Implemented health checker for textures provider from Mojang's API

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New configuration param `QUEUE_STRATEGY` with the default value `periodic`.
 - New configuration params: `MOJANG_API_BASE_URL` and `MOJANG_SESSION_SERVER_BASE_URL`, that allow you to spoof
   Mojang API base addresses.
+- New health checker, that ensures that response for textures provider from Mojang's API is valid.
 
 ### Fixed
 - Handle the case when there is no textures property in Mojang's response.

di/mojang_textures.go

@@ -189,6 +189,7 @@ func newMojangTexturesBatchUUIDsProviderFullBusStrategy(config *viper.Viper) *mo
 }
 
 func newMojangTexturesRemoteUUIDsProvider(
+	container *di.Container,
 	config *viper.Viper,
 	emitter mojangtextures.Emitter,
 ) (*mojangtextures.RemoteApiUuidsProvider, error) {
@@ -197,6 +198,20 @@ func newMojangTexturesRemoteUUIDsProvider(
 		return nil, fmt.Errorf("unable to parse remote url: %w", err)
 	}
 
+	if err := container.Provide(func(emitter es.Subscriber, config *viper.Viper) *namedHealthChecker {
+		config.SetDefault("healthcheck.mojang_api_textures_provider_cool_down_duration", time.Minute+10*time.Second)
+
+		return &namedHealthChecker{
+			Name: "mojang-api-textures-provider-response-checker",
+			Checker: es.MojangApiTexturesProviderResponseChecker(
+				emitter,
+				config.GetDuration("healthcheck.mojang_api_textures_provider_cool_down_duration"),
+			),
+		}
+	}); err != nil {
+		return nil, err
+	}
+
 	return &mojangtextures.RemoteApiUuidsProvider{
 		Emitter: emitter,
 		Url:     *remoteUrl,

eventsubscribers/health_checkers.go

@@ -32,33 +32,16 @@ func DatabaseChecker(connection Pingable) healthcheck.CheckerFunc {
 }
 
 func MojangBatchUuidsProviderResponseChecker(dispatcher Subscriber, resetDuration time.Duration) healthcheck.CheckerFunc {
-	var mutex sync.Mutex
-	var lastCallErr error
-	var expireTimer *time.Timer
+	errHolder := &expiringErrHolder{D: resetDuration}
 	dispatcher.Subscribe(
 		"mojang_textures:batch_uuids_provider:result",
 		func(usernames []string, profiles []*mojang.ProfileInfo, err error) {
-			mutex.Lock()
-			defer mutex.Unlock()
-
-			lastCallErr = err
-			if expireTimer != nil {
-				expireTimer.Stop()
-			}
-
-			expireTimer = time.AfterFunc(resetDuration, func() {
-				mutex.Lock()
-				lastCallErr = nil
-				mutex.Unlock()
-			})
+			errHolder.Set(err)
 		},
 	)
 
 	return func(ctx context.Context) error {
-		mutex.Lock()
-		defer mutex.Unlock()
-
-		return lastCallErr
+		return errHolder.Get()
 	}
 }
 
@@ -82,3 +65,47 @@ func MojangBatchUuidsProviderQueueLengthChecker(dispatcher Subscriber, maxLength
 		return errors.New("the maximum number of tasks in the queue has been exceeded")
 	}
 }
+
+func MojangApiTexturesProviderResponseChecker(dispatcher Subscriber, resetDuration time.Duration) healthcheck.CheckerFunc {
+	errHolder := &expiringErrHolder{D: resetDuration}
+	dispatcher.Subscribe(
+		"mojang_textures:mojang_api_textures_provider:after_request",
+		func(uuid string, profile *mojang.SignedTexturesResponse, err error) {
+			errHolder.Set(err)
+		},
+	)
+
+	return func(ctx context.Context) error {
+		return errHolder.Get()
+	}
+}
+
+type expiringErrHolder struct {
+	D   time.Duration
+	err error
+	l   sync.Mutex
+	t   *time.Timer
+}
+
+func (h *expiringErrHolder) Get() error {
+	h.l.Lock()
+	defer h.l.Unlock()
+
+	return h.err
+}
+
+func (h *expiringErrHolder) Set(err error) {
+	h.l.Lock()
+	defer h.l.Unlock()
+	if h.t != nil {
+		h.t.Stop()
+		h.t = nil
+	}
+
+	h.err = err
+	if err != nil {
+		h.t = time.AfterFunc(h.D, func() {
+			h.Set(nil)
+		})
+	}
+}

eventsubscribers/health_checkers_test.go

@@ -56,7 +56,7 @@ func TestMojangBatchUuidsProviderChecker(t *testing.T) {
 		checker := MojangBatchUuidsProviderResponseChecker(d, time.Millisecond)
 		assert.Nil(t, checker(context.Background()))
 	})
-	//
+
 	t.Run("when no error occurred", func(t *testing.T) {
 		d := dispatcher.New()
 		checker := MojangBatchUuidsProviderResponseChecker(d, time.Millisecond)
@@ -107,3 +107,40 @@ func TestMojangBatchUuidsProviderQueueLengthChecker(t *testing.T) {
 		}
 	})
 }
+
+func TestMojangApiTexturesProviderResponseChecker(t *testing.T) {
+	t.Run("empty state", func(t *testing.T) {
+		d := dispatcher.New()
+		checker := MojangApiTexturesProviderResponseChecker(d, time.Millisecond)
+		assert.Nil(t, checker(context.Background()))
+	})
+
+	t.Run("when no error occurred", func(t *testing.T) {
+		d := dispatcher.New()
+		checker := MojangApiTexturesProviderResponseChecker(d, time.Millisecond)
+		d.Emit("mojang_textures:mojang_api_textures_provider:after_request",
+			"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+			&mojang.SignedTexturesResponse{},
+			nil,
+		)
+		assert.Nil(t, checker(context.Background()))
+	})
+
+	t.Run("when error occurred", func(t *testing.T) {
+		d := dispatcher.New()
+		checker := MojangApiTexturesProviderResponseChecker(d, time.Millisecond)
+		err := errors.New("some error occurred")
+		d.Emit("mojang_textures:mojang_api_textures_provider:after_request", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", nil, err)
+		assert.Equal(t, err, checker(context.Background()))
+	})
+
+	t.Run("should reset value after passed duration", func(t *testing.T) {
+		d := dispatcher.New()
+		checker := MojangApiTexturesProviderResponseChecker(d, 20*time.Millisecond)
+		err := errors.New("some error occurred")
+		d.Emit("mojang_textures:mojang_api_textures_provider:after_request", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", nil, err)
+		assert.Equal(t, err, checker(context.Background()))
+		time.Sleep(40 * time.Millisecond)
+		assert.Nil(t, checker(context.Background()))
+	})
+}

mojangtextures/batch_uuids_provider_test.go

@@ -196,10 +196,15 @@ func (suite *batchUuidsProviderTestSuite) TestShouldNotSendRequestWhenNoJobsAreR
 		close(done)
 	})
 
-	_ = suite.GetUuidAsync("username") // Schedule one username to run the queue
+	r := suite.GetUuidAsync("username") // Schedule one username to run the queue
 
 	suite.Strategy.Iterate(0, 1) // Return no jobs and indicate that there is one job in queue
-	<-done
+	select {
+	case <-r:
+		// fail
+	case <-done:
+		return
+	}
 }
 
 // Test written for multiple usernames to ensure that the error

mojangtextures/mojang_api_textures_provider.go

@@ -13,7 +13,7 @@ type MojangApiTexturesProvider struct {
 func (ctx *MojangApiTexturesProvider) GetTextures(uuid string) (*mojang.SignedTexturesResponse, error) {
 	ctx.Emit("mojang_textures:mojang_api_textures_provider:before_request", uuid)
 	result, err := uuidToTextures(uuid, true)
-	ctx.Emit("mojang_textures:mojang_api_textures_provider:after_request", result, err)
+	ctx.Emit("mojang_textures:mojang_api_textures_provider:after_request", uuid, result, err)
 
 	return result, err
 }

mojangtextures/mojang_api_textures_provider_test.go

@@ -64,6 +64,7 @@ func (suite *mojangApiTexturesProviderTestSuite) TestGetTextures() {
 	).Once()
 	suite.Emitter.On("Emit",
 		"mojang_textures:mojang_api_textures_provider:after_request",
+		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
 		expectedResult,
 		nil,
 	).Once()
@@ -85,6 +86,7 @@ func (suite *mojangApiTexturesProviderTestSuite) TestGetTexturesWithError() {
 	).Once()
 	suite.Emitter.On("Emit",
 		"mojang_textures:mojang_api_textures_provider:after_request",
+		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
 		expectedResponse,
 		expectedError,
 	).Once()