Merge pull request #58 from grafana/feat/add-close-with-log-on-err

runutil: Add CloseWithLogOnErr function

CHANGELOG.md

@@ -15,3 +15,4 @@
 * [ENHANCEMENT] Replace go-kit/kit/log with go-kit/log. #52
 * [ENHANCEMENT] Add spanlogger package. #42
 * [BUGFIX] spanlogger: Support multiple tenant IDs. #59
+* [ENHANCEMENT] Add runutil.CloseWithLogOnErr function. #58

runutil/runutil.go

@@ -0,0 +1,31 @@
+package runutil
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/pkg/errors"
+
+	"github.com/grafana/dskit/multierror"
+)
+
+// CloseWithErrCapture closes closer and wraps any error with the provided message and assigns it to err.
+func CloseWithErrCapture(err *error, closer io.Closer, msg string) {
+	merr := multierror.New(*err, errors.Wrap(closer.Close(), msg))
+	*err = merr.Err()
+}
+
+// CloseWithLogOnErr closes an io.Closer and logs any relevant error from it wrapped with the provided format string and
+// args.
+func CloseWithLogOnErr(logger log.Logger, closer io.Closer, format string, args ...interface{}) {
+	err := closer.Close()
+	if err == nil || errors.Is(err, os.ErrClosed) {
+		return
+	}
+
+	msg := fmt.Sprintf(format, args...)
+	level.Warn(logger).Log("msg", "detected close error", "err", fmt.Sprintf("%s: %s", msg, err.Error()))
+}

runutil/runutil_test.go

@@ -0,0 +1,58 @@
+package runutil
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/go-kit/log/level"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCloseWithLogOnErr(t *testing.T) {
+	t.Run("With non-close error", func(t *testing.T) {
+		closer := fakeCloser{err: fmt.Errorf("an error")}
+		logger := fakeLogger{}
+
+		CloseWithLogOnErr(&logger, closer, "closing failed")
+
+		assert.Equal(t, []interface{}{
+			"level", level.WarnValue(), "msg", "detected close error", "err", "closing failed: an error",
+		}, logger.keyvals)
+	})
+
+	t.Run("With no error", func(t *testing.T) {
+		closer := fakeCloser{}
+		logger := fakeLogger{}
+
+		CloseWithLogOnErr(&logger, closer, "closing failed")
+
+		assert.Empty(t, logger.keyvals)
+	})
+
+	t.Run("With closed error", func(t *testing.T) {
+		closer := fakeCloser{err: os.ErrClosed}
+		logger := fakeLogger{}
+
+		CloseWithLogOnErr(&logger, closer, "closing failed")
+
+		assert.Empty(t, logger.keyvals)
+	})
+}
+
+type fakeCloser struct {
+	err error
+}
+
+func (c fakeCloser) Close() error {
+	return c.err
+}
+
+type fakeLogger struct {
+	keyvals []interface{}
+}
+
+func (l *fakeLogger) Log(keyvals ...interface{}) error {
+	l.keyvals = keyvals
+	return nil
+}