Add Task

src/com/massivecraft/massivecore/Couple.java

@@ -91,7 +91,7 @@ public class Couple<A, B> implements Entry<A, B>, Cloneable, Serializable
 			this.getSecond(), that.getSecond()
 		);
 	}
-	
+
 	// -------------------------------------------- //
 	// CLONE
 	// -------------------------------------------- //

src/com/massivecraft/massivecore/Task.java

@@ -0,0 +1,113 @@
+package com.massivecraft.massivecore;
+
+import com.massivecraft.massivecore.collections.MassiveList;
+import com.massivecraft.massivecore.util.Txt;
+
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * This class is for tasks that are only run infrequently such as once a day
+ * and whose frequency must stay consistent between server restarts.
+ * An example is Faction taxing which must happen exactly once a day.
+ */
+public abstract class Task extends Engine
+{
+	// -------------------------------------------- //
+	// FIELDS
+	// -------------------------------------------- //
+
+	private boolean mustBeTaskServer = false;
+	public boolean mustBeTaskServer() { return mustBeTaskServer; }
+	public void setMustBeTaskServer(boolean mustBeTaskServer) { this.mustBeTaskServer = mustBeTaskServer; }
+
+	private boolean logTimeSpent = false;
+	public boolean isLoggingTimeSpent() { return logTimeSpent; }
+	public void setLoggingTimeSpent(boolean logTimeSpent) { this.logTimeSpent = logTimeSpent; }
+
+	private List<Supplier<Boolean>> conditions = new MassiveList<>();
+	public List<Supplier<Boolean>> getConditions() { return conditions; }
+	public void setConditions(List<Supplier<Boolean>> conditions) { this.conditions = conditions; }
+	public void addCondition(Supplier<Boolean> condition) { this.conditions.add(condition); }
+	public boolean areConditionsMet()
+	{
+		return conditions.stream().map(Supplier::get).allMatch(b -> b == true);
+	}
+
+	// -------------------------------------------- //
+	// CONSTRUCT
+	// -------------------------------------------- //
+
+	public Task()
+	{
+		this.setPeriod(60 * 20L); // Once a minute
+	}
+
+	// -------------------------------------------- //
+	// INVOKE
+	// -------------------------------------------- //
+
+	@Override
+	public void run()
+	{
+		// Should it be the task server?
+		if (this.mustBeTaskServer() && ! MassiveCore.isTaskServer()) return;
+
+		// So the delay millis is lower than one? (could for example be zero)
+		// This probably means the task should not be executed at all.
+		if (this.getPeriodMillis() < 1) return;
+
+		// Other conditions
+		if (!this.areConditionsMet()) return;
+
+		// INVOCATION
+		long nowMillis = System.currentTimeMillis();
+		long lastMillis = this.getPreviousMillis();
+
+		long currentInvocation = this.getInvocationFromMillis(nowMillis);
+		long lastInvocation = this.getInvocationFromMillis(lastMillis);
+
+		if (currentInvocation == lastInvocation) return;
+
+		// Log time spent and invoke
+		if (this.isLoggingTimeSpent())
+		{
+			String message = Txt.parse("<h>Running %s.", this.getClass().getSimpleName());
+			this.getPlugin().log(message);
+		}
+
+		long startNano = System.nanoTime();
+		this.invoke(nowMillis);
+		this.setPreviousMillis(nowMillis);
+		long endNano = System.nanoTime();
+
+		double elapsedSeconds = (endNano - startNano) / 1000_000_000D;
+		if (this.isLoggingTimeSpent())
+		{
+			String msg = String.format("<i>Took <h>%.2f <i>seconds.", elapsedSeconds);
+			msg = Txt.parse(msg);
+			this.getPlugin().log(msg);
+		}
+	}
+
+	public abstract void invoke(long now);
+
+	// -------------------------------------------- //
+	// TASK MILLIS AND INVOCATION
+	// -------------------------------------------- //
+	// The invocation is the amount of periods from UNIX time to now.
+	// It will increment by one when a period has passed.
+
+	public abstract long getPreviousMillis();
+	public abstract void setPreviousMillis(long millis);
+
+	public abstract long getPeriodMillis();
+	public abstract long getOffsetMillis();
+
+	// Here we accept millis from inside the period by rounding down.
+	private long getInvocationFromMillis(long millis)
+	{
+		return (millis - this.getOffsetMillis()) / this.getPeriodMillis();
+	}
+
+}