fix(config): references between different sources are consistent when watch

config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"context"
 	"errors"
+	"fmt"
 	"reflect"
 	"sync"
 	"time"
@@ -60,8 +61,28 @@ func New(opts ...Option) Config {
 }
 
 func (c *config) watch(w Watcher) {
+	reloadReader := func(opts options) (Reader, error) {
+		r := newReader(c.opts)
+		for _, src := range c.opts.sources {
+			kvs, err := src.Load()
+			if err != nil {
+				return nil, fmt.Errorf("failed to load config source: %w", err)
+			}
+			for _, v := range kvs {
+				log.Debugf("config loaded: %s format: %s", v.Key, v.Format)
+			}
+			if err = r.Merge(kvs...); err != nil {
+				return nil, fmt.Errorf("failed to merge config source: %w", err)
+			}
+		}
+		if err := r.Resolve(); err != nil {
+			return nil, fmt.Errorf("failed to resolve config: %w", err)
+		}
+		return r, nil
+	}
+
 	for {
-		kvs, err := w.Next()
+		_, err := w.Next()
 		if err != nil {
 			if errors.Is(err, context.Canceled) {
 				log.Infof("watcher's ctx cancel : %v", err)
@@ -71,14 +92,12 @@ func (c *config) watch(w Watcher) {
 			log.Errorf("failed to watch next config: %v", err)
 			continue
 		}
-		if err := c.reader.Merge(kvs...); err != nil {
-			log.Errorf("failed to merge next config: %v", err)
-			continue
-		}
-		if err := c.reader.Resolve(); err != nil {
-			log.Errorf("failed to resolve next config: %v", err)
+		r, err := reloadReader(c.opts)
+		if err != nil {
+			log.Errorf("failed to reload reader all sources: %v", err)
 			continue
 		}
+		c.reader = r
 		c.cached.Range(func(key, value interface{}) bool {
 			k := key.(string)
 			v := value.(Value)

config/config_test.go

@@ -182,3 +182,74 @@ func TestConfig(t *testing.T) {
 		t.Error("len(testConf.Endpoints) is not equal to 2")
 	}
 }
+
+func AssertStringValue(t *testing.T, expect any, v Value) bool {
+	t.Helper()
+	vs, err := v.String()
+	if err != nil {
+		t.Errorf("get string value error: %s", err.Error())
+		return false
+	}
+	if vs != expect {
+		t.Errorf("value '%s' not equal '%s'", vs, expect)
+		return false
+	}
+	return true
+}
+
+func TestConfig_WatchBetweenSourcesReferenceConfig(t *testing.T) {
+	testJSON := `
+{
+	"foo": "${remote.foo}"
+}
+`
+	testJSON2 := `
+{
+	"remote": {
+		"foo": "bar"
+	}
+}
+`
+	testJSONUpdate := `
+{
+	"remote": {
+		"foo": "bar2"
+	}
+}
+`
+	src1 := newTestJSONSource(testJSON)
+	src2 := newTestJSONSource(testJSON2)
+	opts := options{
+		sources:  []Source{src1, src2},
+		decoder:  defaultDecoder,
+		resolver: defaultResolver,
+	}
+	cf := &config{}
+	cf.opts = opts
+	cf.reader = newReader(opts)
+
+	// load config
+	if err := cf.Load(); err != nil {
+		t.Fatal(err)
+	}
+
+	if !AssertStringValue(t, "bar", cf.Value("foo")) {
+		t.FailNow()
+	}
+	if !AssertStringValue(t, "bar", cf.Value("remote.foo")) {
+		t.FailNow()
+	}
+
+	// update remote.foo value
+	src2.data = testJSONUpdate
+	src2.sig <- struct{}{}
+	// wait for watch to finish
+	src2.sig <- struct{}{}
+
+	if !AssertStringValue(t, "bar2", cf.Value("foo")) {
+		t.FailNow()
+	}
+	if !AssertStringValue(t, "bar2", cf.Value("remote.foo")) {
+		t.FailNow()
+	}
+}