From b0b2f28d7c4df62e23879c241c4419135ef6f365 Mon Sep 17 00:00:00 2001
From: Duncan Dam <59436522+Duncan-Ultra@users.noreply.github.com>
Date: Wed, 5 Jun 2024 14:37:52 +0700
Subject: [PATCH] [BLOCK-2347] fix concurrent map writes (#48)

---
 dgraphql/resolvers/trxcache.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/dgraphql/resolvers/trxcache.go b/dgraphql/resolvers/trxcache.go
index 94a06a31..41790e5b 100644
--- a/dgraphql/resolvers/trxcache.go
+++ b/dgraphql/resolvers/trxcache.go
@@ -4,12 +4,14 @@ package resolvers
 
 import (
 	"container/list"
+	"sync"
 )
 
 type TrxCache struct {
 	capacity int
 	data     map[string]*list.Element
 	order    list.List
+	mu       sync.RWMutex
 }
 
 func NewTrxCache(capacity int) *TrxCache {
@@ -21,6 +23,9 @@ func NewTrxCache(capacity int) *TrxCache {
 }
 
 func (c *TrxCache) Put(key string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
 	if ele, exists := c.data[key]; exists {
 		// If key already exists, move it to the front
 		c.order.MoveToFront(ele)
@@ -38,6 +43,9 @@ func (c *TrxCache) Put(key string) {
 }
 
 func (c *TrxCache) Exists(key string) bool {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
 	_, exists := c.data[key]
 	return exists
 }