From 2acf340482308937748ed8d0524bd8c91fdce0bf Mon Sep 17 00:00:00 2001
From: Yannik Bretschneider <ybretsch@gmail.com>
Date: Sun, 6 Jun 2021 17:45:41 +0200
Subject: [PATCH] feat: changed implementation to fixed thread pool

---
 .../server/lobbymanager/LobbyRunner.java      | 59 +++++++++++--------
 1 file changed, 33 insertions(+), 26 deletions(-)

diff --git a/Server/src/main/java/uulm/teamname/marvelous/server/lobbymanager/LobbyRunner.java b/Server/src/main/java/uulm/teamname/marvelous/server/lobbymanager/LobbyRunner.java
index a73bf1d..de402c8 100644
--- a/Server/src/main/java/uulm/teamname/marvelous/server/lobbymanager/LobbyRunner.java
+++ b/Server/src/main/java/uulm/teamname/marvelous/server/lobbymanager/LobbyRunner.java
@@ -1,13 +1,17 @@
 package uulm.teamname.marvelous.server.lobbymanager;
 
 import org.tinylog.Logger;
+import uulm.teamname.marvelous.server.Server;
+import uulm.teamname.marvelous.server.lobby.Lobby;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Class meant for running lobbies. It manages said lobbys, creates threads for it, and moves it into an executor
@@ -24,56 +28,59 @@ public class LobbyRunner {
     }
 
 
-    private final HashMap<LobbyConnection, Thread> activeLobbies;
+    private final ExecutorService lobbyExecutor;
+    private final HashSet<LobbyConnection> activeLobbies;
 
     private LobbyRunner() {
-        this.activeLobbies = new HashMap<>();
+        this.lobbyExecutor = Executors.newFixedThreadPool(Server.getMaxLobbies());
+        this.activeLobbies = new HashSet<>();
+    }
+
+    boolean canAddLobby() {
+        return activeLobbies.size() <= Server.getMaxLobbies();
     }
 
     /** Starts a new thread for the current LobbyConnection, and adds it to the currently active lobbies */
     void startLobby(LobbyConnection connection) {
         Logger.trace("Starting lobby connection thread '{}'", connection.gameID);
-        synchronized (activeLobbies) {
-            if (activeLobbies.containsKey(connection)) {
-                Logger.warn("Already active lobby was started again. This is probably a bug.");
-            } else {
-                Logger.trace("Creating lobby thread 'Lobby-{}'...", connection.gameID);
-                var lobbyThread = new Thread(connection, "Lobby-" + connection.gameID);
-                Logger.trace("Creating mapping from LobbyConnection to newly created thread");
-                activeLobbies.put(connection, lobbyThread);
-                Logger.debug("Starting new lobby thread '{}'", lobbyThread.getName());
-                lobbyThread.start();
-            }
-        }
-    }
-
-    /** Calls {@link Thread#notify()}  on the given lobbyConnection's thread */
-    void notifyLobby(LobbyConnection toNotify) {
-        var lobbyThread = activeLobbies.get(toNotify);
-        if (lobbyThread == null) {
-            Logger.warn("Tried to notify non-existent lobby thread. This is probably a bug.");
+        if (activeLobbies.contains(connection)) {
+            Logger.warn("Already active lobby was started again. This is probably a bug.");
+        } else if (!canAddLobby()) {
+            Logger.warn("Scheduling lobby to be started while no thread is free. This might be a bug.");
+            activeLobbies.add(connection);
+            lobbyExecutor.execute(connection);
         } else {
-            lobbyThread.notify();
+            Logger.trace("Executing LobbyThread 'Lobby-{}'...", connection.gameID);
+            activeLobbies.add(connection);
+            lobbyExecutor.execute(connection);
         }
     }
 
     void removeLobby(LobbyConnection lobby) {
         synchronized (activeLobbies) {
-            var lobbyThread = activeLobbies.get(lobby);
-            if (lobbyThread == null) {
+            if (!activeLobbies.contains(lobby)) {
                 Logger.warn("Tried to remove non-existent lobby thread. This is probably a bug.");
             } else {
                 Logger.debug("Stopping and removing lobby '{}'", lobby.gameID);
                 lobby.terminateConnection();
-                lobbyThread.notify();
                 activeLobbies.remove(lobby);
             }
         }
     }
 
+    boolean isStarted(LobbyConnection connection) {
+        return activeLobbies.contains(connection);
+    }
+
     /** Shutdown all threads, destroy the lobbies, and close everything up */
     void shutdownAll() {
         Logger.info("Stopping and removing all LobbyThreads");
-        activeLobbies.keySet().forEach(this::removeLobby);
+        activeLobbies.forEach(LobbyConnection::terminateConnection);
+        try {
+            lobbyExecutor.awaitTermination(5, TimeUnit.SECONDS);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        lobbyExecutor.shutdownNow();
     }
 }