refactor: clean up files in matching-service

apps/matching-service/README.md

@@ -29,7 +29,7 @@ go mod tidy
 - `MATCH_TIMEOUT`: The time in seconds to wait for a match before timing out.
 - `REDIS_URL`: The URL for the Redis server. Default is `localhost:6379`.
 
-4. Start a local redis server:
+4. Start a local Redis server:
 
 ```bash
 docker run -d -p 6379:6379 redis

apps/matching-service/handlers/websocket.go

@@ -123,44 +123,42 @@ func createTimeoutContext() (context.Context, context.CancelFunc, error) {
 	return ctx, cancel, nil
 }
 
+// Cleans up the data associated with the user before ending the websocket connection.
+// If user is already removed, then nothing happens.
+func cleanUpUser(username string) {
+	// Cleanup Redis
+	processes.CleanUpUser(processes.GetRedisClient(), username, context.Background())
+
+	// Removes the match context and active
+	if cancelFunc, exists := matchContexts[username]; exists {
+		cancelFunc()
+		delete(matchContexts, username)
+	}
+	if _, exists := activeConnections[username]; exists {
+		delete(activeConnections, username)
+	}
+	if _, exists := matchFoundChannels[username]; exists {
+		delete(matchFoundChannels, username)
+	}
+}
+
 // waitForResult waits for a match result, timeout, or cancellation.
 func waitForResult(ws *websocket.Conn, ctx, timeoutCtx, matchCtx context.Context, matchFoundChan chan models.MatchFound, username string) {
 	select {
 	case <-ctx.Done():
 		log.Println("Matching cancelled")
-		// Cleanup Redis
-		processes.CleanUpUser(processes.GetRedisClient(), username, context.Background())
-		// Remove the match context and active
-		if _, exists := matchContexts[username]; exists {
-			delete(matchContexts, username)
-		}
-		if _, exists := activeConnections[username]; exists {
-			delete(activeConnections, username)
-		}
-		if _, exists := matchFoundChannels[username]; exists {
-			delete(matchFoundChannels, username)
-		}
-
+		cleanUpUser(username)
 		return
 	case <-timeoutCtx.Done():
 		log.Println("Connection timed out")
-		// Cleanup Redis
-		processes.CleanUpUser(processes.GetRedisClient(), username, context.Background())
-		// Remove the match context and active
-		if _, exists := matchContexts[username]; exists {
-			delete(matchContexts, username)
-		}
-		if _, exists := activeConnections[username]; exists {
-			delete(activeConnections, username)
-		}
-		if _, exists := matchFoundChannels[username]; exists {
-			delete(matchFoundChannels, username)
-		}
-
 		sendTimeoutResponse(ws)
+		cleanUpUser(username)
 		return
 	case <-matchCtx.Done():
 		log.Println("Match found for user: " + username)
+
+		// NOTE: user is already cleaned-up in the other process,
+		// so there is no need to clean up again.
 		return
 	case result, ok := <-matchFoundChan:
 		if !ok {
@@ -169,8 +167,11 @@ func waitForResult(ws *websocket.Conn, ctx, timeoutCtx, matchCtx context.Context
 			return
 		}
 		log.Println("Match found for user: " + username)
-		// Notify the users about the match
-		notifyMatch(result.User, result.MatchedUser, result)
+		// Notify the user about the match
+		notifyMatches(result.User, result)
+
+		// NOTE: user and other user are already cleaned up in a separate matching algorithm process
+		// so no clean up is required here.
 		return
 	}
 }
@@ -186,45 +187,15 @@ func sendTimeoutResponse(ws *websocket.Conn) {
 	}
 }
 
-func notifyMatch(username, matchedUsername string, result models.MatchFound) {
+// Notify matches
+func notifyMatches(username string, result models.MatchFound) {
 	mu.Lock()
 	defer mu.Unlock()
 
-	// Send message to the first user
+	// Send message to matched user
 	if userConn, userExists := activeConnections[username]; userExists {
 		if err := userConn.WriteJSON(result); err != nil {
 			log.Printf("Error sending message to user %s: %v\n", username, err)
 		}
 	}
-
-	// Send message to the matched user
-	if matchedUserConn, matchedUserExists := activeConnections[matchedUsername]; matchedUserExists {
-		result.User, result.MatchedUser = result.MatchedUser, result.User // Swap User and MatchedUser values
-		if err := matchedUserConn.WriteJSON(result); err != nil {
-			log.Printf("Error sending message to user %s: %v\n", username, err)
-		}
-	}
-
-	// Remove the match context for both users and cancel for matched user
-	if cancelFunc, exists := matchContexts[username]; exists {
-		cancelFunc()
-		delete(matchContexts, username)
-	}
-
-	if cancelFunc2, exists := matchContexts[matchedUsername]; exists {
-		cancelFunc2()
-		delete(matchContexts, matchedUsername)
-	}
-
-	// Remove the match channels
-	if _, exists := matchFoundChannels[username]; exists {
-		delete(matchFoundChannels, username)
-	}
-	if _, exists := matchFoundChannels[matchedUsername]; exists {
-		delete(matchFoundChannels, matchedUsername)
-	}
-
-	// Remove users from the activeConnections map
-	delete(activeConnections, username)
-	delete(activeConnections, matchedUsername)
 }

apps/matching-service/main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"context"
 	"fmt"
 	"log"
 	"matching-service/handlers"
@@ -10,7 +9,6 @@ import (
 	"os"
 
 	"github.com/joho/godotenv"
-	"github.com/redis/go-redis/v9"
 )
 
 func main() {
@@ -19,33 +17,17 @@ func main() {
 	if err != nil {
 		log.Fatalf("err loading: %v", err)
 	}
-	port := os.Getenv("PORT")
-
-	// Retrieve redis url env variable and setup the redis client
-	redisAddr := os.Getenv("REDIS_URL")
-	client := redis.NewClient(&redis.Options{
-		Addr:     redisAddr,
-		Password: "", // no password set
-		DB:       0,  // use default DB
-	})
-
-	// Ping the redis server
-	_, err = client.Ping(context.Background()).Result()
-	if err != nil {
-		log.Fatalf("Could not connect to Redis: %v", err)
-	} else {
-		log.Println("Connected to Redis at the following address: " + redisAddr)
-	}
-
-	// Set redis client
-	processes.SetRedisClient(client)
+
+	// Setup redis client
+	processes.SetupRedisClient()
 
 	// Run a goroutine that matches users
-
+	
 	// Routes
 	http.HandleFunc("/match", handlers.HandleWebSocketConnections)
-
+	
 	// Start the server
+	port := os.Getenv("PORT")
 	log.Println(fmt.Sprintf("Server starting on :%s", port))
 	err = http.ListenAndServe(fmt.Sprintf(":%s", port), nil)
 	if err != nil {

apps/matching-service/models/complexity.go

@@ -0,0 +1,67 @@
+package models
+
+import (
+	"log"
+	"strings"
+)
+
+// Get the highest common difficulty (aka complexity) between two users,
+// If no common difficulty found, choose the min of the 2 arrays.
+func GetCommonDifficulty(userArr []string, matchedUserArr []string) string {
+	commonDifficulties := make([]int, 3)
+	for i := range commonDifficulties {
+		commonDifficulties[i] = 0
+	}
+
+	for _, difficulty := range userArr {
+		formattedDifficulty := strings.ToLower(difficulty)
+		switch formattedDifficulty {
+		case "easy":
+			commonDifficulties[0]++
+		case "medium":
+			commonDifficulties[1]++
+		case "hard":
+			commonDifficulties[2]++
+		default:
+			log.Println("Unknown difficulty specified: " + difficulty)
+		}
+	}
+
+	for _, difficulty := range matchedUserArr {
+		formattedDifficulty := strings.ToLower(difficulty)
+		switch formattedDifficulty {
+		case "easy":
+			commonDifficulties[0]++
+		case "medium":
+			commonDifficulties[1]++
+		case "hard":
+			commonDifficulties[2]++
+		default:
+			log.Println("Unknown difficulty specified: " + difficulty)
+		}
+	}
+
+	lowest := "Hard"
+	for i := 2; i >= 0; i-- {
+		if commonDifficulties[i] == 2 {
+			switch i {
+			case 0:
+				return "Easy"
+			case 1:
+				return "Medium"
+			case 2:
+				return "Hard"
+			}
+		} else if commonDifficulties[i] > 0 {
+			switch i {
+			case 0:
+				lowest = "Easy"
+			case 1:
+				lowest = "Medium"
+			case 2:
+				lowest = "Hard"
+			}
+		}
+	}
+	return lowest
+}

apps/matching-service/processes/constants.go

@@ -0,0 +1,17 @@
+package processes
+
+import (
+	"context"
+	"sync"
+
+	"github.com/redis/go-redis/v9"
+)
+
+const matchmakingQueueRedisKey = "matchmaking_queue"
+
+var (
+	redisClient          *redis.Client
+	matchingRoutineMutex sync.Mutex // Mutex to ensure only one matchmaking goroutine is running
+	redisAccessMutex     sync.Mutex // Mutex for Redis access for concurrency safety
+	ctx                  = context.Background()
+)