refactor(ngcc): remove unused LockFileWithSignalHandlers (#35938)

PR Close #35938

packages/compiler-cli/ngcc/src/locking/lock_file_with_signal_handlers.ts

@@ -1,83 +0,0 @@
-/**
- * @license
- * Copyright Google Inc. All Rights Reserved.
- *
- * 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 * as process from 'process';
-import {CachedFileSystem, FileSystem} from '../../../src/ngtsc/file_system';
-import {LockFile, getLockFilePath} from './lock_file';
-
-export class LockFileWithSignalHandlers implements LockFile {
-  constructor(protected fs: FileSystem) {}
-
-  path = getLockFilePath(this.fs);
-
-  write(): void {
-    try {
-      this.addSignalHandlers();
-      // To avoid race conditions, we check for existence of the lock-file by actually trying to
-      // create it exclusively.
-      return this.fs.writeFile(this.path, process.pid.toString(), /* exclusive */ true);
-    } catch (e) {
-      this.removeSignalHandlers();
-      throw e;
-    }
-  }
-
-  read(): string {
-    try {
-      if (this.fs instanceof CachedFileSystem) {
-        // This file is "volatile", it might be changed by an external process,
-        // so we cannot rely upon the cached value when reading it.
-        this.fs.invalidateCaches(this.path);
-      }
-      return this.fs.readFile(this.path);
-    } catch {
-      return '{unknown}';
-    }
-  }
-
-  remove() {
-    this.removeSignalHandlers();
-    if (this.fs.exists(this.path)) {
-      this.fs.removeFile(this.path);
-    }
-  }
-
-  /**
-   * Capture CTRL-C and terminal closing events.
-   * When these occur we remove the lock-file and exit.
-   */
-  protected addSignalHandlers() {
-    process.addListener('SIGINT', this.signalHandler);
-    process.addListener('SIGHUP', this.signalHandler);
-  }
-
-  /**
-   * Clear the event handlers to prevent leakage.
-   */
-  protected removeSignalHandlers() {
-    process.removeListener('SIGINT', this.signalHandler);
-    process.removeListener('SIGHUP', this.signalHandler);
-  }
-
-  /**
-   * This handler needs to be defined as a property rather than a method
-   * so that it can be passed around as a bound function.
-   */
-  protected signalHandler =
-      () => {
-        this.remove();
-        this.exit(1);
-      }
-
-  /**
-   * This function wraps `process.exit()` which makes it easier to manage in unit tests,
-   * since it is not possible to mock out `process.exit()` when it is called from signal handlers.
-   */
-  protected exit(code: number): void {
-    process.exit(code);
-  }
-}