perf(@angular-devkit/build-angular): avoid extra TypeScript emits wit…

…h esbuild rebuilds

To further improve incremental rebuild performance of the experimental esbuild-based browser
application builder, the output of the TypeScript file loader within the Angular compiler plugin
are now cached in memory by the input file name and invalidated via the file watching events.
This allows an additional TypeScript emit including the associated transformations per input file
to be avoided if the file has not changed or has not been affected by other files within the
TypeScript program.

(cherry picked from commit 1c87de6)

packages/angular_devkit/build_angular/src/builders/browser-esbuild/compiler-plugin.ts

@@ -8,7 +8,6 @@
 
 import type { CompilerHost, NgtscProgram } from '@angular/compiler-cli';
 import { transformAsync } from '@babel/core';
-import * as assert from 'assert';
 import type {
   OnStartResult,
   OutputFile,
@@ -17,9 +16,11 @@ import type {
   Plugin,
   PluginBuild,
 } from 'esbuild';
-import { promises as fs } from 'fs';
-import { platform } from 'os';
-import * as path from 'path';
+import * as assert from 'node:assert';
+import * as fs from 'node:fs/promises';
+import { platform } from 'node:os';
+import * as path from 'node:path';
+import { pathToFileURL } from 'node:url';
 import ts from 'typescript';
 import angularApplicationPreset from '../../babel/presets/application';
 import { requiresLinking } from '../../babel/webpack-loader';
@@ -133,11 +134,13 @@ const WINDOWS_SEP_REGEXP = new RegExp(`\\${path.win32.sep}`, 'g');
 export class SourceFileCache extends Map<string, ts.SourceFile> {
   readonly modifiedFiles = new Set<string>();
   readonly babelFileCache = new Map<string, Uint8Array>();
+  readonly typeScriptFileCache = new Map<string, Uint8Array>();
 
   invalidate(files: Iterable<string>): void {
     this.modifiedFiles.clear();
     for (let file of files) {
       this.babelFileCache.delete(file);
+      this.typeScriptFileCache.delete(pathToFileURL(file).href);
 
       // Normalize separators to allow matching TypeScript Host paths
       if (USING_WINDOWS) {
@@ -355,6 +358,17 @@ export function createCompilerPlugin(
         previousBuilder = builder;
 
         await profileAsync('NG_ANALYZE_PROGRAM', () => angularCompiler.analyzeAsync());
+        const affectedFiles = profileSync('NG_FIND_AFFECTED', () =>
+          findAffectedFiles(builder, angularCompiler),
+        );
+
+        if (pluginOptions.sourceFileCache) {
+          for (const affected of affectedFiles) {
+            pluginOptions.sourceFileCache.typeScriptFileCache.delete(
+              pathToFileURL(affected.fileName).href,
+            );
+          }
+        }
 
         function* collectDiagnostics(): Iterable<ts.Diagnostic> {
           // Collect program level diagnostics
@@ -364,7 +378,6 @@ export function createCompilerPlugin(
           yield* builder.getGlobalDiagnostics();
 
           // Collect source file specific diagnostics
-          const affectedFiles = findAffectedFiles(builder, angularCompiler);
           const optimizeFor =
             affectedFiles.size > 1 ? OptimizeFor.WholeProgram : OptimizeFor.SingleFile;
           for (const sourceFile of builder.getSourceFiles()) {
@@ -434,41 +447,56 @@ export function createCompilerPlugin(
             async () => {
               assert.ok(fileEmitter, 'Invalid plugin execution order');
 
-              const typescriptResult = await fileEmitter(
-                pluginOptions.fileReplacements?.[args.path] ?? args.path,
+              // The filename is currently used as a cache key. Since the cache is memory only,
+              // the options cannot change and do not need to be represented in the key. If the
+              // cache is later stored to disk, then the options that affect transform output
+              // would need to be added to the key as well as a check for any change of content.
+              let contents = pluginOptions.sourceFileCache?.typeScriptFileCache.get(
+                pathToFileURL(args.path).href,
               );
-              if (!typescriptResult) {
-                // No TS result indicates the file is not part of the TypeScript program.
-                // If allowJs is enabled and the file is JS then defer to the next load hook.
-                if (compilerOptions.allowJs && /\.[cm]?js$/.test(args.path)) {
-                  return undefined;
+
+              if (contents === undefined) {
+                const typescriptResult = await fileEmitter(
+                  pluginOptions.fileReplacements?.[args.path] ?? args.path,
+                );
+                if (!typescriptResult) {
+                  // No TS result indicates the file is not part of the TypeScript program.
+                  // If allowJs is enabled and the file is JS then defer to the next load hook.
+                  if (compilerOptions.allowJs && /\.[cm]?js$/.test(args.path)) {
+                    return undefined;
+                  }
+
+                  // Otherwise return an error
+                  return {
+                    errors: [
+                      {
+                        text: `File '${args.path}' is missing from the TypeScript compilation.`,
+                        notes: [
+                          {
+                            text: `Ensure the file is part of the TypeScript program via the 'files' or 'include' property.`,
+                          },
+                        ],
+                      },
+                    ],
+                  };
                 }
 
-                // Otherwise return an error
-                return {
-                  errors: [
-                    {
-                      text: `File '${args.path}' is missing from the TypeScript compilation.`,
-                      notes: [
-                        {
-                          text: `Ensure the file is part of the TypeScript program via the 'files' or 'include' property.`,
-                        },
-                      ],
-                    },
-                  ],
-                };
-              }
+                const data = typescriptResult.content ?? '';
+                // The pre-transformed data is used as a cache key. Since the cache is memory only,
+                // the options cannot change and do not need to be represented in the key. If the
+                // cache is later stored to disk, then the options that affect transform output
+                // would need to be added to the key as well.
+                contents = babelDataCache.get(data);
+                if (contents === undefined) {
+                  const transformedData = await transformWithBabel(args.path, data, pluginOptions);
+                  contents = Buffer.from(transformedData, 'utf-8');
+                  babelDataCache.set(data, contents);
+                }
 
-              const data = typescriptResult.content ?? '';
-              // The pre-transformed data is used as a cache key. Since the cache is memory only,
-              // the options cannot change and do not need to be represented in the key. If the
-              // cache is later stored to disk, then the options that affect transform output
-              // would need to be added to the key as well.
-              let contents = babelDataCache.get(data);
-              if (contents === undefined) {
-                const transformedData = await transformWithBabel(args.path, data, pluginOptions);
-                contents = Buffer.from(transformedData, 'utf-8');
-                babelDataCache.set(data, contents);
+                pluginOptions.sourceFileCache?.typeScriptFileCache.set(
+                  pathToFileURL(args.path).href,
+                  contents,
+                );
               }
 
               return {