feat(ngcc): support reverting a file written by FileWriter (#36626)

This commit adds a `revertFile()` method to `FileWriter`, which can
revert a transformed file (and its backup - if any) written by the
`FileWriter`.

In a subsequent commit, this will be used to allow ngcc to recover
when a worker process crashes in the middle of processing a task.

PR Close #36626

packages/compiler-cli/ngcc/src/writing/file_writer.ts

@@ -6,7 +6,8 @@
  * 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 {EntryPointJsonProperty} from '../packages/entry_point';
+import {AbsoluteFsPath} from '../../../src/ngtsc/file_system';
+import {EntryPoint, EntryPointJsonProperty} from '../packages/entry_point';
 import {EntryPointBundle} from '../packages/entry_point_bundle';
 import {FileToWrite} from '../rendering/utils';
 
@@ -17,4 +18,18 @@ export interface FileWriter {
   writeBundle(
       bundle: EntryPointBundle, transformedFiles: FileToWrite[],
       formatProperties: EntryPointJsonProperty[]): void;
+
+  /**
+   * Revert the changes to an entry-point processed for the specified format-properties by the same
+   * `FileWriter` implementation.
+   *
+   * @param entryPoint The entry-point to revert.
+   * @param transformedFilePaths The original paths of the transformed files. (The transformed files
+   *     may be written at the same or a different location, depending on the `FileWriter`
+   *     implementation.)
+   * @param formatProperties The format-properties pointing to the entry-point.
+   */
+  revertBundle(
+      entryPoint: EntryPoint, transformedFilePaths: AbsoluteFsPath[],
+      formatProperties: EntryPointJsonProperty[]): void;
 }

packages/compiler-cli/ngcc/src/writing/in_place_file_writer.ts

@@ -5,9 +5,9 @@
  * 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 {absoluteFrom, dirname, FileSystem} from '../../../src/ngtsc/file_system';
+import {absoluteFrom, AbsoluteFsPath, dirname, FileSystem} from '../../../src/ngtsc/file_system';
 import {Logger} from '../logging/logger';
-import {EntryPointJsonProperty} from '../packages/entry_point';
+import {EntryPoint, EntryPointJsonProperty} from '../packages/entry_point';
 import {EntryPointBundle} from '../packages/entry_point_bundle';
 import {FileToWrite} from '../rendering/utils';
 
@@ -29,6 +29,14 @@ export class InPlaceFileWriter implements FileWriter {
     transformedFiles.forEach(file => this.writeFileAndBackup(file));
   }
 
+  revertBundle(
+      _entryPoint: EntryPoint, transformedFilePaths: AbsoluteFsPath[],
+      _formatProperties: EntryPointJsonProperty[]): void {
+    for (const filePath of transformedFilePaths) {
+      this.revertFileAndBackup(filePath);
+    }
+  }
+
   protected writeFileAndBackup(file: FileToWrite): void {
     this.fs.ensureDir(dirname(file.path));
     const backPath = absoluteFrom(`${file.path}${NGCC_BACKUP_EXTENSION}`);
@@ -51,4 +59,15 @@ export class InPlaceFileWriter implements FileWriter {
       this.fs.writeFile(file.path, file.contents);
     }
   }
+
+  protected revertFileAndBackup(filePath: AbsoluteFsPath): void {
+    if (this.fs.exists(filePath)) {
+      this.fs.removeFile(filePath);
+
+      const backPath = absoluteFrom(`${filePath}${NGCC_BACKUP_EXTENSION}`);
+      if (this.fs.exists(backPath)) {
+        this.fs.moveFile(backPath, filePath);
+      }
+    }
+  }
 }

packages/compiler-cli/ngcc/src/writing/new_entry_point_file_writer.ts

@@ -45,6 +45,27 @@ export class NewEntryPointFileWriter extends InPlaceFileWriter {
     this.updatePackageJson(entryPoint, formatProperties, ngccFolder);
   }
 
+  revertBundle(
+      entryPoint: EntryPoint, transformedFilePaths: AbsoluteFsPath[],
+      formatProperties: EntryPointJsonProperty[]): void {
+    // IMPLEMENTATION NOTE:
+    //
+    // The changes made by `copyBundle()` are not reverted here. The non-transformed copied files
+    // are identical to the original ones and they will be overwritten when re-processing the
+    // entry-point anyway.
+    //
+    // This way, we avoid the overhead of having to inform the master process about all source files
+    // being copied in `copyBundle()`.
+
+    // Revert the transformed files.
+    for (const filePath of transformedFilePaths) {
+      this.revertFile(filePath, entryPoint.package);
+    }
+
+    // Revert any changes to `package.json`.
+    this.revertPackageJson(entryPoint, formatProperties);
+  }
+
   protected copyBundle(
       bundle: EntryPointBundle, packagePath: AbsoluteFsPath, ngccFolder: AbsoluteFsPath) {
     bundle.src.program.getSourceFiles().forEach(sourceFile => {
@@ -71,6 +92,17 @@ export class NewEntryPointFileWriter extends InPlaceFileWriter {
     }
   }
 
+  protected revertFile(filePath: AbsoluteFsPath, packagePath: AbsoluteFsPath): void {
+    if (isDtsPath(filePath.replace(/\.map$/, ''))) {
+      // This is either `.d.ts` or `.d.ts.map` file
+      super.revertFileAndBackup(filePath);
+    } else if (this.fs.exists(filePath)) {
+      const relativePath = relative(packagePath, filePath);
+      const newFilePath = join(packagePath, NGCC_DIRECTORY, relativePath);
+      this.fs.removeFile(newFilePath);
+    }
+  }
+
   protected updatePackageJson(
       entryPoint: EntryPoint, formatProperties: EntryPointJsonProperty[],
       ngccFolder: AbsoluteFsPath) {
@@ -105,4 +137,25 @@ export class NewEntryPointFileWriter extends InPlaceFileWriter {
 
     update.writeChanges(packageJsonPath, packageJson);
   }
+
+  protected revertPackageJson(entryPoint: EntryPoint, formatProperties: EntryPointJsonProperty[]) {
+    if (formatProperties.length === 0) {
+      // No format properties need reverting.
+      return;
+    }
+
+    const packageJson = entryPoint.packageJson;
+    const packageJsonPath = join(entryPoint.path, 'package.json');
+
+    // Revert all properties in `package.json` (both in memory and on disk).
+    // Since `updatePackageJson()` only adds properties, it is safe to just remove them (if they
+    // exist).
+    const update = this.pkgJsonUpdater.createUpdate();
+
+    for (const formatProperty of formatProperties) {
+      update.addChange([`${formatProperty}${NGCC_PROPERTY_EXTENSION}`], undefined);
+    }
+
+    update.writeChanges(packageJsonPath, packageJson);
+  }
 }