repl: don't use deprecated domain module

Author: avivkeller

doc/api/repl.md

@@ -157,28 +157,11 @@ changes:
                  repl is used as standalone program.
 -->
 
-The REPL uses the [`domain`][] module to catch all uncaught exceptions for that
-REPL session.
+The REPL uses the [`process.setUncaughtExceptionCaptureCallback()`][] to catch all uncaught exceptions for that
+REPL session. For more information on potential side effects, refer to it's documentation.
 
-This use of the [`domain`][] module in the REPL has these side effects:
-
-* Uncaught exceptions only emit the [`'uncaughtException'`][] event in the
-  standalone REPL. Adding a listener for this event in a REPL within
-  another Node.js program results in [`ERR_INVALID_REPL_INPUT`][].
-
-  ```js
-  const r = repl.start();
-
-  r.write('process.on("uncaughtException", () => console.log("Foobar"));\n');
-  // Output stream includes:
-  //   TypeError [ERR_INVALID_REPL_INPUT]: Listeners for `uncaughtException`
-  //   cannot be used in the REPL
-
-  r.close();
-  ```
-
-* Trying to use [`process.setUncaughtExceptionCaptureCallback()`][] throws
-  an [`ERR_DOMAIN_CANNOT_SET_UNCAUGHT_EXCEPTION_CAPTURE`][] error.
+When trying to use [`process.setUncaughtExceptionCaptureCallback()`][] while a REPL
+is active, [`ERR_INVALID_REPL_INPUT`][] will be thrown.
 
 #### Assignment of the `_` (underscore) variable
 
@@ -768,12 +751,9 @@ avoiding open network interfaces.
 
 [TTY keybindings]: readline.md#tty-keybindings
 [ZSH]: https://en.wikipedia.org/wiki/Z_shell
-[`'uncaughtException'`]: process.md#event-uncaughtexception
 [`--no-experimental-repl-await`]: cli.md#--no-experimental-repl-await
-[`ERR_DOMAIN_CANNOT_SET_UNCAUGHT_EXCEPTION_CAPTURE`]: errors.md#err_domain_cannot_set_uncaught_exception_capture
 [`ERR_INVALID_REPL_INPUT`]: errors.md#err_invalid_repl_input
 [`curl(1)`]: https://curl.haxx.se/docs/manpage.html
-[`domain`]: domain.md
 [`process.setUncaughtExceptionCaptureCallback()`]: process.md#processsetuncaughtexceptioncapturecallbackfn
 [`readline.InterfaceCompleter`]: readline.md#use-of-the-completer-function
 [`repl.ReplServer`]: #class-replserver

lib/repl.js

@@ -60,6 +60,7 @@ const {
   ArrayPrototypeUnshift,
   Boolean,
   Error: MainContextError,
+  FunctionPrototypeApply,
   FunctionPrototypeBind,
   JSONStringify,
   MathMaxApply,
@@ -76,9 +77,9 @@ const {
   ReflectApply,
   RegExp,
   RegExpPrototypeExec,
+  SafeMap,
   SafePromiseRace,
   SafeSet,
-  SafeWeakSet,
   StringPrototypeCharAt,
   StringPrototypeCodePointAt,
   StringPrototypeEndsWith,
@@ -118,6 +119,7 @@ const { inspect } = require('internal/util/inspect');
 const vm = require('vm');
 
 const { runInThisContext, runInContext } = vm.Script.prototype;
+const { setUncaughtExceptionCaptureCallback } = process;
 
 const path = require('path');
 const fs = require('fs');
@@ -138,7 +140,6 @@ ArrayPrototypeForEach(
   BuiltinModule.getSchemeOnlyModuleNames(),
   (lib) => ArrayPrototypePush(nodeSchemeBuiltinLibs, `node:${lib}`),
 );
-const domain = require('domain');
 let debug = require('internal/util/debuglog').debuglog('repl', (fn) => {
   debug = fn;
 });
@@ -191,6 +192,7 @@ const {
 const {
   makeContextifyScript,
 } = require('internal/vm');
+const { createHook } = require('async_hooks');
 let nextREPLResourceNumber = 1;
 // This prevents v8 code cache from getting confused and using a different
 // cache from a resource of the same name
@@ -205,13 +207,44 @@ const globalBuiltins =
   new SafeSet(vm.runInNewContext('Object.getOwnPropertyNames(globalThis)'));
 
 const parentModule = module;
-const domainSet = new SafeWeakSet();
 
 const kBufferedCommandSymbol = Symbol('bufferedCommand');
 const kContextId = Symbol('contextId');
 const kLoadingSymbol = Symbol('loading');
+const kListeningREPLs = new SafeSet();
+const kAsyncREPLMap = new SafeMap();
+let kActiveREPL;
+const kAsyncHook = createHook({
+  init(asyncId) {
+    if (kActiveREPL) {
+      kAsyncREPLMap.set(asyncId, kActiveREPL);
+    }
+  },
+
+  before(asyncId) {
+    kActiveREPL = kAsyncREPLMap.get(asyncId) || kActiveREPL;
+  },
 
-let addedNewListener = false;
+  destroy(asyncId) {
+    kAsyncREPLMap.delete(asyncId);
+  },
+});
+
+let kHasSetUncaughtListener = false;
+
+function handleUncaughtException(er) {
+  kActiveREPL?._onEvalError(er);
+}
+
+function removeListeningREPL(repl) {
+  kListeningREPLs.delete(repl);
+  if (kListeningREPLs.size === 0) {
+    kAsyncHook.disable();
+    kHasSetUncaughtListener = false;
+    setUncaughtExceptionCaptureCallback(null);
+    process.setUncaughtExceptionCaptureCallback = setUncaughtExceptionCaptureCallback;
+  }
+}
 
 try {
   // Hack for require.resolve("./relative") to work properly.
@@ -347,7 +380,6 @@ function REPLServer(prompt,
 
   this.allowBlockingCompletions = !!options.allowBlockingCompletions;
   this.useColors = !!options.useColors;
-  this._domain = options.domain || domain.create();
   this.useGlobal = !!useGlobal;
   this.ignoreUndefined = !!ignoreUndefined;
   this.replMode = replMode || module.exports.REPL_MODE_SLOPPY;
@@ -370,28 +402,8 @@ function REPLServer(prompt,
     // It is possible to introspect the running REPL accessing this variable
     // from inside the REPL. This is useful for anyone working on the REPL.
     module.exports.repl = this;
-  } else if (!addedNewListener) {
-    // Add this listener only once and use a WeakSet that contains the REPLs
-    // domains. Otherwise we'd have to add a single listener to each REPL
-    // instance and that could trigger the `MaxListenersExceededWarning`.
-    process.prependListener('newListener', (event, listener) => {
-      if (event === 'uncaughtException' &&
-          process.domain &&
-          listener.name !== 'domainUncaughtExceptionClear' &&
-          domainSet.has(process.domain)) {
-        // Throw an error so that the event will not be added and the current
-        // domain takes over. That way the user is notified about the error
-        // and the current code evaluation is stopped, just as any other code
-        // that contains an error.
-        throw new ERR_INVALID_REPL_INPUT(
-          'Listeners for `uncaughtException` cannot be used in the REPL');
-      }
-    });
-    addedNewListener = true;
   }
 
-  domainSet.add(this._domain);
-
   const savedRegExMatches = ['', '', '', '', '', '', '', '', '', ''];
   const sep = '\u0000\u0000\u0000';
   const regExMatcher = new RegExp(`^${sep}(.*)${sep}(.*)${sep}(.*)${sep}(.*)` +
@@ -613,13 +625,8 @@ function REPLServer(prompt,
         }
       } catch (e) {
         err = e;
-
-        if (process.domain) {
-          debug('not recoverable, send to domain');
-          process.domain.emit('error', err);
-          process.domain.exit();
-          return;
-        }
+        self._onEvalError(e);
+        return;
       }
 
       if (awaitPromise && !err) {
@@ -645,10 +652,8 @@ function REPLServer(prompt,
             const result = (await promise)?.value;
             finishExecution(null, result);
           } catch (err) {
-            if (err && process.domain) {
-              debug('not recoverable, send to domain');
-              process.domain.emit('error', err);
-              process.domain.exit();
+            if (err) {
+              self._onEvalError(err);
               return;
             }
             finishExecution(err);
@@ -666,10 +671,17 @@ function REPLServer(prompt,
     }
   }
 
-  self.eval = self._domain.bind(eval_);
+  self.eval = function(...args) {
+    try {
+      kActiveREPL = this;
+      FunctionPrototypeApply(eval_, this, args);
+    } catch (e) {
+      self._onEvalError(e);
+    }
+  };
 
-  self._domain.on('error', function debugDomainError(e) {
-    debug('domain error');
+  self._onEvalError = function _onEvalError(e) {
+    debug('eval error');
     let errStack = '';
 
     if (typeof e === 'object' && e !== null) {
@@ -697,11 +709,6 @@ function REPLServer(prompt,
       });
       decorateErrorStack(e);
 
-      if (e.domainThrown) {
-        delete e.domain;
-        delete e.domainThrown;
-      }
-
       if (isError(e)) {
         if (e.stack) {
           if (e.name === 'SyntaxError') {
@@ -779,7 +786,20 @@ function REPLServer(prompt,
       self.lines.level = [];
       self.displayPrompt();
     }
-  });
+  };
+  kListeningREPLs.add(self);
+
+  if (!kHasSetUncaughtListener) {
+    kAsyncHook.enable();
+    process.setUncaughtExceptionCaptureCallback = () => {
+      throw new ERR_INVALID_REPL_INPUT();
+    };
+    // Set to null first to prevent ERR_UNCAUGHT_EXCEPTION_CAPTURE_ALREADY_SET from
+    // being thrown on set.
+    setUncaughtExceptionCaptureCallback(null);
+    setUncaughtExceptionCaptureCallback(handleUncaughtException);
+    kHasSetUncaughtListener = true;
+  }
 
   self.clearBufferedCommand();
 
@@ -952,7 +972,7 @@ function REPLServer(prompt,
           self.displayPrompt();
           return;
         }
-        self._domain.emit('error', e.err || e);
+        self._onEvalError(e.err || e);
       }
 
       // Clear buffer if no SyntaxErrors
@@ -972,8 +992,7 @@ function REPLServer(prompt,
         self.output.write(self.writer(ret) + '\n');
       }
 
-      // Display prompt again (unless we already did by emitting the 'error'
-      // event on the domain instance).
+      // Display prompt again
       if (!e) {
         self.displayPrompt();
       }
@@ -1083,15 +1102,17 @@ REPLServer.prototype.clearBufferedCommand = function clearBufferedCommand() {
 REPLServer.prototype.close = function close() {
   if (this.terminal && this._flushing && !this._closingOnFlush) {
     this._closingOnFlush = true;
-    this.once('flushHistory', () =>
-      ReflectApply(Interface.prototype.close, this, []),
-    );
+    this.once('flushHistory', () => {
+      removeListeningREPL(this);
+      ReflectApply(Interface.prototype.close, this, []);
+    });
 
     return;
   }
-  process.nextTick(() =>
-    ReflectApply(Interface.prototype.close, this, []),
-  );
+  process.nextTick(() => {
+    removeListeningREPL(this);
+    ReflectApply(Interface.prototype.close, this, []);
+  });
 };
 
 REPLServer.prototype.createContext = function() {

test/fixtures/repl-tab-completion-nested-repls.js

@@ -32,9 +32,7 @@ const putIn = new ArrayStream();
 const testMe = repl.start('', putIn);
 
 // Some errors are passed to the domain, but do not callback.
-testMe._domain.on('error', function(err) {
-  throw err;
-});
+testMe._onEvalError = (err) => { throw err };
 
 // Nesting of structures causes REPL to use a nested REPL for completion.
 putIn.run([

test/parallel/test-repl-domain.js

@@ -35,11 +35,11 @@ const putIn = new ArrayStream();
 const testMe = repl.start('', putIn);
 
 // Some errors might be passed to the domain.
-testMe._domain.on('error', function(reason) {
+testMe._onEvalError = function(reason) {
   const err = new Error('Test failed');
   err.reason = reason;
   throw err;
-});
+};
 
 const testFile = [
   'let inner = (function() {',

test/parallel/test-repl-save-load.js

@@ -26,7 +26,7 @@ const testMe = repl.start({
 });
 
 // Some errors are passed to the domain, but do not callback
-testMe._domain.on('error', assert.ifError);
+testMe._onEvalError = assert.ifError;
 
 // Tab complete provides built in libs for import()
 testMe.complete('import(\'', common.mustCall((error, data) => {

test/parallel/test-repl-tab-complete-import.js

@@ -61,7 +61,7 @@ const testMe = repl.start({
 });
 
 // Some errors are passed to the domain, but do not callback
-testMe._domain.on('error', assert.ifError);
+testMe._onEvalError = assert.ifError;
 
 // Tab Complete will not break in an object literal
 putIn.run([

test/parallel/test-repl-tab-complete.js

@@ -11,7 +11,7 @@ const testMe = repl.start('', putIn, function(cmd, context, filename,
   callback(null, cmd);
 });
 
-testMe._domain.on('error', common.mustNotCall());
+testMe._onEvalError = common.mustNotCall();
 
 testMe.complete('', function(err, results) {
   assert.strictEqual(err, null);