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esm: remove proxy for builtin exports #29737

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esm: remove proxy for builtin exports #29737

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41b5cc9
esm: remove proxy for builtin exports
bfarias-godaddy Sep 27, 2019
a961763
reviews
bfarias-godaddy Sep 27, 2019
6c49aa3
docs
bfarias-godaddy Sep 27, 2019
ada2f6e
Update doc/api/modules.md
bmeck Oct 1, 2019
089de0b
fixup replaceme
guybedford Oct 5, 2019
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136 changes: 84 additions & 52 deletions lib/internal/bootstrap/loaders.js
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Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,7 @@ function NativeModule(id) {
this.id = id;
this.exports = {};
this.reflect = undefined;
this.esmFacade = undefined;
this.exportKeys = undefined;
this.loaded = false;
this.loading = false;
Expand Down Expand Up @@ -211,15 +212,19 @@ function requireWithFallbackInDeps(request) {
}

// This is exposed for public loaders
NativeModule.prototype.compileForPublicLoader = function(needToProxify) {
NativeModule.prototype.compileForPublicLoader = function(needToSyncExports) {
if (!this.canBeRequiredByUsers) {
// No code because this is an assertion against bugs
// eslint-disable-next-line no-restricted-syntax
throw new Error(`Should not compile ${this.id} for public use`);
}
this.compile();
if (needToProxify && !this.exportKeys) {
this.proxifyExports();
if (needToSyncExports) {
if (!this.exportKeys) {
this.exportKeys = Object.keys(this.exports);
}
this.getESMFacade();
this.syncExports();
}
return this.exports;
};
Expand All @@ -230,61 +235,88 @@ const getOwn = (target, property, receiver) => {
undefined;
};

NativeModule.prototype.getURL = function() {
return `node:${this.id}`;
};

NativeModule.prototype.getESMFacade = function() {
if (this.esmFacade) return this.esmFacade;
const createDynamicModule = nativeModuleRequire(
'internal/modules/esm/create_dynamic_module');
const url = this.getURL();
return this.esmFacade = createDynamicModule(
[], [...this.exportKeys, 'default'], url, (reflect) => {
this.reflect = reflect;
this.syncExports();
reflect.exports.default.set(this.exports);
});
};

// Provide named exports for all builtin libraries so that the libraries
// may be imported in a nicer way for ESM users. The default export is left
// as the entire namespace (module.exports) and wrapped in a proxy such
// that APMs and other behavior are still left intact.
NativeModule.prototype.proxifyExports = function() {
this.exportKeys = Object.keys(this.exports);

const update = (property, value) => {
if (this.reflect !== undefined &&
ObjectPrototype.hasOwnProperty(this.reflect.exports, property))
this.reflect.exports[property].set(value);
};

const handler = {
__proto__: null,
defineProperty: (target, prop, descriptor) => {
// Use `Object.defineProperty` instead of `Reflect.defineProperty`
// to throw the appropriate error if something goes wrong.
Object.defineProperty(target, prop, descriptor);
if (typeof descriptor.get === 'function' &&
!Reflect.has(handler, 'get')) {
handler.get = (target, prop, receiver) => {
const value = Reflect.get(target, prop, receiver);
if (ObjectPrototype.hasOwnProperty(target, prop))
update(prop, value);
return value;
};
}
update(prop, getOwn(target, prop));
return true;
},
deleteProperty: (target, prop) => {
if (Reflect.deleteProperty(target, prop)) {
update(prop, undefined);
return true;
}
return false;
},
set: (target, prop, value, receiver) => {
const descriptor = Reflect.getOwnPropertyDescriptor(target, prop);
if (Reflect.set(target, prop, value, receiver)) {
if (descriptor && typeof descriptor.set === 'function') {
for (const key of this.exportKeys) {
update(key, getOwn(target, key, receiver));
}
} else {
update(prop, getOwn(target, prop, receiver));
}
return true;
}
return false;
NativeModule.prototype.syncExports = function() {

// const update = (property, value) => {
// if (this.reflect !== undefined &&
// ObjectPrototype.hasOwnProperty(this.reflect.exports, property))
// this.reflect.exports[property].set(value);
// };

const names = this.exportKeys;
if (this.reflect) {
for (let i = 0; i < names.length; i++) {
const exportName = names[i];
if (exportName === 'default') continue;
this.reflect.exports[exportName].set(
getOwn(this.exports, exportName, this.exports)
);
}
};
}

this.exports = new Proxy(this.exports, handler);
// const handler = {
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I assume this code will be removed before shipping?

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yes, cleanup and docs are pending semantic reviews

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Sounds good, I'll leave this thread as a reminder.

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@jkrems should be good for another review

// __proto__: null,
// defineProperty: (target, prop, descriptor) => {
// // Use `Object.defineProperty` instead of `Reflect.defineProperty`
// // to throw the appropriate error if something goes wrong.
// Object.defineProperty(target, prop, descriptor);
// if (typeof descriptor.get === 'function' &&
// !Reflect.has(handler, 'get')) {
// handler.get = (target, prop, receiver) => {
// const value = Reflect.get(target, prop, receiver);
// if (ObjectPrototype.hasOwnProperty(target, prop))
// update(prop, value);
// return value;
// };
// }
// update(prop, getOwn(target, prop));
// return true;
// },
// deleteProperty: (target, prop) => {
// if (Reflect.deleteProperty(target, prop)) {
// update(prop, undefined);
// return true;
// }
// return false;
// },
// set: (target, prop, value, receiver) => {
// const descriptor = Reflect.getOwnPropertyDescriptor(target, prop);
// if (Reflect.set(target, prop, value, receiver)) {
// if (descriptor && typeof descriptor.set === 'function') {
// for (const key of this.exportKeys) {
// update(key, getOwn(target, key, receiver));
// }
// } else {
// update(prop, getOwn(target, prop, receiver));
// }
// return true;
// }
// return false;
// }
// };

// this.exports = new Proxy(this.exports, handler);
};

NativeModule.prototype.compile = function() {
Expand Down
8 changes: 8 additions & 0 deletions lib/internal/modules/cjs/loader.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1120,6 +1120,14 @@ Module._preloadModules = function(requests) {
parent.require(requests[n]);
};

Module.syncESMExports = function syncESMExports() {
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for (const mod of NativeModule.map.values()) {
if (mod.canBeRequiredByUsers) {
mod.syncExports();
}
}
};

// Backwards compatibility
Module.Module = Module;

Expand Down
12 changes: 4 additions & 8 deletions lib/internal/modules/esm/translators.js
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Original file line number Diff line number Diff line change
Expand Up @@ -128,14 +128,10 @@ translators.set('builtin', async function builtinStrategy(url) {
if (!module) {
throw new ERR_UNKNOWN_BUILTIN_MODULE(id);
}
return createDynamicModule(
[], [...module.exportKeys, 'default'], url, (reflect) => {
debug(`Loading BuiltinModule ${url}`);
module.reflect = reflect;
for (const key of module.exportKeys)
reflect.exports[key].set(module.exports[key]);
reflect.exports.default.set(module.exports);
});
debug(`Loading BuiltinModule ${url}`);
const facade = module.getESMFacade();
module.syncExports();
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return facade;
});

// Strategy for loading a JSON file
Expand Down
24 changes: 22 additions & 2 deletions test/es-module/test-esm-live-binding.mjs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
// Flags: --experimental-modules
import '../common/index.mjs';
import assert from 'assert';
import { syncESMExports } from 'module';

import fs, { readFile, readFileSync } from 'fs';
import events, { defaultMaxListeners } from 'events';
Expand All @@ -14,10 +15,12 @@ const s = Symbol();
const fn = () => s;

Reflect.deleteProperty(fs, 'readFile');
syncESMExports();

assert.deepStrictEqual([fs.readFile, readFile], [undefined, undefined]);

fs.readFile = fn;
syncESMExports();

assert.deepStrictEqual([fs.readFile(), readFile()], [s, s]);

Expand All @@ -26,10 +29,12 @@ Reflect.defineProperty(fs, 'readFile', {
configurable: true,
writable: true,
});
syncESMExports();

assert.deepStrictEqual([fs.readFile(), readFile()], [s, s]);

Reflect.deleteProperty(fs, 'readFile');
syncESMExports();

assert.deepStrictEqual([fs.readFile, readFile], [undefined, undefined]);

Expand All @@ -39,10 +44,14 @@ Reflect.defineProperty(fs, 'readFile', {
get() { return count; },
configurable: true,
});
syncESMExports();

assert.deepStrictEqual([readFile, fs.readFile], [0, 0]);

count++;
syncESMExports();

assert.deepStrictEqual([readFile, fs.readFile, readFile], [0, 1, 1]);
assert.deepStrictEqual([fs.readFile, readFile], [1, 1]);

let otherValue;

Expand All @@ -62,6 +71,7 @@ Reflect.defineProperty(fs, 'readFileSync', {
});

fs.readFile = 2;
syncESMExports();

assert.deepStrictEqual([readFile, readFileSync], [undefined, 2]);

Expand All @@ -86,17 +96,23 @@ Reflect.defineProperty(Function.prototype, 'defaultMaxListeners', {
});
},
});
syncESMExports();

assert.strictEqual(defaultMaxListeners, originDefaultMaxListeners);
assert.strictEqual(events.defaultMaxListeners, originDefaultMaxListeners);

assert.strictEqual(++events.defaultMaxListeners,
events.defaultMaxListeners += 1;

assert.strictEqual(events.defaultMaxListeners,
originDefaultMaxListeners + 1);

syncESMExports();

assert.strictEqual(defaultMaxListeners, originDefaultMaxListeners + 1);
assert.strictEqual(Function.prototype.defaultMaxListeners, 1);

Function.prototype.defaultMaxListeners = 'foo';
syncESMExports();

assert.strictEqual(Function.prototype.defaultMaxListeners, 'foo');
assert.strictEqual(events.defaultMaxListeners, originDefaultMaxListeners + 1);
Expand All @@ -117,16 +133,19 @@ const p = {
};

util.__proto__ = p; // eslint-disable-line no-proto
syncESMExports();

assert.strictEqual(util.foo, 1);

util.foo = 'bar';
syncESMExports();

assert.strictEqual(count, 1);
assert.strictEqual(util.foo, 'bar');
assert.strictEqual(p.foo, 2);

p.foo = 'foo';
syncESMExports();

assert.strictEqual(p.foo, 'foo');

Expand All @@ -135,6 +154,7 @@ util.__proto__ = utilProto; // eslint-disable-line no-proto

Reflect.deleteProperty(util, 'foo');
Reflect.deleteProperty(Function.prototype, 'defaultMaxListeners');
syncESMExports();

assert.throws(
() => Object.defineProperty(events, 'defaultMaxListeners', { value: 3 }),
Expand Down