534 lines
16 KiB
JavaScript
534 lines
16 KiB
JavaScript
/* Copyright 2018 Mozilla Foundation
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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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*/
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/* eslint no-var: error, prefer-const: error */
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import {
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AbortException, assert, createPromiseCapability, MissingPDFException,
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ReadableStream, UnexpectedResponseException, UnknownErrorException
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} from './util';
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const CallbackKind = {
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UNKNOWN: 0,
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DATA: 1,
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ERROR: 2,
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};
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const StreamKind = {
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UNKNOWN: 0,
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CANCEL: 1,
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CANCEL_COMPLETE: 2,
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CLOSE: 3,
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ENQUEUE: 4,
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ERROR: 5,
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PULL: 6,
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PULL_COMPLETE: 7,
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START_COMPLETE: 8,
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};
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function wrapReason(reason) {
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if (typeof PDFJSDev === 'undefined' ||
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PDFJSDev.test('!PRODUCTION || TESTING')) {
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assert(reason instanceof Error ||
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(typeof reason === 'object' && reason !== null),
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'wrapReason: Expected "reason" to be a (possibly cloned) Error.');
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}
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if (typeof reason !== 'object' || reason === null) {
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return reason;
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}
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switch (reason.name) {
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case 'AbortException':
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return new AbortException(reason.message);
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case 'MissingPDFException':
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return new MissingPDFException(reason.message);
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case 'UnexpectedResponseException':
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return new UnexpectedResponseException(reason.message, reason.status);
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case 'UnknownErrorException':
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return new UnknownErrorException(reason.message, reason.details);
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default:
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return new UnknownErrorException(reason.message, reason.toString());
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}
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}
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class MessageHandler {
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constructor(sourceName, targetName, comObj) {
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this.sourceName = sourceName;
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this.targetName = targetName;
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this.comObj = comObj;
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this.callbackId = 1;
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this.streamId = 1;
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this.postMessageTransfers = true;
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this.streamSinks = Object.create(null);
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this.streamControllers = Object.create(null);
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this.callbackCapabilities = Object.create(null);
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this.actionHandler = Object.create(null);
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this._onComObjOnMessage = (event) => {
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const data = event.data;
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if (data.targetName !== this.sourceName) {
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return;
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}
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if (data.stream) {
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this._processStreamMessage(data);
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return;
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}
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if (data.callback) {
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const callbackId = data.callbackId;
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const capability = this.callbackCapabilities[callbackId];
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if (!capability) {
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throw new Error(`Cannot resolve callback ${callbackId}`);
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}
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delete this.callbackCapabilities[callbackId];
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if (data.callback === CallbackKind.DATA) {
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capability.resolve(data.data);
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} else if (data.callback === CallbackKind.ERROR) {
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capability.reject(wrapReason(data.reason));
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} else {
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throw new Error('Unexpected callback case');
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}
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return;
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}
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const action = this.actionHandler[data.action];
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if (!action) {
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throw new Error(`Unknown action from worker: ${data.action}`);
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}
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if (data.callbackId) {
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const sourceName = this.sourceName;
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const targetName = data.sourceName;
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new Promise(function(resolve) {
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resolve(action(data.data));
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}).then(function(result) {
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comObj.postMessage({
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sourceName,
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targetName,
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callback: CallbackKind.DATA,
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callbackId: data.callbackId,
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data: result,
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});
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}, function(reason) {
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comObj.postMessage({
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sourceName,
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targetName,
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callback: CallbackKind.ERROR,
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callbackId: data.callbackId,
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reason: wrapReason(reason),
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});
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});
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return;
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}
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if (data.streamId) {
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this._createStreamSink(data);
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return;
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}
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action(data.data);
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};
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comObj.addEventListener('message', this._onComObjOnMessage);
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}
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on(actionName, handler) {
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if (typeof PDFJSDev === 'undefined' ||
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PDFJSDev.test('!PRODUCTION || TESTING')) {
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assert(typeof handler === 'function',
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'MessageHandler.on: Expected "handler" to be a function.');
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}
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const ah = this.actionHandler;
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if (ah[actionName]) {
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throw new Error(`There is already an actionName called "${actionName}"`);
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}
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ah[actionName] = handler;
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}
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/**
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* Sends a message to the comObj to invoke the action with the supplied data.
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* @param {string} actionName - Action to call.
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* @param {JSON} data - JSON data to send.
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* @param {Array} [transfers] - List of transfers/ArrayBuffers.
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*/
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send(actionName, data, transfers) {
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this._postMessage({
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sourceName: this.sourceName,
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targetName: this.targetName,
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action: actionName,
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data,
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}, transfers);
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}
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/**
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* Sends a message to the comObj to invoke the action with the supplied data.
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* Expects that the other side will callback with the response.
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* @param {string} actionName - Action to call.
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* @param {JSON} data - JSON data to send.
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* @param {Array} [transfers] - List of transfers/ArrayBuffers.
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* @returns {Promise} Promise to be resolved with response data.
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*/
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sendWithPromise(actionName, data, transfers) {
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const callbackId = this.callbackId++;
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const capability = createPromiseCapability();
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this.callbackCapabilities[callbackId] = capability;
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try {
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this._postMessage({
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sourceName: this.sourceName,
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targetName: this.targetName,
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action: actionName,
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callbackId,
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data,
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}, transfers);
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} catch (ex) {
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capability.reject(ex);
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}
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return capability.promise;
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}
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/**
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* Sends a message to the comObj to invoke the action with the supplied data.
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* Expect that the other side will callback to signal 'start_complete'.
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* @param {string} actionName - Action to call.
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* @param {JSON} data - JSON data to send.
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* @param {Object} queueingStrategy - Strategy to signal backpressure based on
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* internal queue.
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* @param {Array} [transfers] - List of transfers/ArrayBuffers.
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* @returns {ReadableStream} ReadableStream to read data in chunks.
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*/
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sendWithStream(actionName, data, queueingStrategy, transfers) {
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const streamId = this.streamId++;
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const sourceName = this.sourceName;
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const targetName = this.targetName;
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const comObj = this.comObj;
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return new ReadableStream({
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start: (controller) => {
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const startCapability = createPromiseCapability();
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this.streamControllers[streamId] = {
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controller,
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startCall: startCapability,
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pullCall: null,
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cancelCall: null,
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isClosed: false,
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};
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this._postMessage({
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sourceName,
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targetName,
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action: actionName,
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streamId,
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data,
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desiredSize: controller.desiredSize,
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}, transfers);
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// Return Promise for Async process, to signal success/failure.
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return startCapability.promise;
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},
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pull: (controller) => {
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const pullCapability = createPromiseCapability();
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this.streamControllers[streamId].pullCall = pullCapability;
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.PULL,
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streamId,
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desiredSize: controller.desiredSize,
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});
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// Returning Promise will not call "pull"
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// again until current pull is resolved.
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return pullCapability.promise;
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},
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cancel: (reason) => {
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assert(reason instanceof Error, 'cancel must have a valid reason');
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const cancelCapability = createPromiseCapability();
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this.streamControllers[streamId].cancelCall = cancelCapability;
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this.streamControllers[streamId].isClosed = true;
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.CANCEL,
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streamId,
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reason: wrapReason(reason),
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});
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// Return Promise to signal success or failure.
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return cancelCapability.promise;
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},
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}, queueingStrategy);
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}
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/**
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* @private
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*/
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_createStreamSink(data) {
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const self = this;
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const action = this.actionHandler[data.action];
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const streamId = data.streamId;
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const sourceName = this.sourceName;
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const targetName = data.sourceName;
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const comObj = this.comObj;
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const streamSink = {
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enqueue(chunk, size = 1, transfers) {
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if (this.isCancelled) {
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return;
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}
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const lastDesiredSize = this.desiredSize;
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this.desiredSize -= size;
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// Enqueue decreases the desiredSize property of sink,
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// so when it changes from positive to negative,
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// set ready as unresolved promise.
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if (lastDesiredSize > 0 && this.desiredSize <= 0) {
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this.sinkCapability = createPromiseCapability();
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this.ready = this.sinkCapability.promise;
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}
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self._postMessage({
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sourceName,
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targetName,
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stream: StreamKind.ENQUEUE,
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streamId,
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chunk,
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}, transfers);
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},
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close() {
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if (this.isCancelled) {
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return;
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}
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this.isCancelled = true;
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.CLOSE,
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streamId,
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});
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delete self.streamSinks[streamId];
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},
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error(reason) {
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assert(reason instanceof Error, 'error must have a valid reason');
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if (this.isCancelled) {
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return;
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}
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this.isCancelled = true;
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.ERROR,
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streamId,
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reason: wrapReason(reason),
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});
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},
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sinkCapability: createPromiseCapability(),
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onPull: null,
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onCancel: null,
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isCancelled: false,
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desiredSize: data.desiredSize,
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ready: null,
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};
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streamSink.sinkCapability.resolve();
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streamSink.ready = streamSink.sinkCapability.promise;
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this.streamSinks[streamId] = streamSink;
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new Promise(function(resolve) {
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resolve(action(data.data, streamSink));
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}).then(function() {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.START_COMPLETE,
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streamId,
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success: true,
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});
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}, function(reason) {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.START_COMPLETE,
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streamId,
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reason: wrapReason(reason),
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});
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});
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}
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/**
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* @private
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*/
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_processStreamMessage(data) {
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const streamId = data.streamId;
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const sourceName = this.sourceName;
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const targetName = data.sourceName;
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const comObj = this.comObj;
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switch (data.stream) {
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case StreamKind.START_COMPLETE:
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if (data.success) {
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this.streamControllers[streamId].startCall.resolve();
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} else {
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this.streamControllers[streamId].startCall.reject(
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wrapReason(data.reason));
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}
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break;
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case StreamKind.PULL_COMPLETE:
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if (data.success) {
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this.streamControllers[streamId].pullCall.resolve();
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} else {
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this.streamControllers[streamId].pullCall.reject(
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wrapReason(data.reason));
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}
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break;
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case StreamKind.PULL:
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// Ignore any pull after close is called.
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if (!this.streamSinks[streamId]) {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.PULL_COMPLETE,
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streamId,
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success: true,
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});
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break;
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}
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// Pull increases the desiredSize property of sink,
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// so when it changes from negative to positive,
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// set ready property as resolved promise.
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if (this.streamSinks[streamId].desiredSize <= 0 &&
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data.desiredSize > 0) {
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this.streamSinks[streamId].sinkCapability.resolve();
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}
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// Reset desiredSize property of sink on every pull.
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this.streamSinks[streamId].desiredSize = data.desiredSize;
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const { onPull, } = this.streamSinks[data.streamId];
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new Promise(function(resolve) {
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resolve(onPull && onPull());
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}).then(function() {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.PULL_COMPLETE,
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streamId,
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success: true,
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});
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}, function(reason) {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.PULL_COMPLETE,
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streamId,
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reason: wrapReason(reason),
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});
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});
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break;
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case StreamKind.ENQUEUE:
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assert(this.streamControllers[streamId],
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'enqueue should have stream controller');
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if (this.streamControllers[streamId].isClosed) {
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break;
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}
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this.streamControllers[streamId].controller.enqueue(data.chunk);
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break;
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case StreamKind.CLOSE:
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assert(this.streamControllers[streamId],
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'close should have stream controller');
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if (this.streamControllers[streamId].isClosed) {
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break;
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}
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this.streamControllers[streamId].isClosed = true;
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this.streamControllers[streamId].controller.close();
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this._deleteStreamController(streamId);
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break;
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case StreamKind.ERROR:
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assert(this.streamControllers[streamId],
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'error should have stream controller');
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this.streamControllers[streamId].controller.error(
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wrapReason(data.reason));
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this._deleteStreamController(streamId);
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break;
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case StreamKind.CANCEL_COMPLETE:
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if (data.success) {
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this.streamControllers[streamId].cancelCall.resolve();
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} else {
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this.streamControllers[streamId].cancelCall.reject(
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wrapReason(data.reason));
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}
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this._deleteStreamController(streamId);
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break;
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case StreamKind.CANCEL:
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if (!this.streamSinks[streamId]) {
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break;
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}
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const { onCancel, } = this.streamSinks[data.streamId];
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new Promise(function(resolve) {
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resolve(onCancel && onCancel(wrapReason(data.reason)));
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}).then(function() {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.CANCEL_COMPLETE,
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streamId,
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success: true,
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});
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}, function(reason) {
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comObj.postMessage({
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sourceName,
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targetName,
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stream: StreamKind.CANCEL_COMPLETE,
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streamId,
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reason: wrapReason(reason),
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});
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});
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this.streamSinks[streamId].sinkCapability.reject(
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wrapReason(data.reason));
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this.streamSinks[streamId].isCancelled = true;
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delete this.streamSinks[streamId];
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break;
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default:
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throw new Error('Unexpected stream case');
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}
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}
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/**
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* @private
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*/
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async _deleteStreamController(streamId) {
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// Delete the `streamController` only when the start, pull, and cancel
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// capabilities have settled, to prevent `TypeError`s.
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await Promise.all([
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this.streamControllers[streamId].startCall,
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this.streamControllers[streamId].pullCall,
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this.streamControllers[streamId].cancelCall
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].map(function(capability) {
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return capability && capability.promise.catch(function() { });
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}));
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delete this.streamControllers[streamId];
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}
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|
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/**
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* Sends raw message to the comObj.
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* @param {Object} message - Raw message.
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* @param transfers List of transfers/ArrayBuffers, or undefined.
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* @private
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*/
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_postMessage(message, transfers) {
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if (transfers && this.postMessageTransfers) {
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this.comObj.postMessage(message, transfers);
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} else {
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this.comObj.postMessage(message);
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}
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}
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destroy() {
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this.comObj.removeEventListener('message', this._onComObjOnMessage);
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}
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}
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export {
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MessageHandler,
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};
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