final

src/Main.java

@@ -4,18 +4,35 @@ import server.Server;
 import server.ServerBuilder;
 
 import java.io.IOException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 public class Main {
+    public static ExecutorService executor;
 
-    public static void main(String[] args) throws IOException {
+    public static void main(String[] args)  {
+        executor = Executors.newFixedThreadPool(2);
         Director director = new Director();
         ServerBuilder builder = new ServerBuilder(args);
 //        try (Server server = builder.build()) {
 //            server.start();
 //        }
         // builder.setPort(16379);
-        ReplicaConnectionService service = null;
-        director.buildReplica(builder, service);
-
+        executor.submit(() -> {
+            ReplicaConnectionService service = null;
+            try {
+                director.buildReplica(builder, service);
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        });
+        executor.submit(() -> {
+                    try (Server server = builder.build()) {
+                        server.start();
+                    } catch (IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                }
+        );
     }
 }
\ No newline at end of file

src/client/Client.java

@@ -35,7 +35,7 @@ public abstract class Client extends Thread {
             }
             handleClient(reader, outputStream);
         } catch (IOException e) {
-            logger.log(Level.SEVERE, e.getMessage());
+            logger.log(Level.SEVERE, e.getMessage(), e);
         }
     }
 

src/client/master/MasterClient.java

@@ -9,8 +9,11 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.net.Socket;
 import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class MasterClient extends Client {
+    private static final Logger logger = Logger.getLogger(MasterClient.class.getName());
 
     public MasterClient(Socket socket) {
         super(socket);
@@ -18,13 +21,17 @@ public class MasterClient extends Client {
     }
 
     @Override
-    protected void handleClient(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
+    protected void handleClient(BufferedReader bufferedReader, OutputStream outputStream) {
         String line;
-        while ((line = bufferedReader.readLine()) != null) {
-            if (line.isEmpty()) continue;
-            List<String> parsedCommands = commandParser.parseCommand(bufferedReader, line);
-            ClientCommandHandler commandHandler = new ClientCommandHandler(parsedCommands, outputStream);
-            commandHandler.execute();
+        try {
+            while ((line = bufferedReader.readLine()) != null) {
+                if (line.isEmpty()) continue;
+                List<String> parsedCommands = commandParser.parseCommand(bufferedReader, line);
+                ClientCommandHandler commandHandler = new ClientCommandHandler(parsedCommands, outputStream);
+                commandHandler.execute();
+            }
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, e.getMessage(),e);
         }
     }
 }

src/client/replica/ReplicaClient.java

@@ -12,30 +12,33 @@ import java.net.Socket;
 import java.util.List;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class ReplicaClient extends Client {
     private final CommandByteCounter commandByteCounter;
     private final ExecutorService executorService;
+    private static final Logger logger = Logger.getLogger(ReplicaClient.class.getName());
 
     public ReplicaClient(BufferedReader reader, Socket socket) {
         super(reader, socket);
-        System.out.println("Client");
         this.commandByteCounter = CommandByteCounter.getInstance();
         this.executorService = Executors.newSingleThreadExecutor();
     }
 
     @Override
-    protected void handleClient(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
+    protected void handleClient(BufferedReader bufferedReader, OutputStream outputStream) {
         String line;
-        System.out.println("Handling");
-        while ((line = bufferedReader.readLine()) != null) {
-            if (line.isEmpty()) continue;
-            List<String> parsedCommands = commandParser.parseCommand(bufferedReader, line);
-            System.out.println("ReplicaClient parse: " + parsedCommands);
-            addBytes(parsedCommands);
-            CommandProcessable commandHandler = new ReplicaCommandHandler(parsedCommands);
-            Thread thread = new Thread(commandHandler);
-            thread.start();
+        try {
+            while ((line = bufferedReader.readLine()) != null) {
+                if (line.isEmpty()) continue;
+                List<String> parsedCommands = commandParser.parseCommand(bufferedReader, line);
+                addBytes(parsedCommands);
+                CommandProcessable command = new ReplicaCommandHandler(parsedCommands);
+                executorService.submit(command);
+            }
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, e.getMessage(),e);
         }
     }
 

src/command/CommandHandler.java

-package command;
-
-import java.io.IOException;
-
-public interface CommandHandler {
-    byte[] execute() throws IOException;
-}

src/command/CommandInvoker.java

@@ -9,8 +9,7 @@ public class CommandInvoker {
 
     public static byte[] invoke(CommandExecutable<byte[]> command) throws IOException {
         String commandClassName = command.getClass().getName();
-        String threadName = Thread.currentThread().getName();
-        logger.log(Level.INFO, "Executing command: " + commandClassName + " on thread: " + threadName);
+        logger.log(Level.INFO, "Executing command: " + commandClassName);
         byte[] result = command.execute();
         logger.log(Level.INFO, "Command executed successfully: " + commandClassName);
 

src/command/EchoCommand.java

@@ -13,6 +13,10 @@ public class EchoCommand implements CommandExecutable<byte[]> {
 
     @Override
     public byte[] execute() {
-        return (Response.getResponse(args.getFirst()));
+        if (!args.isEmpty()) {
+            return (Response.getResponse(args.getFirst()));
+        } else {
+            return "".getBytes();
+        }
     }
 }

src/command/ReplConfCommand.java

 package command;
 
 import model.Command;
-import server.ReceivedFromReplica;
 
 import java.util.List;
 

src/command/SetCommand.java

@@ -18,22 +18,26 @@ public class SetCommand implements CommandExecutable<byte[]> {
 
     @Override
     public byte[] execute() {
-        Map<String, String> commandsMap = IntStream.iterate(2, i -> i < args.size(), i -> i + 2)
-                .boxed()
-                .collect(Collectors.toMap(i -> args.get(i).toLowerCase(), i -> args.get(i + 1), (a, b) -> b));
+        if (!args.isEmpty()) {
+            Map<String, String> commandsMap = IntStream.iterate(2, i -> i < args.size(), i -> i + 2)
+                    .boxed()
+                    .collect(Collectors.toMap(i -> args.get(i).toLowerCase(), i -> args.get(i + 1), (a, b) -> b));
 
-        String value = args.get(1);
-        String expiration = commandsMap.get(Command.PX.getValue().toLowerCase());
-        if (expiration != null) {
-            try {
-                Long expirationTime = Long.parseLong(expiration);
-                storage.save(args.getFirst().toLowerCase(), value, expirationTime);
-            } catch (NumberFormatException e) {
-                System.out.println("NumberFormatException:  " + e.getMessage());
+            String value = args.get(1);
+            String expiration = commandsMap.get(Command.PX.getValue().toLowerCase());
+            if (expiration != null) {
+                try {
+                    Long expirationTime = Long.parseLong(expiration);
+                    storage.save(args.getFirst().toLowerCase(), value, expirationTime);
+                } catch (NumberFormatException e) {
+                    System.out.println("NumberFormatException:  " + e.getMessage());
+                }
+            } else {
+                storage.save(args.getFirst().toLowerCase(), value);
             }
+            return ("+OK\r\n".getBytes());
         } else {
-            storage.save(args.getFirst().toLowerCase(), value);
+            return "wrong args".getBytes();
         }
-        return ("+OK\r\n".getBytes());
     }
 }

src/command/UnknownCommand.java

 package command;
 
 
+import java.util.Objects;
+
 public class UnknownCommand implements CommandExecutable<byte[]> {
+    private static String message;
+
+    public UnknownCommand(String message) {
+        UnknownCommand.message = message;
+    }
+
+    public UnknownCommand() {
+    }
+
     @Override
     public byte[] execute() {
-        return (("-" + "Unknown Command" + "\r\n").getBytes());
+        return ((Objects.requireNonNullElse(message, "-" + "Unknown Command" + "\r\n")).getBytes());
     }
 }

src/command/handshake/PingCommandSender.java

 package command.handshake;
 
-
 import model.Command;
 import parser.CommandParser;
 
@@ -8,16 +7,30 @@ import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class PingCommandSender extends CommandSender {
+    private static final Logger logger = Logger.getLogger(PingCommandSender.class.getName());
+
     public PingCommandSender(CommandParser commandParser) {
         super(commandParser);
     }
 
     @Override
     public void sendCommand(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
-        byte[] bytes = commandParser.getResponseFromCommandArray(List.of(Command.PING.getValue().toLowerCase())).getBytes();
-        outputStream.write(bytes);
-        outputStream.flush();
+        try {
+            logger.info("Sending PING command.");
+
+            byte[] bytes = commandParser.getResponseFromCommandArray(
+                    List.of(Command.PING.getValue().toLowerCase())).getBytes();
+            outputStream.write(bytes);
+            outputStream.flush();
+
+            logger.info("PING command sent successfully.");
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, "Failed to send PING command: " + e.getMessage(), e);
+            throw new IOException("Failed to send PING command: " + e.getMessage(), e);
+        }
     }
 }

src/command/handshake/ReplConfCommandSender.java

 package command.handshake;
 
-
 import model.Command;
 import parser.CommandParser;
 
@@ -8,8 +7,11 @@ import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class ReplConfCommandSender extends CommandSender {
+    private static final Logger logger = Logger.getLogger(ReplConfCommandSender.class.getName());
     private final String port;
 
     public ReplConfCommandSender(String port, CommandParser commandParser) {
@@ -19,36 +21,84 @@ public class ReplConfCommandSender extends CommandSender {
 
     @Override
     public void sendCommand(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
-        String replconfResp = "";
-        replconfResp = getReplConfResp(bufferedReader, outputStream);
+        try {
+            logger.info("Starting REPLCONF command sequence.");
+
+            if (sendReplConfResp(bufferedReader, outputStream)) {
+                logger.info("REPLCONF listening-port sent successfully.");
+
+                if (sendReplConfCapa(bufferedReader, outputStream)) {
+                    logger.info("REPLCONF capa sent successfully.");
 
-        if (!replconfResp.isEmpty()) {
-            replconfResp = sendReplConfCapa(bufferedReader, outputStream);
+                    sendPsyncCommand(outputStream);
+                    logger.info("PSYNC command sent successfully.");
+                }
+            }
+
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, "Failed to send REPLCONF command sequence: " + e.getMessage(), e);
+            throw new IOException("Failed to send REPLCONF command: " + e.getMessage(), e);
         }
-        if (!replconfResp.isEmpty()) {
-            outputStream.write(commandParser.getResponseFromCommandArray(List.of(Command.PSYNC.getValue(), "?", "-1")).getBytes());
+    }
+
+    private boolean sendReplConfCapa(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
+        try {
+            outputStream.write(commandParser.getResponseFromCommandArray(List.of(
+                            Command.REPLCONF.getValue(),
+                            "capa",
+                            "npsync2")
+                    ).getBytes()
+            );
+            outputStream.flush();
+
+            String response = bufferedReader.readLine();
+            if (response == null) {
+                throw new IOException("No response received after sending REPLCONF capa.");
+            }
+
+            logger.info("Received response after REPLCONF capa: " + response);
+            return !response.isEmpty();
+        } catch (IOException e) {
+            logger.log(Level.WARNING, "Error during sending REPLCONF capa: " + e.getMessage(), e);
+            throw e;
         }
     }
 
-    private String sendReplConfCapa(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
-        outputStream.write(commandParser.getResponseFromCommandArray(List.of(
-                        Command.REPLCONF.getValue(),
-                        "capa",
-                        "npsync2")
-                ).getBytes()
-        );
-        outputStream.flush();
-        return bufferedReader.readLine();
+    private boolean sendReplConfResp(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
+        try {
+            outputStream.write(commandParser.getResponseFromCommandArray(List.of(
+                            Command.REPLCONF.getValue(),
+                            "listening-port",
+                            String.valueOf(port))
+                    ).getBytes()
+            );
+            outputStream.flush();
+
+            String response = bufferedReader.readLine();
+            if (response == null) {
+                throw new IOException("No response received after sending REPLCONF listening-port.");
+            }
+
+            logger.info("Received response after REPLCONF listening-port: " + response);
+            return !response.isEmpty();
+        } catch (IOException e) {
+            logger.log(Level.WARNING, "Error during sending REPLCONF listening-port: " + e.getMessage(), e);
+            throw e;
+        }
     }
 
-    private String getReplConfResp(BufferedReader bufferedReader, OutputStream outputStream) throws IOException {
-        outputStream.write(commandParser.getResponseFromCommandArray(List.of(
-                        Command.REPLCONF.getValue(),
-                        "listening-port",
-                        String.valueOf(port))
-                ).getBytes()
-        );
-        outputStream.flush();
-        return bufferedReader.readLine();
+    private void sendPsyncCommand(OutputStream outputStream) throws IOException {
+        try {
+            outputStream.write(commandParser.getResponseFromCommandArray(List.of(
+                            Command.PSYNC.getValue(),
+                            "?",
+                            "-1"))
+                    .getBytes()
+            );
+            outputStream.flush();
+        } catch (IOException e) {
+            logger.log(Level.WARNING, "Error during sending PSYNC command: " + e.getMessage(), e);
+            throw e;
+        }
     }
 }

src/command/replica/ReplicaSetCommand.java

@@ -6,12 +6,15 @@ import storage.Storage;
 
 import java.util.List;
 import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
 public class ReplicaSetCommand implements CommandExecutable<Void> {
     private final Storage storage = Storage.getInstance();
     private final List<String> args;
+    private static final Logger logger = Logger.getLogger(ReplicaSetCommand.class.getName());
 
     public ReplicaSetCommand(List<String> args) {
         this.args = args;
@@ -30,7 +33,7 @@ public class ReplicaSetCommand implements CommandExecutable<Void> {
                 Long expirationTime = Long.parseLong(expiration);
                 storage.save(args.getFirst().toLowerCase(), value, expirationTime);
             } catch (NumberFormatException e) {
-                System.out.println("NumberFormatException:  " + e.getMessage());
+                logger.log(Level.SEVERE, "NumberFormatException", e);
             }
         } else {
             storage.save(args.getFirst().toLowerCase(), value);

src/factory/CommandFactory.java

@@ -33,7 +33,6 @@ public class CommandFactory implements Factory {
         };
     }
 
-    // Overloaded method for additional dependencies
     public CommandExecutable<byte[]> getCommand(Command command, List<String> args, SendToReplica sender, OutputStream os) {
         return switch (command) {
             case PING -> new PingCommand();

src/factory/replica/ReplicaCommandFactory.java

@@ -23,7 +23,6 @@ public class ReplicaCommandFactory implements Factory {
 
     @Override
     public CommandExecutable<?> getCommand(Command command, List<String> args) {
-        System.out.println("Factory get instance from " + command.getValue());
         return switch (command) {
             case SET -> new ReplicaSetCommand(args);
             case REPLCONF -> new ReplicaReplConfCommand();

src/handlers/ClientCommandHandler.java

@@ -2,6 +2,7 @@ package handlers;
 
 import command.CommandExecutable;
 import command.CommandInvoker;
+import command.UnknownCommand;
 import factory.CommandFactory;
 import model.Command;
 import parser.CommandParser;
@@ -28,6 +29,7 @@ public class ClientCommandHandler {
         this.os = outputStream;
         this.commandParser = new CommandParser();
         this.sendToReplica = SendToReplica.getInstance();
+        sendToReplica.start();
     }
 
     public void execute() {
@@ -38,6 +40,12 @@ public class ClientCommandHandler {
 
         try {
             Command command = CommandUtil.getCommand(commands.getFirst());
+            if (command == null) {
+                logger.log(Level.SEVERE, "The client send UnRecognized command.");
+                CommandExecutable<byte[]> result = new UnknownCommand("UnRecognized command");
+                byte[] response = result.execute();
+                writeResponse(response);
+            }
             List<String> replicaCommand = createReplicaCommand(commands);
             byte[] result = executeCommand(command);
             sendReplicaCommand(replicaCommand);

src/handlers/replica/ConnectionHandler.java

@@ -8,11 +8,16 @@ import parser.CommandParser;
 import util.RdbBytesReader;
 
 import java.io.BufferedReader;
+import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.net.Socket;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class ConnectionHandler {
+    private static final Logger logger = Logger.getLogger(ConnectionHandler.class.getName());
+
     private final Socket socket;
     private final RdbBytesReader reader;
     private final int port;
@@ -21,22 +26,25 @@ public class ConnectionHandler {
 
     public ConnectionHandler(Socket socket, CommandParser commandParser, int port) {
         this.socket = socket;
-        commandSender = new PingCommandSender(commandParser);
+        this.commandSender = new PingCommandSender(commandParser);
         this.port = port;
         this.reader = new RdbBytesReader();
         this.commandParser = commandParser;
-        System.out.println("Connection handler");
     }
 
     public BufferedReader handleConnection() {
-        try {
-            OutputStream outputStream = socket.getOutputStream();
-            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+        try (OutputStream outputStream = socket.getOutputStream();
+             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()))) {
             commandSender.sendCommand(bufferedReader, outputStream);
+
             String line;
             while ((line = bufferedReader.readLine()) != null) {
-                if (line.isEmpty()) continue;
-                System.out.println("GET CONNECTION : process line: " + line);
+                if (line.isEmpty()) {
+                    continue;
+                }
+
+                logger.info("Processing line: " + line);
+
                 if (line.equalsIgnoreCase("+" + Command.PONG.getValue())) {
                     this.commandSender = new ReplConfCommandSender(String.valueOf(port), commandParser);
                     commandSender.sendCommand(bufferedReader, outputStream);
@@ -44,10 +52,11 @@ public class ConnectionHandler {
                     return reader.read(bufferedReader);
                 }
             }
+        } catch (IOException e) {
+            logger.log(Level.SEVERE, "I/O error during connection handling: " + e.getMessage(), e);
         } catch (Exception e) {
-            System.out.println(e.getMessage());
+            logger.log(Level.SEVERE, "Unexpected error during connection handling: " + e.getMessage(), e);
         }
         return null;
     }
-
 }

src/handlers/replica/ReplicaCommandHandler.java

@@ -18,7 +18,6 @@ public class ReplicaCommandHandler implements CommandProcessable {
     private final ReplicaCommandFactory factory = ReplicaCommandFactory.getInstance();
 
     public ReplicaCommandHandler(List<String> commands) {
-        logger.info("replica command handler");
         this.commands = Collections.unmodifiableList(commands);
     }
 
@@ -35,7 +34,6 @@ public class ReplicaCommandHandler implements CommandProcessable {
                 logger.warning("Invalid command detected.");
                 return;
             }
-            logger.info("Executing");
             CommandExecutable<?> commandProcessor = factory.getCommand(command, commands.subList(1, commands.size()));
             executeCommand(commandProcessor);
         } catch (Exception e) {

src/server/ReceivedFromReplica.java

-package server;
-
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicInteger;
-
-public class ReceivedFromReplica {
-    private final AtomicInteger atomicInteger;
-    private final AtomicBoolean atomicBoolean;
-
-
-    public ReceivedFromReplica() {
-        synchronized (this) {
-            atomicBoolean = new AtomicBoolean(false);
-            atomicInteger = new AtomicInteger(0);
-        }
-    }
-
-
-    public void receive() {
-        atomicInteger.getAndIncrement();
-    }
-
-    public int getReceivedCount() {
-        return atomicInteger.get();
-    }
-
-
-    public void reset() {
-        System.out.println("reset values");
-        synchronized (this) {
-            atomicBoolean.set(false);
-            atomicInteger.set(0);
-        }
-    }
-
-}

src/server/SendToReplica.java

@@ -11,6 +11,7 @@ import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 
 public class SendToReplica implements Closeable {
@@ -31,9 +32,6 @@ public class SendToReplica implements Closeable {
         return SendToReplicaHolder.INSTANCE;
     }
 
-    public String getCountConnectedReplicas() {
-        return String.valueOf(connectedReplicas.size());
-    }
 
     public void start() {
         executorService.submit(this::processCommands);
@@ -49,11 +47,12 @@ public class SendToReplica implements Closeable {
             byte[] commandBytes = command.getBytes();
             connectedReplicas.forEach(replica -> {
                 try {
-                    OutputStream outputStream = replica.os();
-                    outputStream.write(commandBytes);
-                    outputStream.flush();
+                    try (OutputStream outputStream = replica.os()) {
+                        outputStream.write(commandBytes);
+                        outputStream.flush();
+                    }
                 } catch (IOException e) {
-                    logger.severe("Failed to send command to replica ");
+                    logger.log(Level.SEVERE, "Failed to send command to replica ", e);
                 }
             });
         }
@@ -67,9 +66,7 @@ public class SendToReplica implements Closeable {
         }
     }
 
-    public int getCountCommands() {
-        return countCommands.getAndSet(0);
-    }
+
 
     public void addConnection(OutputStream outputStream) {
         connectedReplicas.add(new ConnectedReplica(outputStream));

src/storage/LRUCachePolicy.java

@@ -12,7 +12,7 @@ public class LRUCachePolicy<K, V> implements CachePolicy<K, V> {
 
     public LRUCachePolicy(int maxCapacity, int threshold) {
         this.cacheMap = new ConcurrentHashMap<>(maxCapacity);
-        RdbFileReader<String,String> reader = new RdbFileReader<>();
+        RdbFileReader<String, String> reader = new RdbFileReader<>();
         cacheMap.putAll((Map<? extends K, ? extends V>) reader.readFile());
         this.threshold = threshold;
         this.accessOrder = new ConcurrentLinkedQueue<>();

src/storage/StorageManager.java

 package storage;
 
-import java.util.Date;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class StorageManager {
     private final Storage storage;
     private final ScheduledExecutorService scheduler;
+    private static final Logger logger = Logger.getLogger(StorageManager.class.getName());
 
     public StorageManager() {
         this.storage = Storage.getInstance();
@@ -17,7 +19,7 @@ public class StorageManager {
 
     private void performMaintenance() {
         storage.runCachePolicy();
-        System.out.println("Maintenance performed at: " + Date.from(java.time.Clock.systemUTC().instant()));
+        logger.log(Level.INFO, "Maintenance Started");
     }
 
     public void shutdown() {

src/util/CommandByteCounter.java

@@ -5,7 +5,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class CommandByteCounter {
-    private static volatile CommandByteCounter instance;
     private final AtomicInteger bytes;
     private final AtomicBoolean isFirst;
 
@@ -14,15 +13,12 @@ public class CommandByteCounter {
         isFirst = new AtomicBoolean(true);
     }
 
+    private static final class InstanceHolder {
+        private static final CommandByteCounter instance = new CommandByteCounter();
+    }
+
     public static CommandByteCounter getInstance() {
-        if (instance == null) {
-            synchronized (CommandByteCounter.class) {
-                if (instance == null) {
-                    instance = new CommandByteCounter();
-                }
-            }
-        }
-        return instance;
+        return InstanceHolder.instance;
     }
 
     public void setIsFirst(boolean b) {
@@ -38,9 +34,6 @@ public class CommandByteCounter {
         bytes.addAndGet(bytesLength);
     }
 
-    public void renewBytes(int bytes) {
-        this.bytes.set(this.bytes.get() + bytes);
-    }
 
     public Integer getBytes() {
         return bytes.get();