Phase-tech: Adding tests and checkstyle for the project

build.gradle

@@ -1,6 +1,7 @@
 plugins {
     id 'java'
     id 'application'
+    id 'checkstyle'
 }
 
 group = 'org.example'
@@ -13,6 +14,7 @@ repositories {
 dependencies {
     testImplementation platform('org.junit:junit-bom:5.10.0')
     testImplementation 'org.junit.jupiter:junit-jupiter'
+    testImplementation 'org.mockito:mockito-junit-jupiter:5.12.0'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 
@@ -26,4 +28,9 @@ tasks.withType(JavaCompile).configureEach {
 
 test {
     useJUnitPlatform()
+    systemProperty 'net.bytebuddy.experimental', 'true'
+}
+
+checkstyle {
+    configFile = file('config/checkstyle/checkstyle.xml')
 }

config/checkstyle/checkstyle.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+        "https://checkstyle.org/dtds/configuration_1_3.dtd">
+<module name="Checker">
+    <property name="charset" value="UTF-8"/>
+
+    <module name="TreeWalker">
+        <module name="UnusedImports"/>
+        <module name="AvoidStarImport"/>
+        <module name="NeedBraces"/>
+        <module name="EmptyBlock"/>
+    </module>
+
+    <module name="LineLength">
+        <property name="max" value="140"/>
+    </module>
+</module>

src/main/java/org/cache/Main.java

@@ -3,6 +3,7 @@
 import org.cache.core.LocalCache;
 import org.cache.core.ValueType;
 import org.cache.eviction.LruEvictionPolicy;
+import org.cache.network.connection.ClientConnectionHandler;
 import org.cache.network.TcpCacheServer;
 import org.cache.protocol.CommandParser;
 import org.cache.protocol.CommandProcessor;
@@ -12,8 +13,12 @@
 import org.cache.protocol.codec.ValueCodecRegistry;
 
 import java.io.IOException;
+import java.net.ServerSocket;
+import java.util.concurrent.Executors;
 
 public class Main {
+    private static final int SERVER_THREAD_COUNT = 16;
+
     public static void main(String[] args) throws IOException {
         int port = args.length > 0 ? Integer.parseInt(args[0]) : 2020;
         var cache = new LocalCache<String>(1_000, new LruEvictionPolicy<>());
@@ -24,7 +29,14 @@ public static void main(String[] args) throws IOException {
         var commandProcessor = new CommandProcessor<>(cache, commandParser, valueCodecs);
 
 
-        try (cache; var server = new TcpCacheServer(port, commandProcessor)) {
+        try (cache;
+             var serverSocket = new ServerSocket(port);
+             var executor = Executors.newFixedThreadPool(SERVER_THREAD_COUNT);
+             var server = new TcpCacheServer(
+                     serverSocket,
+                     executor,
+                     socket -> new ClientConnectionHandler(socket, commandProcessor)
+             )) {
             server.start();
         }
     }

src/main/java/org/cache/client/CacheClient.java

@@ -2,6 +2,7 @@
 
 import org.cache.core.metrics.Snapshot;
 
+import java.util.List;
 import java.util.Optional;
 
 public interface CacheClient<K, V> {
@@ -19,4 +20,10 @@ public interface CacheClient<K, V> {
     int size();
 
     void clear();
+
+    void push(K key, V value);
+
+    List<V> lrange(K key, int to);
+
+    List<V> lrange(K key, int from, int to);
 }

src/main/java/org/cache/client/TcpCacheClient.java

@@ -24,6 +24,7 @@ public class TcpCacheClient<K, V> implements CacheClient<K, V>, AutoCloseable {
     private static final int FIRST_VALUE_INDEX = 1;
     private static final int METRIC_NAME_VALUE_START_INDEX = 1;
     private static final int METRIC_NAME_VALUE_PAIR_SIZE = 2;
+    private static final int DEFAULT_LRANGE_FROM_INDEX = 0;
 
     private final RespConnection connection;
     private final KeyCodec<K> keyCodec;
@@ -45,6 +46,12 @@ public TcpCacheClient(
         }
     }
 
+    TcpCacheClient(RespConnection connection, KeyCodec<K> keyCodec, Serializer<V> valueSerializer) {
+        this.connection = connection;
+        this.keyCodec = keyCodec;
+        this.valueSerializer = valueSerializer;
+    }
+
     @Override
     public void put(K key, V value, long ttl) {
         expectOk(List.of("PUT", keyCodec.encode(key), valueSerializer.encode(value), Long.toString(ttl)));
@@ -127,6 +134,34 @@ public void clear() {
         expectOk(List.of("CLEAR"));
     }
 
+    @Override
+    public void push(K key, V value) {
+        expectOk(List.of("PUSH", keyCodec.encode(key), valueSerializer.encode(value)));
+    }
+
+    @Override
+    public List<V> lrange(K key, int to) {
+        return lrange(key, DEFAULT_LRANGE_FROM_INDEX, to);
+    }
+
+    @Override
+    public List<V> lrange(K key, int from, int to) {
+        List<String> response = send(List.of(
+                "LRANGE",
+                keyCodec.encode(key),
+                Integer.toString(from),
+                Integer.toString(to)
+        ));
+
+        if (isResponse(response, ResponseConstants.NOT_FOUND.name(), SINGLE_PART_RESPONSE_SIZE)) {
+            return List.of();
+        }
+
+        return response.stream()
+                .map(valueSerializer::decode)
+                .toList();
+    }
+
     @Override
     public void close() {
         try {

src/main/java/org/cache/eviction/LruEvictionPolicy.java

@@ -46,7 +46,9 @@ public synchronized void onKeyAccessed(K key) {
     @Override
     public synchronized void onKeyRemoved(K key) {
         var removedNode = keyMap.get(key);
-        if (removedNode == null) return;
+        if (removedNode == null) {
+            return;
+        }
 
         var prevNode = removedNode.prev;
         var nextNode = removedNode.next;
@@ -67,4 +69,4 @@ public synchronized Optional<K> selectVictim() {
 
         return Optional.ofNullable(selectedNode.value);
     }
-}
+}

src/main/java/org/cache/eviction/MruEvictionPolicy.java

@@ -46,7 +46,9 @@ public synchronized void onKeyAccessed(K key) {
     @Override
     public synchronized void onKeyRemoved(K key) {
         var removedNode = keyMap.get(key);
-        if (removedNode == null) return;
+        if (removedNode == null) {
+            return;
+        }
 
         var prevNode = removedNode.prev;
         var nextNode = removedNode.next;
@@ -67,4 +69,4 @@ public synchronized Optional<K> selectVictim() {
 
         return Optional.ofNullable(selectedNode.value);
     }
-}
+}

src/main/java/org/cache/network/ClientConnectionHandlerFactory.java

@@ -0,0 +1,9 @@
+package org.cache.network;
+
+import java.net.Socket;
+
+@FunctionalInterface
+public interface ClientConnectionHandlerFactory {
+
+    Runnable create(Socket socket);
+}

src/main/java/org/cache/network/TcpCacheServer.java

@@ -1,36 +1,32 @@
 package org.cache.network;
 
-import org.cache.network.connection.ClientConnectionHandler;
-import org.cache.protocol.CommandProcessor;
-
 import java.io.IOException;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 
 public class TcpCacheServer implements AutoCloseable {
 
-    private final int port;
-    private final CommandProcessor<?> commandProcessor;
     private final ExecutorService executor;
+    private final ClientConnectionHandlerFactory handlerFactory;
     private ServerSocket serverSocket;
 
-    private static final int THREAD_COUNT = 16;
-
-    public TcpCacheServer(int port, CommandProcessor<?> commandProcessor) {
-        this.port = port;
-        this.commandProcessor = commandProcessor;
-        this.executor = Executors.newFixedThreadPool(THREAD_COUNT);
+    public TcpCacheServer(
+            ServerSocket serverSocket,
+            ExecutorService executor,
+            ClientConnectionHandlerFactory handlerFactory
+    ) {
+        this.serverSocket = serverSocket;
+        this.executor = executor;
+        this.handlerFactory = handlerFactory;
     }
 
     public void start() throws IOException {
-        serverSocket = new ServerSocket(port);
-        System.out.println("TCP cache server listening on port " + port);
+        System.out.println("TCP cache server listening on port " + serverSocket.getLocalPort());
 
         while (!Thread.currentThread().isInterrupted() && !serverSocket.isClosed()) {
             Socket socket = serverSocket.accept();
-            executor.submit(new ClientConnectionHandler(socket, commandProcessor));
+            executor.submit(handlerFactory.create(socket));
         }
     }
 

src/main/java/org/cache/network/connection/RespConnection.java

@@ -11,7 +11,14 @@
 
 import static java.nio.charset.StandardCharsets.US_ASCII;
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static org.cache.protocol.ProtocolConstants.*;
+import static org.cache.protocol.ProtocolConstants.ARRAY_PREFIX;
+import static org.cache.protocol.ProtocolConstants.BULK_STRING_PREFIX;
+import static org.cache.protocol.ProtocolConstants.CARRIAGE_RETURN;
+import static org.cache.protocol.ProtocolConstants.CRLF;
+import static org.cache.protocol.ProtocolConstants.ERROR_PREFIX;
+import static org.cache.protocol.ProtocolConstants.INTEGER_PREFIX;
+import static org.cache.protocol.ProtocolConstants.SIMPLE_STRING_PREFIX;
+import static org.cache.protocol.ProtocolConstants.NEW_LINE;
 import static org.cache.protocol.RegexConstants.COMMA_WITH_OPTIONAL_WHITESPACE;
 import static org.cache.protocol.RegexConstants.KEY_VALUE_SEPARATOR;
 import static org.cache.protocol.RegexConstants.SPACE;

src/main/java/org/cache/protocol/CommandParser.java

@@ -2,7 +2,18 @@
 
 import org.cache.core.ValueType;
 import org.cache.protocol.codec.KeyCodec;
-import org.cache.protocol.commands.*;
+import org.cache.protocol.commands.CacheCommand;
+import org.cache.protocol.commands.ClearCommand;
+import org.cache.protocol.commands.CommandType;
+import org.cache.protocol.commands.DeleteCommand;
+import org.cache.protocol.commands.GetCommand;
+import org.cache.protocol.commands.InvalidCommand;
+import org.cache.protocol.commands.LrangeCommand;
+import org.cache.protocol.commands.MetricsCommand;
+import org.cache.protocol.commands.PushCommand;
+import org.cache.protocol.commands.PutCommand;
+import org.cache.protocol.commands.SizeCommand;
+import org.cache.protocol.commands.UnknownCommand;
 
 import java.util.List;
 

src/main/java/org/cache/protocol/codec/ListValueCodec.java

@@ -1,6 +1,10 @@
 package org.cache.protocol.codec;
 
-import java.io.*;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 

src/main/java/org/cache/protocol/commands/LrangeCommand.java

@@ -9,7 +9,9 @@
 import java.util.List;
 import java.util.Optional;
 
-import static org.cache.protocol.commands.ResponseConstants.*;
+import static org.cache.protocol.commands.ResponseConstants.ERROR;
+import static org.cache.protocol.commands.ResponseConstants.LIST;
+import static org.cache.protocol.commands.ResponseConstants.NOT_FOUND;
 
 public class LrangeCommand<K> implements CacheCommand<K> {
 

src/main/java/org/cache/protocol/commands/PutCommand.java

@@ -5,8 +5,6 @@
 import org.cache.protocol.codec.ValueCodec;
 import org.cache.protocol.codec.ValueCodecRegistry;
 
-import java.util.Arrays;
-
 import static org.cache.protocol.commands.ResponseConstants.OK;
 
 public class PutCommand<K> implements CacheCommand<K> {