logfile: Close reader when caller cancels

This allows for an individual decode operation to be cancelled while the
log reader is reading data from a log file by closing the underlying file.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

daemon/logger/loggerutils/logfile.go

@@ -605,7 +605,7 @@ func (cfo *compressedFileOpener) ReaderAt(ctx context.Context) (_ sizeReaderAtCl
 	}
 	defer gzr.Close()
 
-	// Extract the last log entry timestramp from the gzip header
+	// Extract the last log entry timestamp from the gzip header
 	// Use this to determine if we even need to read this file based on inputs
 	extra := &rotateFileMetadata{}
 	err = json.Unmarshal(gzr.Header.Extra, extra)
@@ -803,6 +803,7 @@ func tailFiles(ctx context.Context, files []fileOpener, watcher *logger.LogWatch
 	}()
 
 	for _, ra := range readers {
+		ra := ra
 		select {
 		case <-watcher.WatchConsumerGone():
 			return false
@@ -813,6 +814,12 @@ func tailFiles(ctx context.Context, files []fileOpener, watcher *logger.LogWatch
 
 		dec.Reset(ra)
 
+		cancel := context.AfterFunc(ctx, func() {
+			if err := ra.Close(); err != nil {
+				log.G(ctx).WithError(err).Debug("Error closing log reader")
+			}
+		})
+
 		ok := fwd.Do(ctx, watcher, func() (*logger.Message, error) {
 			msg, err := dec.Decode()
 			if err != nil && !errors.Is(err, io.EOF) {
@@ -827,11 +834,8 @@ func tailFiles(ctx context.Context, files []fileOpener, watcher *logger.LogWatch
 			}
 			return msg, err
 		})
-		if err := ra.Close(); err != nil {
-			log.G(ctx).WithError(err).Debug("Error closing log reader")
-		}
+		cancel()
 		idx++
-
 		if !ok {
 			return false
 		}

daemon/logger/loggerutils/logfile_test.go

@@ -150,14 +150,14 @@ func TestTailFiles(t *testing.T) {
 		f3 := bytes.NewBuffer(nil)
 		writeMsg(f3, msg5)
 
-		// [bytes.Buffer] is not a SizeReaderAt, so we need to convert it here
+		// [bytes.Buffer] is not a SizeReaderAt, so we need to convert it here.
 		files := makeOpener(bytes.NewReader(f1.Bytes()), bytes.NewReader(f2.Bytes()), bytes.NewReader(f3.Bytes()))
 
 		// At this point we our log "files" should have 4 log messages in it
-		// intersperesed with some junk that is invalid json
+		// interspersed with some junk that is invalid json.
 
 		// We need a zero size watcher so that we can tell the decoder to give us
-		// a syntax error
+		// a syntax error.
 		watcher := logger.NewLogWatcher()
 
 		config := logger.ReadConfig{Tail: 4}

daemon/logs.go

@@ -27,9 +27,7 @@ import (
 func (daemon *Daemon) ContainerLogs(ctx context.Context, containerName string, config *containertypes.LogsOptions) (messages <-chan *backend.LogMessage, isTTY bool, retErr error) {
 	ctx, span := tracing.StartSpan(ctx, "daemon.ContainerLogs")
 	defer func() {
-		if retErr != nil {
-			span.SetStatus(retErr)
-		}
+		span.SetStatus(retErr)
 		span.End()
 	}()