commit

node_modules/discord.js/src/sharding/Shard.js

@@ -0,0 +1,448 @@
+'use strict';
+
+const EventEmitter = require('node:events');
+const path = require('node:path');
+const process = require('node:process');
+const { setTimeout, clearTimeout } = require('node:timers');
+const { setTimeout: sleep } = require('node:timers/promises');
+const { DiscordjsError, ErrorCodes } = require('../errors');
+const ShardEvents = require('../util/ShardEvents');
+const { makeError, makePlainError } = require('../util/Util');
+let childProcess = null;
+let Worker = null;
+
+/**
+ * A self-contained shard created by the {@link ShardingManager}. Each one has a {@link ChildProcess} that contains
+ * an instance of the bot and its {@link Client}. When its child process/worker exits for any reason, the shard will
+ * spawn a new one to replace it as necessary.
+ * @extends {EventEmitter}
+ */
+class Shard extends EventEmitter {
+  constructor(manager, id) {
+    super();
+
+    if (manager.mode === 'process') childProcess = require('node:child_process');
+    else if (manager.mode === 'worker') Worker = require('node:worker_threads').Worker;
+
+    /**
+     * Manager that created the shard
+     * @type {ShardingManager}
+     */
+    this.manager = manager;
+
+    /**
+     * The shard's id in the manager
+     * @type {number}
+     */
+    this.id = id;
+
+    /**
+     * Arguments for the shard's process (only when {@link ShardingManager#mode} is `process`)
+     * @type {string[]}
+     */
+    this.args = manager.shardArgs ?? [];
+
+    /**
+     * Arguments for the shard's process executable (only when {@link ShardingManager#mode} is `process`)
+     * @type {string[]}
+     */
+    this.execArgv = manager.execArgv;
+
+    /**
+     * Environment variables for the shard's process, or workerData for the shard's worker
+     * @type {Object}
+     */
+    this.env = Object.assign({}, process.env, {
+      SHARDING_MANAGER: true,
+      SHARDS: this.id,
+      SHARD_COUNT: this.manager.totalShards,
+      DISCORD_TOKEN: this.manager.token,
+    });
+
+    /**
+     * Whether the shard's {@link Client} is ready
+     * @type {boolean}
+     */
+    this.ready = false;
+
+    /**
+     * Process of the shard (if {@link ShardingManager#mode} is `process`)
+     * @type {?ChildProcess}
+     */
+    this.process = null;
+
+    /**
+     * Worker of the shard (if {@link ShardingManager#mode} is `worker`)
+     * @type {?Worker}
+     */
+    this.worker = null;
+
+    /**
+     * Ongoing promises for calls to {@link Shard#eval}, mapped by the `script` they were called with
+     * @type {Map<string, Promise>}
+     * @private
+     */
+    this._evals = new Map();
+
+    /**
+     * Ongoing promises for calls to {@link Shard#fetchClientValue}, mapped by the `prop` they were called with
+     * @type {Map<string, Promise>}
+     * @private
+     */
+    this._fetches = new Map();
+
+    /**
+     * Listener function for the {@link ChildProcess}' `exit` event
+     * @type {Function}
+     * @private
+     */
+    this._exitListener = null;
+  }
+
+  /**
+   * Forks a child process or creates a worker thread for the shard.
+   * <warn>You should not need to call this manually.</warn>
+   * @param {number} [timeout=30000] The amount in milliseconds to wait until the {@link Client} has become ready
+   * before resolving (`-1` or `Infinity` for no wait)
+   * @returns {Promise<ChildProcess>}
+   */
+  spawn(timeout = 30_000) {
+    if (this.process) throw new DiscordjsError(ErrorCodes.ShardingProcessExists, this.id);
+    if (this.worker) throw new DiscordjsError(ErrorCodes.ShardingWorkerExists, this.id);
+
+    this._exitListener = this._handleExit.bind(this, undefined, timeout);
+
+    if (this.manager.mode === 'process') {
+      this.process = childProcess
+        .fork(path.resolve(this.manager.file), this.args, {
+          env: this.env,
+          execArgv: this.execArgv,
+        })
+        .on('message', this._handleMessage.bind(this))
+        .on('exit', this._exitListener);
+    } else if (this.manager.mode === 'worker') {
+      this.worker = new Worker(path.resolve(this.manager.file), { workerData: this.env })
+        .on('message', this._handleMessage.bind(this))
+        .on('exit', this._exitListener);
+    }
+
+    this._evals.clear();
+    this._fetches.clear();
+
+    const child = this.process ?? this.worker;
+
+    /**
+     * Emitted upon the creation of the shard's child process/worker.
+     * @event Shard#spawn
+     * @param {ChildProcess|Worker} process Child process/worker that was created
+     */
+    this.emit(ShardEvents.Spawn, child);
+
+    if (timeout === -1 || timeout === Infinity) return Promise.resolve(child);
+    return new Promise((resolve, reject) => {
+      const cleanup = () => {
+        clearTimeout(spawnTimeoutTimer);
+        this.off('ready', onReady);
+        this.off('disconnect', onDisconnect);
+        this.off('death', onDeath);
+      };
+
+      const onReady = () => {
+        cleanup();
+        resolve(child);
+      };
+
+      const onDisconnect = () => {
+        cleanup();
+        reject(new DiscordjsError(ErrorCodes.ShardingReadyDisconnected, this.id));
+      };
+
+      const onDeath = () => {
+        cleanup();
+        reject(new DiscordjsError(ErrorCodes.ShardingReadyDied, this.id));
+      };
+
+      const onTimeout = () => {
+        cleanup();
+        reject(new DiscordjsError(ErrorCodes.ShardingReadyTimeout, this.id));
+      };
+
+      const spawnTimeoutTimer = setTimeout(onTimeout, timeout);
+      this.once('ready', onReady);
+      this.once('disconnect', onDisconnect);
+      this.once('death', onDeath);
+    });
+  }
+
+  /**
+   * Immediately kills the shard's process/worker and does not restart it.
+   */
+  kill() {
+    if (this.process) {
+      this.process.removeListener('exit', this._exitListener);
+      this.process.kill();
+    } else {
+      this.worker.removeListener('exit', this._exitListener);
+      this.worker.terminate();
+    }
+
+    this._handleExit(false);
+  }
+
+  /**
+   * Options used to respawn a shard.
+   * @typedef {Object} ShardRespawnOptions
+   * @property {number} [delay=500] How long to wait between killing the process/worker and
+   * restarting it (in milliseconds)
+   * @property {number} [timeout=30000] The amount in milliseconds to wait until the {@link Client}
+   * has become ready before resolving (`-1` or `Infinity` for no wait)
+   */
+
+  /**
+   * Kills and restarts the shard's process/worker.
+   * @param {ShardRespawnOptions} [options] Options for respawning the shard
+   * @returns {Promise<ChildProcess>}
+   */
+  async respawn({ delay = 500, timeout = 30_000 } = {}) {
+    this.kill();
+    if (delay > 0) await sleep(delay);
+    return this.spawn(timeout);
+  }
+
+  /**
+   * Sends a message to the shard's process/worker.
+   * @param {*} message Message to send to the shard
+   * @returns {Promise<Shard>}
+   */
+  send(message) {
+    return new Promise((resolve, reject) => {
+      if (this.process) {
+        this.process.send(message, err => {
+          if (err) reject(err);
+          else resolve(this);
+        });
+      } else {
+        this.worker.postMessage(message);
+        resolve(this);
+      }
+    });
+  }
+
+  /**
+   * Fetches a client property value of the shard.
+   * @param {string} prop Name of the client property to get, using periods for nesting
+   * @returns {Promise<*>}
+   * @example
+   * shard.fetchClientValue('guilds.cache.size')
+   *   .then(count => console.log(`${count} guilds in shard ${shard.id}`))
+   *   .catch(console.error);
+   */
+  fetchClientValue(prop) {
+    // Shard is dead (maybe respawning), don't cache anything and error immediately
+    if (!this.process && !this.worker) {
+      return Promise.reject(new DiscordjsError(ErrorCodes.ShardingNoChildExists, this.id));
+    }
+
+    // Cached promise from previous call
+    if (this._fetches.has(prop)) return this._fetches.get(prop);
+
+    const promise = new Promise((resolve, reject) => {
+      const child = this.process ?? this.worker;
+
+      const listener = message => {
+        if (message?._fetchProp !== prop) return;
+        child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
+        this._fetches.delete(prop);
+        if (!message._error) resolve(message._result);
+        else reject(makeError(message._error));
+      };
+
+      this.incrementMaxListeners(child);
+      child.on('message', listener);
+
+      this.send({ _fetchProp: prop }).catch(err => {
+        child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
+        this._fetches.delete(prop);
+        reject(err);
+      });
+    });
+
+    this._fetches.set(prop, promise);
+    return promise;
+  }
+
+  /**
+   * Evaluates a script or function on the shard, in the context of the {@link Client}.
+   * @param {string|Function} script JavaScript to run on the shard
+   * @param {*} [context] The context for the eval
+   * @returns {Promise<*>} Result of the script execution
+   */
+  eval(script, context) {
+    // Stringify the script if it's a Function
+    const _eval = typeof script === 'function' ? `(${script})(this, ${JSON.stringify(context)})` : script;
+
+    // Shard is dead (maybe respawning), don't cache anything and error immediately
+    if (!this.process && !this.worker) {
+      return Promise.reject(new DiscordjsError(ErrorCodes.ShardingNoChildExists, this.id));
+    }
+
+    // Cached promise from previous call
+    if (this._evals.has(_eval)) return this._evals.get(_eval);
+
+    const promise = new Promise((resolve, reject) => {
+      const child = this.process ?? this.worker;
+
+      const listener = message => {
+        if (message?._eval !== _eval) return;
+        child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
+        this._evals.delete(_eval);
+        if (!message._error) resolve(message._result);
+        else reject(makeError(message._error));
+      };
+
+      this.incrementMaxListeners(child);
+      child.on('message', listener);
+
+      this.send({ _eval }).catch(err => {
+        child.removeListener('message', listener);
+        this.decrementMaxListeners(child);
+        this._evals.delete(_eval);
+        reject(err);
+      });
+    });
+
+    this._evals.set(_eval, promise);
+    return promise;
+  }
+
+  /**
+   * Handles a message received from the child process/worker.
+   * @param {*} message Message received
+   * @private
+   */
+  _handleMessage(message) {
+    if (message) {
+      // Shard is ready
+      if (message._ready) {
+        this.ready = true;
+        /**
+         * Emitted upon the shard's {@link Client#event:shardReady} event.
+         * @event Shard#ready
+         */
+        this.emit(ShardEvents.Ready);
+        return;
+      }
+
+      // Shard has disconnected
+      if (message._disconnect) {
+        this.ready = false;
+        /**
+         * Emitted upon the shard's {@link Client#event:shardDisconnect} event.
+         * @event Shard#disconnect
+         */
+        this.emit(ShardEvents.Disconnect);
+        return;
+      }
+
+      // Shard is attempting to reconnect
+      if (message._reconnecting) {
+        this.ready = false;
+        /**
+         * Emitted upon the shard's {@link Client#event:shardReconnecting} event.
+         * @event Shard#reconnecting
+         */
+        this.emit(ShardEvents.Reconnecting);
+        return;
+      }
+
+      // Shard is requesting a property fetch
+      if (message._sFetchProp) {
+        const resp = { _sFetchProp: message._sFetchProp, _sFetchPropShard: message._sFetchPropShard };
+        this.manager.fetchClientValues(message._sFetchProp, message._sFetchPropShard).then(
+          results => this.send({ ...resp, _result: results }),
+          err => this.send({ ...resp, _error: makePlainError(err) }),
+        );
+        return;
+      }
+
+      // Shard is requesting an eval broadcast
+      if (message._sEval) {
+        const resp = { _sEval: message._sEval, _sEvalShard: message._sEvalShard };
+        this.manager._performOnShards('eval', [message._sEval], message._sEvalShard).then(
+          results => this.send({ ...resp, _result: results }),
+          err => this.send({ ...resp, _error: makePlainError(err) }),
+        );
+        return;
+      }
+
+      // Shard is requesting a respawn of all shards
+      if (message._sRespawnAll) {
+        const { shardDelay, respawnDelay, timeout } = message._sRespawnAll;
+        this.manager.respawnAll({ shardDelay, respawnDelay, timeout }).catch(() => {
+          // Do nothing
+        });
+        return;
+      }
+    }
+
+    /**
+     * Emitted upon receiving a message from the child process/worker.
+     * @event Shard#message
+     * @param {*} message Message that was received
+     */
+    this.emit(ShardEvents.Message, message);
+  }
+
+  /**
+   * Handles the shard's process/worker exiting.
+   * @param {boolean} [respawn=this.manager.respawn] Whether to spawn the shard again
+   * @param {number} [timeout] The amount in milliseconds to wait until the {@link Client}
+   * has become ready (`-1` or `Infinity` for no wait)
+   * @private
+   */
+  _handleExit(respawn = this.manager.respawn, timeout) {
+    /**
+     * Emitted upon the shard's child process/worker exiting.
+     * @event Shard#death
+     * @param {ChildProcess|Worker} process Child process/worker that exited
+     */
+    this.emit(ShardEvents.Death, this.process ?? this.worker);
+
+    this.ready = false;
+    this.process = null;
+    this.worker = null;
+    this._evals.clear();
+    this._fetches.clear();
+
+    if (respawn) this.spawn(timeout).catch(err => this.emit(ShardEvents.Error, err));
+  }
+
+  /**
+   * Increments max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  incrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners + 1);
+    }
+  }
+
+  /**
+   * Decrements max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  decrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners - 1);
+    }
+  }
+}
+
+module.exports = Shard;

node_modules/discord.js/src/sharding/ShardClientUtil.js

@@ -0,0 +1,278 @@
+'use strict';
+
+const process = require('node:process');
+const { DiscordjsError, DiscordjsTypeError, ErrorCodes } = require('../errors');
+const Events = require('../util/Events');
+const { makeError, makePlainError } = require('../util/Util');
+
+/**
+ * Helper class for sharded clients spawned as a child process/worker, such as from a {@link ShardingManager}.
+ * Utilises IPC to send and receive data to/from the master process and other shards.
+ */
+class ShardClientUtil {
+  constructor(client, mode) {
+    /**
+     * Client for the shard
+     * @type {Client}
+     */
+    this.client = client;
+
+    /**
+     * Mode the shard was spawned with
+     * @type {ShardingManagerMode}
+     */
+    this.mode = mode;
+
+    /**
+     * Message port for the master process (only when {@link ShardClientUtil#mode} is `worker`)
+     * @type {?MessagePort}
+     */
+    this.parentPort = null;
+
+    if (mode === 'process') {
+      process.on('message', this._handleMessage.bind(this));
+      client.on('ready', () => {
+        process.send({ _ready: true });
+      });
+      client.on('disconnect', () => {
+        process.send({ _disconnect: true });
+      });
+      client.on('reconnecting', () => {
+        process.send({ _reconnecting: true });
+      });
+    } else if (mode === 'worker') {
+      this.parentPort = require('node:worker_threads').parentPort;
+      this.parentPort.on('message', this._handleMessage.bind(this));
+      client.on('ready', () => {
+        this.parentPort.postMessage({ _ready: true });
+      });
+      client.on('disconnect', () => {
+        this.parentPort.postMessage({ _disconnect: true });
+      });
+      client.on('reconnecting', () => {
+        this.parentPort.postMessage({ _reconnecting: true });
+      });
+    }
+  }
+
+  /**
+   * Array of shard ids of this client
+   * @type {number[]}
+   * @readonly
+   */
+  get ids() {
+    return this.client.options.shards;
+  }
+
+  /**
+   * Total number of shards
+   * @type {number}
+   * @readonly
+   */
+  get count() {
+    return this.client.options.shardCount;
+  }
+
+  /**
+   * Sends a message to the master process.
+   * @param {*} message Message to send
+   * @returns {Promise<void>}
+   * @emits Shard#message
+   */
+  send(message) {
+    return new Promise((resolve, reject) => {
+      if (this.mode === 'process') {
+        process.send(message, err => {
+          if (err) reject(err);
+          else resolve();
+        });
+      } else if (this.mode === 'worker') {
+        this.parentPort.postMessage(message);
+        resolve();
+      }
+    });
+  }
+
+  /**
+   * Fetches a client property value of each shard, or a given shard.
+   * @param {string} prop Name of the client property to get, using periods for nesting
+   * @param {number} [shard] Shard to fetch property from, all if undefined
+   * @returns {Promise<*|Array<*>>}
+   * @example
+   * client.shard.fetchClientValues('guilds.cache.size')
+   *   .then(results => console.log(`${results.reduce((prev, val) => prev + val, 0)} total guilds`))
+   *   .catch(console.error);
+   * @see {@link ShardingManager#fetchClientValues}
+   */
+  fetchClientValues(prop, shard) {
+    return new Promise((resolve, reject) => {
+      const parent = this.parentPort ?? process;
+
+      const listener = message => {
+        if (message?._sFetchProp !== prop || message._sFetchPropShard !== shard) return;
+        parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
+        if (!message._error) resolve(message._result);
+        else reject(makeError(message._error));
+      };
+      this.incrementMaxListeners(parent);
+      parent.on('message', listener);
+
+      this.send({ _sFetchProp: prop, _sFetchPropShard: shard }).catch(err => {
+        parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
+        reject(err);
+      });
+    });
+  }
+
+  /**
+   * Evaluates a script or function on all shards, or a given shard, in the context of the {@link Client}s.
+   * @param {Function} script JavaScript to run on each shard
+   * @param {BroadcastEvalOptions} [options={}] The options for the broadcast
+   * @returns {Promise<*|Array<*>>} Results of the script execution
+   * @example
+   * client.shard.broadcastEval(client => client.guilds.cache.size)
+   *   .then(results => console.log(`${results.reduce((prev, val) => prev + val, 0)} total guilds`))
+   *   .catch(console.error);
+   * @see {@link ShardingManager#broadcastEval}
+   */
+  broadcastEval(script, options = {}) {
+    return new Promise((resolve, reject) => {
+      const parent = this.parentPort ?? process;
+      if (typeof script !== 'function') {
+        reject(new DiscordjsTypeError(ErrorCodes.ShardingInvalidEvalBroadcast));
+        return;
+      }
+      script = `(${script})(this, ${JSON.stringify(options.context)})`;
+
+      const listener = message => {
+        if (message?._sEval !== script || message._sEvalShard !== options.shard) return;
+        parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
+        if (!message._error) resolve(message._result);
+        else reject(makeError(message._error));
+      };
+      this.incrementMaxListeners(parent);
+      parent.on('message', listener);
+      this.send({ _sEval: script, _sEvalShard: options.shard }).catch(err => {
+        parent.removeListener('message', listener);
+        this.decrementMaxListeners(parent);
+        reject(err);
+      });
+    });
+  }
+
+  /**
+   * Requests a respawn of all shards.
+   * @param {MultipleShardRespawnOptions} [options] Options for respawning shards
+   * @returns {Promise<void>} Resolves upon the message being sent
+   * @see {@link ShardingManager#respawnAll}
+   */
+  respawnAll({ shardDelay = 5_000, respawnDelay = 500, timeout = 30_000 } = {}) {
+    return this.send({ _sRespawnAll: { shardDelay, respawnDelay, timeout } });
+  }
+
+  /**
+   * Handles an IPC message.
+   * @param {*} message Message received
+   * @private
+   */
+  async _handleMessage(message) {
+    if (!message) return;
+    if (message._fetchProp) {
+      try {
+        const props = message._fetchProp.split('.');
+        let value = this.client;
+        for (const prop of props) value = value[prop];
+        this._respond('fetchProp', { _fetchProp: message._fetchProp, _result: value });
+      } catch (err) {
+        this._respond('fetchProp', { _fetchProp: message._fetchProp, _error: makePlainError(err) });
+      }
+    } else if (message._eval) {
+      try {
+        this._respond('eval', { _eval: message._eval, _result: await this.client._eval(message._eval) });
+      } catch (err) {
+        this._respond('eval', { _eval: message._eval, _error: makePlainError(err) });
+      }
+    }
+  }
+
+  /**
+   * Sends a message to the master process, emitting an error from the client upon failure.
+   * @param {string} type Type of response to send
+   * @param {*} message Message to send
+   * @private
+   */
+  _respond(type, message) {
+    this.send(message).catch(err => {
+      const error = new Error(`Error when sending ${type} response to master process: ${err.message}`);
+      error.stack = err.stack;
+      /**
+       * Emitted when the client encounters an error.
+       * <warn>Errors thrown within this event do not have a catch handler, it is
+       * recommended to not use async functions as `error` event handlers. See the
+       * [Node.js docs](https://nodejs.org/api/events.html#capture-rejections-of-promises) for details.</warn>
+       * @event Client#error
+       * @param {Error} error The error encountered
+       */
+      this.client.emit(Events.Error, error);
+    });
+  }
+
+  /**
+   * Creates/gets the singleton of this class.
+   * @param {Client} client The client to use
+   * @param {ShardingManagerMode} mode Mode the shard was spawned with
+   * @returns {ShardClientUtil}
+   */
+  static singleton(client, mode) {
+    if (!this._singleton) {
+      this._singleton = new this(client, mode);
+    } else {
+      client.emit(
+        Events.Warn,
+        'Multiple clients created in child process/worker; only the first will handle sharding helpers.',
+      );
+    }
+    return this._singleton;
+  }
+
+  /**
+   * Get the shard id for a given guild id.
+   * @param {Snowflake} guildId Snowflake guild id to get shard id for
+   * @param {number} shardCount Number of shards
+   * @returns {number}
+   */
+  static shardIdForGuildId(guildId, shardCount) {
+    const shard = Number(BigInt(guildId) >> 22n) % shardCount;
+    if (shard < 0) throw new DiscordjsError(ErrorCodes.ShardingShardMiscalculation, shard, guildId, shardCount);
+    return shard;
+  }
+
+  /**
+   * Increments max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  incrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners + 1);
+    }
+  }
+
+  /**
+   * Decrements max listeners by one for a given emitter, if they are not zero.
+   * @param {EventEmitter|process} emitter The emitter that emits the events.
+   * @private
+   */
+  decrementMaxListeners(emitter) {
+    const maxListeners = emitter.getMaxListeners();
+    if (maxListeners !== 0) {
+      emitter.setMaxListeners(maxListeners - 1);
+    }
+  }
+}
+
+module.exports = ShardClientUtil;

node_modules/discord.js/src/sharding/ShardingManager.js

@@ -0,0 +1,326 @@
+'use strict';
+
+const EventEmitter = require('node:events');
+const fs = require('node:fs');
+const path = require('node:path');
+const process = require('node:process');
+const { setTimeout: sleep } = require('node:timers/promises');
+const { Collection } = require('@discordjs/collection');
+const Shard = require('./Shard');
+const { DiscordjsError, DiscordjsTypeError, DiscordjsRangeError, ErrorCodes } = require('../errors');
+const { mergeDefault, fetchRecommendedShardCount } = require('../util/Util');
+
+/**
+ * This is a utility class that makes multi-process sharding of a bot an easy and painless experience.
+ * It works by spawning a self-contained {@link ChildProcess} or {@link Worker} for each individual shard, each
+ * containing its own instance of your bot's {@link Client}. They all have a line of communication with the master
+ * process, and there are several useful methods that utilise it in order to simplify tasks that are normally difficult
+ * with sharding. It can spawn a specific number of shards or the amount that Discord suggests for the bot, and takes a
+ * path to your main bot script to launch for each one.
+ * @extends {EventEmitter}
+ */
+class ShardingManager extends EventEmitter {
+  /**
+   * The mode to spawn shards with for a {@link ShardingManager}. Can be either one of:
+   * * 'process' to use child processes
+   * * 'worker' to use [Worker threads](https://nodejs.org/api/worker_threads.html)
+   * @typedef {string} ShardingManagerMode
+   */
+
+  /**
+   * The options to spawn shards with for a {@link ShardingManager}.
+   * @typedef {Object} ShardingManagerOptions
+   * @property {string|number} [totalShards='auto'] Number of total shards of all shard managers or "auto"
+   * @property {string|number[]} [shardList='auto'] List of shards to spawn or "auto"
+   * @property {ShardingManagerMode} [mode='process'] Which mode to use for shards
+   * @property {boolean} [respawn=true] Whether shards should automatically respawn upon exiting
+   * @property {string[]} [shardArgs=[]] Arguments to pass to the shard script when spawning
+   * (only available when mode is set to 'process')
+   * @property {string[]} [execArgv=[]] Arguments to pass to the shard script executable when spawning
+   * (only available when mode is set to 'process')
+   * @property {string} [token] Token to use for automatic shard count and passing to shards
+   */
+
+  /**
+   * @param {string} file Path to your shard script file
+   * @param {ShardingManagerOptions} [options] Options for the sharding manager
+   */
+  constructor(file, options = {}) {
+    super();
+    options = mergeDefault(
+      {
+        totalShards: 'auto',
+        mode: 'process',
+        respawn: true,
+        shardArgs: [],
+        execArgv: [],
+        token: process.env.DISCORD_TOKEN,
+      },
+      options,
+    );
+
+    /**
+     * Path to the shard script file
+     * @type {string}
+     */
+    this.file = file;
+    if (!file) throw new DiscordjsError(ErrorCodes.ClientInvalidOption, 'File', 'specified.');
+    if (!path.isAbsolute(file)) this.file = path.resolve(process.cwd(), file);
+    const stats = fs.statSync(this.file);
+    if (!stats.isFile()) throw new DiscordjsError(ErrorCodes.ClientInvalidOption, 'File', 'a file');
+
+    /**
+     * List of shards this sharding manager spawns
+     * @type {string|number[]}
+     */
+    this.shardList = options.shardList ?? 'auto';
+    if (this.shardList !== 'auto') {
+      if (!Array.isArray(this.shardList)) {
+        throw new DiscordjsTypeError(ErrorCodes.ClientInvalidOption, 'shardList', 'an array.');
+      }
+      this.shardList = [...new Set(this.shardList)];
+      if (this.shardList.length < 1) {
+        throw new DiscordjsRangeError(ErrorCodes.ClientInvalidOption, 'shardList', 'at least 1 id.');
+      }
+      if (
+        this.shardList.some(
+          shardId => typeof shardId !== 'number' || isNaN(shardId) || !Number.isInteger(shardId) || shardId < 0,
+        )
+      ) {
+        throw new DiscordjsTypeError(ErrorCodes.ClientInvalidOption, 'shardList', 'an array of positive integers.');
+      }
+    }
+
+    /**
+     * Amount of shards that all sharding managers spawn in total
+     * @type {number}
+     */
+    this.totalShards = options.totalShards || 'auto';
+    if (this.totalShards !== 'auto') {
+      if (typeof this.totalShards !== 'number' || isNaN(this.totalShards)) {
+        throw new DiscordjsTypeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'a number.');
+      }
+      if (this.totalShards < 1) {
+        throw new DiscordjsRangeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'at least 1.');
+      }
+      if (!Number.isInteger(this.totalShards)) {
+        throw new DiscordjsRangeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'an integer.');
+      }
+    }
+
+    /**
+     * Mode for shards to spawn with
+     * @type {ShardingManagerMode}
+     */
+    this.mode = options.mode;
+    if (this.mode !== 'process' && this.mode !== 'worker') {
+      throw new DiscordjsRangeError(ErrorCodes.ClientInvalidOption, 'Sharding mode', '"process" or "worker"');
+    }
+
+    /**
+     * Whether shards should automatically respawn upon exiting
+     * @type {boolean}
+     */
+    this.respawn = options.respawn;
+
+    /**
+     * An array of arguments to pass to shards (only when {@link ShardingManager#mode} is `process`)
+     * @type {string[]}
+     */
+    this.shardArgs = options.shardArgs;
+
+    /**
+     * An array of arguments to pass to the executable (only when {@link ShardingManager#mode} is `process`)
+     * @type {string[]}
+     */
+    this.execArgv = options.execArgv;
+
+    /**
+     * Token to use for obtaining the automatic shard count, and passing to shards
+     * @type {?string}
+     */
+    this.token = options.token?.replace(/^Bot\s*/i, '') ?? null;
+
+    /**
+     * A collection of shards that this manager has spawned
+     * @type {Collection<number, Shard>}
+     */
+    this.shards = new Collection();
+
+    process.env.SHARDING_MANAGER = true;
+    process.env.SHARDING_MANAGER_MODE = this.mode;
+    process.env.DISCORD_TOKEN = this.token;
+  }
+
+  /**
+   * Creates a single shard.
+   * <warn>Using this method is usually not necessary if you use the spawn method.</warn>
+   * @param {number} [id=this.shards.size] Id of the shard to create
+   * <info>This is usually not necessary to manually specify.</info>
+   * @returns {Shard} Note that the created shard needs to be explicitly spawned using its spawn method.
+   */
+  createShard(id = this.shards.size) {
+    const shard = new Shard(this, id);
+    this.shards.set(id, shard);
+    /**
+     * Emitted upon creating a shard.
+     * @event ShardingManager#shardCreate
+     * @param {Shard} shard Shard that was created
+     */
+    this.emit('shardCreate', shard);
+    return shard;
+  }
+
+  /**
+   * Options used to spawn multiple shards.
+   * @typedef {Object} MultipleShardSpawnOptions
+   * @property {number|string} [amount=this.totalShards] Number of shards to spawn
+   * @property {number} [delay=5500] How long to wait in between spawning each shard (in milliseconds)
+   * @property {number} [timeout=30000] The amount in milliseconds to wait until the {@link Client} has become ready
+   */
+
+  /**
+   * Spawns multiple shards.
+   * @param {MultipleShardSpawnOptions} [options] Options for spawning shards
+   * @returns {Promise<Collection<number, Shard>>}
+   */
+  async spawn({ amount = this.totalShards, delay = 5500, timeout = 30_000 } = {}) {
+    // Obtain/verify the number of shards to spawn
+    if (amount === 'auto') {
+      amount = await fetchRecommendedShardCount(this.token);
+    } else {
+      if (typeof amount !== 'number' || isNaN(amount)) {
+        throw new DiscordjsTypeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'a number.');
+      }
+      if (amount < 1) throw new DiscordjsRangeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'at least 1.');
+      if (!Number.isInteger(amount)) {
+        throw new DiscordjsTypeError(ErrorCodes.ClientInvalidOption, 'Amount of shards', 'an integer.');
+      }
+    }
+
+    // Make sure this many shards haven't already been spawned
+    if (this.shards.size >= amount) throw new DiscordjsError(ErrorCodes.ShardingAlreadySpawned, this.shards.size);
+    if (this.shardList === 'auto' || this.totalShards === 'auto' || this.totalShards !== amount) {
+      this.shardList = [...Array(amount).keys()];
+    }
+    if (this.totalShards === 'auto' || this.totalShards !== amount) {
+      this.totalShards = amount;
+    }
+
+    if (this.shardList.some(shardId => shardId >= amount)) {
+      throw new DiscordjsRangeError(
+        ErrorCodes.ClientInvalidOption,
+        'Amount of shards',
+        'bigger than the highest shardId in the shardList option.',
+      );
+    }
+
+    // Spawn the shards
+    for (const shardId of this.shardList) {
+      const promises = [];
+      const shard = this.createShard(shardId);
+      promises.push(shard.spawn(timeout));
+      if (delay > 0 && this.shards.size !== this.shardList.length) promises.push(sleep(delay));
+      await Promise.all(promises); // eslint-disable-line no-await-in-loop
+    }
+
+    return this.shards;
+  }
+
+  /**
+   * Sends a message to all shards.
+   * @param {*} message Message to be sent to the shards
+   * @returns {Promise<Shard[]>}
+   */
+  broadcast(message) {
+    const promises = [];
+    for (const shard of this.shards.values()) promises.push(shard.send(message));
+    return Promise.all(promises);
+  }
+
+  /**
+   * Options for {@link ShardingManager#broadcastEval} and {@link ShardClientUtil#broadcastEval}.
+   * @typedef {Object} BroadcastEvalOptions
+   * @property {number} [shard] Shard to run script on, all if undefined
+   * @property {*} [context] The JSON-serializable values to call the script with
+   */
+
+  /**
+   * Evaluates a script on all shards, or a given shard, in the context of the {@link Client}s.
+   * @param {Function} script JavaScript to run on each shard
+   * @param {BroadcastEvalOptions} [options={}] The options for the broadcast
+   * @returns {Promise<*|Array<*>>} Results of the script execution
+   */
+  broadcastEval(script, options = {}) {
+    if (typeof script !== 'function') {
+      return Promise.reject(new DiscordjsTypeError(ErrorCodes.ShardingInvalidEvalBroadcast));
+    }
+    return this._performOnShards('eval', [`(${script})(this, ${JSON.stringify(options.context)})`], options.shard);
+  }
+
+  /**
+   * Fetches a client property value of each shard, or a given shard.
+   * @param {string} prop Name of the client property to get, using periods for nesting
+   * @param {number} [shard] Shard to fetch property from, all if undefined
+   * @returns {Promise<*|Array<*>>}
+   * @example
+   * manager.fetchClientValues('guilds.cache.size')
+   *   .then(results => console.log(`${results.reduce((prev, val) => prev + val, 0)} total guilds`))
+   *   .catch(console.error);
+   */
+  fetchClientValues(prop, shard) {
+    return this._performOnShards('fetchClientValue', [prop], shard);
+  }
+
+  /**
+   * Runs a method with given arguments on all shards, or a given shard.
+   * @param {string} method Method name to run on each shard
+   * @param {Array<*>} args Arguments to pass through to the method call
+   * @param {number} [shard] Shard to run on, all if undefined
+   * @returns {Promise<*|Array<*>>} Results of the method execution
+   * @private
+   */
+  _performOnShards(method, args, shard) {
+    if (this.shards.size === 0) return Promise.reject(new DiscordjsError(ErrorCodes.ShardingNoShards));
+
+    if (typeof shard === 'number') {
+      if (this.shards.has(shard)) return this.shards.get(shard)[method](...args);
+      return Promise.reject(new DiscordjsError(ErrorCodes.ShardingShardNotFound, shard));
+    }
+
+    if (this.shards.size !== this.shardList.length) {
+      return Promise.reject(new DiscordjsError(ErrorCodes.ShardingInProcess));
+    }
+
+    const promises = [];
+    for (const sh of this.shards.values()) promises.push(sh[method](...args));
+    return Promise.all(promises);
+  }
+
+  /**
+   * Options used to respawn all shards.
+   * @typedef {Object} MultipleShardRespawnOptions
+   * @property {number} [shardDelay=5000] How long to wait between shards (in milliseconds)
+   * @property {number} [respawnDelay=500] How long to wait between killing a shard's process and restarting it
+   * (in milliseconds)
+   * @property {number} [timeout=30000] The amount in milliseconds to wait for a shard to become ready before
+   * continuing to another (`-1` or `Infinity` for no wait)
+   */
+
+  /**
+   * Kills all running shards and respawns them.
+   * @param {MultipleShardRespawnOptions} [options] Options for respawning shards
+   * @returns {Promise<Collection<number, Shard>>}
+   */
+  async respawnAll({ shardDelay = 5_000, respawnDelay = 500, timeout = 30_000 } = {}) {
+    let s = 0;
+    for (const shard of this.shards.values()) {
+      const promises = [shard.respawn({ delay: respawnDelay, timeout })];
+      if (++s < this.shards.size && shardDelay > 0) promises.push(sleep(shardDelay));
+      await Promise.all(promises); // eslint-disable-line no-await-in-loop
+    }
+    return this.shards;
+  }
+}
+
+module.exports = ShardingManager;