1d2f787d6a
This rule is *not* currently enabled in mozilla-central, but it appears commented out[1] in the ESLint definition file; see https://searchfox.org/mozilla-central/rev/c80fa7258c935223fe319c5345b58eae85d4c6ae/tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js#238-239 Unfortunately this rule is, for fairly obvious reasons, impossible to `--fix` automatically (even partially) and each case thus required careful manual analysis. Hence this ESLint rule is, by some margin, probably the most difficult one that we've enabled thus far. However, using this rule does seem like a good idea in general since allowing variable shadowing could lead to subtle (and difficult to find) bugs or at the very least confusing code. Please find additional details about the ESLint rule at https://eslint.org/docs/rules/no-shadow --- [1] Most likely, a very large number of lint errors have prevented this rule from being enabled thus far.
587 lines
17 KiB
JavaScript
587 lines
17 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,
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assert,
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createPromiseCapability,
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MissingPDFException,
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UnexpectedResponseException,
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UnknownErrorException,
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} from "./util.js";
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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 (
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typeof PDFJSDev === "undefined" ||
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PDFJSDev.test("!PRODUCTION || TESTING")
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) {
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assert(
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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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} else {
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if (typeof reason !== "object" || reason === null) {
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return reason;
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}
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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 cbSourceName = this.sourceName;
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const cbTargetName = data.sourceName;
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new Promise(function(resolve) {
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resolve(action(data.data));
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}).then(
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function(result) {
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comObj.postMessage({
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sourceName: cbSourceName,
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targetName: cbTargetName,
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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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},
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function(reason) {
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comObj.postMessage({
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sourceName: cbSourceName,
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targetName: cbTargetName,
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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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);
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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 (
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typeof PDFJSDev === "undefined" ||
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PDFJSDev.test("!PRODUCTION || TESTING")
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) {
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assert(
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typeof handler === "function",
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'MessageHandler.on: Expected "handler" to be a function.'
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);
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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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{
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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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},
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transfers
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);
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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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{
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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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},
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transfers
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);
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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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{
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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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{
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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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},
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transfers
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);
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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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},
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queueingStrategy
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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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_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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{
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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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},
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transfers
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);
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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(
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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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},
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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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/**
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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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}
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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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}
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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 (
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this.streamSinks[streamId].desiredSize <= 0 &&
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data.desiredSize > 0
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) {
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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(
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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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},
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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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);
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break;
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case StreamKind.ENQUEUE:
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assert(
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this.streamControllers[streamId],
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"enqueue should have stream controller"
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);
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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(
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this.streamControllers[streamId],
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"close should have stream controller"
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);
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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(
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this.streamControllers[streamId],
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"error should have stream controller"
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);
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this.streamControllers[streamId].controller.error(
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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_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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}
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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(
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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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},
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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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);
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this.streamSinks[streamId].sinkCapability.reject(
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wrapReason(data.reason)
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);
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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.allSettled(
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[
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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;
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})
|
|
);
|
|
delete this.streamControllers[streamId];
|
|
}
|
|
|
|
/**
|
|
* Sends raw message to the comObj.
|
|
* @param {Object} message - Raw message.
|
|
* @param transfers List of transfers/ArrayBuffers, or undefined.
|
|
* @private
|
|
*/
|
|
_postMessage(message, transfers) {
|
|
if (transfers && this.postMessageTransfers) {
|
|
this.comObj.postMessage(message, transfers);
|
|
} else {
|
|
this.comObj.postMessage(message);
|
|
}
|
|
}
|
|
|
|
destroy() {
|
|
this.comObj.removeEventListener("message", this._onComObjOnMessage);
|
|
}
|
|
}
|
|
|
|
export { MessageHandler };
|