fix(config): fix data race (#1316)

* data race

* fix values

* lock

config/file/file_test.go

@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sync"
 	"testing"
 	"time"
 
@@ -288,3 +289,35 @@ func testScan(t *testing.T, c config.Config) {
 	}
 	t.Log(conf)
 }
+
+func TestMergeDataRace(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "test_config.json")
+	defer os.Remove(path)
+	if err := ioutil.WriteFile(path, []byte(_testJSON), 0666); err != nil {
+		t.Error(err)
+	}
+	c := config.New(config.WithSource(
+		NewSource(path),
+	))
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 100; i++ {
+			var conf struct{}
+			if err := c.Scan(&conf); err != nil {
+				t.Error(err)
+			}
+		}
+	}()
+
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 100; i++ {
+			if err := c.Load(); err != nil {
+				t.Error(err)
+			}
+		}
+	}()
+	wg.Wait()
+}

config/reader.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"strings"
+	"sync"
 
 	"github.com/imdario/mergo"
 	"google.golang.org/protobuf/encoding/protojson"
@@ -23,17 +24,21 @@ type Reader interface {
 type reader struct {
 	opts   options
 	values map[string]interface{}
+	lock   sync.Mutex
 }
 
 func newReader(opts options) Reader {
 	return &reader{
 		opts:   opts,
 		values: make(map[string]interface{}),
+		lock:   sync.Mutex{},
 	}
 }
 
 func (r *reader) Merge(kvs ...*KeyValue) error {
+	r.lock.Lock()
 	merged, err := cloneMap(r.values)
+	r.lock.Unlock()
 	if err != nil {
 		return err
 	}
@@ -46,19 +51,27 @@ func (r *reader) Merge(kvs ...*KeyValue) error {
 			return err
 		}
 	}
+	r.lock.Lock()
 	r.values = merged
+	r.lock.Unlock()
 	return nil
 }
 
 func (r *reader) Value(path string) (Value, bool) {
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	return readValue(r.values, path)
 }
 
 func (r *reader) Source() ([]byte, error) {
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	return marshalJSON(convertMap(r.values))
 }
 
 func (r *reader) Resolve() error {
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	return r.opts.resolver(r.values)
 }