Added quartz scheduler and used this instead of manual scheduled executor service.

Author: andrewlalis

build.gradle

@@ -27,14 +27,16 @@ dependencies {
     implementation 'com.h2database:h2:1.4.200'
     implementation 'com.zaxxer:HikariCP:5.0.0'
 
+    implementation 'org.quartz-scheduler:quartz:2.3.2'
+
     // Lombok annotations
     compileOnly 'org.projectlombok:lombok:1.18.22'
     annotationProcessor 'org.projectlombok:lombok:1.18.22'
     testCompileOnly 'org.projectlombok:lombok:1.18.22'
     testAnnotationProcessor 'org.projectlombok:lombok:1.18.22'
 
     // Logging
-    implementation 'ch.qos.logback:logback-classic:1.2.6'
+    implementation 'ch.qos.logback:logback-classic:1.2.7'
 
     // JUnit tests
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'

src/main/java/net/javadiscord/javabot2/Bot.java

@@ -10,17 +10,17 @@
 import net.javadiscord.javabot2.command.SlashCommandListener;
 import net.javadiscord.javabot2.config.BotConfig;
 import net.javadiscord.javabot2.db.DbHelper;
-import net.javadiscord.javabot2.systems.moderation.ModerationService;
+import net.javadiscord.javabot2.tasks.ScheduledTasks;
 import org.javacord.api.DiscordApi;
 import org.javacord.api.DiscordApiBuilder;
 import org.javacord.api.entity.intent.Intent;
+import org.quartz.SchedulerException;
 
 import java.nio.file.Path;
 import java.time.ZoneOffset;
 import java.util.TimeZone;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
 
 /**
  * The main program entry point.
@@ -81,7 +81,13 @@ public static void main(String[] args) {
 				"commands/moderation.yaml"
 		);
 		api.addSlashCommandCreateListener(commandListener);
-		initScheduledTasks(api);
+		try {
+			ScheduledTasks.init(api);
+			log.info("Initialized scheduled tasks.");
+		} catch (SchedulerException e) {
+			log.error("Could not initialize all scheduled tasks.", e);
+			api.disconnect();
+		}
 	}
 
 	/**
@@ -106,13 +112,4 @@ private static MongoDatabase initMongoDatabase() {
 		warnCollection.createIndex(Indexes.descending("createdAt"), new IndexOptions().unique(false));
 		return db;
 	}
-
-	private static void initScheduledTasks(DiscordApi api) {
-		// Regularly check for and unmute users whose mutes have expired.
-		asyncPool.scheduleAtFixedRate(() -> {
-			for (var server : api.getServers()) {
-				new ModerationService(api, config.get(server).getModeration()).unmuteExpired();
-			}
-		}, 1L, 1L, TimeUnit.MINUTES);
-	}
 }

src/main/java/net/javadiscord/javabot2/tasks/ScheduledTasks.java

@@ -0,0 +1,73 @@
+package net.javadiscord.javabot2.tasks;
+
+import net.javadiscord.javabot2.tasks.jobs.DiscordApiJob;
+import net.javadiscord.javabot2.tasks.jobs.UnmuteExpiredJob;
+import org.javacord.api.DiscordApi;
+import org.quartz.*;
+import org.quartz.impl.StdSchedulerFactory;
+
+/**
+ * This class is responsible for setting up all scheduled tasks that the bot
+ * should run periodically, using the Quartz {@link Scheduler}. To add new tasks
+ * to the schedule, add them to the {@link ScheduledTasks#scheduleAllTasks(Scheduler, DiscordApi)}
+ * method.
+ */
+public class ScheduledTasks {
+	// Hide the constructor.
+	private ScheduledTasks() {}
+
+	/**
+	 * Initializes all scheduled jobs and starts the scheduler. Also adds a
+	 * shutdown hook that gracefully stops the scheduler when the program ends.
+	 * @param api The Discord API, which may be needed by some jobs.
+	 * @throws SchedulerException If an error occurs while starting the scheduler.
+	 */
+	public static void init(DiscordApi api) throws SchedulerException {
+		Scheduler scheduler = StdSchedulerFactory.getDefaultScheduler();
+		scheduleAllTasks(scheduler, api);
+		scheduler.start();
+		// Add a hook to shut down the scheduler cleanly when the program terminates.
+		Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+			try {
+				scheduler.shutdown();
+			} catch (SchedulerException e) {
+				e.printStackTrace();
+			}
+		}));
+	}
+
+	/**
+	 * This method is where all tasks are scheduled. <strong>Add scheduled tasks
+	 * to the scheduler using this method!</strong>
+	 * @param scheduler The scheduler to use.
+	 * @param api The Discord API.
+	 * @throws SchedulerException If an error occurs while adding a task.
+	 */
+	private static void scheduleAllTasks(Scheduler scheduler, DiscordApi api) throws SchedulerException {
+		scheduleApiJob(scheduler, api, UnmuteExpiredJob.class, SimpleScheduleBuilder.repeatMinutelyForever());
+	}
+
+	/**
+	 * Convenience method for scheduling an API-dependent job using a single
+	 * trigger that follows a given schedule.
+	 * @param scheduler The scheduler to add the job to.
+	 * @param api The Discord API.
+	 * @param type The type of job to schedule.
+	 * @param scheduleBuilder A schedule builder that the trigger will use.
+	 * @throws SchedulerException If an error occurs while adding the job.
+	 * @see SimpleScheduleBuilder
+	 * @see CronScheduleBuilder
+	 * @see CalendarIntervalScheduleBuilder
+	 */
+	private static void scheduleApiJob(
+			Scheduler scheduler,
+			DiscordApi api,
+			Class<? extends DiscordApiJob> type,
+			ScheduleBuilder<?> scheduleBuilder
+	) throws SchedulerException {
+		scheduler.scheduleJob(
+				DiscordApiJob.build(type, api),
+				TriggerBuilder.newTrigger().withSchedule(scheduleBuilder).build()
+		);
+	}
+}

src/main/java/net/javadiscord/javabot2/tasks/jobs/DiscordApiJob.java

@@ -0,0 +1,33 @@
+package net.javadiscord.javabot2.tasks.jobs;
+
+import org.javacord.api.DiscordApi;
+import org.quartz.*;
+
+import java.util.Map;
+
+/**
+ * A type of job which requires a reference to a {@link DiscordApi} to be
+ * available at execution time. Extend this class if your job needs the api.
+ */
+public abstract class DiscordApiJob implements Job {
+	@Override
+	public void execute(JobExecutionContext context) throws JobExecutionException {
+		DiscordApi api = (DiscordApi) context.getJobDetail().getJobDataMap().get("discord-api");
+		execute(context, api);
+	}
+
+	protected abstract void execute(JobExecutionContext context, DiscordApi api) throws JobExecutionException;
+
+	/**
+	 * Builder method that produces a {@link JobDetail} for the given job type,
+	 * with job data initialized to include a reference to the given Discord API.
+	 * @param jobType The type of job to create a job detail for.
+	 * @param api The Discord API.
+	 * @return The created job detail.
+	 */
+	public static JobDetail build(Class<? extends DiscordApiJob> jobType, DiscordApi api) {
+		return JobBuilder.newJob(jobType)
+				.usingJobData(new JobDataMap(Map.of("discord-api", api)))
+				.build();
+	}
+}

src/main/java/net/javadiscord/javabot2/tasks/jobs/UnmuteExpiredJob.java

@@ -0,0 +1,18 @@
+package net.javadiscord.javabot2.tasks.jobs;
+
+import net.javadiscord.javabot2.Bot;
+import net.javadiscord.javabot2.systems.moderation.ModerationService;
+import org.javacord.api.DiscordApi;
+import org.quartz.JobExecutionContext;
+
+/**
+ * Job which unmutes users whose mutes have expired.
+ */
+public class UnmuteExpiredJob extends DiscordApiJob {
+	@Override
+	protected void execute(JobExecutionContext context, DiscordApi api) {
+		for (var server : api.getServers()) {
+			new ModerationService(api, Bot.config.get(server).getModeration()).unmuteExpired();
+		}
+	}
+}

src/main/resources/quartz.properties

@@ -0,0 +1,2 @@
+org.quartz.threadPool.threadCount = 4
+org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore