118 lines
4.5 KiB
JavaScript
118 lines
4.5 KiB
JavaScript
import Connection from "./Connection";
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import {sha256} from "./utils";
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/**
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* The connection manager keeps track of active connections (WebSocket connections, see Connection).
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*
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* Its refresh() method reconciles state changes with the target state by closing/opening connections
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* as required. This is done pretty much exactly the same way as in the Android app.
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*/
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class ConnectionManager {
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constructor() {
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this.connections = new Map(); // ConnectionId -> Connection (hash, see below)
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this.stateListener = null; // Fired when connection state changes
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this.notificationListener = null; // Fired when new notifications arrive
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}
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registerStateListener(listener) {
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this.stateListener = listener;
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}
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resetStateListener() {
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this.stateListener = null;
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}
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registerNotificationListener(listener) {
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this.notificationListener = listener;
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}
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resetNotificationListener() {
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this.notificationListener = null;
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}
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/**
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* This function figures out which websocket connections should be running by comparing the
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* current state of the world (connections) with the target state (targetIds).
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*
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* It uses a "connectionId", which is sha256($subscriptionId|$username|$password) to identify
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* connections. If any of them change, the connection is closed/replaced.
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*/
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async refresh(subscriptions, users) {
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if (!subscriptions || !users) {
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return;
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}
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console.log(`[ConnectionManager] Refreshing connections`);
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const subscriptionsWithUsersAndConnectionId = await Promise.all(subscriptions
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.map(async s => {
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const [user] = users.filter(u => u.baseUrl === s.baseUrl);
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const connectionId = await makeConnectionId(s, user);
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return {...s, user, connectionId};
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}));
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const targetIds = subscriptionsWithUsersAndConnectionId.map(s => s.connectionId);
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const deletedIds = Array.from(this.connections.keys()).filter(id => !targetIds.includes(id));
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// Create and add new connections
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subscriptionsWithUsersAndConnectionId.forEach(subscription => {
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const subscriptionId = subscription.id;
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const connectionId = subscription.connectionId;
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const added = !this.connections.get(connectionId)
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if (added) {
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const baseUrl = subscription.baseUrl;
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const topic = subscription.topic;
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const user = subscription.user;
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const since = subscription.last;
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const connection = new Connection(
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connectionId,
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subscriptionId,
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baseUrl,
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topic,
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user,
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since,
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(subscriptionId, notification) => this.notificationReceived(subscriptionId, notification),
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(subscriptionId, state) => this.stateChanged(subscriptionId, state)
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);
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this.connections.set(connectionId, connection);
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console.log(`[ConnectionManager] Starting new connection ${connectionId} (subscription ${subscriptionId} with user ${user ? user.username : "anonymous"})`);
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connection.start();
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}
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});
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// Delete old connections
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deletedIds.forEach(id => {
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console.log(`[ConnectionManager] Closing connection ${id}`);
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const connection = this.connections.get(id);
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this.connections.delete(id);
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connection.close();
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});
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}
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stateChanged(subscriptionId, state) {
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if (this.stateListener) {
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try {
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this.stateListener(subscriptionId, state);
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} catch (e) {
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console.error(`[ConnectionManager] Error updating state of ${subscriptionId} to ${state}`, e);
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}
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}
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}
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notificationReceived(subscriptionId, notification) {
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if (this.notificationListener) {
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try {
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this.notificationListener(subscriptionId, notification);
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} catch (e) {
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console.error(`[ConnectionManager] Error handling notification for ${subscriptionId}`, e);
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}
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}
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}
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}
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const makeConnectionId = async (subscription, user) => {
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const hash = (user)
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? await sha256(`${subscription.id}|${user.username}|${user.password}`)
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: await sha256(`${subscription.id}`);
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return hash.substring(0, 10);
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}
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const connectionManager = new ConnectionManager();
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export default connectionManager;
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