bootstrap: merge main thread and worker thread initializations

Instead of doing the initializations of worker threads using small
helper functions that are also used by the main thread initialization,
wrap everything into a common prepareExecution() function with
an isMainThread switch to turn off initializations that shouldn't
be done for worker threads, so that we don't have to replicate
all the initialization steps in the worker code, which can be
error-prone.

PR-URL: #44869
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/main/worker_thread.js

@@ -14,24 +14,8 @@ const {
 } = primordials;
 
 const {
-  patchProcessObject,
-  setupCoverageHooks,
-  setupInspectorHooks,
-  setupWarningHandler,
-  setupFetch,
-  setupWebCrypto,
-  setupCustomEvent,
-  setupDebugEnv,
-  setupPerfHooks,
-  initializeDeprecations,
-  initializeWASI,
-  initializeCJSLoader,
-  initializeESMLoader,
-  initializeFrozenIntrinsics,
-  initializeReport,
-  initializeSourceMapsHandlers,
-  loadPreloadModules,
-  setupTraceCategoryState,
+  prepareWorkerThreadExecution,
+  setupUserModules,
   markBootstrapComplete
 } = require('internal/process/pre_execution');
 
@@ -60,28 +44,13 @@ const {
   onGlobalUncaughtException
 } = require('internal/process/execution');
 
-const publicWorker = require('worker_threads');
 let debug = require('internal/util/debuglog').debuglog('worker', (fn) => {
   debug = fn;
 });
 
 const assert = require('internal/assert');
 
-patchProcessObject();
-setupInspectorHooks();
-setupDebugEnv();
-
-setupWarningHandler();
-setupFetch();
-setupWebCrypto();
-setupCustomEvent();
-initializeSourceMapsHandlers();
-
-// Since worker threads cannot switch cwd, we do not need to
-// overwrite the process.env.NODE_V8_COVERAGE variable.
-if (process.env.NODE_V8_COVERAGE) {
-  setupCoverageHooks(process.env.NODE_V8_COVERAGE);
-}
+prepareWorkerThreadExecution();
 
 debug(`[${threadId}] is setting up worker child environment`);
 
@@ -126,23 +95,11 @@ port.on('message', (message) => {
       hasStdin
     } = message;
 
-    setupTraceCategoryState();
-    setupPerfHooks();
-    initializeReport();
-    if (manifestSrc) {
-      require('internal/process/policy').setup(manifestSrc, manifestURL);
-    }
-    initializeDeprecations();
-    initializeWASI();
-
-    require('internal/dns/utils').initializeDns();
-
-    initializeCJSLoader();
-    initializeESMLoader();
-
     if (argv !== undefined) {
       ArrayPrototypePushApply(process.argv, argv);
     }
+
+    const publicWorker = require('worker_threads');
     publicWorker.parentPort = publicPort;
     publicWorker.workerData = workerData;
 
@@ -164,10 +121,10 @@ port.on('message', (message) => {
     };
     workerIo.sharedCwdCounter = cwdCounter;
 
-    const CJSLoader = require('internal/modules/cjs/loader');
-    assert(!CJSLoader.hasLoadedAnyUserCJSModule);
-    loadPreloadModules();
-    initializeFrozenIntrinsics();
+    if (manifestSrc) {
+      require('internal/process/policy').setup(manifestSrc, manifestURL);
+    }
+    setupUserModules();
 
     if (!hasStdin)
       process.stdin.push(null);
@@ -198,6 +155,7 @@ port.on('message', (message) => {
       // runMain here might be monkey-patched by users in --require.
       // XXX: the monkey-patchability here should probably be deprecated.
       ArrayPrototypeSplice(process.argv, 1, 0, filename);
+      const CJSLoader = require('internal/modules/cjs/loader');
       CJSLoader.Module.runMain(filename);
     }
   } else if (message.type === STDIO_PAYLOAD) {

lib/internal/process/pre_execution.js

@@ -33,12 +33,26 @@ const {
   isBuildingSnapshot,
 } = require('v8').startupSnapshot;
 
-function prepareMainThreadExecution(expandArgv1 = false,
-                                    initialzeModules = true) {
-  refreshRuntimeOptions();
+function prepareMainThreadExecution(expandArgv1 = false, initialzeModules = true) {
+  prepareExecution({
+    expandArgv1,
+    initialzeModules,
+    isMainThread: true
+  });
+}
+
+function prepareWorkerThreadExecution() {
+  prepareExecution({
+    expandArgv1: false,
+    initialzeModules: false,  // Will need to initialize it after policy setup
+    isMainThread: false
+  });
+}
 
-  // TODO(joyeecheung): this is also necessary for workers when they deserialize
-  // this toggle from the snapshot.
+function prepareExecution(options) {
+  const { expandArgv1, initialzeModules, isMainThread } = options;
+
+  refreshRuntimeOptions();
   reconnectZeroFillToggle();
 
   // Patch the process object with legacy properties and normalizations
@@ -60,48 +74,57 @@ function prepareMainThreadExecution(expandArgv1 = false,
   }
 
   setupDebugEnv();
-
-  // Print stack trace on `SIGINT` if option `--trace-sigint` presents.
-  setupStacktracePrinterOnSigint();
-
   // Process initial diagnostic reporting configuration, if present.
   initializeReport();
-  initializeReportSignalHandlers();  // Main-thread-only.
-
-  initializeHeapSnapshotSignalHandlers();
-
-  // If the process is spawned with env NODE_CHANNEL_FD, it's probably
-  // spawned by our child_process module, then initialize IPC.
-  // This attaches some internal event listeners and creates:
-  // process.send(), process.channel, process.connected,
-  // process.disconnect().
-  setupChildProcessIpcChannel();
-
-  // Load policy from disk and parse it.
-  initializePolicy();
-
-  // If this is a worker in cluster mode, start up the communication
-  // channel. This needs to be done before any user code gets executed
-  // (including preload modules).
-  initializeClusterIPC();
-
   initializeSourceMapsHandlers();
   initializeDeprecations();
   initializeWASI();
-
   require('internal/dns/utils').initializeDns();
 
-  require('internal/v8/startup_snapshot').runDeserializeCallbacks();
+  if (isMainThread) {
+    assert(internalBinding('worker').isMainThread);
+    // Worker threads will get the manifest in the message handler.
+    const policy = readPolicyFromDisk();
+    if (policy) {
+      require('internal/process/policy')
+        .setup(policy.manifestSrc, policy.manifestURL);
+    }
 
-  if (!initialzeModules) {
-    return;
+    // Print stack trace on `SIGINT` if option `--trace-sigint` presents.
+    setupStacktracePrinterOnSigint();
+    initializeReportSignalHandlers();  // Main-thread-only.
+    initializeHeapSnapshotSignalHandlers();
+    // If the process is spawned with env NODE_CHANNEL_FD, it's probably
+    // spawned by our child_process module, then initialize IPC.
+    // This attaches some internal event listeners and creates:
+    // process.send(), process.channel, process.connected,
+    // process.disconnect().
+    setupChildProcessIpcChannel();
+    // If this is a worker in cluster mode, start up the communication
+    // channel. This needs to be done before any user code gets executed
+    // (including preload modules).
+    initializeClusterIPC();
+
+    // TODO(joyeecheung): do this for worker threads as well.
+    require('internal/v8/startup_snapshot').runDeserializeCallbacks();
+  } else {
+    assert(!internalBinding('worker').isMainThread);
+    // The setup should be called in LOAD_SCRIPT message handler.
+    assert(!initialzeModules);
+  }
+
+  if (initialzeModules) {
+    setupUserModules();
   }
+}
 
+function setupUserModules() {
   initializeCJSLoader();
   initializeESMLoader();
   const CJSLoader = require('internal/modules/cjs/loader');
   assert(!CJSLoader.hasLoadedAnyUserCJSModule);
   loadPreloadModules();
+  // Need to be done after --require setup.
   initializeFrozenIntrinsics();
 }
 
@@ -476,7 +499,7 @@ function initializeClusterIPC() {
   }
 }
 
-function initializePolicy() {
+function readPolicyFromDisk() {
   const experimentalPolicy = getOptionValue('--experimental-policy');
   if (experimentalPolicy) {
     process.emitWarning('Policies are experimental.',
@@ -520,8 +543,9 @@ function initializePolicy() {
         throw new ERR_MANIFEST_ASSERT_INTEGRITY(manifestURL, realIntegrities);
       }
     }
-    require('internal/process/policy')
-      .setup(src, manifestURL.href);
+    return {
+      manifestSrc: src, manifestURL: manifestURL.href
+    };
   }
 }
 
@@ -603,25 +627,8 @@ function markBootstrapComplete() {
 }
 
 module.exports = {
-  refreshRuntimeOptions,
-  patchProcessObject,
-  setupCoverageHooks,
-  setupWarningHandler,
-  setupFetch,
-  setupWebCrypto,
-  setupCustomEvent,
-  setupDebugEnv,
-  setupPerfHooks,
+  setupUserModules,
   prepareMainThreadExecution,
-  initializeDeprecations,
-  initializeESMLoader,
-  initializeFrozenIntrinsics,
-  initializeSourceMapsHandlers,
-  loadPreloadModules,
-  setupTraceCategoryState,
-  setupInspectorHooks,
-  initializeReport,
-  initializeCJSLoader,
-  initializeWASI,
+  prepareWorkerThreadExecution,
   markBootstrapComplete
 };