worker: improve error (de)serialization

Author: addaleax

lib/internal/error-serdes.js

@@ -0,0 +1,118 @@
+'use strict';
+
+const Buffer = require('buffer').Buffer;
+const { serialize, deserialize } = require('v8');
+const { SafeSet } = require('internal/safe_globals');
+
+const kSerializedError = 0;
+const kSerializedObject = 1;
+const kInspectedError = 2;
+
+const GetPrototypeOf = Object.getPrototypeOf;
+const GetOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
+const GetOwnPropertyNames = Object.getOwnPropertyNames;
+const DefineProperty = Object.defineProperty;
+const Assign = Object.assign;
+const ObjectPrototypeToString =
+    Function.prototype.call.bind(Object.prototype.toString);
+const ForEach = Function.prototype.call.bind(Array.prototype.forEach);
+const Call = Function.prototype.call.bind(Function.prototype.call);
+
+const errors = {
+  Error, TypeError, RangeError, URIError, SyntaxError, ReferenceError, EvalError
+};
+const errorConstructorNames = new SafeSet(Object.keys(errors));
+
+function TryGetAllProperties(object, target = object) {
+  const all = Object.create(null);
+  if (object === null)
+    return all;
+  Assign(all, TryGetAllProperties(GetPrototypeOf(object), target));
+  const keys = GetOwnPropertyNames(object);
+  ForEach(keys, (key) => {
+    const descriptor = GetOwnPropertyDescriptor(object, key);
+    const getter = descriptor.get;
+    if (getter && key !== '__proto__') {
+      try {
+        descriptor.value = Call(getter, target);
+      } catch (e) {}
+    }
+    if ('value' in descriptor && typeof descriptor.value !== 'function') {
+      delete descriptor.get;
+      delete descriptor.set;
+      all[key] = descriptor;
+    }
+  });
+  return all;
+}
+
+function GetConstructors(object) {
+  const constructors = [];
+
+  for (var current = object;
+    current !== null;
+    current = GetPrototypeOf(current)) {
+    const desc = GetOwnPropertyDescriptor(current, 'constructor');
+    if (desc && desc.value) {
+      DefineProperty(constructors, constructors.length, {
+        value: desc.value, enumerable: true
+      });
+    }
+  }
+
+  return constructors;
+}
+
+function GetName(object) {
+  const desc = GetOwnPropertyDescriptor(object, 'name');
+  return desc && desc.value;
+}
+
+let util;
+function lazyUtil() {
+  if (!util)
+    util = require('util');
+  return util;
+}
+
+function serializeError(error) {
+  try {
+    if (typeof error === 'object' &&
+        ObjectPrototypeToString(error) === '[object Error]') {
+      const constructors = GetConstructors(error);
+      for (var i = constructors.length - 1; i >= 0; i--) {
+        const name = GetName(constructors[i]);
+        if (errorConstructorNames.has(name)) {
+          try { error.stack; } catch (e) {}
+          const serialized = serialize({
+            constructor: name,
+            properties: TryGetAllProperties(error)
+          });
+          return Buffer.concat([Buffer.from([kSerializedError]), serialized]);
+        }
+      }
+    }
+  } catch (e) {}
+  try {
+    const serialized = serialize(error);
+    return Buffer.concat([Buffer.from([kSerializedObject]), serialized]);
+  } catch (e) {}
+  return Buffer.concat([Buffer.from([kInspectedError]),
+                        Buffer.from(lazyUtil().inspect(error), 'utf8')]);
+}
+
+function deserializeError(error) {
+  switch (error[0]) {
+    case kSerializedError:
+      const { constructor, properties } = deserialize(error.slice(1));
+      const ctor = errors[constructor];
+      return Object.create(ctor.prototype, properties);
+    case kSerializedObject:
+      return deserialize(error.slice(1));
+    case kInspectedError:
+      return error.toString('utf8', 1);
+  }
+  require('assert').fail('This should not happen');
+}
+
+module.exports = { serializeError, deserializeError };

lib/internal/worker.js

@@ -1,12 +1,13 @@
 'use strict';
 
-const Buffer = require('buffer').Buffer;
 const EventEmitter = require('events');
 const assert = require('assert');
 const path = require('path');
 const util = require('util');
 const errors = require('internal/errors');
 
+const { serializeError, deserializeError } = require('internal/error-serdes');
+
 const { MessagePort, MessageChannel } = process.binding('messaging');
 util.inherits(MessagePort, EventEmitter);
 
@@ -220,14 +221,6 @@ function setupChild(evalScript) {
   port.start();
 }
 
-// TODO(addaleax): These can be improved a lot.
-function serializeError(error) {
-  return Buffer.from(util.inspect(error), 'utf8');
-}
-
-function deserializeError(error) {
-  return error.toString('utf8');
-}
 
 module.exports = {
   MessagePort,

node.gyp

@@ -95,6 +95,7 @@
       'lib/internal/crypto/util.js',
       'lib/internal/encoding.js',
       'lib/internal/errors.js',
+      'lib/internal/error-serdes.js',
       'lib/internal/freelist.js',
       'lib/internal/fs.js',
       'lib/internal/http.js',

test/parallel/test-error-serdes.js

@@ -0,0 +1,46 @@
+// Flags: --expose-internals
+'use strict';
+require('../common');
+const assert = require('assert');
+const errors = require('internal/errors');
+const { serializeError, deserializeError } = require('internal/error-serdes');
+
+function cycle(err) {
+  return deserializeError(serializeError(err));
+}
+
+assert.strictEqual(cycle(0), 0);
+assert.strictEqual(cycle(-1), -1);
+assert.strictEqual(cycle(1.4), 1.4);
+assert.strictEqual(cycle(null), null);
+assert.strictEqual(cycle(undefined), undefined);
+assert.strictEqual(cycle('foo'), 'foo');
+
+{
+  const err = cycle(new Error('foo'));
+  assert(err instanceof Error);
+  assert.strictEqual(err.name, 'Error');
+  assert.strictEqual(err.message, 'foo');
+  assert(/^Error: foo\n/.test(err.stack));
+}
+
+assert.strictEqual(cycle(new RangeError('foo')).name, 'RangeError');
+assert.strictEqual(cycle(new TypeError('foo')).name, 'TypeError');
+assert.strictEqual(cycle(new ReferenceError('foo')).name, 'ReferenceError');
+assert.strictEqual(cycle(new URIError('foo')).name, 'URIError');
+assert.strictEqual(cycle(new EvalError('foo')).name, 'EvalError');
+assert.strictEqual(cycle(new SyntaxError('foo')).name, 'SyntaxError');
+
+class SubError extends Error {}
+
+assert.strictEqual(cycle(new SubError('foo')).name, 'Error');
+
+assert.deepStrictEqual(cycle({ message: 'foo' }), { message: 'foo' });
+assert.strictEqual(cycle(Function), '[Function: Function]');
+
+{
+  const err = new errors.TypeError('ERR_INVALID_ARG_TYPE', 'object', 'object');
+  assert(/^TypeError \[ERR_INVALID_ARG_TYPE\]:/.test(err));
+  assert.strictEqual(err.name, 'TypeError [ERR_INVALID_ARG_TYPE]');
+  assert.strictEqual(err.code, 'ERR_INVALID_ARG_TYPE');
+}

test/parallel/test-worker-uncaught-exception-async.js

@@ -7,8 +7,7 @@ if (isMainThread) {
   const w = new Worker(__filename);
   w.on('message', common.mustNotCall());
   w.on('error', common.mustCall((err) => {
-    // TODO(addaleax): be more specific here
-    assert(/foo/.test(err));
+    assert(/^Error: foo$/.test(err));
   }));
 } else {
   setImmediate(() => {

test/parallel/test-worker-uncaught-exception.js

@@ -7,8 +7,7 @@ if (isMainThread) {
   const w = new Worker(__filename);
   w.on('message', common.mustNotCall());
   w.on('error', common.mustCall((err) => {
-    // TODO(addaleax): be more specific here
-    assert(/foo/.test(err));
+    assert(/^Error: foo$/.test(err));
   }));
 } else {
   throw new Error('foo');