From a07c414e7290f780255fac335171a8fab152dced Mon Sep 17 00:00:00 2001
From: Martin Boehm <martin.boehm@1mbsoftware.net>
Date: Thu, 1 Feb 2018 11:24:53 +0100
Subject: [PATCH] Repeatedly with debounce synchronize index and mempool

---
 blockbook.go | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/blockbook.go b/blockbook.go
index eaa7d447..6db7b5e2 100644
--- a/blockbook.go
+++ b/blockbook.go
@@ -189,31 +189,55 @@ func main() {
 	<-chanSyncMempoolDone
 }
 
+func tickAndDebounce(tickTime time.Duration, debounceTime time.Duration, input chan struct{}, f func()) {
+	timer := time.NewTimer(tickTime)
+Loop:
+	for {
+		timerChan := timer.C
+		select {
+		case _, ok := <-input:
+			timer.Stop()
+			// exit loop on closed channel
+			if !ok {
+				break Loop
+			}
+			// debounce for debounceTime
+			timer = time.NewTimer(debounceTime)
+		case <-timerChan:
+			// do the action and start the loop again
+			f()
+			timer = time.NewTimer(tickTime)
+		}
+	}
+}
+
 func syncIndexLoop() {
 	defer close(chanSyncIndexDone)
 	glog.Info("syncIndexLoop starting")
-	for range chanSyncIndex {
+	// resync index about every 15 minutes if there are no chanSyncIndex requests, with debounce 1 second
+	tickAndDebounce(935093*time.Millisecond, 1009*time.Millisecond, chanSyncIndex, func() {
 		if err := resyncIndex(); err != nil {
-			glog.Error(err)
+			glog.Error("syncIndexLoop", err)
 		}
-	}
+	})
 	glog.Info("syncIndexLoop stopped")
 }
 
 func syncMempoolLoop() {
 	defer close(chanSyncMempoolDone)
 	glog.Info("syncMempoolLoop starting")
-	for range chanSyncMempool {
+	// resync mempool about every minute if there are no chanSyncMempool requests, with debounce 1 second
+	tickAndDebounce(60017*time.Millisecond, 1009*time.Millisecond, chanSyncMempool, func() {
 		if err := mempool.Resync(); err != nil {
-			glog.Error(err)
+			glog.Error("syncMempoolLoop", err)
 		}
-	}
+	})
 	glog.Info("syncMempoolLoop stopped")
 }
 
 func mqHandler(m *bchain.MQMessage) {
 	body := hex.EncodeToString(m.Body)
-	glog.V(2).Infof("MQ: %s-%d  %s", m.Topic, m.Sequence, body)
+	glog.V(1).Infof("MQ: %s-%d  %s", m.Topic, m.Sequence, body)
 	if m.Topic == "hashblock" {
 		chanSyncIndex <- struct{}{}
 	} else if m.Topic == "hashtx" {