From 832a602bedc98a2abf952ce2ebe99c454eb49b21 Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Mon, 21 Apr 2025 10:53:48 -0700
Subject: [PATCH] Reuse DataView for reading mapped result data.

---
 src/lib/gpu/index.ts | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/lib/gpu/index.ts b/src/lib/gpu/index.ts
index af6f545..d4c1ba9 100644
--- a/src/lib/gpu/index.ts
+++ b/src/lib/gpu/index.ts
@@ -21,6 +21,7 @@ export class NanoPowGpu {
 	static #cpuBuffer: GPUBuffer
 	static #uboBuffer: GPUBuffer
 	static #uboView: DataView
+	static #resultView: DataView
 	static #bindGroupLayout: GPUBindGroupLayout
 	static #searchPipeline: GPUComputePipeline
 	static #validatePipeline: GPUComputePipeline
@@ -151,7 +152,7 @@ export class NanoPowGpu {
 		console.table(averages)
 	}
 
-	static async #dispatch (pipeline: GPUComputePipeline, seed: bigint, hash: string, difficulty: bigint, passes: number): Promise<DataView> {
+	static async #dispatch (pipeline: GPUComputePipeline, seed: bigint, hash: string, difficulty: bigint, passes: number): Promise<void> {
 		if (this.#device == null) throw new Error(`WebGPU device failed to load.`)
 		// Set up uniform buffer object
 		// Note: u32 size is 4, but total alignment must be multiple of 16
@@ -205,20 +206,18 @@ export class NanoPowGpu {
 		this.#device.queue.submit([commandEncoder.finish()])
 
 		// Read results back to Javascript and then unmap buffer after reading
-		let data = null
 		try {
 			await this.#cpuBuffer.mapAsync(GPUMapMode.READ)
 			await this.#device.queue.onSubmittedWorkDone()
-			data = new DataView(this.#cpuBuffer.getMappedRange().slice(0))
+			this.#resultView = new DataView(this.#cpuBuffer.getMappedRange().slice(0))
 			this.#cpuBuffer.unmap()
 		} catch (err) {
 			console.warn(`Error getting data from GPU. ${err}`)
 			this.#cpuBuffer.unmap()
 			this.reset()
 		}
-		if (this.#debug) console.log('gpuBuffer data', data)
-		if (data == null) throw new Error(`Failed to get data from buffer.`)
-		return data
+		if (this.#debug) console.log('gpuBuffer data', this.#resultView)
+		if (this.#resultView == null) throw new Error(`Failed to get data from buffer.`)
 	}
 
 	/**
@@ -281,10 +280,10 @@ export class NanoPowGpu {
 			const random1 = Math.floor(Math.random() * 0xffffffff)
 			const seed = (BigInt(random0) << 32n) | BigInt(random1)
 			if (this.#debug) console.log('seed', seed.toString(16).padStart(16, '0'))
-			const data = await this.#dispatch(this.#searchPipeline, seed, hash, difficulty, effort)
-			const found = !!data.getUint32(0)
-			nonce = data.getBigUint64(8, true)
-			result = data.getBigUint64(16, true)
+			await this.#dispatch(this.#searchPipeline, seed, hash, difficulty, effort)
+			const found = !!this.#resultView.getUint32(0)
+			nonce = this.#resultView.getBigUint64(8, true)
+			result = this.#resultView.getBigUint64(16, true)
 			this.#busy = !found
 			times.push(performance.now() - start)
 		} while (this.#busy)
@@ -352,9 +351,9 @@ export class NanoPowGpu {
 
 		const seed = BigInt(`0x${work}`)
 		if (this.#debug) console.log('work', work)
-		const data = await this.#dispatch(this.#validatePipeline, seed, hash, difficulty, 1)
-		nonce = data.getBigUint64(8, true)
-		result = data.getBigUint64(16, true)
+		await this.#dispatch(this.#validatePipeline, seed, hash, difficulty, 1)
+		nonce = this.#resultView.getBigUint64(8, true)
+		result = this.#resultView.getBigUint64(16, true)
 		this.#busy = false
 		if (this.#debug) console.log('nonce', nonce, nonce.toString(16).padStart(16, '0'))
 		if (this.#debug) console.log('result', result, result.toString(16).padStart(16, '0'))
-- 
2.34.1