refactor: stop HttpServer manually instead of interruption

src/main/kotlin/net/ccbluex/netty/http/HttpServer.kt

@@ -20,7 +20,9 @@
 package net.ccbluex.netty.http
 
 import io.netty.bootstrap.ServerBootstrap
+import io.netty.channel.Channel
 import io.netty.channel.ChannelOption
+import io.netty.channel.EventLoopGroup
 import io.netty.channel.epoll.Epoll
 import io.netty.channel.epoll.EpollEventLoopGroup
 import io.netty.channel.epoll.EpollServerSocketChannel
@@ -32,6 +34,9 @@ import net.ccbluex.netty.http.middleware.Middleware
 import net.ccbluex.netty.http.rest.RouteController
 import net.ccbluex.netty.http.websocket.WebSocketController
 import org.apache.logging.log4j.LogManager
+import java.net.InetSocketAddress
+import java.util.concurrent.locks.ReentrantLock
+import kotlin.concurrent.withLock
 
 
 /**
@@ -44,22 +49,32 @@ class HttpServer {
     val routeController = RouteController()
     val webSocketController = WebSocketController()
 
-    val middlewares = mutableListOf<Middleware>()
+    private val lock = ReentrantLock()
+
+    internal val middlewares = mutableListOf<Middleware>()
+
+    private var bossGroup: EventLoopGroup? = null
+    private var workerGroup: EventLoopGroup? = null
+    private var serverChannel: Channel? = null
 
     companion object {
         internal val logger = LogManager.getLogger("HttpServer")
     }
 
-    fun middleware(middleware: Middleware) {
+    fun middleware(middleware: Middleware) = apply {
         middlewares += middleware
     }
 
     /**
      * Starts the Netty server on the specified port.
+     *
+     * @param port The port of HTTP server. `0` means to auto select one.
+     *
+     * @return actual port of server.
      */
-    fun start(port: Int) {
-        val bossGroup = if (Epoll.isAvailable()) EpollEventLoopGroup() else NioEventLoopGroup()
-        val workerGroup = if (Epoll.isAvailable()) EpollEventLoopGroup() else NioEventLoopGroup()
+    fun start(port: Int): Int = lock.withLock {
+        bossGroup = if (Epoll.isAvailable()) EpollEventLoopGroup(1) else NioEventLoopGroup(1)
+        workerGroup = if (Epoll.isAvailable()) EpollEventLoopGroup() else NioEventLoopGroup()
 
         try {
             logger.info("Starting Netty server...")
@@ -70,21 +85,35 @@ class HttpServer {
                 .handler(LoggingHandler(LogLevel.INFO))
                 .childHandler(HttpChannelInitializer(this))
             val ch = b.bind(port).sync().channel()
+            serverChannel = ch
 
             logger.info("Netty server started on port $port.")
-            ch.closeFuture().sync()
-        } catch (e: InterruptedException) {
-            logger.error("Netty server interrupted", e)
+
+            return@withLock (ch.localAddress() as InetSocketAddress).port
         } catch (t: Throwable) {
             logger.error("Netty server failed - $port", t)
-
+            stop()
             // Forward the exception because we ran into an unexpected error
             throw t
-        } finally {
-            bossGroup.shutdownGracefully()
-            workerGroup.shutdownGracefully()
         }
+    }
 
+    /**
+     * Stops the Netty server gracefully.
+     */
+    fun stop() = lock.withLock {
+        logger.info("Shutting down Netty server...")
+        try {
+            serverChannel?.close()?.sync()
+            bossGroup?.shutdownGracefully()?.sync()
+            workerGroup?.shutdownGracefully()?.sync()
+        } catch (e: Exception) {
+            logger.warn("Error during shutdown", e)
+        } finally {
+            serverChannel = null
+            bossGroup = null
+            workerGroup = null
+        }
         logger.info("Netty server stopped.")
     }
 

src/test/kotlin/HttpMiddlewareServerTest.kt

@@ -7,9 +7,6 @@ import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.Response
 import org.junit.jupiter.api.*
-import java.io.File
-import java.nio.file.Files
-import kotlin.concurrent.thread
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
 import kotlin.test.assertTrue
@@ -21,7 +18,7 @@ import kotlin.test.assertTrue
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 class HttpMiddlewareServerTest {
 
-    private lateinit var serverThread: Thread
+    private lateinit var server: HttpServer
     private val client = OkHttpClient()
 
     /**
@@ -32,9 +29,7 @@ class HttpMiddlewareServerTest {
     @BeforeAll
     fun initialize() {
         // Start the HTTP server in a separate thread
-        serverThread = thread {
-            startHttpServer()
-        }
+        server = startHttpServer()
 
         // Allow the server some time to start
         Thread.sleep(1000)
@@ -46,14 +41,14 @@ class HttpMiddlewareServerTest {
      */
     @AfterAll
     fun cleanup() {
-        serverThread.interrupt()
+        server.stop()
     }
 
     /**
      * This function starts the HTTP server with routing configured for
      * different difficulty levels.
      */
-    private fun startHttpServer() {
+    private fun startHttpServer(): HttpServer {
         val server = HttpServer()
 
         server.routeController.apply {
@@ -74,6 +69,7 @@ class HttpMiddlewareServerTest {
         }
 
         server.start(8080)  // Start the server on port 8080
+        return server
     }
 
     @Suppress("UNUSED_PARAMETER")

src/test/kotlin/HttpServerTest.kt

@@ -9,7 +9,6 @@ import okhttp3.Response
 import org.junit.jupiter.api.*
 import java.io.File
 import java.nio.file.Files
-import kotlin.concurrent.thread
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
 import kotlin.test.assertTrue
@@ -22,7 +21,7 @@ import kotlin.test.assertTrue
 class HttpServerTest {
 
     private lateinit var folder: File
-    private lateinit var serverThread: Thread
+    private lateinit var server: HttpServer
     private val client = OkHttpClient()
 
     /**
@@ -44,9 +43,7 @@ class HttpServerTest {
         File(subFolder, "index.html").writeText("Hello, World!")
 
         // Start the HTTP server in a separate thread
-        serverThread = thread {
-            startHttpServer(folder)
-        }
+        server = startHttpServer(folder)
 
         // Allow the server some time to start
         Thread.sleep(1000)
@@ -58,15 +55,15 @@ class HttpServerTest {
      */
     @AfterAll
     fun cleanup() {
-        serverThread.interrupt()
+        server.stop()
         folder.deleteRecursively() // Clean up the temporary folder
     }
 
     /**
      * This function starts the HTTP server with routing configured for
      * different difficulty levels.
      */
-    private fun startHttpServer(folder: File) {
+    private fun startHttpServer(folder: File): HttpServer {
         val server = HttpServer()
 
         server.routeController.apply {
@@ -97,6 +94,7 @@ class HttpServerTest {
         }
 
         server.start(8080)  // Start the server on port 8080
+        return server
     }
 
     @Suppress("UNUSED_PARAMETER")