#1: Add broadcaster structure to broadcast results of the same usernames

api/mojang/queue/broadcast.go

@@ -0,0 +1,53 @@
+package queue
+
+import (
+	"sync"
+
+	"github.com/elyby/chrly/api/mojang"
+)
+
+type broadcastMap struct {
+	lock      sync.Mutex
+	listeners map[string][]chan *mojang.SignedTexturesResponse
+}
+
+func newBroadcaster() *broadcastMap {
+	return &broadcastMap{
+		listeners: make(map[string][]chan *mojang.SignedTexturesResponse),
+	}
+}
+
+// Returns a boolean value, which will be true if the username passed didn't exist before
+func (c *broadcastMap) AddListener(username string, resultChan chan *mojang.SignedTexturesResponse) bool {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	val, alreadyHasSource := c.listeners[username]
+	if alreadyHasSource {
+		c.listeners[username] = append(val, resultChan)
+		return false
+	}
+
+	c.listeners[username] = []chan *mojang.SignedTexturesResponse{resultChan}
+
+	return true
+}
+
+func (c *broadcastMap) BroadcastAndRemove(username string, result *mojang.SignedTexturesResponse) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	val, ok := c.listeners[username]
+	if !ok {
+		return
+	}
+
+	for _, channel := range val {
+		go func(channel chan *mojang.SignedTexturesResponse) {
+			channel <- result
+			close(channel)
+		}(channel)
+	}
+
+	delete(c.listeners, username)
+}

api/mojang/queue/broadcast_test.go

@@ -0,0 +1,75 @@
+package queue
+
+import (
+	"github.com/elyby/chrly/api/mojang"
+
+	testify "github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestBroadcastMap_GetOrAppend(t *testing.T) {
+	t.Run("first call when username didn't exist before should return true", func(t *testing.T) {
+		assert := testify.New(t)
+
+		broadcaster := newBroadcaster()
+		channel := make(chan *mojang.SignedTexturesResponse)
+		isFirstListener := broadcaster.AddListener("mock", channel)
+
+		assert.True(isFirstListener)
+		listeners, ok := broadcaster.listeners["mock"]
+		assert.True(ok)
+		assert.Len(listeners, 1)
+		assert.Equal(channel, listeners[0])
+	})
+
+	t.Run("subsequent calls should return false", func(t *testing.T) {
+		assert := testify.New(t)
+
+		broadcaster := newBroadcaster()
+		channel1 := make(chan *mojang.SignedTexturesResponse)
+		isFirstListener := broadcaster.AddListener("mock", channel1)
+
+		assert.True(isFirstListener)
+
+		channel2 := make(chan *mojang.SignedTexturesResponse)
+		isFirstListener = broadcaster.AddListener("mock", channel2)
+
+		assert.False(isFirstListener)
+
+		channel3 := make(chan *mojang.SignedTexturesResponse)
+		isFirstListener = broadcaster.AddListener("mock", channel3)
+
+		assert.False(isFirstListener)
+	})
+}
+
+func TestBroadcastMap_BroadcastAndRemove(t *testing.T) {
+	t.Run("should broadcast to all listeners and remove the key", func(t *testing.T) {
+		assert := testify.New(t)
+
+		broadcaster := newBroadcaster()
+		channel1 := make(chan *mojang.SignedTexturesResponse)
+		channel2 := make(chan *mojang.SignedTexturesResponse)
+		broadcaster.AddListener("mock", channel1)
+		broadcaster.AddListener("mock", channel2)
+
+		result := &mojang.SignedTexturesResponse{Id: "mockUuid"}
+		broadcaster.BroadcastAndRemove("mock", result)
+
+		assert.Equal(result, <-channel1)
+		assert.Equal(result, <-channel2)
+
+		channel3 := make(chan *mojang.SignedTexturesResponse)
+		isFirstListener := broadcaster.AddListener("mock", channel3)
+		assert.True(isFirstListener)
+	})
+
+	t.Run("call on not exists username", func(t *testing.T) {
+		assert := testify.New(t)
+
+		assert.NotPanics(func() {
+			broadcaster := newBroadcaster()
+			broadcaster.BroadcastAndRemove("mock", &mojang.SignedTexturesResponse{})
+		})
+	})
+}

api/mojang/queue/jobs_structure.go

@@ -14,8 +14,8 @@ type jobItem struct {
 }
 
 type jobsQueue struct {
+	lock  sync.Mutex
 	items []*jobItem
-	lock  sync.RWMutex
 }
 
 func (s *jobsQueue) New() *jobsQueue {

api/mojang/queue/queue.go

@@ -20,20 +20,30 @@ type JobsQueue struct {
 
 	onFirstCall sync.Once
 	queue       jobsQueue
+	broadcast   *broadcastMap
 }
 
 func (ctx *JobsQueue) GetTexturesForUsername(username string) chan *mojang.SignedTexturesResponse {
 	ctx.onFirstCall.Do(func() {
 		ctx.queue.New()
+		ctx.broadcast = newBroadcaster()
 		ctx.startQueue()
 	})
 
+	responseChan := make(chan *mojang.SignedTexturesResponse)
+	isFirstListener := ctx.broadcast.AddListener(username, responseChan)
+	if isFirstListener {
 		resultChan := make(chan *mojang.SignedTexturesResponse)
-	// TODO: prevent of adding the same username more than once
 		ctx.queue.Enqueue(&jobItem{username, resultChan})
 		// TODO: return nil if processing takes more than 5 seconds
 
-	return resultChan
+		go func() {
+			result := <-resultChan
+			ctx.broadcast.BroadcastAndRemove(username, result)
+		}()
+	}
+
+	return responseChan
 }
 
 func (ctx *JobsQueue) startQueue() {

api/mojang/queue/queue_test.go

@@ -3,6 +3,7 @@ package queue
 import (
 	"crypto/rand"
 	"encoding/base64"
+	"time"
 
 	"github.com/elyby/chrly/api/mojang"
 
@@ -135,6 +136,64 @@ func (suite *QueueTestSuite) TestReceiveTexturesForMoreThan100Usernames() {
 	suite.Iterate()
 }
 
+func (suite *QueueTestSuite) TestReceiveTexturesForTheSameUsernames() {
+	suite.MojangApi.On("UsernameToUuids", []string{"maksimkurb"}).Once().Return([]*mojang.ProfileInfo{
+		{Id: "0d252b7218b648bfb86c2ae476954d32", Name: "maksimkurb"},
+	}, nil)
+	suite.MojangApi.On("UuidToTextures", "0d252b7218b648bfb86c2ae476954d32", true).Once().Return(
+		&mojang.SignedTexturesResponse{Id: "0d252b7218b648bfb86c2ae476954d32", Name: "maksimkurb"},
+		nil,
+	)
+
+	resultChan1 := suite.Queue.GetTexturesForUsername("maksimkurb")
+	resultChan2 := suite.Queue.GetTexturesForUsername("maksimkurb")
+
+	suite.Iterate()
+
+	result1 := <-resultChan1
+	result2 := <-resultChan2
+
+	if suite.Assert().NotNil(result1) {
+		suite.Assert().Equal("0d252b7218b648bfb86c2ae476954d32", result1.Id)
+		suite.Assert().Equal("maksimkurb", result1.Name)
+
+		suite.Assert().Equal(result1, result2)
+	}
+}
+
+func (suite *QueueTestSuite) TestReceiveTexturesForUsernameThatAlreadyProcessing() {
+	suite.MojangApi.On("UsernameToUuids", []string{"maksimkurb"}).Once().Return([]*mojang.ProfileInfo{
+		{Id: "0d252b7218b648bfb86c2ae476954d32", Name: "maksimkurb"},
+	}, nil)
+	suite.MojangApi.On("UuidToTextures", "0d252b7218b648bfb86c2ae476954d32", true).
+		Once().
+		After(10*time.Millisecond). // Simulate long round trip
+		Return(
+			&mojang.SignedTexturesResponse{Id: "0d252b7218b648bfb86c2ae476954d32", Name: "maksimkurb"},
+			nil,
+		)
+
+	resultChan1 := suite.Queue.GetTexturesForUsername("maksimkurb")
+
+	// Note that for entire test there is only one iteration
+	suite.Iterate()
+
+	// Let it meet delayed UuidToTextures request
+	time.Sleep(5 * time.Millisecond)
+
+	resultChan2 := suite.Queue.GetTexturesForUsername("maksimkurb")
+
+	result1 := <-resultChan1
+	result2 := <-resultChan2
+
+	if suite.Assert().NotNil(result1) {
+		suite.Assert().Equal("0d252b7218b648bfb86c2ae476954d32", result1.Id)
+		suite.Assert().Equal("maksimkurb", result1.Name)
+
+		suite.Assert().Equal(result1, result2)
+	}
+}
+
 func (suite *QueueTestSuite) TestDoNothingWhenNoTasks() {
 	suite.MojangApi.On("UsernameToUuids", []string{"maksimkurb"}).Once().Return([]*mojang.ProfileInfo{}, nil)