Add 2 minute period unmined txs processing (#209)

* Add 2 minute period unmined txs processing

* Fix ineffective control operator

* Move global var to constant

cmd/metamorph.go

@@ -35,11 +35,12 @@ import (
 )
 
 const (
-	DbModeBadger   = "badger"
-	DbModeDynamoDB = "dynamodb"
-	DbModePostgres = "postgres"
-	DbModeSQLiteM  = "sqlite_memory"
-	DbModeSQLite   = "sqlite"
+	DbModeBadger     = "badger"
+	DbModeDynamoDB   = "dynamodb"
+	DbModePostgres   = "postgres"
+	DbModeSQLiteM    = "sqlite_memory"
+	DbModeSQLite     = "sqlite"
+	unminedTxsPeriod = 2 * time.Minute
 )
 
 func StartMetamorph(logger utils.Logger) (func(), error) {
@@ -155,11 +156,18 @@ func StartMetamorph(logger utils.Logger) (func(), error) {
 		// that can be deferred to reset the TTY when the program exits.
 		defer metamorphProcessor.PrintStatsOnKeypress()()
 	}
+	ticker := time.NewTimer(unminedTxsPeriod)
+	stopUnminedProcessor := make(chan bool)
 
 	go func() {
-		// load all transactions into memory from disk that have not been seen on the network
-		// this will make sure they are re-broadcast until a response is received
-		metamorphProcessor.LoadUnmined()
+		for {
+			select {
+			case <-stopUnminedProcessor:
+				return
+			case <-ticker.C:
+				metamorphProcessor.LoadUnmined()
+			}
+		}
 	}()
 
 	// create a channel to receive mined block messages from the block tx service
@@ -307,6 +315,8 @@ func StartMetamorph(logger utils.Logger) (func(), error) {
 
 	return func() {
 		logger.Infof("Shutting down metamorph")
+
+		stopUnminedProcessor <- true
 		metamorphProcessor.Shutdown()
 		err = s.Close(context.Background())
 		if err != nil {