refactor(ngcc): support running callback before writing transformed files (#36626)

This commit enhances the `CompileFn`, which is used to process each
entry-point, to support running a passed-in callback (and wait for it to
complete) before proceeding with writing the transformed files to disk.

This functionality is currently not used. In a subsequent commit, it
will be used for passing info from worker processes to the master
process that will allow ngcc to recover when a worker process crashes in
the middle of processing a task.

PR Close #36626

packages/compiler-cli/ngcc/src/execution/api.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {FileToWrite} from '../rendering/utils';
 import {Task, TaskCompletedCallback, TaskQueue} from './tasks/api';
 
 /**
@@ -16,10 +17,12 @@ import {Task, TaskCompletedCallback, TaskQueue} from './tasks/api';
 export type AnalyzeEntryPointsFn = () => TaskQueue;
 
 /** The type of the function that can process/compile a task. */
-export type CompileFn = (task: Task) => void;
+export type CompileFn<T> = (task: Task) => void|T;
 
 /** The type of the function that creates the `CompileFn` function used to process tasks. */
-export type CreateCompileFn = (onTaskCompleted: TaskCompletedCallback) => CompileFn;
+export type CreateCompileFn = <T extends void|Promise<void>>(
+    beforeWritingFiles: (transformedFiles: FileToWrite[]) => T,
+    onTaskCompleted: TaskCompletedCallback) => CompileFn<T>;
 
 /**
  * A class that orchestrates and executes the required work (i.e. analyzes the entry-points,

packages/compiler-cli/ngcc/src/execution/cluster/worker.ts

@@ -62,17 +62,18 @@ export async function startWorker(logger: Logger, createCompileFn: CreateCompile
   }
 
   const compile = createCompileFn(
+      () => {},
       (_task, outcome, message) => sendMessageToMaster({type: 'task-completed', outcome, message}));
 
 
   // Listen for `ProcessTaskMessage`s and process tasks.
-  cluster.worker.on('message', (msg: MessageToWorker) => {
+  cluster.worker.on('message', async (msg: MessageToWorker) => {
     try {
       switch (msg.type) {
         case 'process-task':
           logger.debug(
               `[Worker #${cluster.worker.id}] Processing task: ${stringifyTask(msg.task)}`);
-          return compile(msg.task);
+          return await compile(msg.task);
         default:
           throw new Error(
               `[Worker #${cluster.worker.id}] Invalid message received: ${JSON.stringify(msg)}`);

packages/compiler-cli/ngcc/src/execution/create_compile_function.ts

@@ -31,7 +31,7 @@ export function getCreateCompileFn(
     createNewEntryPointFormats: boolean, errorOnFailedEntryPoint: boolean,
     enableI18nLegacyMessageIdFormat: boolean, tsConfig: ParsedConfiguration|null,
     pathMappings: PathMappings|undefined): CreateCompileFn {
-  return onTaskCompleted => {
+  return (beforeWritingFiles, onTaskCompleted) => {
     const fileWriter = getFileWriter(
         fileSystem, logger, pkgJsonUpdater, createNewEntryPointFormats, errorOnFailedEntryPoint);
     const {Transformer} = require('../packages/transformer');
@@ -69,11 +69,20 @@ export function getCreateCompileFn(
           logger.warn(replaceTsWithNgInErrors(
               ts.formatDiagnosticsWithColorAndContext(result.diagnostics, bundle.src.host)));
         }
-        fileWriter.writeBundle(bundle, result.transformedFiles, formatPropertiesToMarkAsProcessed);
 
-        logger.debug(`  Successfully compiled ${entryPoint.name} : ${formatProperty}`);
+        const writeBundle = () => {
+          fileWriter.writeBundle(
+              bundle, result.transformedFiles, formatPropertiesToMarkAsProcessed);
 
-        onTaskCompleted(task, TaskProcessingOutcome.Processed, null);
+          logger.debug(`  Successfully compiled ${entryPoint.name} : ${formatProperty}`);
+          onTaskCompleted(task, TaskProcessingOutcome.Processed, null);
+        };
+
+        const beforeWritingResult = beforeWritingFiles(result.transformedFiles);
+
+        return (beforeWritingResult instanceof Promise) ?
+            beforeWritingResult.then(writeBundle) as ReturnType<typeof beforeWritingFiles>:
+            writeBundle();
       } else {
         const errors = replaceTsWithNgInErrors(
             ts.formatDiagnosticsWithColorAndContext(result.diagnostics, bundle.src.host));

packages/compiler-cli/ngcc/src/execution/single_process_executor.ts

@@ -23,7 +23,7 @@ export abstract class SingleProcessorExecutorBase {
 
     const taskQueue = analyzeEntryPoints();
     const onTaskCompleted = this.createTaskCompletedCallback(taskQueue);
-    const compile = createCompileFn(onTaskCompleted);
+    const compile = createCompileFn(() => {}, onTaskCompleted);
 
     // Process all tasks.
     this.logger.debug('Processing tasks...');

packages/compiler-cli/ngcc/test/execution/cluster/worker_spec.ts

@@ -57,12 +57,12 @@ describe('startWorker()', () => {
 
     it('should create the `compileFn()`', () => {
       startWorker(mockLogger, createCompileFnSpy);
-      expect(createCompileFnSpy).toHaveBeenCalledWith(jasmine.any(Function));
+      expect(createCompileFnSpy).toHaveBeenCalledWith(jasmine.any(Function), jasmine.any(Function));
     });
 
     it('should set up `compileFn()` to send `task-completed` messages to master', () => {
       startWorker(mockLogger, createCompileFnSpy);
-      const onTaskCompleted: TaskCompletedCallback = createCompileFnSpy.calls.argsFor(0)[0];
+      const onTaskCompleted: TaskCompletedCallback = createCompileFnSpy.calls.argsFor(0)[1];
 
       onTaskCompleted(null as any, TaskProcessingOutcome.Processed, null);
       expect(processSendSpy).toHaveBeenCalledTimes(1);

packages/compiler-cli/ngcc/test/execution/single_processor_executor_spec.ts

@@ -132,14 +132,15 @@ describe('SingleProcessExecutor', () => {
           {allTasksCompleted: true, getNextTask: jasmine.any(Function)})]);
     });
 
-    it('should pass the created TaskCompletedCallback to the createCompileFn', () => {
+    it('should pass the necessary callbacks to createCompileFn', () => {
+      const beforeWritingFiles = jasmine.any(Function);
+      const onTaskCompleted = () => {};
       const createCompileFn =
           jasmine.createSpy('createCompileFn').and.returnValue(function compileFn() {});
-      function onTaskCompleted() {}
       createTaskCompletedCallback.and.returnValue(onTaskCompleted);
       executor.execute(noTasks, createCompileFn);
       expect(createCompileFn).toHaveBeenCalledTimes(1);
-      expect(createCompileFn).toHaveBeenCalledWith(onTaskCompleted);
+      expect(createCompileFn).toHaveBeenCalledWith(beforeWritingFiles, onTaskCompleted);
     });
   });
 });