Fix ready check for segments blocking

transcoder/src/stream.go

@@ -24,8 +24,10 @@ type Stream struct {
 	// channel open if the segment is not ready. closed if ready.
 	// one can check if segment 1 is open by doing:
 	//
-	//  _, ready := <- ts.segments[1]
+	//  ts.isSegmentReady(1).
 	//
+	// You can also wait for it to be ready (non-blocking if already ready) by doing:
+	//  <-ts.segments[i]
 	segments []chan (struct{})
 	heads    []int32
 	commands []*exec.Cmd
@@ -33,13 +35,38 @@ type Stream struct {
 	lock sync.RWMutex
 }
 
+func NewStream(file *FileStream) Stream {
+	ret := Stream{
+		file:     file,
+		Clients:  make([]string, 0),
+		segments: make([]chan struct{}, len(file.Keyframes)),
+		heads:    make([]int32, 0),
+		commands: make([]*exec.Cmd, 0),
+	}
+	for seg := range ret.segments {
+		ret.segments[seg] = make(chan struct{})
+	}
+	// Copy default value before use is safe. Next warning can be safely ignored
+	return ret
+}
+
+// Remember to lock before calling this.
+func (ts *Stream) isSegmentReady(segment int32) bool {
+	select {
+	case _, ready := <-ts.segments[segment]:
+		return ready
+	default:
+		return false
+	}
+}
+
 func (ts *Stream) run(start int32) error {
 	// Start the transcode up to the 100th segment (or less)
 	// Stop at the first finished segment
 	end := min(start+100, int32(len(ts.file.Keyframes)))
 	ts.lock.RLock()
 	for i := start; i < end; i++ {
-		if _, ready := <-ts.segments[i]; ready {
+		if ts.isSegmentReady(i) {
 			end = i
 			break
 		}
@@ -112,14 +139,14 @@ func (ts *Stream) run(start int32) error {
 			ts.lock.Lock()
 			close(ts.segments[segment])
 			ts.heads[encoder_id] = segment
+			ts.lock.Unlock()
 
 			if int32(len(ts.segments)) == segment+1 {
 				// file finished, ffmped will finish soon on it's own
-			} else if _, ready := <-ts.segments[segment+1]; ready {
+			} else if ts.isSegmentReady(segment + 1) {
 				// ask ffmpeg to stop gracefully (nicer cmd.Process.Kill())
 				cmd.Process.Signal(os.Interrupt)
 			}
-			ts.lock.Unlock()
 		}
 
 		if err := scanner.Err(); err != nil {
@@ -164,16 +191,18 @@ func (ts *Stream) GetIndex(client string) (string, error) {
 
 func (ts *Stream) GetSegment(segment int32, client string) (string, error) {
 	ts.lock.RLock()
-	_, ready := <-ts.segments[segment]
+	ready := ts.isSegmentReady(segment)
 	ts.lock.RUnlock()
 
 	if !ready {
 		// Only start a new encode if there is more than 10s between the current encoder and the segment.
-		if ts.getMinEncoderDistance(ts.file.Keyframes[segment]) > 10 {
+		if distance := ts.getMinEncoderDistance(ts.file.Keyframes[segment]); distance > 10 {
 			err := ts.run(segment)
 			if err != nil {
 				return "", err
 			}
+		} else {
+			log.Printf("Waiting for segment %d since encoder head is %fs aways", segment, distance)
 		}
 
 		ts.lock.RLock()
@@ -195,6 +224,9 @@ func (ts *Stream) getMinEncoderDistance(time float64) float64 {
 		}
 		return ts.file.Keyframes[i] - time
 	})
+	if len(distances) == 0 {
+		return math.Inf(1)
+	}
 	return slices.Min(distances)
 }
 

transcoder/src/videostream.go

@@ -2,7 +2,7 @@ package src
 
 import (
 	"fmt"
-	"os/exec"
+	"log"
 )
 
 type VideoStream struct {
@@ -10,22 +10,12 @@ type VideoStream struct {
 	quality Quality
 }
 
-func NewVideoStream(file *FileStream, quality Quality) (*VideoStream, error) {
-	ret := VideoStream{
-		Stream: Stream{
-			file:     file,
-			Clients:  make([]string, 4),
-			segments: make([]chan struct{}, len(file.Keyframes)),
-			heads:    make([]int32, 1),
-			commands: make([]*exec.Cmd, 1),
-		},
+func NewVideoStream(file *FileStream, quality Quality) *VideoStream {
+	log.Printf("Creating a new video stream for %s in quality %s", file.Path, quality)
+	return &VideoStream{
+		Stream:  NewStream(file),
 		quality: quality,
 	}
-	for seg := range ret.segments {
-		ret.segments[seg] = make(chan struct{})
-	}
-	ret.run(0)
-	return &ret, nil
 }
 
 func (vs *VideoStream) getOutPath() string {