perf(hash): use lookup-table hex encoding in sha256 paths

Author: kavinsood

server/src/chunkedDocStore.ts

@@ -1,4 +1,5 @@
 import * as Y from "yjs";
+import { sha256Hex } from "./hex";
 
 const CHECKPOINT_FORMAT = "yaos-doc-checkpoint-v2";
 const JOURNAL_META_FORMAT = "yaos-doc-journal-v1";
@@ -179,13 +180,6 @@ function chunkArray<T>(arr: T[], size: number): T[][] {
 	return out;
 }
 
-async function sha256Hex(bytes: Uint8Array): Promise<string> {
-	const digest = await crypto.subtle.digest("SHA-256", bytes);
-	return Array.from(new Uint8Array(digest))
-		.map((value) => value.toString(16).padStart(2, "0"))
-		.join("");
-}
-
 async function getManyBatched<T>(
 	storage: StorageLike | TransactionLike,
 	keys: string[],

server/src/hex.ts

@@ -0,0 +1,20 @@
+const BYTE_TO_HEX: string[] = (() => {
+	const table = new Array<string>(256);
+	for (let i = 0; i < 256; i++) {
+		table[i] = i.toString(16).padStart(2, "0");
+	}
+	return table;
+})();
+
+export function bytesToHex(bytes: Uint8Array): string {
+	let out = "";
+	for (let i = 0; i < bytes.length; i++) {
+		out += BYTE_TO_HEX[bytes[i]!]!;
+	}
+	return out;
+}
+
+export async function sha256Hex(bytes: Uint8Array): Promise<string> {
+	const digest = await crypto.subtle.digest("SHA-256", bytes);
+	return bytesToHex(new Uint8Array(digest));
+}

server/src/index.ts

@@ -1,6 +1,7 @@
 import { getServerByName } from "partyserver";
 import * as Y from "yjs";
 import { mapWithConcurrency } from "./concurrency";
+import { sha256Hex } from "./hex";
 import { ServerConfig, type StoredServerConfig } from "./config";
 import {
 	blobKey,
@@ -167,10 +168,7 @@ function rejectSocket(
 
 async function hashToken(token: string): Promise<string> {
 	const bytes = new TextEncoder().encode(token);
-	const digest = await crypto.subtle.digest("SHA-256", bytes);
-	return Array.from(new Uint8Array(digest))
-		.map((value) => value.toString(16).padStart(2, "0"))
-		.join("");
+	return sha256Hex(bytes);
 }
 
 function supportsBuckets(env: Env): boolean {

src/main.ts

@@ -1,4 +1,4 @@
-import { MarkdownView, Modal, Notice, Plugin, TFile, normalizePath } from "obsidian";
+import { MarkdownView, Modal, Notice, Plugin, TFile, arrayBufferToHex, normalizePath } from "obsidian";
 import {
 	DEFAULT_SETTINGS,
 	VaultSyncSettingTab,
@@ -2661,9 +2661,7 @@ export default class VaultCrdtSyncPlugin extends Plugin {
 	private async sha256Hex(text: string): Promise<string> {
 		const data = new TextEncoder().encode(text);
 		const digest = await crypto.subtle.digest("SHA-256", data);
-		return Array.from(new Uint8Array(digest))
-			.map((b) => b.toString(16).padStart(2, "0"))
-			.join("");
+		return arrayBufferToHex(digest);
 	}
 
 	private async exportDiagnostics(): Promise<void> {