Merge b2de50a into a90f28b

components/batch/batch.go

@@ -0,0 +1,62 @@
+package batcher
+
+import (
+	"bytes"
+	"time"
+
+	"github.com/benbjohnson/clock"
+	"github.com/redBorder/rbforwarder/types"
+)
+
+// Batch groups multiple messages
+type Batch struct {
+	Group        string
+	Message      *types.Message
+	Buff         *bytes.Buffer
+	MessageCount uint       // Current number of messages in the buffer
+	Next         types.Next // Call to pass the message to the next handler
+}
+
+// NewBatch creates a new instance of Batch
+func NewBatch(m *types.Message, group string, next types.Next, clk clock.Clock,
+	timeoutMillis uint, ready chan *Batch) *Batch {
+	payload, _ := m.PopPayload()
+	b := &Batch{
+		Group:        group,
+		Next:         next,
+		Message:      m,
+		MessageCount: 1,
+		Buff:         bytes.NewBuffer(payload),
+	}
+
+	if timeoutMillis != 0 {
+		timer := clk.Timer(time.Duration(timeoutMillis) * time.Millisecond)
+
+		go func() {
+			<-timer.C
+			if b.MessageCount > 0 {
+				ready <- b
+			}
+		}()
+	}
+
+	return b
+}
+
+// Send the batch of messages to the next handler in the pipeline
+func (b *Batch) Send(cb func()) {
+	b.Message.PushPayload(b.Buff.Bytes())
+	cb()
+	b.Next(b.Message)
+}
+
+// Add merges a new message in the buffer
+func (b *Batch) Add(m *types.Message) {
+	newReport := m.Reports.Pop()
+	b.Message.Reports.Push(newReport)
+
+	newPayload, _ := m.PopPayload()
+	b.Buff.Write(newPayload)
+
+	b.MessageCount++
+}

components/batch/batcher.go

@@ -0,0 +1,53 @@
+package batcher
+
+import (
+	"github.com/benbjohnson/clock"
+	"github.com/redBorder/rbforwarder/types"
+)
+
+// Batcher allows to merge multiple messages in a single one
+type Batcher struct {
+	id           int               // Worker ID
+	batches      map[string]*Batch // Collection of batches pending
+	readyBatches chan *Batch
+	clk          clock.Clock
+
+	config Config // Batcher configuration
+}
+
+// Init starts a gorutine that can receive:
+// - New messages that will be added to a existing or new batch of messages
+// - A batch of messages that is ready to send (i.e. batch timeout has expired)
+func (b *Batcher) Init(id int) {
+	b.id = id
+	b.batches = make(map[string]*Batch)
+	b.readyBatches = make(chan *Batch)
+	b.clk = clock.New()
+
+	go func() {
+		for batch := range b.readyBatches {
+			batch.Send(func() {
+				delete(b.batches, batch.Group)
+			})
+		}
+	}()
+}
+
+// OnMessage is called when a new message is receive. Add the new message to
+// a batch
+func (b *Batcher) OnMessage(m *types.Message, next types.Next, done types.Done) {
+	if group, exists := m.Opts["batch_group"].(string); exists {
+		if batch, exists := b.batches[group]; exists {
+			batch.Add(m)
+			if batch.MessageCount >= b.config.Limit {
+				b.readyBatches <- batch
+			}
+		} else {
+			b.batches[group] = NewBatch(m, group, next, b.clk, b.config.TimeoutMillis, b.readyBatches)
+		}
+
+		return
+	}
+
+	next(m)
+}

components/batch/batcher_test.go

@@ -0,0 +1,212 @@
+package batcher
+
+import (
+	"testing"
+	"time"
+
+	"github.com/benbjohnson/clock"
+	"github.com/redBorder/rbforwarder/types"
+	. "github.com/smartystreets/goconvey/convey"
+	"github.com/stretchr/testify/mock"
+)
+
+type NexterDoner struct {
+	mock.Mock
+	nextCalled chan *types.Message
+}
+
+func (nd *NexterDoner) Next(m *types.Message) {
+	nd.Called(m)
+	nd.nextCalled <- m
+}
+
+func TestBatcher(t *testing.T) {
+	Convey("Given a batcher", t, func() {
+		batcher := &Batcher{
+			config: Config{
+				TimeoutMillis:     1000,
+				Limit:             10,
+				MaxPendingBatches: 10,
+			},
+		}
+
+		batcher.Init(0)
+		batcher.clk = clock.NewMock()
+
+		Convey("When a message is received with no batch group", func() {
+			m := types.NewMessage()
+			m.PushPayload([]byte("Hello World"))
+
+			nd := new(NexterDoner)
+			nd.nextCalled = make(chan *types.Message, 1)
+			nd.On("Next", mock.AnythingOfType("*types.Message")).Times(1)
+
+			batcher.OnMessage(m, nd.Next, nil)
+
+			Convey("Message should be present on the batch", func() {
+				nd.AssertExpectations(t)
+				m := <-nd.nextCalled
+				So(len(batcher.batches), ShouldEqual, 0)
+				payload, err := m.PopPayload()
+				So(err, ShouldBeNil)
+				So(string(payload), ShouldEqual, "Hello World")
+			})
+		})
+
+		Convey("When a message is received, but not yet sent", func() {
+			m := types.NewMessage()
+			m.PushPayload([]byte("Hello World"))
+			m.Opts = map[string]interface{}{
+				"batch_group": "group1",
+			}
+			m.Reports.Push("Report")
+
+			batcher.OnMessage(m, nil, nil)
+
+			Convey("Message should be present on the batch", func() {
+				batch, exists := batcher.batches["group1"]
+				So(exists, ShouldBeTrue)
+
+				data := batch.Buff.Bytes()
+				So(string(data), ShouldEqual, "Hello World")
+
+				opts := batch.Message.Opts
+				So(opts["batch_group"], ShouldEqual, "group1")
+
+				report := batch.Message.Reports.Pop().(string)
+				So(report, ShouldEqual, "Report")
+
+				So(len(batcher.batches), ShouldEqual, 1)
+			})
+		})
+
+		Convey("When the max number of messages is reached", func() {
+			var messages []*types.Message
+
+			for i := 0; i < int(batcher.config.Limit); i++ {
+				m := types.NewMessage()
+				m.PushPayload([]byte("ABC"))
+				m.Opts = map[string]interface{}{
+					"batch_group": "group1",
+				}
+				m.Reports.Push("Report")
+
+				messages = append(messages, m)
+			}
+
+			nd := new(NexterDoner)
+			nd.nextCalled = make(chan *types.Message)
+			nd.On("Next", mock.AnythingOfType("*types.Message")).Times(1)
+
+			for i := 0; i < int(batcher.config.Limit); i++ {
+				batcher.OnMessage(messages[i], nd.Next, nil)
+			}
+
+			Convey("The batch should be sent", func() {
+				m := <-nd.nextCalled
+				nd.AssertExpectations(t)
+				data, err := m.PopPayload()
+
+				So(err, ShouldBeNil)
+				So(string(data), ShouldEqual, "ABCABCABCABCABCABCABCABCABCABC")
+				So(m.Reports.Size(), ShouldEqual, batcher.config.Limit)
+				So(batcher.batches["group1"], ShouldBeNil)
+				So(len(batcher.batches), ShouldEqual, 0)
+			})
+		})
+
+		Convey("When the timeout expires", func() {
+			var messages []*types.Message
+
+			for i := 0; i < 5; i++ {
+				m := types.NewMessage()
+				m.PushPayload([]byte("Hello World"))
+				m.Opts = map[string]interface{}{
+					"batch_group": "group1",
+				}
+				m.Reports.Push("Report")
+
+				messages = append(messages, m)
+			}
+
+			nd := new(NexterDoner)
+			nd.nextCalled = make(chan *types.Message, 1)
+			nd.On("Next", mock.AnythingOfType("*types.Message")).Times(1)
+
+			for i := 0; i < 5; i++ {
+				batcher.OnMessage(messages[i], nd.Next, nil)
+			}
+
+			clk := batcher.clk.(*clock.Mock)
+
+			Convey("The batch should be sent", func() {
+				clk.Add(500 * time.Millisecond)
+				So(batcher.batches["group1"], ShouldNotBeNil)
+				clk.Add(500 * time.Millisecond)
+				<-nd.nextCalled
+				So(batcher.batches["group1"], ShouldBeNil)
+				So(len(batcher.batches), ShouldEqual, 0)
+				nd.AssertExpectations(t)
+			})
+		})
+
+		Convey("When multiple messages are received with differente groups", func() {
+			m1 := types.NewMessage()
+			m1.PushPayload([]byte("MESSAGE 1"))
+			m1.Opts = map[string]interface{}{
+				"batch_group": "group1",
+			}
+			m2 := types.NewMessage()
+			m2.PushPayload([]byte("MESSAGE 2"))
+			m2.Opts = map[string]interface{}{
+				"batch_group": "group2",
+			}
+			m3 := types.NewMessage()
+			m3.PushPayload([]byte("MESSAGE 3"))
+			m3.Opts = map[string]interface{}{
+				"batch_group": "group2",
+			}
+
+			nd := new(NexterDoner)
+			nd.nextCalled = make(chan *types.Message, 2)
+			nd.On("Next", mock.AnythingOfType("*types.Message")).Times(2)
+
+			batcher.OnMessage(m1, nd.Next, nil)
+			batcher.OnMessage(m2, nd.Next, nil)
+			batcher.OnMessage(m3, nd.Next, nil)
+
+			Convey("Each message should be in its group", func() {
+				group1 := batcher.batches["group1"].Buff.Bytes()
+				So(string(group1), ShouldEqual, "MESSAGE 1")
+
+				group2 := batcher.batches["group2"].Buff.Bytes()
+				So(string(group2), ShouldEqual, "MESSAGE 2MESSAGE 3")
+
+				So(len(batcher.batches), ShouldEqual, 2)
+			})
+
+			Convey("After a timeout the messages should be sent", func() {
+				clk := batcher.clk.(*clock.Mock)
+				So(len(batcher.batches), ShouldEqual, 2)
+
+				clk.Add(time.Duration(batcher.config.TimeoutMillis) * time.Millisecond)
+
+				group1 := <-nd.nextCalled
+				group1Data, err := group1.PopPayload()
+				So(err, ShouldBeNil)
+
+				group2 := <-nd.nextCalled
+				group2Data, err := group2.PopPayload()
+				So(err, ShouldBeNil)
+
+				So(string(group1Data), ShouldEqual, "MESSAGE 1")
+				So(string(group2Data), ShouldEqual, "MESSAGE 2MESSAGE 3")
+				So(batcher.batches["group1"], ShouldBeNil)
+				So(batcher.batches["group2"], ShouldBeNil)
+				So(len(batcher.batches), ShouldEqual, 0)
+
+				nd.AssertExpectations(t)
+			})
+		})
+	})
+}