Implemented timeouts, audio sample buffers, and fast-start depending on client

MeteorLight.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"time"
 )
 
 func getQueueEntryFromBody(body []byte) *QueueTrackEntry {
@@ -111,13 +112,13 @@ func main() {
 		//TODO: close properly
 		for {
 			if e := getRandomTrack(); e != nil {
-				queue.QueueEmpty <- e
 				nr = e
 				sendNowRandom(nr)
+				queue.QueueEmpty <- e
 			} else if e = getFallbackTrack(); e != nil {
-				queue.QueueEmpty <- e
 				nr = e
 				sendNowRandom(nr)
+				queue.QueueEmpty <- e
 			}
 		}
 	}()
@@ -311,7 +312,13 @@ func main() {
 			Handler: http.HandlerFunc(queue.HandleRadioRequest),
 		}
 
-		if err := server.ListenAndServe(); err != nil {
+		//setup a timeout to prevent slow clients blocking. See https://github.com/golang/go/issues/16100
+		timeoutListener, err := newListener("tcp", server.Addr, time.Second*5, time.Second*5)
+		if err != nil {
+			log.Panic(err)
+		}
+
+		if err = server.Serve(timeoutListener); err != nil {
 			log.Panic(err)
 		}
 	}()

README.md

@@ -4,7 +4,7 @@ Radio streamer ([kawa](https://github.com/Luminarys/kawa) drop-in compatible).
 
 This project is a Work in Progress.
 
-`TODO: proper handling of audio queue <-> data queue, timeouts, ICY metadata`
+`TODO: ICY metadata`
 
 # Improvements / differences from Kawa
 * Does not use libav ([see supported formats/codecs on Kirika](https://git.gammaspectra.live/S.O.N.G/Kirika#codecs-supported))
@@ -13,9 +13,13 @@ This project is a Work in Progress.
 * Does not restart stream per-track, instead being a continuous stream without parameter changes.
 * Normalized channels / sample rates for mounts.
 * Implements ICY metadata
-* Uses sample/timed packet buffers, instead of kawa byte buffers, which cause wild differences between endpoints. Mounts usually align within 0.2s of each other, depending on client.
+* Uses sample/timed packet buffers, instead of kawa byte buffers, which caused wild differences between endpoints. Mounts usually align within 0.2s of each other, depending on client.
+  * Use `queue.buffer_size` to specify number of seconds to buffer
 * Implements `queue.nr` and `/random` (To be Deprecated/Changed)
 
+# Future improvements
+* Allow playback of files by URL, not just by path
+* Implement precise timing information side-channel
 
 ## Dependencies
 ### Go >= 1.18
@@ -38,6 +42,7 @@ Before continuing, you will need to install the dependencies listed above.
 ### From Git repository
 ```shell
 $ git clone https://git.gammaspectra.live/S.O.N.G/MeteorLight.git && cd MeteorLight
+# create/edit config.toml
 $ go run . 
 ```
 

config.go

@@ -13,6 +13,7 @@ type Config struct {
 		NowRandom         string `toml:"nr"`
 		FallbackPath      string `toml:"fallback"`
 		BufferLengthInKiB int    `toml:"buffer_len"`
+		BufferSeconds     int    `toml:"buffer_size"`
 	} `toml:"queue"`
 	Radio struct {
 		Port int    `toml:"port"`

example_config.toml

@@ -26,13 +26,18 @@ np="http://localhost:8012/api/np"
 #
 # An HTTP POST is issued to this URL when MeteorLight fetches a random track. The body
 # will be identical to the JSON blob in memory.
+# Can be left empty to not send nr events
 nr="http://localhost:8012/api/nr"
 #
 # When no tracks are available for whatever reason (such as external service
 # outages), this track will be played.
 fallback="/tmp/in.flac"
 # Length of buffer to maintain in KiB (not implemented)
-buffer_len=4096
+# buffer_len=4096
+# Duration in seconds of buffer to maintain. Set 0 for automatic mode depending on requesting client.
+# Maximum 10 seconds.
+# Do note buffer is counted from start of frame, not end, for removal purposes. This depends on format and can be a second or so at times.
+buffer_duration=0
 
 [radio]
 #

go.mod

@@ -3,7 +3,7 @@ module git.gammaspectra.live/S.O.N.G/MeteorLight
 go 1.18
 
 require (
-	git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303091537-9e01c732f300
+	git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303134137-d0976eac62c4
 	github.com/BurntSushi/toml v1.0.0
 )
 

go.sum

@@ -1,5 +1,5 @@
-git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303091537-9e01c732f300 h1:tBRw3QkXCkybDhZ5lwqjNDbyB4YfI2pJ8ZXR+pkago0=
-git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303091537-9e01c732f300/go.mod h1:NYC/3wOINygtTYvAqEtMfgWBeJ/9Gfv0NvDxnWmg+yA=
+git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303134137-d0976eac62c4 h1:2o+FJxxoN4pv2h/ZnhY7p0Cnr79tVDocD3UycH3Dmmk=
+git.gammaspectra.live/S.O.N.G/Kirika v0.0.0-20220303134137-d0976eac62c4/go.mod h1:NYC/3wOINygtTYvAqEtMfgWBeJ/9Gfv0NvDxnWmg+yA=
 git.gammaspectra.live/S.O.N.G/go-fdkaac v0.0.0-20220228131722-e9cb84c52f48 h1:MaKiBfXQl0keyfdCi1PxGOKRTiWhIs8PqCal5GhKDi0=
 git.gammaspectra.live/S.O.N.G/go-fdkaac v0.0.0-20220228131722-e9cb84c52f48/go.mod h1:pkWt//S9hLVEQaJDPu/cHHPk8vPpo/0+zHy0me4LIP4=
 git.gammaspectra.live/S.O.N.G/go-pus v0.0.0-20220227175608-6cc027f24dba h1:JEaxCVgdr3XXAuDCPAx7ttLFZaaHzTEzG+oRnVUtUKU=

listener.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"net"
+	"sync/atomic"
+	"time"
+)
+
+type listener struct {
+	net.Listener
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+}
+
+func (l *listener) Accept() (net.Conn, error) {
+	c, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	tc := &Conn{
+		Conn:                     c,
+		ReadTimeout:              l.ReadTimeout,
+		WriteTimeout:             l.WriteTimeout,
+		ReadThreshold:            int32((l.ReadTimeout * 1024) / time.Second),
+		WriteThreshold:           int32((l.WriteTimeout * 1024) / time.Second),
+		BytesReadFromDeadline:    0,
+		BytesWrittenFromDeadline: 0,
+	}
+	return tc, nil
+}
+
+// Conn wraps a net.Conn, and sets a deadline for every read
+// and write operation.
+type Conn struct {
+	net.Conn
+	ReadTimeout              time.Duration
+	WriteTimeout             time.Duration
+	ReadThreshold            int32
+	WriteThreshold           int32
+	BytesReadFromDeadline    int32
+	BytesWrittenFromDeadline int32
+}
+
+func (c *Conn) Read(b []byte) (n int, err error) {
+	if atomic.LoadInt32(&c.BytesReadFromDeadline) > c.ReadThreshold {
+		atomic.StoreInt32(&c.BytesReadFromDeadline, 0)
+		// we set both read and write deadlines here otherwise after the request
+		// is read writing the response fails with an i/o timeout error
+		err = c.Conn.SetDeadline(time.Now().Add(c.ReadTimeout))
+		if err != nil {
+			return 0, err
+		}
+	}
+	n, err = c.Conn.Read(b)
+	atomic.AddInt32(&c.BytesReadFromDeadline, int32(n))
+	return
+}
+
+func (c *Conn) Write(b []byte) (n int, err error) {
+	if atomic.LoadInt32(&c.BytesWrittenFromDeadline) > c.WriteThreshold {
+		atomic.StoreInt32(&c.BytesWrittenFromDeadline, 0)
+		// we extend the read deadline too, not sure it's necessary,
+		// but it doesn't hurt
+		err = c.Conn.SetDeadline(time.Now().Add(c.WriteTimeout))
+		if err != nil {
+			return
+		}
+	}
+	n, err = c.Conn.Write(b)
+	atomic.AddInt32(&c.BytesWrittenFromDeadline, int32(n))
+	return
+}
+
+func newListener(network, addr string, readTimeout, writeTimeout time.Duration) (net.Listener, error) {
+	l, err := net.Listen(network, addr)
+	if err != nil {
+		return nil, err
+	}
+
+	tl := &listener{
+		Listener:     l,
+		ReadTimeout:  readTimeout,
+		WriteTimeout: writeTimeout,
+	}
+	return tl, nil
+}

mount.go

@@ -34,6 +34,7 @@ type StreamMount struct {
 	Mount      string
 	MimeType   string
 	Packetizer packetizer.Packetizer
+	SampleRate int
 
 	listeners     []*StreamListener
 	listenersLock sync.Mutex
@@ -48,6 +49,8 @@ func NewStreamMount(source audio.Source, mount string, codec string, container s
 	reader, writer := io.Pipe()
 	var packetizerEntry packetizer.Packetizer
 
+	sampleRate := source.SampleRate
+
 	switch codec {
 	case "opus":
 		encoderFormat = opus.NewFormat()
@@ -127,6 +130,7 @@ func NewStreamMount(source audio.Source, mount string, codec string, container s
 	}
 
 	if opusFormat, ok := encoderFormat.(opus.Format); ok {
+		sampleRate = opus.FixedSampleRate
 		go func() {
 			defer writer.Close()
 			if err := opusFormat.Encode(audio.NewResampleFilter(opus.FixedSampleRate, audio.Linear, 0).Process(source), writer, options); err != nil {
@@ -146,14 +150,18 @@ func NewStreamMount(source audio.Source, mount string, codec string, container s
 		Mount:      mount,
 		MimeType:   mimeType,
 		Packetizer: packetizerEntry,
+		SampleRate: sampleRate,
 	}
 }
 
-func (m *StreamMount) removeDiscard() {
+func (m *StreamMount) removeDiscard(sampleNumber int64) {
 	for i, p := range m.keepBuffer {
-		if p.KeepMode() == packetizer.Discard {
+		if p.KeepMode() == packetizer.Discard && p.GetSampleNumber() <= sampleNumber {
 			m.keepBuffer = append(m.keepBuffer[:i], m.keepBuffer[i+1:]...)
-			m.removeDiscard()
+			m.removeDiscard(sampleNumber)
+			break
+		} else if p.GetSampleNumber() > sampleNumber {
+			//they are placed in order
 			break
 		}
 	}
@@ -236,7 +244,9 @@ func (m *StreamMount) Process(group *sync.WaitGroup) {
 			toRemove = toRemove[:0]
 		}
 
-		m.removeDiscard() //always remove discards
+		sampleLimit := packet.GetSampleNumber() - int64(maxBufferSize*m.SampleRate)
+
+		m.removeDiscard(sampleLimit) //always remove discards
 
 		switch packet.KeepMode() {
 		case packetizer.KeepLast:

queue.go

@@ -15,8 +15,11 @@ import (
 	"path"
 	"strings"
 	"sync"
+	"time"
 )
 
+const maxBufferSize = 10
+
 type QueueTrackEntry struct {
 	QueueIdentifier audio.QueueIdentifier
 	Path            string
@@ -49,9 +52,8 @@ func NewQueue(config *Config) *Queue {
 		audioQueue: audio.NewQueue(44100, 2),
 	}
 	blocksPerSecond := 20
-	bufferSeconds := blocksPerSecond * 1
 
-	sources := SplitAudioSource(audio.NewFilterChain(q.audioQueue.GetSource(), audio.NewRealTimeFilter(blocksPerSecond), audio.NewBufferFilter(bufferSeconds)), len(config.Streams))
+	sources := SplitAudioSource(audio.NewFilterChain(q.audioQueue.GetSource(), audio.NewBufferFilter(16), audio.NewRealTimeFilter(blocksPerSecond), audio.NewBufferFilter(maxBufferSize*blocksPerSecond)), len(config.Streams))
 	for i, s := range q.config.Streams {
 		mount := NewStreamMount(sources[i], s.MountPath, s.Codec, s.Container, s.Bitrate)
 		if mount == nil {
@@ -226,7 +228,8 @@ func (q *Queue) Remove(identifier audio.QueueIdentifier) bool {
 }
 
 type httpWriter struct {
-	writer http.ResponseWriter
+	timeout time.Duration
+	writer  http.ResponseWriter
 }
 
 func (h *httpWriter) Write(p []byte) (n int, err error) {
@@ -247,9 +250,10 @@ func (h *httpWriter) Close() (err error) {
 
 func (h *httpWriter) Flush() {
 	if h.writer != nil {
-		if flusher, ok := h.writer.(http.Flusher); ok {
+		//TODO: not deadline aware?
+		/*if flusher, ok := h.writer.(http.Flusher); ok {
 			flusher.Flush()
-		}
+		}*/
 	}
 }
 
@@ -276,7 +280,7 @@ func (q *Queue) HandleRadioRequest(writer http.ResponseWriter, request *http.Req
 			writer.Header().Set("Cache-Control", "no-store, max-age=0, no-transform")
 			writer.Header().Set("X-Content-Type-Options", "nosniff")
 
-			byteWriter := &httpWriter{writer: writer}
+			byteWriter := &httpWriter{writer: writer, timeout: time.Second * 2}
 
 			var wgClient sync.WaitGroup
 
@@ -311,6 +315,37 @@ func (q *Queue) HandleRadioRequest(writer http.ResponseWriter, request *http.Req
 				uriPath += "?" + request.URL.Query().Encode()
 			}
 
+			getKnownBufferSize := func() time.Duration {
+				userAgent := request.Header.Get("user-agent")
+				if strings.Index(userAgent, "libmpv") != -1 || strings.Index(userAgent, "mpv ") != -1 { //mpv
+					return time.Millisecond * 2500
+				} else if strings.Index(userAgent, "libvlc") != -1 { //VLC
+					return time.Millisecond * 2500
+				} else if strings.Index(userAgent, "lavf/") != -1 { //ffplay
+					return time.Millisecond * 2500
+				} else if strings.Index(userAgent, "gvfs/") != -1 { //gvfs
+					return time.Millisecond * 2500
+				} else if strings.Index(userAgent, "Music Player Daemon ") != -1 { //MPD
+					return time.Millisecond * 2500
+				} else if strings.Index(userAgent, " Chrome/") != -1 { //Chromium-based
+					return time.Millisecond * 5000
+				} else if strings.Index(userAgent, " Safari/") != -1 { //Safari-based
+					return time.Millisecond * 5000
+				} else if strings.Index(userAgent, " Gecko/") != -1 { //Gecko-based (Firefox)
+					return time.Millisecond * 5000
+				} else if request.Header.Get("icy-metadata") == "1" { //other unknown players
+					return time.Millisecond * 5000
+				}
+
+				//fallback and provide maximum buffer
+				return time.Second * maxBufferSize
+			}
+
+			sampleBufferLimit := int64(q.config.Queue.BufferSeconds * mount.SampleRate)
+			if q.config.Queue.BufferSeconds == 0 { //auto buffer setup based on user agent and other client headers
+				sampleBufferLimit = int64(getKnownBufferSize().Seconds() * float64(mount.SampleRate))
+			}
+
 			mount.AddListener(&StreamListener{
 				Information: ListenerInformation{
 					Mount:   mount.Mount,
@@ -318,9 +353,14 @@ func (q *Queue) HandleRadioRequest(writer http.ResponseWriter, request *http.Req
 					Headers: headers,
 				},
 				Start: func(packets []packetizer.Packet) error {
-					for _, p := range packets {
-						if err := writeCallback(p); err != nil {
-							return err
+					if len(packets) > 0 {
+						sampleBufferMin := packets[len(packets)-1].GetSampleNumber() - sampleBufferLimit
+						for _, p := range packets {
+							if p.KeepMode() != packetizer.Discard || p.GetSampleNumber() >= sampleBufferMin {
+								if err := writeCallback(p); err != nil {
+									return err
+								}
+							}
 						}
 					}
 					return nil