add countdown timer

common/countdown/countdown.go

@@ -0,0 +1,83 @@
+// A countdown timer that will mostly be used by XDPoS v2 consensus engine
+package countdown
+
+import (
+	"sync"
+	"time"
+
+	"github.com/XinFinOrg/XDPoSChain/log"
+)
+
+type CountdownTimer struct {
+	lock            sync.RWMutex // Protects the Initilised field
+	resetc          chan int
+	quitc           chan chan struct{}
+	Initilised      bool
+	timeoutDuration time.Duration
+	// Triggered when the countdown timer timeout for the `timeoutDuration` period, it will pass current timestamp to the callback function
+	OnTimeoutFn func(time time.Time) error
+}
+
+func NewCountDown(duration time.Duration) *CountdownTimer {
+	return &CountdownTimer{
+		resetc:          make(chan int),
+		quitc:           make(chan chan struct{}),
+		Initilised:      false,
+		timeoutDuration: duration,
+	}
+}
+
+// Completely stop the countdown timer from running.
+func (t *CountdownTimer) StopTimer() {
+	q := make(chan struct{})
+	t.quitc <- q
+	<-q
+}
+
+// Reset will start the countdown timer if it's already stopped, or simply reset the countdown time back to the defual `duration`
+func (t *CountdownTimer) Reset() {
+	if !t.getInitilisedValue() {
+		t.setInitilised(true)
+		go t.startTimer()
+	} else {
+		t.resetc <- 0
+	}
+}
+
+// A long running process that
+func (t *CountdownTimer) startTimer() {
+	// Make sure we mark Initilised to false when we quit the countdown
+	defer t.setInitilised(false)
+	timer := time.NewTimer(t.timeoutDuration)
+	// We start with a inf loop
+	for {
+		select {
+		case q := <-t.quitc:
+			log.Debug("Quit countdown timer")
+			close(q)
+			return
+		case <-timer.C:
+			log.Debug("Countdown time reached!")
+			err := t.OnTimeoutFn(time.Now())
+			if err != nil {
+				log.Error("OnTimeoutFn error", err)
+			}
+		case <-t.resetc:
+			log.Debug("Reset countdown timer")
+			timer.Reset(t.timeoutDuration)
+		}
+	}
+}
+
+// Set the desired value to Initilised with lock to avoid race condition
+func (t *CountdownTimer) setInitilised(value bool) {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+	t.Initilised = value
+}
+
+func (t *CountdownTimer) getInitilisedValue() bool {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+	return t.Initilised
+}

common/countdown/countdown_test.go

@@ -0,0 +1,93 @@
+package countdown
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCountdownWillCallback(t *testing.T) {
+
+	called := make(chan int)
+	OnTimeoutFn := func(time time.Time) error {
+		called <- 1
+		return nil
+	}
+
+	countdown := NewCountDown(1000 * time.Millisecond)
+	countdown.OnTimeoutFn = OnTimeoutFn
+	countdown.Reset()
+	<-called
+	fmt.Println("Times up, successfully called OnTimeoutFn")
+}
+
+func TestCountdownShouldReset(t *testing.T) {
+	called := make(chan int)
+	OnTimeoutFn := func(time time.Time) error {
+		called <- 1
+		return nil
+	}
+
+	countdown := NewCountDown(5000 * time.Millisecond)
+	countdown.OnTimeoutFn = OnTimeoutFn
+	// Check countdown did not start
+	assert.False(t, countdown.Initilised)
+	countdown.Reset()
+	// Now the countdown should already started
+	assert.True(t, countdown.Initilised)
+	expectedCalledTime := time.Now().Add(9000 * time.Millisecond)
+	resetTimer := time.NewTimer(4000 * time.Millisecond)
+
+firstReset:
+	for {
+		select {
+		case <-called:
+			if time.Now().After(expectedCalledTime) {
+				// Make sure the countdown runs forever
+				assert.True(t, countdown.Initilised)
+				fmt.Println("Correctly reset the countdown once")
+			} else {
+				t.Fatalf("Countdown did not reset correctly first time")
+			}
+			break firstReset
+		case <-resetTimer.C:
+			countdown.Reset()
+		}
+	}
+
+	// Now the countdown is paused after calling the callback function, let's reset it again
+	assert.True(t, countdown.Initilised)
+	expectedTimeAfterReset := time.Now().Add(5000 * time.Millisecond)
+	countdown.Reset()
+	<-called
+	// Always initilised
+	assert.True(t, countdown.Initilised)
+	if time.Now().After(expectedTimeAfterReset) {
+		fmt.Println("Correctly reset the countdown second time")
+	} else {
+		t.Fatalf("Countdown did not reset correctly second time")
+	}
+}
+
+func TestCountdownShouldBeAbleToStop(t *testing.T) {
+	called := make(chan int)
+	OnTimeoutFn := func(time time.Time) error {
+		called <- 1
+		return nil
+	}
+
+	countdown := NewCountDown(5000 * time.Millisecond)
+	countdown.OnTimeoutFn = OnTimeoutFn
+	// Check countdown did not start
+	assert.False(t, countdown.Initilised)
+	countdown.Reset()
+	// Now the countdown should already started
+	assert.True(t, countdown.Initilised)
+	// Try manually stop the timer before it triggers the callback
+	stopTimer := time.NewTimer(4000 * time.Millisecond)
+	<-stopTimer.C
+	countdown.StopTimer()
+	assert.False(t, countdown.Initilised)
+}

consensus/XDPoS/engines/engine_v2/engine.go

@@ -1,25 +1,40 @@
 package engine_v2
 
 import (
+	"time"
+
 	"github.com/XinFinOrg/XDPoSChain/common"
+	"github.com/XinFinOrg/XDPoSChain/common/countdown"
 	"github.com/XinFinOrg/XDPoSChain/consensus"
 	"github.com/XinFinOrg/XDPoSChain/core/types"
 	"github.com/XinFinOrg/XDPoSChain/ethdb"
+	"github.com/XinFinOrg/XDPoSChain/log"
 	"github.com/XinFinOrg/XDPoSChain/params"
 )
 
 type XDPoS_v2 struct {
-	config      *params.XDPoSConfig // Consensus engine configuration parameters
-	db          ethdb.Database      // Database to store and retrieve snapshot checkpoints
-	BroadcastCh chan interface{}
-	BFTQueue    chan interface{}
+	config        *params.XDPoSConfig // Consensus engine configuration parameters
+	db            ethdb.Database      // Database to store and retrieve snapshot checkpoints
+	BroadcastCh   chan interface{}
+	BFTQueue      chan interface{}
+	timeoutWorker *countdown.CountdownTimer // Timer to generate broadcast timeout msg if threashold reached
 }
 
 func New(config *params.XDPoSConfig, db ethdb.Database) *XDPoS_v2 {
-	return &XDPoS_v2{
-		config: config,
-		db:     db,
+	// Setup Timer
+	// TODO: (hashlab) Introduce consensus v2 engine specific config under the main config struct
+	duration := 50000 * time.Millisecond // Hardcoded value until we move it to a config (XIN-72)
+	timer := countdown.NewCountDown(duration)
+
+	engine := &XDPoS_v2{
+		config:        config,
+		db:            db,
+		timeoutWorker: timer,
 	}
+	// Add callback to the timer
+	timer.OnTimeoutFn = engine.onCountdownTimeout
+
+	return engine
 }
 
 func NewFaker(db ethdb.Database, config *params.XDPoSConfig) *XDPoS_v2 {
@@ -239,3 +254,15 @@ func (consensus *XDPoS_v2) sendTimeout() error {
 func (consensus *XDPoS_v2) sendSyncInfo() error {
 	return nil
 }
+
+/*
+	Function that will be called by timer when countdown reaches its threshold.
+	In the engine v2, we would need to broadcast timeout messages to other peers
+*/
+func (consensus *XDPoS_v2) onCountdownTimeout(time time.Time) error {
+	err := consensus.sendTimeout()
+	if err != nil {
+		log.Error("Error while sending out timeout message at time: ", time)
+	}
+	return nil
+}