Fix a deadlock in TaskLoop

internal/taskloop/taskloop.go

@@ -85,6 +85,8 @@ func (l *Loop) Run(ctx context.Context, t func(context.Context)) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
+	case <-l.done:
+		return ErrClosed
 	case l.tasks <- task{t, done}:
 		<-done
 

internal/taskloop/taskloop_test.go

@@ -0,0 +1,60 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package taskloop
+
+import (
+	"context"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRunReturnsErrClosedWhenLoopClosing(t *testing.T) {
+	loop := New(func() {})
+
+	blockStarted := make(chan struct{})
+	releaseBlock := make(chan struct{})
+	go func() {
+		_ = loop.Run(context.Background(), func(context.Context) {
+			close(blockStarted)
+			<-releaseBlock
+		})
+	}()
+	<-blockStarted
+
+	var secondRan atomic.Bool
+	errCh := make(chan error, 1)
+	go func() {
+		errCh <- loop.Run(context.Background(), func(context.Context) {
+			secondRan.Store(true)
+		})
+	}()
+
+	time.Sleep(10 * time.Millisecond)
+
+	closeDone := make(chan struct{})
+	go func() {
+		loop.Close()
+		close(closeDone)
+	}()
+
+	select {
+	case err := <-errCh:
+		assert.ErrorIs(t, err, ErrClosed)
+	case <-time.After(time.Second):
+		assert.Fail(t, "Run did not return after loop close")
+	}
+
+	close(releaseBlock)
+
+	select {
+	case <-closeDone:
+	case <-time.After(time.Second):
+		assert.Fail(t, "Close did not return")
+	}
+
+	assert.False(t, secondRan.Load(), "second task should not excute after loop is closed")
+}