Adding LRU Strategy

src/Main.java

@@ -9,7 +9,8 @@ public class Main {
         ServerBuilder builder = new ServerBuilder();
         director.buildMaster(builder);
         builder.port(16379);
-        Server server = builder.build();
-        server.start();
+        try (Server server = builder.build()) {
+            server.start();
+        }
     }
 }
\ No newline at end of file

src/factory/CommandFactory.java

@@ -12,7 +12,6 @@ public class CommandFactory implements Factory {
     }
 
     public CommandFactory() {
-
     }
 
     public static CommandFactory getInstance() {

src/server/Server.java

@@ -2,6 +2,7 @@ package server;
 
 import client.Client;
 import client.primary.MasterClient;
+import storage.StorageManager;
 
 import java.io.IOException;
 import java.net.ServerSocket;
@@ -9,12 +10,13 @@ import java.net.Socket;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
-public class Server {
-    private  final int PORT ;
+public class Server implements AutoCloseable {
+    private final int PORT;
     private final ExecutorService executor;
     private final String role;
+    StorageManager manager = new StorageManager();
 
-    private static Server instance;
+    private static volatile Server instance;
 
     Server(int port, String role) {
         PORT = port;
@@ -22,9 +24,11 @@ public class Server {
         this.executor = Executors.newVirtualThreadPerTaskExecutor();
     }
 
-    public static synchronized Server getInstance(int PORT,String role) throws IOException {
-        if (instance == null) {
-            instance = new Server(PORT,role);
+    public static Server getInstance(int PORT, String role) throws IOException {
+        if (role.equalsIgnoreCase("master")) {
+            if (instance == null) {
+                instance = new Server(PORT, role);
+            }
         }
         return instance;
     }
@@ -51,4 +55,9 @@ public class Server {
             task.run();
         });
     }
+
+    @Override
+    public void close() {
+        manager.shutdown();
+    }
 }

src/storage/CachePolicy.java

+package storage;
+
+public interface CachePolicy<K, V> {
+    void add(K key, V value);
+    V retrieve(K key);
+    void delete(K key);
+    void runMaintenance();
+}
\ No newline at end of file

src/storage/LRUCachePolicy.java

+package storage;
+
+import java.util.Map;
+import java.util.Queue;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+public class LRUCachePolicy<K, V> implements CachePolicy<K, V> {
+    private final int maxCapacity;
+    private final Map<K, V> cacheMap;
+    private final Queue<K> accessOrder;
+
+    public LRUCachePolicy(int maxCapacity) {
+        this.maxCapacity = maxCapacity;
+        this.cacheMap = new ConcurrentHashMap<>(maxCapacity);
+        this.accessOrder = new ConcurrentLinkedQueue<>();
+    }
+
+    @Override
+    public void add(K key, V value) {
+        cacheMap.put(key, value);
+        updateAccessOrder(key);
+    }
+
+    @Override
+    public V retrieve(K key) {
+        V value = cacheMap.get(key);
+        if (value != null) {
+            updateAccessOrder(key);
+        }
+        return value;
+    }
+
+    @Override
+    public void delete(K key) {
+        cacheMap.remove(key);
+        accessOrder.remove(key);
+    }
+
+    @Override
+    public void runMaintenance() {
+        while (cacheMap.size() > maxCapacity) {
+            evictLeastRecentlyUsed();
+        }
+    }
+
+    private void updateAccessOrder(K key) {
+        accessOrder.remove(key);
+        accessOrder.offer(key);
+    }
+
+    private void evictLeastRecentlyUsed() {
+        while (!accessOrder.isEmpty()) {
+            K leastRecentKey = accessOrder.poll();
+            if (cacheMap.containsKey(leastRecentKey)) {
+                delete(leastRecentKey);
+                break;
+            }
+        }
+    }
+}
\ No newline at end of file

src/storage/Storage.java

 package storage;
 
-
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 public class Storage {
-    private final Map<String, String> storage = new ConcurrentHashMap<>(10000);
-    private final Map<String, Long> timeToExpiration = new ConcurrentHashMap<>(10000);
-    private final Map<String, Long> currentTimeForKey = new ConcurrentHashMap<>(10000);
-
+    private final int capacity = 10000;
+    private final CachePolicy<String, String> storage;
+    private final Map<String, Long> timeToExpiration = new ConcurrentHashMap<>(capacity);
+    private final Map<String, Long> currentTimeForKey = new ConcurrentHashMap<>(capacity);
 
     private Storage() {
-        //    RdbFileReader reader = new RdbFileReader();
-        //Map<String, String> stringStringMap = reader.readFile();
-        //  storage.putAll(stringStringMap);
-        //Map<String, Long> keysExpiration = reader.getKeysExpiration();
-        //  timeToExpiration.putAll(keysExpiration);
+        this.storage = new LRUCachePolicy<>(capacity);
     }
 
     private static final class StorageHolder {
-        private static final Storage storage = new Storage();
+        private static final Storage instance = new Storage();
     }
 
-
     public static Storage getInstance() {
-        return StorageHolder.storage;
+        return StorageHolder.instance;
     }
 
     public void save(String key, String value) {
-        storage.put(key, value);
+        storage.add(key, value);
     }
 
-    public void save(String key, String value, Long time) {
-        System.out.println("SAVE Storage: " + key);
+    public void save(String key, String value, Long expirationTime) {
         currentTimeForKey.put(key, System.currentTimeMillis());
-        timeToExpiration.put(key, time);
+        timeToExpiration.put(key, expirationTime);
         save(key, value);
     }
 
     public String get(String key) {
-        if (isExpired(key)) return "";
-        return storage.get(key);
+        if (isExpired(key)) {
+            remove(key);
+            return "";
+        }
+        return storage.retrieve(key);
     }
 
     private boolean isExpired(String key) {
@@ -61,5 +57,12 @@ public class Storage {
         return false;
     }
 
-
-}
+    private void remove(String key) {
+        storage.delete(key);
+        timeToExpiration.remove(key);
+        currentTimeForKey.remove(key);
+    }
+    void runCachePolicy() {
+        storage.runMaintenance();
+    }
+}
\ No newline at end of file

src/storage/StorageManager.java

+package storage;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+public class StorageManager {
+    private final Storage storage;
+    private final ScheduledExecutorService scheduler;
+
+    public StorageManager() {
+        this.storage = Storage.getInstance();
+        this.scheduler = Executors.newSingleThreadScheduledExecutor();
+        scheduler.scheduleAtFixedRate(this::performMaintenance, 5, 5, TimeUnit.MINUTES);
+    }
+
+    public Storage getStorage() {
+        return storage;
+    }
+
+    private void performMaintenance() {
+        storage.runCachePolicy();
+        System.out.println("Maintenance performed at: " + System.currentTimeMillis());
+    }
+
+    public void shutdown() {
+        scheduler.shutdown();
+        try {
+            if (!scheduler.awaitTermination(60, TimeUnit.SECONDS)) {
+                scheduler.shutdownNow();
+            }
+        } catch (InterruptedException e) {
+            scheduler.shutdownNow();
+        }
+    }
+}
\ No newline at end of file