121 lines
3.9 KiB
JavaScript
121 lines
3.9 KiB
JavaScript
/**
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* A singleton class {@link game#time} which keeps the official Server and World time stamps.
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* Uses a basic implementation of https://www.geeksforgeeks.org/cristians-algorithm/ for synchronization.
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*/
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class GameTime {
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constructor(socket) {
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/**
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* The most recently synchronized timestamps retrieved from the server.
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* @type {{clientTime: number, serverTime: number, worldTime: number}}
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*/
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this._time = {};
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/**
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* The average one-way latency across the most recent 5 trips
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* @type {number}
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*/
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this._dt = 0;
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/**
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* The most recent five synchronization durations
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* @type {number[]}
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*/
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this._dts = [];
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// Perform an initial sync
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if ( socket ) this.sync(socket);
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}
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/**
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* The amount of time to delay before re-syncing the official server time.
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* @type {number}
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*/
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static SYNC_INTERVAL_MS = 1000 * 60 * 5;
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/* -------------------------------------------- */
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/* Properties */
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/* -------------------------------------------- */
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/**
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* The current server time based on the last synchronization point and the approximated one-way latency.
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* @type {number}
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*/
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get serverTime() {
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const t1 = Date.now();
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const dt = t1 - this._time.clientTime;
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if ( dt > GameTime.SYNC_INTERVAL_MS ) this.sync();
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return this._time.serverTime + dt;
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}
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/* -------------------------------------------- */
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/**
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* The current World time based on the last recorded value of the core.time setting
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* @type {number}
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*/
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get worldTime() {
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return this._time.worldTime;
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}
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/* -------------------------------------------- */
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/* Methods */
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/* -------------------------------------------- */
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/**
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* Advance the game time by a certain number of seconds
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* @param {number} seconds The number of seconds to advance (or rewind if negative) by
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* @param {object} [options] Additional options passed to game.settings.set
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* @returns {Promise<number>} The new game time
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*/
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async advance(seconds, options) {
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return game.settings.set("core", "time", this.worldTime + seconds, options);
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}
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/* -------------------------------------------- */
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/**
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* Synchronize the local client game time with the official time kept by the server
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* @param {Socket} socket The connected server Socket instance
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* @returns {Promise<GameTime>}
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*/
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async sync(socket) {
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socket = socket ?? game.socket;
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// Get the official time from the server
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const t0 = Date.now();
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const time = await new Promise(resolve => socket.emit("time", resolve));
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const t1 = Date.now();
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// Adjust for trip duration
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if ( this._dts.length >= 5 ) this._dts.unshift();
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this._dts.push(t1 - t0);
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// Re-compute the average one-way duration
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this._dt = Math.round(this._dts.reduce((total, t) => total + t, 0) / (this._dts.length * 2));
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// Adjust the server time and return the adjusted time
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time.clientTime = t1 - this._dt;
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this._time = time;
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console.log(`${vtt} | Synchronized official game time in ${this._dt}ms`);
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return this;
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}
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/* -------------------------------------------- */
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/* Event Handlers and Callbacks */
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/* -------------------------------------------- */
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/**
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* Handle follow-up actions when the official World time is changed
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* @param {number} worldTime The new canonical World time.
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* @param {object} options Options passed from the requesting client where the change was made
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* @param {string} userId The ID of the User who advanced the time
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*/
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onUpdateWorldTime(worldTime, options, userId) {
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const dt = worldTime - this._time.worldTime;
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this._time.worldTime = worldTime;
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Hooks.callAll("updateWorldTime", worldTime, dt, options, userId);
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if ( CONFIG.debug.time ) console.log(`The world time advanced by ${dt} seconds, and is now ${worldTime}.`);
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}
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}
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