90 lines
2.7 KiB
JavaScript
90 lines
2.7 KiB
JavaScript
'use strict';
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var isPromise = require('is-promise');
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function registerPromiseWorker(callback) {
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function postOutgoingMessage(e, messageId, error, result) {
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function postMessage(msg, transferList) {
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/* istanbul ignore if */
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if (typeof self.postMessage !== 'function') { // service worker
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e.ports[0].postMessage(msg, transferList);
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} else { // web worker
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self.postMessage(msg, transferList);
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}
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}
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if (error) {
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/* istanbul ignore else */
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if (typeof console !== 'undefined' && 'error' in console) {
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// This is to make errors easier to debug. I think it's important
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// enough to just leave here without giving the user an option
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// to silence it.
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console.error('Worker caught an error:', error);
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}
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postMessage([messageId, {
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message: error.message
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}]);
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} else {
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if (result instanceof MessageWithTransferList) {
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postMessage([messageId, null, result.message], result.transferList);
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} else {
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postMessage([messageId, null, result]);
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}
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}
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}
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function tryCatchFunc(callback, message) {
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try {
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return {res: callback(message, withTransferList)};
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} catch (e) {
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return {err: e};
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}
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}
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function withTransferList(resMessage, transferList) {
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return new MessageWithTransferList(resMessage, transferList);
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}
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function handleIncomingMessage(e, callback, messageId, message) {
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var result = tryCatchFunc(callback, message);
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if (result.err) {
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postOutgoingMessage(e, messageId, result.err);
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} else if (!isPromise(result.res)) {
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postOutgoingMessage(e, messageId, null, result.res);
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} else {
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result.res.then(function (finalResult) {
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postOutgoingMessage(e, messageId, null, finalResult);
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}, function (finalError) {
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postOutgoingMessage(e, messageId, finalError);
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});
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}
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}
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function onIncomingMessage(e) {
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var payload = e.data;
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if (!Array.isArray(payload) || payload.length !== 2) {
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// message doens't match communication format; ignore
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return;
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}
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var messageId = payload[0];
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var message = payload[1];
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if (typeof callback !== 'function') {
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postOutgoingMessage(e, messageId, new Error(
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'Please pass a function into register().'));
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} else {
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handleIncomingMessage(e, callback, messageId, message);
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}
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}
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function MessageWithTransferList(message, transferList) {
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this.message = message;
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this.transferList = transferList;
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}
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self.addEventListener('message', onIncomingMessage);
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}
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module.exports = registerPromiseWorker; |