Move logging thread-related stuff into separate class

base/src/main/java/de/staropensource/sosengine/base/Engine.java

@@ -344,7 +344,7 @@ public final class Engine extends SubsystemClass {
     public void startThreads() {
         logger.diag("Starting threads");
 
-        Logger.startLoggingThread();
+        LoggingThread.startLoggingThread();
     }
 
     /**

base/src/main/java/de/staropensource/sosengine/base/EngineConfiguration.java

@@ -24,6 +24,7 @@ import de.staropensource.sosengine.base.implementable.Configuration;
 import de.staropensource.sosengine.base.implementable.helper.EventHelper;
 import de.staropensource.sosengine.base.logging.CrashHandler;
 import de.staropensource.sosengine.base.logging.Logger;
+import de.staropensource.sosengine.base.logging.LoggingThread;
 import de.staropensource.sosengine.base.type.EngineState;
 import de.staropensource.sosengine.base.type.logging.LogLevel;
 import de.staropensource.sosengine.base.type.vector.Vec2f;
@@ -327,7 +328,7 @@ public final class EngineConfiguration extends Configuration {
 
                     // Start logging thread automatically
                     if (optimizeLogging && Engine.getInstance().getState() == EngineState.RUNNING)
-                        Logger.startLoggingThread();
+                        LoggingThread.startLoggingThread();
                 }
                 case "optimizeEvents" -> optimizeEvents = parser.getBoolean(group + property);
                 case "optimizeSubsystemInitialization" -> optimizeSubsystemInitialization = parser.getBoolean(group + property);

base/src/main/java/de/staropensource/sosengine/base/logging/Logger.java

@@ -21,18 +21,17 @@ package de.staropensource.sosengine.base.logging;
 
 import de.staropensource.sosengine.base.Engine;
 import de.staropensource.sosengine.base.EngineConfiguration;
+import de.staropensource.sosengine.base.event.LogEvent;
 import de.staropensource.sosengine.base.implementable.LoggingAdapter;
 import de.staropensource.sosengine.base.implementable.helper.EventHelper;
-import de.staropensource.sosengine.base.event.LogEvent;
+import de.staropensource.sosengine.base.implementation.logging.PlainLoggingAdapter;
+import de.staropensource.sosengine.base.implementation.shortcode.EmptyShortcodeConverter;
 import de.staropensource.sosengine.base.internal.implementation.placeholder.logger.*;
 import de.staropensource.sosengine.base.internal.type.QueuedLogMessage;
-import de.staropensource.sosengine.base.implementation.logging.PlainLoggingAdapter;
-import de.staropensource.sosengine.base.type.EngineState;
 import de.staropensource.sosengine.base.type.logging.LogLevel;
 import de.staropensource.sosengine.base.type.logging.LogRule;
 import de.staropensource.sosengine.base.type.logging.LogRuleType;
 import de.staropensource.sosengine.base.utility.PlaceholderEngine;
-import de.staropensource.sosengine.base.implementation.shortcode.EmptyShortcodeConverter;
 import lombok.Getter;
 import lombok.Setter;
 import org.jetbrains.annotations.NotNull;
@@ -53,20 +52,6 @@ import java.util.Scanner;
  */
 @SuppressWarnings({ "JavadocDeclaration" })
 public final class Logger {
-
-    /**
-     * Contains a reference to the logging thread.
-     *
-     * @since v1-alpha1
-     * -- GETTER --
-     * Returns a reference the logging thread.
-     *
-     * @return logging thread reference
-     * @since v1-alpha1
-     */
-    @Getter
-    private static @Nullable Thread loggingThread;
-
     /**
      * Contains a list of {@link QueuedLogMessage}s.
      *
@@ -116,46 +101,6 @@ public final class Logger {
      */
     public Logger() {}
 
-    /**
-     * Starts the logging thread.
-     *
-     * @since v1-alpha1
-     * @see #getLoggingThread()
-     */
-    public static void startLoggingThread() {
-        if (loggingThread == null) {
-            // Logging thread not defined, create and start new one
-            Runnable threadLogic = () -> {
-                while (true) {  // Run in loop
-                    // Stop thread when engine is shutting down
-                    if (Engine.getInstance().getState() == EngineState.SHUTDOWN
-                            || Engine.getInstance().getState() == EngineState.CRASHED
-                            || !EngineConfiguration.getInstance().isOptimizeLogging())
-                        return;
-
-                    // Process all log messages
-                    flushLogMessages();
-
-                    // Sleep for whatever has been configured
-                    long sleepDuration = System.currentTimeMillis() + EngineConfiguration.getInstance().getLoggerPollingSpeed();
-                    while (System.currentTimeMillis() < sleepDuration)
-                        Thread.onSpinWait();
-                }
-            };
-
-            loggingThread = Thread
-                    .ofPlatform()
-                    .daemon()
-                    .name("Logging thread")
-                    .group(Engine.getThreadGroup())
-                    .stackSize(10)
-                    .start(threadLogic);
-        } else
-            // Restart logging thread if dead
-            if (!loggingThread.isAlive())
-                loggingThread.start();
-    }
-
     /**
      * Prints all queued log messages.
      *

base/src/main/java/de/staropensource/sosengine/base/logging/LoggingThread.java

@@ -0,0 +1,126 @@
+/*
+ * STAROPENSOURCE ENGINE SOURCE FILE
+ * Copyright (c) 2024 The StarOpenSource Engine Authors
+ * Licensed under the GNU Affero General Public License v3
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.staropensource.sosengine.base.logging;
+
+import de.staropensource.sosengine.base.Engine;
+import de.staropensource.sosengine.base.EngineConfiguration;
+import de.staropensource.sosengine.base.type.EngineState;
+import lombok.extern.slf4j.Slf4j;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Controls the logging thread of the engine.
+ *
+ * @since v1-alpha4
+ */
+@Slf4j
+@SuppressWarnings({ "JavadocDeclaration" })
+public class LoggingThread {
+    /**
+     * Contains the {@link LoggerInstance} for this instance.
+     *
+     * @see LoggerInstance
+     * @since v1-alpha4
+     */
+    protected static final @NotNull LoggerInstance logger = new LoggerInstance.Builder().setClazz(LoggingThread.class).setOrigin("ENGINE").build();
+
+    /**
+     * Contains the logic of the logging thread.
+     *
+     * @since v1-alpha4
+     */
+    private static final @NotNull Runnable loggingThreadLogic = () -> {
+        while (!Thread.currentThread().isInterrupted()) {
+            // Stop thread when engine is shutting down
+            if (Engine.getInstance().getState() == EngineState.SHUTDOWN
+                    || Engine.getInstance().getState() == EngineState.CRASHED
+                    || !EngineConfiguration.getInstance().isOptimizeLogging())
+                return;
+
+            // Process all log messages
+            Logger.flushLogMessages();
+
+            // Sleep for whatever has been configured
+            if (EngineConfiguration.getInstance().getLoggerPollingSpeed() > 0) {
+                long sleepDuration = System.currentTimeMillis() + EngineConfiguration.getInstance().getLoggerPollingSpeed();
+                while (System.currentTimeMillis() < sleepDuration)
+                    Thread.onSpinWait();
+            }
+        }
+    };
+
+    /**
+     * Contains a reference to the logging thread.
+     *
+     * @since v1-alpha1
+     */
+    private static Thread loggingThread;
+
+    /**
+     * Reconstructs the {@link #loggingThread} thread.
+     *
+     * @throws IllegalStateException if the logging thread's state is not {@link Thread.State#TERMINATED}
+     * @since v1-alpha4
+     */
+    private static void reconstructThread() throws IllegalStateException {
+        if (loggingThread != null && loggingThread.getState() != Thread.State.TERMINATED)
+            throw new IllegalStateException("The logging thread needs to be terminated before reconstruction");
+
+        loggingThread = Thread
+                .ofPlatform()
+                .daemon()
+                .name("Logging thread")
+                .group(Engine.getThreadGroup())
+                .stackSize(10)
+                .unstarted(loggingThreadLogic);
+    }
+
+    /**
+     * Starts the logging thread.
+     *
+     * @since v1-alpha4
+     * @see #loggingThread
+     */
+    public static void startLoggingThread() {
+        if (loggingThread == null)
+            reconstructThread();
+
+        if (loggingThread.isAlive()) {
+            // Executing the thread restart logic prevents blocking the current thread
+            // while still ensuring that the logging thread is properly restarted
+            Thread
+                    .ofVirtual()
+                    .name("Logging thread restart thread")
+                    .start(() -> {
+                        logger.diag("Restarting the logging thread");
+
+                        loggingThread.interrupt();
+
+                        // Make sure that the logging thread is dead before reconstructing and starting it
+                        while (loggingThread.isAlive())
+                            Thread.onSpinWait();
+
+                        reconstructThread();
+                        loggingThread.start();
+                    });
+        } else
+            loggingThread.start();
+    }
+}