bootstrap: simplify initialization of source map handlers

- Move the initialization of process.setSourceMapsEnabled and the maybeCacheGeneratedSourceMap callback to bootstrap/node.js so they are included in the snapshot. - Simplify the handling of --enable-source-maps by explicitly calling setSourceMapsEnabled() during pre-execution.
nodejs · joyeecheung · Jun 2, 2023 · Jun 6, 2023 · Jun 2, 2023 · d6d09ea703bfd6f43b52ae34855a4393223f95ef
commit d6d09ea703bfd6f43b52ae34855a4393223f95ef
diff --git a/lib/internal/bootstrap/node.js b/lib/internal/bootstrap/node.js
@@ -335,6 +335,22 @@ process.emitWarning = emitWarning;
   // Note: only after this point are the timers effective
 }
 
+{
+  const {
+    setSourceMapsEnabled,
+    maybeCacheGeneratedSourceMap,
+  } = require('internal/source_map/source_map_cache');
+  const {
+    setMaybeCacheGeneratedSourceMap,
+  } = internalBinding('errors');
+
+  process.setSourceMapsEnabled = setSourceMapsEnabled;
+  // The C++ land calls back to maybeCacheGeneratedSourceMap()
+  // when code is generated by user with eval() or new Function()
+  // to cache the source maps from the evaluated code, if any.
+  setMaybeCacheGeneratedSourceMap(maybeCacheGeneratedSourceMap);
+}
+
 function setupProcessObject() {
   const EventEmitter = require('events');
   const origProcProto = ObjectGetPrototypeOf(process);

diff --git a/lib/internal/bootstrap/switches/is_main_thread.js b/lib/internal/bootstrap/switches/is_main_thread.js
@@ -305,8 +305,6 @@ if (internalBinding('config').hasInspector) {
 internalBinding('wasm_web_api');
 // Needed to detect whether it's on main thread.
 internalBinding('worker');
-// Needed to setup source maps.
-require('internal/source_map/source_map_cache');
 // Needed by most execution modes.
 require('internal/modules/run_main');
 // Needed to refresh DNS configurations.

diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
@@ -618,11 +618,10 @@ function initializeESMLoader(isLoaderWorker) {
 }
 
 function initializeSourceMapsHandlers() {
-  const { setSourceMapsEnabled, getSourceMapsEnabled } =
-    require('internal/source_map/source_map_cache');
-  process.setSourceMapsEnabled = setSourceMapsEnabled;
-  // Initialize the environment flag of source maps.
-  getSourceMapsEnabled();
+  const {
+    setSourceMapsEnabled,
+  } = require('internal/source_map/source_map_cache');
+  setSourceMapsEnabled(getOptionValue('--enable-source-maps'));
 }
 
 function initializeFrozenIntrinsics() {

diff --git a/lib/internal/source_map/source_map_cache.js b/lib/internal/source_map/source_map_cache.js
@@ -18,7 +18,10 @@ let debug = require('internal/util/debuglog').debuglog('source_map', (fn) => {
 const { getOptionValue } = require('internal/options');
 
 const { validateBoolean } = require('internal/validators');
-const { setMaybeCacheGeneratedSourceMap } = internalBinding('errors');
+const {
+  setSourceMapsEnabled: setSourceMapsNative,
+  setPrepareStackTraceCallback,
+} = internalBinding('errors');
 const { getLazy } = require('internal/util');
 
 // Since the CJS module cache is mutable, which leads to memory leaks when
@@ -41,22 +44,16 @@ const { fileURLToPath, pathToFileURL, URL } = require('internal/url');
 
 let SourceMap;
 
-let sourceMapsEnabled;
+// This is configured with --enable-source-maps during pre-execution.
+let sourceMapsEnabled = false;
 function getSourceMapsEnabled() {
-  if (sourceMapsEnabled === undefined) {
-    setSourceMapsEnabled(getOptionValue('--enable-source-maps'));
-  }
   return sourceMapsEnabled;
 }
 
 function setSourceMapsEnabled(val) {
   validateBoolean(val, 'val');
 
-  const {
-    setSourceMapsEnabled,
-    setPrepareStackTraceCallback,
-  } = internalBinding('errors');
-  setSourceMapsEnabled(val);
+  setSourceMapsNative(val);
   if (val) {
     const {
       prepareStackTrace,
@@ -186,7 +183,6 @@ function maybeCacheGeneratedSourceMap(content) {
     debug(err);
   }
 }
-setMaybeCacheGeneratedSourceMap(maybeCacheGeneratedSourceMap);
 
 function dataFromUrl(sourceURL, sourceMappingURL) {
   try {
@@ -333,5 +329,6 @@ module.exports = {
   getSourceMapsEnabled,
   setSourceMapsEnabled,
   maybeCacheSourceMap,
+  maybeCacheGeneratedSourceMap,
   sourceMapCacheToObject,
 };