From c5306116428ca6a7c6494f911544c916a2e2e21a Mon Sep 17 00:00:00 2001
From: b00ris <b00ris@mail.ru>
Date: Tue, 28 Nov 2017 16:17:15 +0300
Subject: [PATCH] Fix race #452 (#454)

It fixes race conditions in `geth/signal`.
---
 geth/signal/signals.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/geth/signal/signals.go b/geth/signal/signals.go
index aff3c60a5..538d2defb 100644
--- a/geth/signal/signals.go
+++ b/geth/signal/signals.go
@@ -10,6 +10,7 @@ import (
 	"encoding/json"
 
 	"github.com/status-im/status-go/geth/log"
+	"sync"
 )
 
 const (
@@ -47,14 +48,21 @@ type NodeNotificationHandler func(jsonEvent string)
 
 var notificationHandler NodeNotificationHandler = TriggerDefaultNodeNotificationHandler
 
+// notificationHandlerMutex guards notificationHandler for concurrent calls
+var notificationHandlerMutex sync.RWMutex
+
 // SetDefaultNodeNotificationHandler sets notification handler to invoke on Send
 func SetDefaultNodeNotificationHandler(fn NodeNotificationHandler) {
+	notificationHandlerMutex.Lock()
 	notificationHandler = fn
+	notificationHandlerMutex.Unlock()
 }
 
 // ResetDefaultNodeNotificationHandler sets notification handler to default one
 func ResetDefaultNodeNotificationHandler() {
+	notificationHandlerMutex.Lock()
 	notificationHandler = TriggerDefaultNodeNotificationHandler
+	notificationHandlerMutex.Unlock()
 }
 
 // TriggerDefaultNodeNotificationHandler triggers default notification handler (helpful in tests)
@@ -71,6 +79,8 @@ func Send(signal Envelope) {
 //export NotifyNode
 //nolint: golint
 func NotifyNode(jsonEvent *C.char) {
+	notificationHandlerMutex.RLock()
+	defer notificationHandlerMutex.RUnlock()
 	notificationHandler(C.GoString(jsonEvent))
 }