feat: flagd - make sure provider initialize only once (#418)

Signed-off-by: Kavindu Dodanduwa <[email protected]>

Author: Kavindu-Dodan

providers/flagd/pkg/provider.go

@@ -13,6 +13,7 @@ import (
 )
 
 type Provider struct {
+	initialized           bool
 	logger                logr.Logger
 	providerConfiguration *providerConfiguration
 	service               IService
@@ -29,6 +30,7 @@ func NewProvider(opts ...ProviderOption) *Provider {
 	providerConfiguration := NewDefaultConfiguration(log)
 
 	provider := &Provider{
+		initialized:           false,
 		eventStream:           make(chan of.Event),
 		logger:                log,
 		providerConfiguration: providerConfiguration,
@@ -73,7 +75,15 @@ func NewProvider(opts ...ProviderOption) *Provider {
 	return provider
 }
 
-func (p *Provider) Init(evaluationContext of.EvaluationContext) error {
+func (p *Provider) Init(_ of.EvaluationContext) error {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	// avoid reinitialization if initialized
+	if p.initialized {
+		return nil
+	}
+
 	err := p.service.Init()
 	if err != nil {
 		return err
@@ -86,6 +96,7 @@ func (p *Provider) Init(evaluationContext of.EvaluationContext) error {
 	}
 
 	p.status = of.ReadyState
+	p.initialized = true
 
 	// start event handling after the first ready event
 	go func() {
@@ -112,6 +123,10 @@ func (p *Provider) Status() of.State {
 }
 
 func (p *Provider) Shutdown() {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+
+	p.initialized = false
 	p.service.Shutdown()
 }
 

providers/flagd/pkg/provider_test.go

@@ -122,7 +122,7 @@ func TestEventHandling(t *testing.T) {
 
 	svcMock := mock.NewMockIService(ctrl)
 	svcMock.EXPECT().EventChannel().Return(customChan).AnyTimes()
-	svcMock.EXPECT().Init().AnyTimes()
+	svcMock.EXPECT().Init().Times(1)
 
 	provider := NewProvider()
 	provider.service = svcMock
@@ -174,5 +174,44 @@ func TestEventHandling(t *testing.T) {
 	if provider.Status() != of.ErrorState {
 		t.Errorf("expected status to be error, but got %v", provider.Status())
 	}
+}
+
+func TestInitializeOnlyOnce(t *testing.T) {
+	// given
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	eventChan := make(chan of.Event)
+
+	svcMock := mock.NewMockIService(ctrl)
+	svcMock.EXPECT().Init().Times(1)
+	svcMock.EXPECT().EventChannel().Return(eventChan).Times(1)
+	svcMock.EXPECT().Shutdown().Times(1)
+
+	provider := NewProvider()
+	provider.service = svcMock
+
+	// make service ready with events
+	go func() {
+		eventChan <- of.Event{
+			ProviderName: "mock provider",
+			EventType:    of.ProviderReady,
+		}
+	}()
+
+	// multiple init invokes
+	_ = provider.Init(of.EvaluationContext{})
+	_ = provider.Init(of.EvaluationContext{})
+
+	if !provider.initialized {
+		t.Errorf("expected provider to be ready, but got not ready")
+	}
+
+	// shutdown should make provider uninitialized
+	provider.Shutdown()
+
+	if provider.initialized {
+		t.Errorf("expected provider to be not ready, but got ready")
+	}
 
 }