Handle outdated match requests

Author: ruiqi7

backend/matching-service/src/handlers/matchHandler.ts

@@ -23,6 +23,7 @@ export interface MatchRequest {
 }
 
 export interface MatchRequestItem {
+  id: string;
   user: MatchUser;
   complexities: string[];
   categories: string[];
@@ -34,10 +35,13 @@ export interface MatchRequestItem {
 const matches = new Map<string, Match>();
 
 export const sendMatchRequest = async (
-  matchRequest: MatchRequest
+  matchRequest: MatchRequest,
+  requestId: string
 ): Promise<boolean> => {
   const { user, complexities, categories, languages, timeout } = matchRequest;
+
   const matchItem: MatchRequestItem = {
+    id: requestId,
     user: user,
     complexities: complexities,
     categories: categories,

backend/matching-service/src/handlers/websocketHandler.ts

@@ -9,6 +9,7 @@ import {
   getMatchByUid,
 } from "./matchHandler";
 import { io } from "../../server";
+import { v4 as uuidv4 } from "uuid";
 
 enum MatchEvents {
   // Receive
@@ -38,6 +39,7 @@ interface UserConnection {
   socket: Socket;
   connectionTimeout?: NodeJS.Timeout;
   isDisconnecting: boolean;
+  requestId?: string;
 }
 
 const connectionDelay = 3000; // time window to allow for page navigation / refresh
@@ -47,15 +49,18 @@ export const handleWebsocketMatchEvents = (socket: Socket) => {
   socket.removeAllListeners();
 
   socket.on(MatchEvents.USER_CONNECTED, (uid: string) => {
-    console.log(`uid: ${uid} and socket id: ${socket.id}`);
     clearTimeout(userConnections.get(uid)?.connectionTimeout);
     if (userConnections.has(uid)) {
       const matchId = getMatchIdByUid(uid);
       if (matchId) {
         socket.join(matchId);
       }
     }
-    userConnections.set(uid, { socket: socket, isDisconnecting: false });
+    userConnections.set(uid, {
+      socket: socket,
+      isDisconnecting: false,
+      requestId: userConnections.get(uid)?.requestId,
+    });
   });
 
   socket.on(MatchEvents.USER_DISCONNECTED, (uid: string) => {
@@ -74,6 +79,7 @@ export const handleWebsocketMatchEvents = (socket: Socket) => {
       socket: socket,
       connectionTimeout: connectionTimeout,
       isDisconnecting: true,
+      requestId: userConnections.get(uid)?.requestId,
     });
   });
 
@@ -90,9 +96,15 @@ export const handleWebsocketMatchEvents = (socket: Socket) => {
         return;
       }
 
-      userConnections.set(uid, { socket: socket, isDisconnecting: false });
+      const requestId = uuidv4();
+      userConnections.set(uid, {
+        socket: socket,
+        connectionTimeout: userConnections.get(uid)?.connectionTimeout,
+        isDisconnecting: false,
+        requestId: requestId,
+      });
 
-      const sent = await sendMatchRequest(matchRequest);
+      const sent = await sendMatchRequest(matchRequest, requestId);
       if (!sent) {
         socket.emit(MatchEvents.MATCH_REQUEST_ERROR);
         userConnections.delete(uid);
@@ -136,7 +148,15 @@ export const handleWebsocketMatchEvents = (socket: Socket) => {
         socket.to(matchId).emit(MatchEvents.MATCH_UNSUCCESSFUL);
       }
 
-      const sent = await sendMatchRequest(rematchRequest);
+      const uid = rematchRequest.user.id;
+      const requestId = uuidv4();
+      userConnections.set(uid, {
+        socket: socket,
+        isDisconnecting: false,
+        requestId: requestId,
+      });
+
+      const sent = await sendMatchRequest(rematchRequest, requestId);
       if (!sent) {
         socket.emit(MatchEvents.MATCH_REQUEST_ERROR);
       }
@@ -175,6 +195,10 @@ export const handleWebsocketMatchEvents = (socket: Socket) => {
   });
 };
 
+export const isActiveRequest = (uid: string, requestId: string): boolean => {
+  return userConnections.get(uid)?.requestId === requestId;
+};
+
 export const sendMatchFound = (
   matchId: string,
   matchUser1: MatchUser,

backend/matching-service/src/utils/mq_utils.ts

@@ -1,5 +1,5 @@
 import { createMatch, MatchRequestItem } from "../handlers/matchHandler";
-import { isUserConnected } from "../handlers/websocketHandler";
+import { isActiveRequest, isUserConnected } from "../handlers/websocketHandler";
 
 const matchingRequests = new Map<string, MatchRequestItem>();
 
@@ -10,12 +10,17 @@ export const matchUsers = (newRequest: string) => {
     if (
       isExpired(pendingRequest) ||
       !isUserConnected(uid) ||
+      !isActiveRequest(uid, pendingRequest.id) ||
       uid === newRequestUid
     ) {
       matchingRequests.delete(uid);
       continue;
     }
-    if (isExpired(newRequestJson) || !isUserConnected(uid)) {
+    if (
+      isExpired(newRequestJson) ||
+      !isUserConnected(newRequestUid) ||
+      !isActiveRequest(newRequestUid, newRequestJson.id)
+    ) {
       return;
     }
 
@@ -33,16 +38,15 @@ const isExpired = (data: MatchRequestItem): boolean => {
 };
 
 const isMatch = (req1: MatchRequestItem, req2: MatchRequestItem): boolean => {
-  const hasCommonCategory = req1.categories.some((elem) =>
-    req1.categories.includes(elem)
-  );
   const hasCommonComplexity = req1.complexities.some((elem) =>
     req2.complexities.includes(elem)
   );
+  const hasCommonCategory = req1.categories.some((elem) =>
+    req2.categories.includes(elem)
+  );
   const hasCommonLanguage = req1.languages.some((elem) =>
     req2.languages.includes(elem)
   );
 
-  // return hasCommonCategory && hasCommonComplexity && hasCommonLanguage;
-  return true;
+  return hasCommonComplexity && hasCommonCategory && hasCommonLanguage;
 };

frontend/src/pages/Home/index.tsx

@@ -265,14 +265,14 @@ const Home: React.FC = () => {
           color="primary"
           fullWidth
           sx={{ marginTop: 2 }}
-          // disabled={
-          //   !timeout ||
-          //   timeout < minMatchTimeout ||
-          //   timeout > maxMatchTimeout ||
-          //   complexities.length == 0 ||
-          //   categories.length == 0 ||
-          //   languages.length == 0
-          // }
+          disabled={
+            !timeout ||
+            timeout < minMatchTimeout ||
+            timeout > maxMatchTimeout ||
+            complexities.length == 0 ||
+            categories.length == 0 ||
+            languages.length == 0
+          }
           onClick={() =>
             findMatch(complexities, categories, languages, timeout!)
           }