Streamline run log and update handling

runtime/self_update.go

@@ -27,6 +27,7 @@ const (
 	maxSelfUpdateBytes        = int64(512 * 1024 * 1024)
 	maxSelfUpdateEntries      = 8
 	defaultUpdateHealthWait   = 30 * time.Second
+	selfUpdateProgressEvery   = int64(8 * 1024 * 1024)
 )
 
 var ErrSelfUpdateRestartRequested = errors.New("Run self-update restart requested")
@@ -217,6 +218,20 @@ func (worker *Worker) downloadRunUpdate(ctx context.Context, assignment protocol
 	if _, err := file.Seek(offset, io.SeekStart); err != nil {
 		return err
 	}
+	manifest.DownloadedBytes = offset
+	lastPersistedOffset := offset
+	persistProgress := func(force bool) error {
+		if !force && offset < input.SizeBytes && offset-lastPersistedOffset < selfUpdateProgressEvery {
+			return nil
+		}
+		manifest.DownloadedBytes = offset
+		manifest.UpdatedAt = time.Now().UTC()
+		if err := persistSelfUpdateManifest(manifestPath, *manifest); err != nil {
+			return err
+		}
+		lastPersistedOffset = offset
+		return nil
+	}
 	for offset < input.SizeBytes {
 		if ctx.Err() != nil {
 			return ctx.Err()
@@ -239,16 +254,17 @@ func (worker *Worker) downloadRunUpdate(ctx context.Context, assignment protocol
 		if _, err := file.Write(chunk.Payload); err != nil {
 			return err
 		}
-		if err := file.Sync(); err != nil {
-			return err
-		}
 		offset += int64(len(chunk.Payload))
-		manifest.DownloadedBytes = offset
-		manifest.UpdatedAt = time.Now().UTC()
-		if err := persistSelfUpdateManifest(manifestPath, *manifest); err != nil {
+		if err := persistProgress(false); err != nil {
 			return err
 		}
 	}
+	if err := file.Sync(); err != nil {
+		return err
+	}
+	if err := persistProgress(true); err != nil {
+		return err
+	}
 	if err := file.Close(); err != nil {
 		return err
 	}