Adding batched messages + the notion of notifier / zones (not plugged in the system yet)

back/src/Model/PositionNotifier.ts

@@ -0,0 +1,106 @@
+/**
+ * Tracks the position of every player on the map, and sends notifications to the players interested in knowing about the move
+ * (i.e. players that are looking at the zone the player is currently in)
+ *
+ * Internally, the PositionNotifier works with Zones. A zone is a square area of a map.
+ * Each player is in a given zone, and each player tracks one or many zones (depending on the player viewport)
+ *
+ * The PositionNotifier is important for performance. It allows us to send the position of players only to a restricted
+ * number of players around the current player.
+ */
+import {UserEntersCallback, UserLeavesCallback, UserMovesCallback, Zone} from "./Zone";
+import {PointInterface} from "_Model/Websocket/PointInterface";
+import {UserInterface} from "_Model/UserInterface";
+import {ViewportInterface} from "_Model/Websocket/ViewportMessage";
+
+interface ZoneDescriptor {
+    i: number;
+    j: number;
+}
+
+export class PositionNotifier {
+
+    // TODO: we need a way to clean the zones if noone is in the zone and noone listening (to free memory!)
+
+    private zones: Zone[][] = [];
+
+    constructor(private zoneWidth: number, private zoneHeight: number, private onUserEnters: UserEntersCallback, private onUserMoves: UserMovesCallback, private onUserLeaves: UserLeavesCallback) {
+    }
+
+    private getZoneDescriptorFromCoordinates(x: number, y: number): ZoneDescriptor {
+        return {
+            i: Math.floor(x / this.zoneWidth),
+            j: Math.floor(y / this.zoneHeight),
+        }
+    }
+
+    public setViewport(user: UserInterface, viewport: ViewportInterface): void {
+        if (viewport.left > viewport.right || viewport.top > viewport.bottom) {
+            console.warn('Invalid viewport received: ', viewport);
+            return;
+        }
+
+        const oldZones = user.listenedZones;
+        const newZones = new Set<Zone>();
+
+        const topLeftDesc = this.getZoneDescriptorFromCoordinates(viewport.left, viewport.top);
+        const bottomRightDesc = this.getZoneDescriptorFromCoordinates(viewport.right, viewport.bottom);
+
+        for (let j = topLeftDesc.j; j <= bottomRightDesc.j; j++) {
+            for (let i = topLeftDesc.i; i <= bottomRightDesc.i; i++) {
+                newZones.add(this.getZone(i, j));
+            }
+        }
+
+        const addedZones = [...newZones].filter(x => !oldZones.has(x));
+        const removedZones = [...oldZones].filter(x => !newZones.has(x));
+
+        for (const zone of addedZones) {
+            zone.startListening(user);
+        }
+        for (const zone of removedZones) {
+            zone.stopListening(user);
+        }
+    }
+
+    public updatePosition(user: UserInterface, userPosition: PointInterface): void {
+        // Did we change zone?
+        const oldZoneDesc = this.getZoneDescriptorFromCoordinates(user.position.x, user.position.y);
+        const newZoneDesc = this.getZoneDescriptorFromCoordinates(userPosition.x, userPosition.y);
+
+        if (oldZoneDesc.i != newZoneDesc.i || oldZoneDesc.j != newZoneDesc.j) {
+            const oldZone = this.getZone(oldZoneDesc.i, oldZoneDesc.j);
+            const newZone = this.getZone(newZoneDesc.i, newZoneDesc.j);
+
+            // Leave old zone
+            oldZone.leave(user, newZone);
+
+            // Enter new zone
+            newZone.enter(user, oldZone, userPosition);
+        } else {
+            const zone = this.getZone(oldZoneDesc.i, oldZoneDesc.j);
+            zone.move(user, userPosition);
+        }
+    }
+
+    public leave(user: UserInterface): void {
+        const oldZoneDesc = this.getZoneDescriptorFromCoordinates(user.position.x, user.position.y);
+        const oldZone = this.getZone(oldZoneDesc.i, oldZoneDesc.j);
+        oldZone.leave(user, null);
+    }
+
+    private getZone(i: number, j: number): Zone {
+        let zoneRow = this.zones[j];
+        if (zoneRow === undefined) {
+            zoneRow = new Array<Zone>();
+            this.zones[j] = zoneRow;
+        }
+
+        let zone = this.zones[j][i];
+        if (zone === undefined) {
+            zone = new Zone(this.onUserEnters, this.onUserMoves, this.onUserLeaves);
+            this.zones[j][i] = zone;
+        }
+        return zone;
+    }
+}

back/src/Model/UserInterface.ts

@@ -1,9 +1,11 @@
 import { Group } from "./Group";
 import { PointInterface } from "./Websocket/PointInterface";
+import {Zone} from "_Model/Zone";
 
 export interface UserInterface {
     id: string,
     group?: Group,
     position: PointInterface,
-    silent: boolean
+    silent: boolean,
+    listenedZones: Set<Zone>
 }

back/src/Model/Websocket/ExSocketInterface.ts

@@ -2,6 +2,7 @@ import {Socket} from "socket.io";
 import {PointInterface} from "./PointInterface";
 import {Identificable} from "./Identificable";
 import {TokenInterface} from "../../Controller/AuthenticateController";
+import {ViewportInterface} from "_Model/Websocket/ViewportMessage";
 
 export interface ExSocketInterface extends Socket, Identificable {
     token: string;
@@ -11,5 +12,12 @@ export interface ExSocketInterface extends Socket, Identificable {
     name: string;
     characterLayers: string[];
     position: PointInterface;
+    viewport: ViewportInterface;
     isArtillery: boolean; // Whether this socket is opened by Artillery for load testing (hack)
+    /**
+     * Pushes an event that will be sent in the next batch of events
+     */
+    emitInBatch: (event: string | symbol, payload: any) => void;
+    batchedMessages: Array<{ event: string | symbol, payload: any }>;
+    batchTimeout: NodeJS.Timeout|null;
 }

back/src/Model/Websocket/UserMovesMessage.ts

@@ -0,0 +1,11 @@
+import * as tg from "generic-type-guard";
+import {isPointInterface} from "./PointInterface";
+import {isViewport} from "./ViewportMessage";
+
+
+export const isUserMovesInterface =
+    new tg.IsInterface().withProperties({
+        position: isPointInterface,
+        viewport: isViewport,
+    }).get();
+export type UserMovesInterface = tg.GuardedType<typeof isUserMovesInterface>;

back/src/Model/Websocket/ViewportMessage.ts

@@ -0,0 +1,10 @@
+import * as tg from "generic-type-guard";
+
+export const isViewport =
+    new tg.IsInterface().withProperties({
+        left: tg.isNumber,
+        top: tg.isNumber,
+        right: tg.isNumber,
+        bottom: tg.isNumber,
+    }).get();
+export type ViewportInterface = tg.GuardedType<typeof isViewport>;

back/src/Model/World.ts

@@ -6,6 +6,7 @@ import {UserInterface} from "./UserInterface";
 import {ExSocketInterface} from "_Model/Websocket/ExSocketInterface";
 import {PositionInterface} from "_Model/PositionInterface";
 import {Identificable} from "_Model/Websocket/Identificable";
+import {Zone} from "_Model/Zone";
 
 export type ConnectCallback = (user: string, group: Group) => void;
 export type DisconnectCallback = (user: string, group: Group) => void;
@@ -56,7 +57,8 @@ export class World {
         this.users.set(socket.userId, {
             id: socket.userId,
             position: userPosition,
-            silent: false // FIXME: silent should be set at the correct value when joining a room.
+            silent: false, // FIXME: silent should be set at the correct value when joining a room.
+            listenedZones: new Set<Zone>()
         });
         // Let's call update position to trigger the join / leave room
         this.updatePosition(socket, userPosition);

back/src/Model/Zone.ts

@@ -0,0 +1,85 @@
+import {UserInterface} from "./UserInterface";
+import {PointInterface} from "_Model/Websocket/PointInterface";
+import {PositionInterface} from "_Model/PositionInterface";
+
+export type UserEntersCallback = (user: UserInterface) => void;
+export type UserMovesCallback = (user: UserInterface, position: PointInterface) => void;
+export type UserLeavesCallback = (user: UserInterface) => void;
+
+export class Zone {
+    private players: Set<UserInterface> = new Set<UserInterface>();
+    private listeners: Set<UserInterface> = new Set<UserInterface>();
+
+    constructor(private onUserEnters: UserEntersCallback, private onUserMoves: UserMovesCallback, private onUserLeaves: UserLeavesCallback) {
+    }
+
+    /**
+     * A user leaves the zone
+     */
+    public leave(user: UserInterface, newZone: Zone|null) {
+        this.players.delete(user);
+        this.notifyUserLeft(user, newZone);
+    }
+
+    /**
+     * Notify listeners of this zone that this user left
+     */
+    private notifyUserLeft(user: UserInterface, newZone: Zone|null) {
+        for (const listener of this.listeners) {
+            if (listener !== user && (newZone === null || !listener.listenedZones.has(newZone))) {
+                this.onUserLeaves(user);
+            }
+        }
+    }
+
+    public enter(user: UserInterface, oldZone: Zone|null, position: PointInterface) {
+        this.players.add(user);
+        this.notifyUserEnter(user, oldZone, position);
+    }
+
+    /**
+     * Notify listeners of this zone that this user entered
+     */
+    private notifyUserEnter(user: UserInterface, oldZone: Zone|null, position: PointInterface) {
+        for (const listener of this.listeners) {
+            if (listener === user) {
+                continue;
+            }
+            if (oldZone === null || !listener.listenedZones.has(oldZone)) {
+                this.onUserEnters(user);
+            } else {
+                this.onUserMoves(user, position);
+            }
+        }
+    }
+
+    public move(user: UserInterface, position: PointInterface) {
+        for (const listener of this.listeners) {
+            if (listener !== user) {
+                this.onUserMoves(user,position);
+            }
+        }
+    }
+
+    public startListening(user: UserInterface): void {
+        for (const player of this.players) {
+            if (player !== user) {
+                this.onUserEnters(user);
+            }
+        }
+
+        this.listeners.add(user);
+        user.listenedZones.add(this);
+    }
+
+    public stopListening(user: UserInterface): void {
+        for (const player of this.players) {
+            if (player !== user) {
+                this.onUserLeaves(user);
+            }
+        }
+
+        this.listeners.delete(user);
+        user.listenedZones.delete(this);
+    }
+}