bootstrap: use different scripts to setup different configurations

This patch splits the handling of `isMainThread` and
`ownsProcessState` from conditionals in
`lib/internal/bootstrap/node.js` into different scripts under
`lib/internal/bootstrap/switches/`, and call them accordingly
from C++ after `node.js` is run.

This:

- Creates a common denominator of the main thread and the worker
  thread bootstrap that can be snapshotted and shared by
  both.
- Makes it possible to override the configurations on-the-fly.

PR-URL: #30862
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

Author: joyeecheung

lib/internal/bootstrap/node.js

@@ -3,9 +3,7 @@
 // This file is invoked by `node::RunBootstrapping()` in `src/node.cc`, and is
 // responsible for setting up node.js core before executing main scripts
 // under `lib/internal/main/`.
-// This file is currently run to bootstrap both the main thread and the worker
-// threads. Some setups are conditional, controlled with isMainThread and
-// ownsProcessState.
+//
 // This file is expected not to perform any asynchronous operations itself
 // when being executed - those should be done in either
 // `lib/internal/bootstrap/pre_execution.js` or in main scripts. The majority
@@ -22,16 +20,21 @@
 //   module loaders, including `process.binding()`, `process._linkedBinding()`,
 //   `internalBinding()` and `NativeModule`.
 //
-// After this file is run, one of the main scripts under `lib/internal/main/`
-// will be selected by C++ to start the actual execution. The main scripts may
-// run additional setups exported by `lib/internal/bootstrap/pre_execution.js`,
-// depending on the execution mode.
+// This file is run to bootstrap both the main thread and the worker threads.
+// After this file is run, certain properties are setup according to the
+// configuration of the Node.js instance using the files in
+// `lib/internal/bootstrap/switches/`.
+//
+// Then, depending on how the Node.js instance is launched, one of the main
+// scripts in `lib/internal/main` will be selected by C++ to start the actual
+// execution. They may run additional setups exported by
+// `lib/internal/bootstrap/pre_execution.js` depending on the runtime states.
 
 'use strict';
 
 // This file is compiled as if it's wrapped in a function with arguments
 // passed by node::RunBootstrapping()
-/* global process, require, internalBinding, isMainThread, ownsProcessState */
+/* global process, require, internalBinding */
 
 setupPrepareStackTrace();
 
@@ -54,48 +57,12 @@ setupBuffer();
 process.domain = null;
 process._exiting = false;
 
-// Bootstrappers for all threads, including worker threads and main thread
-const perThreadSetup = require('internal/process/per_thread');
-// Bootstrappers for the main thread only
-let mainThreadSetup;
-// Bootstrappers for the worker threads only
-let workerThreadSetup;
-if (ownsProcessState) {
-  mainThreadSetup = require(
-    'internal/process/main_thread_only'
-  );
-} else {
-  workerThreadSetup = require(
-    'internal/process/worker_thread_only'
-  );
-}
-
 // process.config is serialized config.gypi
 process.config = JSONParse(internalBinding('native_module').config);
 
+// Bootstrappers for all threads, including worker threads and main thread
+const perThreadSetup = require('internal/process/per_thread');
 const rawMethods = internalBinding('process_methods');
-// Set up methods and events on the process object for the main thread
-if (isMainThread) {
-  process.abort = rawMethods.abort;
-  const wrapped = mainThreadSetup.wrapProcessMethods(rawMethods);
-  process.umask = wrapped.umask;
-  process.chdir = wrapped.chdir;
-  process.cwd = wrapped.cwd;
-
-  // TODO(joyeecheung): deprecate and remove these underscore methods
-  process._debugProcess = rawMethods._debugProcess;
-  process._debugEnd = rawMethods._debugEnd;
-  process._startProfilerIdleNotifier =
-    rawMethods._startProfilerIdleNotifier;
-  process._stopProfilerIdleNotifier = rawMethods._stopProfilerIdleNotifier;
-} else {
-  const wrapped = workerThreadSetup.wrapProcessMethods(rawMethods);
-
-  process.abort = workerThreadSetup.unavailable('process.abort()');
-  process.chdir = workerThreadSetup.unavailable('process.chdir()');
-  process.umask = wrapped.umask;
-  process.cwd = rawMethods.cwd;
-}
 
 // Set up methods on the process object for all threads
 {
@@ -119,6 +86,11 @@ if (isMainThread) {
   process.memoryUsage = wrapped.memoryUsage;
   process.kill = wrapped.kill;