feat: use worker thread for piece hashing (#198)

Worker threads actually share memory in Node.js so there's no copy
getting the CAR bytes into the worker. This allows WASM piece hashing in
a worker that doesn't stall the main thread.

#### Before

Notice how the spinner is stalled for multiple seconds as piece hashing
is done:


https://github.com/storacha-network/w3cli/assets/152863/5d88f8c5-e7ae-4da3-96ce-a686fb3f2258

#### After

No stall!


https://github.com/storacha-network/w3cli/assets/152863/747a412e-1c27-456b-913f-a4ec6e29498a

Co-authored-by: Alan Shaw <[email protected]>

index.js

@@ -5,12 +5,10 @@ import ora from 'ora'
 import { CID } from 'multiformats/cid'
 import { base64 } from 'multiformats/bases/base64'
 import { identity } from 'multiformats/hashes/identity'
-import * as Digest from 'multiformats/hashes/digest'
 import * as DID from '@ipld/dag-ucan/did'
 import * as dagJSON from '@ipld/dag-json'
 import { CarWriter } from '@ipld/car'
 import { filesFromPaths } from 'files-from-path'
-import * as PieceHasher from 'fr32-sha2-256-trunc254-padded-binary-tree-multihash'
 import * as Account from './account.js'
 
 import { spaceAccess } from '@web3-storage/w3up-client/capability/access'
@@ -26,6 +24,7 @@ import {
   readProofFromBytes,
   uploadListResponseToString,
   startOfLastMonth,
+  pieceHasher,
 } from './lib.js'
 import * as ucanto from '@ucanto/core'
 import { ed25519 } from '@ucanto/principal'
@@ -160,20 +159,7 @@ export async function upload(firstPath, opts) {
     : `Storing ${Math.min(Math.round((totalSent / totalSize) * 100), 100)}%`
 
   const root = await uploadFn({
-    pieceHasher: {
-      code: PieceHasher.code,
-      name: 'fr32-sha2-256-trunc254-padded-binary-tree-multihash',
-      async digest (input) {
-        const hasher = PieceHasher.create()
-        hasher.write(input)
-
-        const bytes = new Uint8Array(hasher.multihashByteLength())
-        hasher.digestInto(bytes, 0, true)
-        hasher.free()
-
-        return Digest.decode(bytes)
-      }
-    },
+    pieceHasher,
     onShardStored: ({ cid, size, piece }) => {
       totalSent += size
       if (opts?.verbose) {

lib.js

@@ -1,5 +1,7 @@
-import fs from 'fs'
-import path from 'path'
+import fs from 'node:fs'
+import path from 'node:path'
+import { Worker } from 'node:worker_threads'
+import { fileURLToPath } from 'node:url'
 // @ts-expect-error no typings :(
 import tree from 'pretty-tree'
 import { importDAG } from '@ucanto/core/delegation'
@@ -28,9 +30,9 @@ import chalk from 'chalk'
  * @typedef {import('@web3-storage/capabilities/types').FilecoinInfoSuccess} FilecoinInfoSuccess
  */
 
-/**
- *
- */
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+
 export function getPkg() {
   // @ts-ignore JSON.parse works with Buffer in Node.js
   return JSON.parse(fs.readFileSync(new URL('./package.json', import.meta.url)))
@@ -347,3 +349,28 @@ export const streamToBlob = async source => {
   }))
   return new Blob(chunks)
 }
+
+const workerPath = path.join(__dirname, 'piece-hasher-worker.js')
+
+/** @see https://github.com/multiformats/multicodec/pull/331/files */
+const pieceHasherCode = 0x1011
+
+/** @type {import('multiformats').MultihashHasher<typeof pieceHasherCode>} */
+export const pieceHasher = {
+  code: pieceHasherCode,
+  name: 'fr32-sha2-256-trunc254-padded-binary-tree',
+  async digest (input) {
+    const bytes = await new Promise((resolve, reject) => {
+      const worker = new Worker(workerPath, { workerData: input })
+      worker.on('message', resolve)
+      worker.on('error', reject)
+      worker.on('exit', (code) => {
+        if (code !== 0) reject(new Error(`Piece hasher worker exited with code: ${code}`))
+      })
+    })
+    const digest = 
+      /** @type {import('multiformats').MultihashDigest<typeof pieceHasherCode>} */
+      (Digest.decode(bytes))
+    return digest
+  }
+}

piece-hasher-worker.js

@@ -0,0 +1,11 @@
+import { parentPort, workerData } from 'node:worker_threads'
+import * as PieceHasher from 'fr32-sha2-256-trunc254-padded-binary-tree-multihash'
+
+const hasher = PieceHasher.create()
+hasher.write(workerData)
+
+const bytes = new Uint8Array(hasher.multihashByteLength())
+hasher.digestInto(bytes, 0, true)
+hasher.free()
+
+parentPort?.postMessage(bytes)