Add a few locks to prevent data races

config.go

@@ -269,12 +269,14 @@ func NewConfigManager(config *Config) (*ConfigManager, error) {
 	}
 	go func() {
 		for range m.notifyCh {
+			m.mx.Lock()
 			for _, lch := range m.listeners {
 				select {
 				case lch <- struct{}{}:
 				default:
 				}
 			}
+			m.mx.Unlock()
 		}
 	}()
 	return m, nil

manager_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"log"
 	"path/filepath"
+	"sync"
 	"testing"
 	"time"
 
@@ -48,6 +49,7 @@ func (e dummyMetadataEntry) toBackup() *Backup {
 }
 
 type dummyMetadataStore struct {
+	mx  sync.Mutex
 	log []dummyMetadataEntry
 }
 
@@ -118,6 +120,9 @@ func groupByBackup(dbAtoms []dummyMetadataEntry) []*Backup {
 }
 
 func (d *dummyMetadataStore) FindAtoms(_ context.Context, req *FindRequest) ([]*Backup, error) {
+	d.mx.Lock()
+	defer d.mx.Unlock()
+
 	var tmp []dummyMetadataEntry
 	for _, l := range d.log {
 		if !l.match(req) {
@@ -130,6 +135,9 @@ func (d *dummyMetadataStore) FindAtoms(_ context.Context, req *FindRequest) ([]*
 }
 
 func (d *dummyMetadataStore) AddDataset(_ context.Context, backup *Backup, ds *Dataset) error {
+	d.mx.Lock()
+	defer d.mx.Unlock()
+
 	log.Printf("AddDataset: %+v", *ds)
 	for _, atom := range ds.Atoms {
 		path := filepath.Join(ds.Source, ds.Name, atom.Name)

repository_restic.go

@@ -7,11 +7,13 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/hashicorp/go-version"
@@ -25,7 +27,7 @@ type resticRepository struct {
 	excludeFiles []string
 	autoPrune    bool
 
-	initialized bool
+	initialized sync.Once
 }
 
 func (r *resticRepository) resticCmd() string {
@@ -122,20 +124,17 @@ func (r *resticRepository) Close() error {
 }
 
 func (r *resticRepository) Init(ctx context.Context, rctx RuntimeContext) error {
-	if r.initialized {
-		return nil
-	}
-
-	// Restic init will fail the second time we run it, ignore
-	// errors.
-	err := rctx.Shell().Run(ctx, fmt.Sprintf(
-		"%s init --quiet || true",
-		r.resticCmd(),
-	))
-	if err == nil {
-		r.initialized = true
-	}
-	return err
+	r.initialized.Do(func() {
+		// Restic init will fail if the repository is already
+		// initialized, ignore errors (but log them).
+		if err := rctx.Shell().Run(ctx, fmt.Sprintf(
+			"%s init --quiet || true",
+			r.resticCmd(),
+		)); err != nil {
+			log.Printf("restic repository init failed (likely harmless): %v", err)
+		}
+	})
+	return nil
 }
 
 func (r *resticRepository) Prepare(ctx context.Context, rctx RuntimeContext, backup *Backup) error {