From 732e7dc93125d00f9fdd39e06ac303a458a36373 Mon Sep 17 00:00:00 2001
From: tamaina <tamaina@hotmail.co.jp>
Date: Wed, 17 May 2023 17:13:32 +0000
Subject: [PATCH] wip

---
 .../src/components/MkImgWithBlurhash.vue      | 41 ++++++++----
 .../src/scripts/worker-multi-dispatch.ts      | 62 +++++++++++++++++++
 2 files changed, 92 insertions(+), 11 deletions(-)
 create mode 100644 packages/frontend/src/scripts/worker-multi-dispatch.ts

diff --git a/packages/frontend/src/components/MkImgWithBlurhash.vue b/packages/frontend/src/components/MkImgWithBlurhash.vue
index ca912fabf5..2967fad450 100644
--- a/packages/frontend/src/components/MkImgWithBlurhash.vue
+++ b/packages/frontend/src/components/MkImgWithBlurhash.vue
@@ -18,12 +18,21 @@
 <script lang="ts">
 import DrawBlurhash from '@/workers/draw-blurhash?worker';
 import TestWebGL2 from '@/workers/test-webgl2?worker';
+import { WorkerMultiDispatch } from '@/scripts/worker-multi-dispatch';
+import { $ref } from 'vue/macros';
 
-const workerPromise = new Promise<Worker | null>(resolve => {
+const workerPromise = new Promise<WorkerMultiDispatch | null>(resolve => {
 	const testWorker = new TestWebGL2();
 	testWorker.addEventListener('message', event => {
-		if (event.data.result) resolve(new DrawBlurhash());
-		else resolve(null);
+		if (event.data.result) {
+			const workers = new WorkerMultiDispatch(
+				() => new DrawBlurhash(),
+				Math.min(navigator.hardwareConcurrency - 1, 4),
+			);
+			resolve(workers);
+		} else {
+			resolve(null);
+		}
 		testWorker.terminate();
 	});
 });
@@ -74,6 +83,7 @@ let canvasWidth = $ref(64);
 let canvasHeight = $ref(64);
 let imgWidth = $ref(props.width);
 let imgHeight = $ref(props.height);
+let usingWorkerNumber = $ref<number>(-1);
 const hide = computed(() => !loaded || props.forceBlurhash);
 
 function waitForDecode() {
@@ -110,17 +120,22 @@ watch([() => props.width, () => props.height, root], () => {
 
 async function draw(transfer: boolean = false) {
 	if (!canvas.value || props.hash == null) return;
-	const worker = await workerPromise;
-	if (worker) {
+	const workers = await workerPromise;
+	if (workers) {
 		let offscreen: OffscreenCanvas | undefined;
 		if (transfer) {
 			offscreen = canvas.value.transferControlToOffscreen();
 		}
-		worker.postMessage({
-			id: viewId,
-			canvas: offscreen ?? undefined,
-			hash: props.hash,
-		}, offscreen ? [offscreen] : []);
+		const workerNumber = workers.postMessage(
+			{
+				id: viewId,
+				canvas: offscreen ?? undefined,
+				hash: props.hash,
+			},
+			offscreen ? [offscreen] : [],
+			usingWorkerNumber === -1 ? undefined : () => usingWorkerNumber,
+		);
+		usingWorkerNumber = workerNumber;
 	} else {
 		try {
 			const work = document.createElement('canvas');
@@ -150,7 +165,11 @@ onMounted(() => {
 });
 
 onUnmounted(() => {
-	workerPromise.then(worker => worker?.postMessage!({ id: viewId, delete: true }));
+	if (usingWorkerNumber !== -1) {
+		workerPromise.then(worker => {
+			worker?.postMessage!({ id: viewId, delete: true }, undefined, () => usingWorkerNumber);
+		});
+	}
 });
 </script>
 
diff --git a/packages/frontend/src/scripts/worker-multi-dispatch.ts b/packages/frontend/src/scripts/worker-multi-dispatch.ts
new file mode 100644
index 0000000000..f1f9ae53b4
--- /dev/null
+++ b/packages/frontend/src/scripts/worker-multi-dispatch.ts
@@ -0,0 +1,62 @@
+function defaultUseWorkerNumber(prev: number, totalWorkers: number) {
+    return prev + 1;
+}
+
+export class WorkerMultiDispatch<POST = any, RETURN = any> {
+    private sym = Symbol('WorkerMultiDispatch');
+    public workers: Worker[] = [];
+    private prevWorkerNumber = 0;
+    private getUseWorkerNumber = defaultUseWorkerNumber;
+    private finalizationRegistry: FinalizationRegistry<symbol>;
+
+    constructor(workerConstructor: () => Worker, concurrency: number, getUseWorkerNumber = defaultUseWorkerNumber) {
+        this.getUseWorkerNumber = getUseWorkerNumber;
+        for (let i = 0; i < concurrency; i++) {
+            this.workers.push(workerConstructor());
+        }
+
+        this.finalizationRegistry = new FinalizationRegistry(() => {
+            this.terminate();
+        });
+        this.finalizationRegistry.register(this, this.sym);
+
+        if (_DEV_) console.log('WorkerMultiDispatch: Created', this);
+    }
+
+    public postMessage(message: POST, options?: Transferable[] | StructuredSerializeOptions, useWorkerNumber: typeof defaultUseWorkerNumber = this.getUseWorkerNumber) {
+        let workerNumber = useWorkerNumber(this.prevWorkerNumber, this.workers.length);
+        workerNumber = Math.abs(Math.round(workerNumber)) % this.workers.length;
+        if (_DEV_) console.log('WorkerMultiDispatch: Posting message to worker', workerNumber, useWorkerNumber);
+        this.prevWorkerNumber = workerNumber;
+
+        // 不毛だがunionをoverloadに突っ込めない
+        // https://stackoverflow.com/questions/66507585/overload-signatures-union-types-and-no-overload-matches-this-call-error
+        // https://github.com/microsoft/TypeScript/issues/14107
+        if (Array.isArray(options)) {
+            this.workers[workerNumber].postMessage(message, options);
+        } else {
+            this.workers[workerNumber].postMessage(message, options);
+        }
+        return workerNumber;
+    }
+
+    public addListener(callback: (this: Worker, ev: MessageEvent<RETURN>) => any, options?: boolean | AddEventListenerOptions) {
+        this.workers.forEach(worker => {
+            worker.addEventListener('message', callback, options);
+        });
+    }
+
+    public removeListener(callback: (this: Worker, ev: MessageEvent<RETURN>) => any, options?: boolean | AddEventListenerOptions) {
+        this.workers.forEach(worker => {
+            worker.removeEventListener('message', callback, options);
+        });
+    }
+
+    public terminate() {
+        this.workers.forEach(worker => {
+            worker.terminate();
+        });
+        this.workers = [];
+        this.finalizationRegistry.unregister(this);
+    }
+}