xplat/js: asyncRequire: redirect async modules to control modules

Reviewed By: davidaurelio

Differential Revision: D6750305

fbshipit-source-id: 4cf3f1b6e0adbe88a9e7afb6a1784d1528e131b2

Libraries/Utilities/asyncRequire.js

@@ -1,121 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @flow
- * @format
- * @providesModule asyncRequire
- */
-
-'use strict';
-
-const dynamicRequire: number => mixed = (require: $FlowFixMe);
-
-/**
- * The bundler must register the dependency properly when generating a call to
- * `asyncRequire`, that allows us to call `require` dynamically with confidence
- * the module ID is indeed valid and available.
- */
-function asyncRequire(moduleID: number): Promise<mixed> {
-  return Promise.resolve()
-    .then(() => {
-      const {segmentId} = (require: $FlowFixMe).unpackModuleId(moduleID);
-      return loadSegment(segmentId);
-    })
-    .then(() => dynamicRequire(moduleID));
-}
-
-let segmentLoaders = new Map();
-
-/**
- * Ensure that a bundle segment is ready for use, for example requiring some of
- * its module. We cache load promises so as to avoid calling `fetchSegment`
- * twice for the same bundle. We assume that once a segment is fetched/loaded,
- * it is never gettting removed during this instance of the JavaScript VM.
- *
- * Segment #0 is the main segment, that is always available by definition, so
- * we never try to load anything.
- *
- * We don't use async/await syntax to avoid depending on `regeneratorRuntime`.
- */
-function loadSegment(segmentId: number): Promise<void> {
-  return Promise.resolve().then(() => {
-    if (segmentId === 0) {
-      return;
-    }
-    if (typeof global.__BUNDLE_DIGEST__ !== 'string') {
-      throw IncorrectBundleSetupError();
-    }
-    const globalDigest = global.__BUNDLE_DIGEST__;
-    let segmentLoader = segmentLoaders.get(segmentId);
-    if (segmentLoader != null) {
-      return segmentLoader;
-    }
-    const {fetchSegment} = global;
-    if (fetchSegment == null) {
-      throw new FetchSegmentNotAvailableError();
-    }
-    segmentLoader = new Promise((resolve, reject) => {
-      fetchSegment(segmentId, error => {
-        if (error != null) {
-          reject(error);
-          return;
-        }
-        resolve();
-      });
-    }).then(() => {
-      const metaModuleId = (require: $FlowFixMe).packModuleId({
-        segmentId,
-        localId: 0,
-      });
-      const metaModule = dynamicRequire(metaModuleId);
-      const digest: string =
-        typeof metaModule === 'object' && metaModule != null
-          ? (metaModule.BUNDLE_DIGEST: $FlowFixMe)
-          : 'undefined';
-      if (digest !== globalDigest) {
-        throw new IncompatibleSegmentError(globalDigest, digest);
-      }
-    });
-    segmentLoaders.set(segmentId, segmentLoader);
-    return segmentLoader;
-  });
-}
-
-class FetchSegmentNotAvailableError extends Error {
-  constructor() {
-    super(
-      'When bundle splitting is enabled, the `global.fetchSegment` function ' +
-        'must be provided to be able to load particular bundle segments.',
-    );
-  }
-}
-
-class IncorrectBundleSetupError extends Error {
-  constructor() {
-    super(
-      'To be able to use split segments, the bundler must define a global ' +
-        'constant `__BUNDLE_DIGEST__` that identifies the bundle uniquely.',
-    );
-  }
-}
-asyncRequire.IncorrectBundleSetupError = IncorrectBundleSetupError;
-
-class IncompatibleSegmentError extends Error {
-  constructor(globalDigest, segmentDigest) {
-    super(
-      'The split segment that is being loaded has been built from a ' +
-        'different version of the code than the main segment. Or, the ' +
-        'bundler is setting up the module #0 of the segment incorrectly. ' +
-        `The global digest is \`${globalDigest}\` while the segment is ` +
-        `\`${segmentDigest}\`.`,
-    );
-  }
-}
-asyncRequire.IncompatibleSegmentError = IncompatibleSegmentError;
-
-module.exports = asyncRequire;