perf(@angular-devkit/build-angular): reuse esbuild generated output file hashes

The development server used with the esbuild-based builders (`application`/`browser-esbuild`) will
now use the recently introduced hash values provided by esbuild in its output files. This removes
the need for each file to be hashed and analyzed on each rebuild during the development server
update analysis.

Author: clydin

packages/angular_devkit/build_angular/src/builders/dev-server/vite-server.ts

@@ -35,16 +35,11 @@ import type { DevServerBuilderOutput } from './webpack-server';
 interface OutputFileRecord {
   contents: Uint8Array;
   size: number;
-  hash?: Buffer;
+  hash?: string;
   updated: boolean;
   servable: boolean;
 }
 
-function hashContent(contents: BinaryLike): Buffer {
-  // TODO: Consider xxhash
-  return createHash('sha256').update(contents).digest();
-}
-
 export async function* serveWithVite(
   serverOptions: NormalizedDevServerOptions,
   builderName: string,
@@ -306,27 +301,22 @@ function analyzeResultFiles(
       continue;
     }
 
-    let fileHash: Buffer | undefined;
     const existingRecord = generatedFiles.get(filePath);
-    if (existingRecord && existingRecord.size === file.contents.byteLength) {
-      // Only hash existing file when needed
-      if (existingRecord.hash === undefined) {
-        existingRecord.hash = hashContent(existingRecord.contents);
-      }
-
-      // Compare against latest result output
-      fileHash = hashContent(file.contents);
-      if (fileHash.equals(existingRecord.hash)) {
-        // Same file
-        existingRecord.updated = false;
-        continue;
-      }
+    if (
+      existingRecord &&
+      existingRecord.size === file.contents.byteLength &&
+      existingRecord.hash === file.hash
+    ) {
+      // Same file
+      existingRecord.updated = false;
+      continue;
     }
 
+    // New or updated file
     generatedFiles.set(filePath, {
       contents: file.contents,
       size: file.contents.byteLength,
-      hash: fileHash,
+      hash: file.hash,
       updated: true,
       servable:
         file.type === BuildOutputFileType.Browser || file.type === BuildOutputFileType.Media,

packages/angular_devkit/build_angular/src/tools/esbuild/bundler-context.ts

@@ -17,7 +17,7 @@ import {
   context,
 } from 'esbuild';
 import { basename, dirname, extname, join, relative } from 'node:path';
-import { createOutputFileFromData, createOutputFileFromText } from './utils';
+import { convertOutputFile } from './utils';
 
 export type BundleContextResult =
   | { errors: Message[]; warnings: Message[] }
@@ -231,9 +231,9 @@ export class BundlerContext {
       }
     }
 
-    const outputFiles = result.outputFiles.map(({ contents, path }) => {
+    const outputFiles = result.outputFiles.map((file) => {
       let fileType: BuildOutputFileType;
-      if (dirname(path) === 'media') {
+      if (dirname(file.path) === 'media') {
         fileType = BuildOutputFileType.Media;
       } else {
         fileType =
@@ -242,7 +242,7 @@ export class BundlerContext {
             : BuildOutputFileType.Browser;
       }
 
-      return createOutputFileFromData(path, contents, fileType);
+      return convertOutputFile(file, fileType);
     });
 
     // Return the successful build results

packages/angular_devkit/build_angular/src/tools/esbuild/utils.ts

@@ -281,6 +281,30 @@ export function createOutputFileFromData(
   };
 }
 
+export function convertOutputFile(file: OutputFile, type: BuildOutputFileType): BuildOutputFile {
+  const { path, contents, hash } = file;
+
+  return {
+    contents,
+    hash,
+    path,
+    type,
+    get text() {
+      return Buffer.from(
+        this.contents.buffer,
+        this.contents.byteOffset,
+        this.contents.byteLength,
+      ).toString('utf-8');
+    },
+    get fullOutputPath(): string {
+      return getFullOutputPath(this);
+    },
+    clone(): BuildOutputFile {
+      return convertOutputFile(this, this.type);
+    },
+  };
+}
+
 export function getFullOutputPath(file: BuildOutputFile): string {
   switch (file.type) {
     case BuildOutputFileType.Browser: