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/*
* Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
* Author: Alex Yatskov <alex@foosoft.net>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
class FrontendApiSender {
constructor() {
this.senderId = FrontendApiSender.generateId(16);
this.ackTimeout = 3000; // 3 seconds
this.responseTimeout = 10000; // 10 seconds
this.callbacks = {};
this.disconnected = false;
this.nextId = 0;
this.port = null;
}
invoke(action, params, target) {
if (this.disconnected) {
return Promise.reject('Disconnected');
}
if (this.port === null) {
this.createPort();
}
const id = `${this.nextId}`;
++this.nextId;
return new Promise((resolve, reject) => {
const info = {id, resolve, reject, ack: false, timer: null};
this.callbacks[id] = info;
info.timer = setTimeout(() => this.onError(id, 'Timeout (ack)'), this.ackTimeout);
this.port.postMessage({id, action, params, target, senderId: this.senderId});
});
}
createPort() {
this.port = chrome.runtime.connect(null, {name: 'backend-api-forwarder'});
this.port.onDisconnect.addListener(this.onDisconnect.bind(this));
this.port.onMessage.addListener(this.onMessage.bind(this));
}
onMessage({type, id, data, senderId}) {
if (senderId !== this.senderId) { return; }
switch (type) {
case 'ack':
this.onAck(id);
break;
case 'result':
this.onResult(id, data);
break;
}
}
onDisconnect() {
this.disconnected = true;
const ids = Object.keys(this.callbacks);
for (const id of ids) {
this.onError(id, 'Disconnected');
}
}
onAck(id) {
if (!this.callbacks.hasOwnProperty(id)) {
console.warn(`ID ${id} not found for ack`);
return;
}
const info = this.callbacks[id];
if (info.ack) {
console.warn(`Request ${id} already ack'd`);
return;
}
info.ack = true;
clearTimeout(info.timer);
info.timer = setTimeout(() => this.onError(id, 'Timeout (response)'), this.responseTimeout);
}
onResult(id, data) {
if (!this.callbacks.hasOwnProperty(id)) {
console.warn(`ID ${id} not found`);
return;
}
const info = this.callbacks[id];
if (!info.ack) {
console.warn(`Request ${id} not ack'd`);
return;
}
delete this.callbacks[id];
clearTimeout(info.timer);
info.timer = null;
if (typeof data.error === 'string') {
info.reject(data.error);
} else {
info.resolve(data.result);
}
}
onError(id, reason) {
if (!this.callbacks.hasOwnProperty(id)) { return; }
const info = this.callbacks[id];
delete this.callbacks[id];
info.timer = null;
info.reject(reason);
}
static generateId(length) {
let id = '';
for (let i = 0; i < length; ++i) {
id += Math.floor(Math.random() * 256).toString(16).padStart(2, '0');
}
return id;
}
}
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