Backup: safe compressor/decompressor closure

go/ioutil/timeout_closer.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2023 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"context"
+	"io"
+	"time"
+)
+
+// TimeoutCloser is an io.Closer that has a timeout for executing the Close() function.
+type TimeoutCloser struct {
+	ctx     context.Context
+	closer  io.Closer
+	timeout time.Duration
+}
+
+func NewTimeoutCloser(ctx context.Context, closer io.Closer, timeout time.Duration) *TimeoutCloser {
+	return &TimeoutCloser{
+		ctx:     ctx,
+		closer:  closer,
+		timeout: timeout,
+	}
+}
+
+func (c *TimeoutCloser) Close() error {
+	done := make(chan error)
+
+	ctx, cancel := context.WithTimeout(c.ctx, c.timeout)
+	defer cancel()
+
+	go func() {
+		defer close(done)
+		done <- c.closer.Close()
+	}()
+	select {
+	case err := <-done:
+		return err
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}

go/ioutil/timeout_closer_test.go

@@ -0,0 +1,53 @@
+/*
+Copyright 2023 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type hangCloser struct {
+	hang bool
+}
+
+func (c hangCloser) Close() error {
+	if c.hang {
+		ch := make(chan bool)
+		ch <- true // hang forever
+	}
+	return nil
+}
+
+func TestTimeoutCloser(t *testing.T) {
+	ctx := context.Background()
+	{
+		closer := NewTimeoutCloser(ctx, &hangCloser{hang: false}, time.Second)
+		err := closer.Close()
+		require.NoError(t, err)
+	}
+	{
+		closer := NewTimeoutCloser(ctx, &hangCloser{hang: true}, time.Second)
+		err := closer.Close()
+		require.Error(t, err)
+		assert.ErrorIs(t, err, context.DeadlineExceeded)
+	}
+}

go/vt/mysqlctl/backup.go

@@ -57,6 +57,11 @@ const (
 	RestoreState = "restore_in_progress"
 	// BackupTimestampFormat is the format in which we save BackupTime and FinishedTime
 	BackupTimestampFormat = "2006-01-02.150405"
+
+	// closeTimeout is the timeout for closing backup files after writing.
+	// The value is a bit arbitrary. How long does it make sense to wait for a Close()? With a cloud-based implementation,
+	// network might be an issue. _Seconds_ are probably too short. The whereabouts of a minute us a reasonable value.
+	closeTimeout = 1 * time.Minute
 )
 
 const (