaces.Track) error {
 
 	// Check to see if track is already downloaded.
 	if _, err := os.Stat(filepath); os.IsNotExist(err) {
-		var cmd *exec.Cmd
+		t.GetWaitGroup().Wait()
+		//waitgroup.wait here
 		logrus.WithFields(logrus.Fields{
 			"url": t.GetURL(),
 			"download-path": filepath,
 			"format" : format,
 			"player" : player,
 		}).Infoln("Downloading track...")
+
+		var cmd *exec.Cmd
 		if t.GetService() == "Mixcloud" {
 			logrus.Infoln("Downloading from Mixcloud...")
 			cmd = exec.Command("youtube-dl", "--verbose", "--no-mtime", "--output", filepath, "--format", format, "--external-downloader", "aria2c", player, t.GetURL())
@@ -64,7 +67,7 @@ func (yt *YouTubeDL) Download(t interfaces.Track) error {
 			logrus.Warnf("%s\n%s\nyoutube-dl: %s", args, string(output), err.Error())
 			return errors.New("Track download failed")
 		}
-
+		t.GetWaitGroup().Done()
 		if viper.GetBool("cache.enabled") {
 			DJ.Cache.CheckDirectorySize()
 		}

commands/add.go

@@ -81,6 +81,9 @@ func (c *AddCommand) Execute(user *gumble.User, args ...string) (string, bool, e
 			lastTrackAdded = track
 		}
 	}
+	if DJ.Queue.Length() > 1{ // If the newly added song is not the next to be played then download it
+		go DJ.YouTubeDL.Download(lastTrackAdded)
+	}
 
 	if numAdded == 0 {
 		return "", true, errors.New(viper.GetString("commands.add.messages.tracks_too_long_error"))

interfaces/track.go

@@ -7,7 +7,10 @@
 
 package interfaces
 
-import "time"
+import (
+	"time"
+	"sync"
+)
 
 // Track is an interface of methods that must be implemented by tracks.
 type Track interface {
@@ -23,4 +26,5 @@ type Track interface {
 	GetDuration() time.Duration
 	GetPlaybackOffset() time.Duration
 	GetPlaylist() Playlist
+	GetWaitGroup() sync.WaitGroup
 }

services/mixcloud.go

@@ -18,6 +18,7 @@ import (
 	"layeh.com/gumble/gumble"
 	"github.com/RichardNysater/mumbledj/bot"
 	"github.com/RichardNysater/mumbledj/interfaces"
+	"sync"
 )
 
 // Mixcloud is a wrapper around the Mixcloud API.
@@ -92,7 +93,7 @@ func (mc *Mixcloud) GetTracks(url string, submitter *gumble.User) ([]interfaces.
 		// Track has no artwork, using profile avatar instead.
 		thumbnail, _ = v.GetString("user", "pictures", "large")
 	}
-
+	var wg sync.WaitGroup
 	track := bot.Track{
 		ID:             id,
 		URL:            trackURL,
@@ -106,6 +107,7 @@ func (mc *Mixcloud) GetTracks(url string, submitter *gumble.User) ([]interfaces.
 		Duration:       duration,
 		PlaybackOffset: offset,
 		Playlist:       nil,
+		WaitGroup:	wg,
 	}
 
 	tracks = append(tracks, track)

services/soundcloud.go

@@ -21,6 +21,7 @@ import (
 	"github.com/RichardNysater/mumbledj/bot"
 	"github.com/RichardNysater/mumbledj/interfaces"
 	"github.com/spf13/viper"
+	"sync"
 )
 
 // SoundCloud is a wrapper around the SoundCloud API.
@@ -174,7 +175,7 @@ func (sc *SoundCloud) getTrack(obj *jason.Object, offset time.Duration, submitte
 		// Track has no artwork, using profile avatar instead.
 		thumbnail, _ = obj.GetString("user", "avatar_url")
 	}
-
+	var wg sync.WaitGroup
 	return bot.Track{
 		ID:             id,
 		URL:            url,
@@ -188,5 +189,6 @@ func (sc *SoundCloud) getTrack(obj *jason.Object, offset time.Duration, submitte
 		Duration:       duration,
 		PlaybackOffset: offset,
 		Playlist:       nil,
+		WaitGroup:	wg,
 	}, nil
 }

services/youtube.go

@@ -22,6 +22,7 @@ import (
 	"github.com/RichardNysater/mumbledj/bot"
 	"github.com/RichardNysater/mumbledj/interfaces"
 	"github.com/spf13/viper"
+	"sync"
 )
 
 // YouTube is a wrapper around the YouTube Data API.
@@ -230,6 +231,7 @@ func (yt *YouTube) getTrack(id string, submitter *gumble.User, offset time.Durat
 	durationString, _ := item.GetString("contentDetails", "duration")
 	durationConverted, _ := duration.FromString(durationString)
 	duration := durationConverted.ToDuration()
+	var wg sync.WaitGroup
 
 	return bot.Track{
 		ID:             id,
@@ -243,5 +245,6 @@ func (yt *YouTube) getTrack(id string, submitter *gumble.User, offset time.Durat
 		Duration:       duration,
 		PlaybackOffset: offset,
 		Playlist:       nil,
+		WaitGroup:	wg,
 	}, nil
 }