From 39327e2e86886e62f51cb676c8e206876a5732d8 Mon Sep 17 00:00:00 2001
From: Ivan Nikitin <cherniy.bumer@gmail.com>
Date: Fri, 10 Dec 2021 20:33:43 +0100
Subject: [PATCH] Fixes memory leak in decodeBuffer + destroys worker after 10
 seconds of inactivity

---
 build/build.ts  |  4 +++-
 src/heic2any.ts | 25 +++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/build/build.ts b/build/build.ts
index 2904948..9b2ea18 100644
--- a/build/build.ts
+++ b/build/build.ts
@@ -45,7 +45,9 @@ async function startBuild() {
 	).replace(
 		/(\\)/g,
 		"\\\\"
-	)}\n${worker}\n\`;\nvar blob = new Blob([workerString], {type: 'application/javascript'});\nwindow.__heic2any__worker = new Worker(URL.createObjectURL(blob));`;
+	)}\n${worker}\n\`;` +
+		"\nwindow.__heic2any__blob = new Blob([workerString], {type: 'application/javascript'});" +
+		"\nwindow.__heic2any__blob_url = URL.createObjectURL(window.__heic2any__blob);";
 
 	console.log("🔨 📄 Fixing main files");
 	main = worker + main;
diff --git a/src/heic2any.ts b/src/heic2any.ts
index 28918b4..31572b3 100644
--- a/src/heic2any.ts
+++ b/src/heic2any.ts
@@ -194,15 +194,36 @@ const utils = {
 	},
 };
 
+function getWorker(): Worker {
+	if (!(window as any).__heic2any__worker)
+		(window as any).__heic2any__worker = new Worker((window as any).__heic2any__blob_url);
+	return (window as any).__heic2any__worker;
+}
+
+let pendingWorkerJobsCount = 0;
+
+function scheduleWorkerDestruction() {
+	setTimeout(() => {
+		if ((window as any).__heic2any__worker && pendingWorkerJobsCount == 0) {
+			(window as any).__heic2any__worker.terminate();
+			delete (window as any).__heic2any__worker;
+		}
+	}, 10000);
+}
+
 function decodeBuffer(buffer: ArrayBuffer): Promise<ImageData[]> {
 	return new Promise((resolve, reject) => {
 		const id = (Math.random() * new Date().getTime()).toString();
 		const message = { id, buffer };
-		const worker = (window as any).__heic2any__worker as Worker;
+		const worker = getWorker();
+		pendingWorkerJobsCount++;
 		worker.postMessage(message);
-		const listener = (message: MessageEvent<any>) => {
+		const listener = (message: MessageEvent) => {
 			if (message.data.id === id) {
 				worker.removeEventListener("message", listener);
+				pendingWorkerJobsCount--;
+				if (pendingWorkerJobsCount == 0)
+					scheduleWorkerDestruction();
 				if (message.data.error)
 					reject(message.data.error);
 				else