132 lines
3.5 KiB
JavaScript
132 lines
3.5 KiB
JavaScript
// Copyright (c) 2016 Timothy Farrell
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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function tryJSON(type, destination, id, data) {
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const packet = [type, destination, id, data];
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try {
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return JSON.stringify(packet);
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} catch (e) {
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return packet;
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}
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}
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export function WorkerPortal(context, worker, isSlave, serialize) {
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const responseMap = new Map();
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const _worker = worker || self;
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const contextIndex = Object.keys(context);
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const _serialize = serialize
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? (type, destination, id, params) => serialize(type, destination, id, params, tryJSON)
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: tryJSON;
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let callCount = 0;
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let enabled = false;
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function post(type, id, destination, params) {
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_worker.postMessage(_serialize(type, destination, id, params));
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}
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function dispatcher(evt) {
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let data;
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try {
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data = JSON.parse(evt.data);
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} catch (e) {
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data = evt.data;
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}
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const destination = data[1];
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const id = data[2];
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const params = data[3];
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function _resolve(value) {
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post(1, id, 0, value);
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}
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function _reject(e) {
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post(1, id, 1, { message: e.message, name: e.name, stack: e.stack });
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}
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// If we have received an RPC response, satisfy the promise.
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if (data[0]) {
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if (responseMap.has(id)) {
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const responses = responseMap.get(id);
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responseMap.delete(id);
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responses[destination](params);
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}
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return;
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}
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// If we have received an RPC call, execute and respond.
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let thennable;
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try {
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thennable = context[contextIndex[destination]].apply(null, params);
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} catch (e) {
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_reject(e);
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}
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if (thennable && typeof thennable.then === 'function') {
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thennable.then(_resolve).catch(_reject);
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} else {
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_resolve(thennable);
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}
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}
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function injectionPointFactory(fnId, callbackFactory) {
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return function(...args) {
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return new Promise((resolve, reject) => {
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if (!enabled && fnId !== 0) {
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reject(new Error('Portal disabled'));
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}
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const id = callCount;
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callCount += 1;
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responseMap.set(id, [callbackFactory ? callbackFactory(resolve) : resolve, reject]);
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post(0, id, fnId, args);
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});
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};
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}
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function resolveExternalInterfaceFactory(resolve) {
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return (linkedFunctionNames, ...rest) => {
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const externalInterface = {};
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linkedFunctionNames.forEach((fnName, index) => {
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externalInterface[fnName] = injectionPointFactory(index);
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});
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enabled = true;
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resolve(externalInterface);
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return contextIndex;
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};
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}
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function cleanup() {
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enabled = false;
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_worker.removeEventListener('message', dispatcher);
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for (let key of responseMap.keys()) {
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try {
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responseMap.get(key)[1](new Error('Portal cleanup called.'));
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} catch (e) {}
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}
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}
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_worker.addEventListener('message', dispatcher);
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if (isSlave) {
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return new Promise(resolve => {
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contextIndex.splice(0, 0, '__init', '__cleanupSlave');
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context.__init = resolveExternalInterfaceFactory(resolve);
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context.__cleanupSlave = cleanup;
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});
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}
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return injectionPointFactory(0, resolveExternalInterfaceFactory)(contextIndex).then(api =>
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Object.assign(api, {
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_cleanup: injectionPointFactory(1, resolve => resolve(cleanup()))
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})
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);
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}
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