fix(ngcc): do not use cached file-system (#36687)

The cached file-system was implemented to speed up ngcc
processing, but in reality most files are not accessed many times
and there is no noticeable degradation in speed by removing it.

Benchmarking `ngcc -l debug` for AIO on a local machine
gave a range of 196-236 seconds with the cache and 197-224
seconds without the cache.

Moreover, when running in parallel mode, ngcc has a separate
file cache for each process. This results in excess memory usage.
Notably the master process, which only does analysis of entry-points
holds on to up to 500Mb for AIO when using the cache compared to
only around 30Mb when not using the cache.

Finally, the file-system cache being incorrectly primed with file
contents before being processed has been the cause of a number
of bugs. For example https://github.com/angular/angular-cli/issues/16860#issuecomment-614694269.

PR Close #36687

integration/ngcc/test.sh

@@ -173,8 +173,7 @@ assertSucceeded "Expected 'ngcc' to log 'Compiling'."
   assertEquals 1 `cat node_modules/@angular/material/button/button.d.ts | grep 'import \* as ɵngcc0' | wc -l`
 
   # Re-compile packages (which requires cleaning up those compiled by a different ngcc version).
-  # (Use sync mode to ensure all tasks share the same `CachedFileSystem` instance.)
-  ngcc --no-async --properties main
+  ngcc --properties main
   assertSucceeded "Expected 'ngcc' to successfully re-compile the packages."
 
   # Ensure previously compiled packages were correctly cleaned up (i.e. no multiple

packages/compiler-cli/ngcc/index.ts

@@ -5,7 +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 {CachedFileSystem, NodeJSFileSystem, setFileSystem} from '../src/ngtsc/file_system';
+import {NodeJSFileSystem, setFileSystem} from '../src/ngtsc/file_system';
 
 import {mainNgcc} from './src/main';
 import {AsyncNgccOptions, NgccOptions, SyncNgccOptions} from './src/ngcc_options';
@@ -17,7 +17,6 @@ export {AsyncNgccOptions, NgccOptions, PathMappings, SyncNgccOptions} from './sr
 export function process(options: AsyncNgccOptions): Promise<void>;
 export function process(options: SyncNgccOptions): void;
 export function process(options: NgccOptions): void|Promise<void> {
-  // Recreate the file system on each call to reset the cache
-  setFileSystem(new CachedFileSystem(new NodeJSFileSystem()));
+  setFileSystem(new NodeJSFileSystem());
   return mainNgcc(options);
 }

packages/compiler-cli/ngcc/main-ngcc.ts

@@ -6,7 +6,6 @@
  * 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 {setFileSystem, CachedFileSystem, NodeJSFileSystem} from '../src/ngtsc/file_system';
 import {mainNgcc} from './src/main';
 import {parseCommandLineOptions} from './src/command_line_options';
 
@@ -14,7 +13,6 @@ import {parseCommandLineOptions} from './src/command_line_options';
 if (require.main === module) {
   process.title = 'ngcc';
   const startTime = Date.now();
-  setFileSystem(new CachedFileSystem(new NodeJSFileSystem()));
   const options = parseCommandLineOptions(process.argv.slice(2));
   (async () => {
     try {

packages/compiler-cli/ngcc/src/command_line_options.ts

@@ -8,7 +8,7 @@
  */
 import * as yargs from 'yargs';
 
-import {resolve, setFileSystem, CachedFileSystem, NodeJSFileSystem} from '../../src/ngtsc/file_system';
+import {resolve, setFileSystem, NodeJSFileSystem} from '../../src/ngtsc/file_system';
 import {ConsoleLogger} from './logging/console_logger';
 import {LogLevel} from './logging/logger';
 import {NgccOptions} from './ngcc_options';
@@ -105,7 +105,7 @@ export function parseCommandLineOptions(args: string[]): NgccOptions {
     process.exit(1);
   }
 
-  setFileSystem(new CachedFileSystem(new NodeJSFileSystem()));
+  setFileSystem(new NodeJSFileSystem());
 
   const baseSourcePath = resolve(options['s'] || './node_modules');
   const propertiesToConsider: string[] = options['p'];

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

@@ -9,7 +9,6 @@
 
 import * as cluster from 'cluster';
 
-import {CachedFileSystem, NodeJSFileSystem, setFileSystem} from '../../../../src/ngtsc/file_system';
 import {parseCommandLineOptions} from '../../command_line_options';
 import {ConsoleLogger} from '../../logging/console_logger';
 import {Logger, LogLevel} from '../../logging/logger';
@@ -28,8 +27,6 @@ if (require.main === module) {
     process.title = 'ngcc (worker)';
 
     try {
-      setFileSystem(new CachedFileSystem(new NodeJSFileSystem()));
-
       const {
         createNewEntryPointFormats = false,
         logger = new ConsoleLogger(LogLevel.info),

packages/compiler-cli/ngcc/src/locking/lock_file_with_child_process/index.ts

@@ -5,10 +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 {ChildProcess, ChildProcessByStdio, fork} from 'child_process';
-import {Readable, Writable} from 'stream';
+import {ChildProcess, fork} from 'child_process';
 
-import {AbsoluteFsPath, CachedFileSystem, FileSystem} from '../../../../src/ngtsc/file_system';
+import {AbsoluteFsPath, FileSystem} from '../../../../src/ngtsc/file_system';
 import {Logger, LogLevel} from '../../logging/logger';
 import {getLockFilePath, LockFile} from '../lock_file';
 
@@ -58,11 +57,6 @@ export class LockFileWithChildProcess implements LockFile {
 
   read(): string {
     try {
-      if (this.fs instanceof CachedFileSystem) {
-        // The lock-file file is "volatile", it might be changed by an external process,
-        // so we must not rely upon the cached value when reading it.
-        this.fs.invalidateCaches(this.path);
-      }
       return this.fs.readFile(this.path);
     } catch {
       return '{unknown}';

packages/compiler-cli/ngcc/test/locking/lockfile_with_child_process/index_spec.ts

@@ -8,7 +8,7 @@
 import {ChildProcess} from 'child_process';
 import * as process from 'process';
 
-import {CachedFileSystem, FileSystem, getFileSystem} from '../../../../src/ngtsc/file_system';
+import {FileSystem, getFileSystem} from '../../../../src/ngtsc/file_system';
 import {runInEachFileSystem} from '../../../../src/ngtsc/file_system/testing';
 import {getLockFilePath} from '../../../src/locking/lock_file';
 import {LockFileWithChildProcess} from '../../../src/locking/lock_file_with_child_process';
@@ -97,18 +97,6 @@ runInEachFileSystem(() => {
         const lockFile = new LockFileUnderTest(fs);
         expect(lockFile.read()).toEqual('{unknown}');
       });
-
-      it('should not read file from the cache, since the file may have been modified externally',
-         () => {
-           const rawFs = getFileSystem();
-           const fs = new CachedFileSystem(rawFs);
-           const lockFile = new LockFileUnderTest(fs);
-           rawFs.writeFile(lockFile.path, '' + process.pid);
-           expect(lockFile.read()).toEqual('' + process.pid);
-           // We need to write to the rawFs to ensure that we don't update the cache at this point
-           rawFs.writeFile(lockFile.path, '444');
-           expect(lockFile.read()).toEqual('444');
-         });
     });
 
     describe('remove()', () => {