When a player disconnects, fail all unresolved requests that were sent to that player

src/libwrapper_shim.js

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+// Copyright © 2021 fvtt-lib-wrapper Rui Pinheiro
+
+'use strict';
+
+// A shim for the libWrapper library
+export let libWrapper = undefined;
+
+Hooks.once('init', () => {
+	// Check if the real module is already loaded - if so, use it
+	if(globalThis.libWrapper && !(globalThis.libWrapper.is_fallback ?? true)) {
+		libWrapper = globalThis.libWrapper;
+		return;
+	}
+
+	// Fallback implementation
+	libWrapper = class {
+		static get is_fallback() { return true };
+
+		static register(module, target, fn, type="MIXED", {chain=undefined}={}) {
+			const is_setter = target.endsWith('#set');
+			target = !is_setter ? target : target.slice(0, -4);
+			const split = target.split('.');
+			const fn_name = split.pop();
+			const root_nm = split.splice(0,1)[0];
+			const _eval = eval; // The browser doesn't expose all global variables (e.g. 'Game') inside globalThis, but it does to an eval. We copy it to a variable to have it run in global scope.
+			const obj = split.reduce((x,y)=>x[y], globalThis[root_nm] ?? _eval(root_nm));
+
+			let iObj = obj;
+			let descriptor = null;
+			while(iObj) {
+				descriptor = Object.getOwnPropertyDescriptor(iObj, fn_name);
+				if(descriptor) break;
+				iObj = Object.getPrototypeOf(iObj);
+			}
+			if(!descriptor || descriptor?.configurable === false) throw `libWrapper Shim: '${target}' does not exist, could not be found, or has a non-configurable descriptor.`;
+
+			let original = null;
+			const wrapper = (chain ?? type != 'OVERRIDE') ? function() { return fn.call(this, original.bind(this), ...arguments); } : function() { return fn.apply(this, arguments); };
+
+			if(!is_setter) {
+				if(descriptor.value) {
+					original = descriptor.value;
+					descriptor.value = wrapper;
+				}
+				else {
+					original = descriptor.get;
+					descriptor.get = wrapper;
+				}
+			}
+			else {
+				if(!descriptor.set) throw `libWrapper Shim: '${target}' does not have a setter`;
+				original = descriptor.set;
+				descriptor.set = wrapper;
+			}
+
+			descriptor.configurable = true;
+			Object.defineProperty(obj, fn_name, descriptor);
+		}
+	}
+});

src/socketlib.js

@@ -1,3 +1,4 @@
+import {libWrapper} from "./libwrapper_shim.js";
 import * as errors from "./errors.js";
 
 const RECIPIENT_TYPES = {
@@ -17,8 +18,9 @@ const MESSAGE_TYPES = {
 
 Hooks.once("init", () => {
 	window.socketlib = new Socketlib();
+	libWrapper.register("socketlib", "Users.prototype.constructor._handleUserActivity", handleUserActivity);
 	Hooks.callAll("socketlib.ready");
-});
+}, "WRAPPER");
 
 class Socketlib {
 	constructor() {
@@ -88,7 +90,7 @@ class SocketlibSocket {
 			return this._executeLocal(func, ...args);
 		}
 		else {
-			if (!game.users.find(user => user.isGM && user.active)) {
+			if (!game.users.find(isActiveGM)) {
 				throw new errors.SocketlibNoGMConnectedError(`Could not execute handler '${name}' (${func.name}) as GM, because no GM is connected.`);
 			}
 			return this._sendRequest(name, args, RECIPIENT_TYPES.ONE_GM);
@@ -304,6 +306,48 @@ class SocketlibSocket {
 function isResponsibleGM() {
 	if (!game.user.isGM)
 		return false;
-	const connectedGMs = game.users.filter(user => user.isGM && user.active);
+	const connectedGMs = game.users.filter(isActiveGM);
 	return !connectedGMs.some(other => other.data._id < game.user.data._id);
 }
+
+function isActiveGM(user) {
+	return user.active && user.isGM;
+}
+
+function handleUserActivity(wrapper, userId, activityData={}) {
+	const user = game.users.get(userId);
+	const wasActive = user.active;
+	const result = wrapper(userId, activityData);
+
+	// If user disconnected
+	if (!user.active && wasActive) {
+		const modules = Array.from(socketlib.modules.values());
+		if (socketlib.system)
+			modules.concat(socketlib.system);
+		const GMConnected = Boolean(game.users.find(isActiveGM));
+		// Reject all promises that are still waiting for a response from this player
+		for (const socket of modules) {
+			const failedRequests = Array.from(socket.pendingRequests.entries()).filter(([id, request]) => {
+				const recipient = request.recipient;
+				const handlerName = request.handlerName;
+				if (recipient === RECIPIENT_TYPES.ONE_GM) {
+					if (!GMConnected) {
+						request.reject(new errors.SocketlibNoGMConnectedError(`Could not execute handler '${handlerName}' as GM, because all GMs disconnected while the execution was being dispatched.`));
+						return true;
+					}
+				}
+				else if (recipient instanceof Array) {
+					if (recipient.includes(userId)) {
+						request.reject(new errors.SocketlibInvalidUserError(`User '${game.users.get(userId).name}' (${userId}) disconnected while handler '${handlerName}' was being dispatched.`));
+						return true;
+					}
+				}
+				return false;
+			});
+			for (const [id, request] of failedRequests) {
+				socket.pendingRequests.delete(id);
+			}
+		}
+	}
+	return result;
+}