[IMPROVE] Cache livechat get agent trigger call (#12083)

packages/rocketchat-livechat/.app/client/lib/triggers.js

@@ -3,8 +3,14 @@ import visitor from '../../imports/client/visitor';
 
 const firedTriggers = JSON.parse(localStorage.getItem('rocketChatFiredTriggers')) || [];
 
+// promise cache for multiple calls (let's say multiple triggers running before the previous finished)
+const agentCacheExpiry = 3600000;
+let agentPromise;
 function getAgent(triggerAction) {
-	return new Promise((resolve, reject) => {
+	if (agentPromise) {
+		return agentPromise;
+	}
+	agentPromise = new Promise((resolve, reject) => {
 		const { params } = triggerAction;
 		if (params.sender === 'queue') {
 			const cache = localStorage.getItem('triggerAgent');
@@ -12,7 +18,7 @@ function getAgent(triggerAction) {
 				const cacheAgent = JSON.parse(cache);
 
 				// cache valid for 1h
-				if (cacheAgent.ts && Date.now() - cacheAgent.ts < 3600000) {
+				if (cacheAgent.ts && Date.now() - cacheAgent.ts < agentCacheExpiry) {
 					return resolve(cacheAgent.agent);
 				}
 			}
@@ -39,6 +45,13 @@ function getAgent(triggerAction) {
 			reject('Unknown sender');
 		}
 	});
+
+	// expire the promise cache as well
+	setTimeout(() => {
+		agentPromise = null;
+	}, agentCacheExpiry);
+
+	return agentPromise;
 }
 
 this.Triggers = (function() {