Populate last hash value in case webhook is slower than the main loop.

cmd/git-sync/main.go

@@ -269,16 +269,17 @@ func main() {
 	log.V(0).Info("starting up", "args", os.Args)
 
 	// Startup webhooks goroutine
-	webhookTriggerChan := make(chan webhookRepoInfo, 1)
+	var webhook *Webhook
 	if *flWebhookURL != "" {
-		webhook := Webhook{
+		webhook = &Webhook{
 			URL:     *flWebhookURL,
 			Method:  *flWebhookMethod,
 			Success: *flWebhookStatusSuccess,
 			Timeout: *flWebhookTimeout,
 			Backoff: *flWebhookBackoff,
+			Data:    NewWebhookData(),
 		}
-		go webhook.run(webhookTriggerChan)
+		go webhook.run()
 	}
 
 	initialSync := true
@@ -301,8 +302,8 @@ func main() {
 			cancel()
 			time.Sleep(waitTime(*flWait))
 			continue
-		} else if changed {
-			err := triggerWebhook(ctx, webhookTriggerChan, *flRev, *flRoot)
+		} else if changed && webhook != nil {
+			err := triggerWebhook(ctx, webhook, *flRev, *flRoot, *flDest)
 			if err != nil {
 				log.Error(err, "triggering webhook failed")
 			}
@@ -692,24 +693,19 @@ func setupGitCookieFile() error {
 	return nil
 }
 
-func triggerWebhook(ctx context.Context, ch chan webhookRepoInfo, rev, gitRoot string) error {
-	info := webhookRepoInfo{}
+func triggerWebhook(ctx context.Context, webhook *Webhook, rev, gitRoot, dest string) error {
+	target := path.Join(gitRoot, dest)
 
-	hash, err := hashForRev(ctx, rev, gitRoot)
+	hash, err := hashForRev(ctx, rev, target)
 	if err != nil {
 		return err
 	}
 
-	info.Hash = hash
-
 	// Trigger webhooks to be called. We do a non-blocking write to the channel as we
 	// don't want to backup the syncing locally because we can't complete a webhook call.
-	// Since the channel has a buffer of 1 we ensure that it is called for a change, but
-	// this allows us to de-dupe calls if they happen before the webhook call completes.
-	select {
-	case ch <- info:
-	default:
-	}
+	// Since the channel has a buffer of 1 we ensure that it is called for a change. Only
+	// the event of the last git hash will be send in case the webhook is not fast enough.
+	webhook.Data.UpdateAndTrigger(hash)
 
 	return nil
 }

cmd/git-sync/webhook.go

@@ -20,15 +20,68 @@ type Webhook struct {
 	Timeout time.Duration
 	// Backoff for failed webhook calls
 	Backoff time.Duration
+
+	Data *webhookData
 }
 
-type webhookRepoInfo struct {
-	Hash string
+type webhookData struct {
+	ch chan struct{}
+
+	newHash string
+	curHash string
 }
 
-func (w *Webhook) Do(info webhookRepoInfo) error {
+func NewWebhookData() *webhookData {
+	return &webhookData{
+		ch: make(chan struct{}, 1),
+	}
+}
+
+func (d *webhookData) UpdateAndTrigger(newHash string) {
+	d.newHash = newHash
+
+	select {
+	case d.ch <- struct{}{}:
+	default:
+	}
+}
+
+func (d *webhookData) updateState() bool {
+	newHash := d.newHash
+	if newHash != d.curHash {
+		d.curHash = newHash
+		return true
+	}
+	return false
+}
+
+func (d *webhookData) Hash() string {
+	d.updateState()
+	return d.curHash
+}
+
+func (d *webhookData) Wait() bool {
+	// wait for message from UpdateAndTrigger
+	<-d.ch
+
+	changed := d.updateState()
+
+	return changed
+}
+
+func (d *webhookData) WaitForChange() {
+	for {
+		changed := d.Wait()
+
+		if changed {
+			return
+		}
+	}
+}
+
+func (w *Webhook) Do(hash string) error {
 	req, err := http.NewRequest(w.Method, w.URL, nil)
-	req.Header.Set("Gitsync-Hash", info.Hash)
+	req.Header.Set("Gitsync-Hash", hash)
 	if err != nil {
 		return err
 	}
@@ -52,13 +105,14 @@ func (w *Webhook) Do(info webhookRepoInfo) error {
 }
 
 // Wait for trigger events from the channel, and send webhooks when triggered
-func (w *Webhook) run(ch chan webhookRepoInfo) {
+func (w *Webhook) run() {
 	for {
-		// Wait for trigger
-		info := <-ch
+		// Wait for trigger and changed hash value
+		w.Data.WaitForChange()
 
 		for {
-			if err := w.Do(info); err != nil {
+			hash := w.Data.Hash()
+			if err := w.Do(hash); err != nil {
 				log.Error(err, "error calling webhook", "url", w.URL)
 				time.Sleep(w.Backoff)
 			} else {

cmd/git-sync/webhook_test.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"testing"
+)
+
+const (
+	hash1 = "1111111111111111111111111111111111111111"
+	hash2 = "2222222222222222222222222222222222222222"
+	hash3 = "3333333333333333333333333333333333333333"
+)
+
+func TestWebhookData(t *testing.T) {
+	t.Run("webhhook consumes first hash value", func(t *testing.T) {
+		whd := NewWebhookData()
+
+		whd.UpdateAndTrigger(hash1)
+		whd.WaitForChange()
+
+		hash := whd.Hash()
+		if hash1 != hash {
+			t.Fatalf("expected hash %s but got %s", hash1, hash)
+		}
+	})
+
+	t.Run("second update wins", func(t *testing.T) {
+		whd := NewWebhookData()
+
+		whd.UpdateAndTrigger(hash1)
+		whd.UpdateAndTrigger(hash2)
+		whd.WaitForChange()
+
+		hash := whd.Hash()
+		if hash2 != hash {
+			t.Fatalf("expected hash %s but got %s", hash2, hash)
+		}
+	})
+
+	t.Run("same hash value does not lead to an update", func(t *testing.T) {
+		whd := NewWebhookData()
+
+		whd.UpdateAndTrigger(hash1)
+		whd.WaitForChange()
+		hash := whd.Hash()
+		if hash1 != hash {
+			t.Fatalf("expected hash %s but got %s", hash1, hash)
+		}
+
+		whd.UpdateAndTrigger(hash1)
+		changed := whd.Wait()
+
+		if changed {
+			t.Fatalf("no change expected")
+		}
+
+		hash = whd.Hash()
+		if hash1 != hash {
+			t.Fatalf("expected hash %s but got %s", hash1, hash)
+		}
+	})
+}