From f84ced215237205e0a115fb2614efc93aafaf740 Mon Sep 17 00:00:00 2001
From: tomasmik <tomasmik@protonmail.com>
Date: Thu, 21 Oct 2021 14:44:12 +0300
Subject: [PATCH] Add a wait timer after each transaction

---
 transfer/multichain_queue_test.go |  4 ++--
 transfer/queue.go                 | 23 +++++++++++++++++++----
 transfer/queue_test.go            |  6 +++---
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/transfer/multichain_queue_test.go b/transfer/multichain_queue_test.go
index 565abef..750d2ad 100644
--- a/transfer/multichain_queue_test.go
+++ b/transfer/multichain_queue_test.go
@@ -62,8 +62,8 @@ func TestMultichainQueue(t *testing.T) {
 	})
 	t.Run("chain does not exist", func(t *testing.T) {
 		mq := NewMultichainQueue()
-		q1 := NewQueue(1)
-		q2 := NewQueue(1)
+		q1 := NewQueue(1, 0)
+		q2 := NewQueue(1, 0)
 		mq.AddQueue(1, q1)
 		mq.AddQueue(2, q2)
 		go q1.Run()
diff --git a/transfer/queue.go b/transfer/queue.go
index afafaed..877e97d 100644
--- a/transfer/queue.go
+++ b/transfer/queue.go
@@ -20,6 +20,7 @@ package transfer
 import (
 	"errors"
 	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/core/types"
 )
@@ -30,7 +31,8 @@ type Queue struct {
 	queue chan queueEntry
 	stop  chan struct{}
 
-	once sync.Once
+	debounce time.Duration
+	once     sync.Once
 }
 
 // ErrQueueClosed is returned when queue is closed and transaction was not processed.
@@ -46,10 +48,11 @@ type queueEntry struct {
 
 // NewQueue returns a new queue. Size for the queue can be given
 // so that more than 1 transaction could be queued at a time.
-func NewQueue(size uint) *Queue {
+func NewQueue(size uint, debounceTime time.Duration) *Queue {
 	return &Queue{
-		queue: make(chan queueEntry, size),
-		stop:  make(chan struct{}, 0),
+		queue:    make(chan queueEntry, size),
+		debounce: debounceTime,
+		stop:     make(chan struct{}, 0),
 	}
 }
 
@@ -67,10 +70,22 @@ func (q *Queue) Run() {
 		case entry := <-q.queue:
 			tx, err := entry.exec()
 			q.resp(tx, err, entry.resp)
+			q.waitAfterSend()
 		}
 	}
 }
 
+func (q *Queue) waitAfterSend() {
+	if q.debounce == 0 {
+		return
+	}
+
+	select {
+	case <-q.stop:
+	case <-time.After(q.debounce):
+	}
+}
+
 func (q *Queue) resp(tx *types.Transaction, err error, ch chan<- QueueResponse) {
 	ch <- QueueResponse{
 		tx:  tx,
diff --git a/transfer/queue_test.go b/transfer/queue_test.go
index a52d87a..8bd0946 100644
--- a/transfer/queue_test.go
+++ b/transfer/queue_test.go
@@ -12,7 +12,7 @@ import (
 
 func TestQueue(t *testing.T) {
 	t.Run("green path", func(t *testing.T) {
-		q := NewQueue(1)
+		q := NewQueue(1, 0)
 		go q.Run()
 		defer q.Stop()
 		fn := func() (*types.Transaction, error) {
@@ -28,7 +28,7 @@ func TestQueue(t *testing.T) {
 		assert.Equal(t, uint64(0x1), tx.Nonce())
 	})
 	t.Run("exec produced an error", func(t *testing.T) {
-		q := NewQueue(1)
+		q := NewQueue(1, 0)
 		go q.Run()
 		defer q.Stop()
 		fn := func() (*types.Transaction, error) {
@@ -43,7 +43,7 @@ func TestQueue(t *testing.T) {
 		assert.Nil(t, tx)
 	})
 	t.Run("closed queue returns an error", func(t *testing.T) {
-		q := NewQueue(1)
+		q := NewQueue(1, 0)
 		q.Stop()
 		fn := func() (*types.Transaction, error) {
 			return types.NewTransaction(1, common.Address{}, big.NewInt(1), 10, big.NewInt(1), []byte{}), nil