Add debug info for chunks loading during deletion

Author: Jikoo

src/main/java/com/github/jikoo/regionerator/DebugLevel.java

@@ -10,6 +10,7 @@ public enum DebugLevel {
 	OFF,
 	LOW,
 	MEDIUM,
-	HIGH
+	HIGH,
+	EXTREME
 
 }

src/main/java/com/github/jikoo/regionerator/DeletionRunnable.java

@@ -148,16 +148,30 @@ private boolean isDeleteEligible(ChunkInfo chunkInfo) {
 			} catch (InterruptedException ignored) {}
 		}
 
+		if (plugin.debug(DebugLevel.HIGH)) {
+			plugin.getDebugListener().monitorChunk(chunkInfo.getChunkX(), chunkInfo.getChunkZ());
+		}
+
+		VisitStatus visitStatus;
 		try {
-			return chunkInfo.getVisitStatus().ordinal() < VisitStatus.VISITED.ordinal();
+			// Calculate VisitStatus including protection hooks.
+			visitStatus = chunkInfo.getVisitStatus();
 		} catch (RuntimeException e) {
+			// Interruption is not due to plugin shutdown, log.
 			if (!this.isCancelled() && plugin.isEnabled()) {
-				// Interruption is not due to plugin shutdown, log.
 				plugin.debug(() -> String.format("Caught an exception getting VisitStatus: %s", e.getMessage()), e);
 			}
+
 			// If an exception occurred, do not delete chunk.
-			return false;
+			visitStatus = VisitStatus.UNKNOWN;
 		}
+
+		if (plugin.debug(DebugLevel.HIGH)) {
+			plugin.getDebugListener().ignoreChunk(chunkInfo.getChunkX(), chunkInfo.getChunkZ());
+		}
+
+		return visitStatus.ordinal() < VisitStatus.VISITED.ordinal();
+
 	}
 
 	public String getRunStats() {

src/main/java/com/github/jikoo/regionerator/Regionerator.java

@@ -3,6 +3,7 @@
 import com.github.jikoo.regionerator.commands.RegioneratorExecutor;
 import com.github.jikoo.regionerator.hooks.Hook;
 import com.github.jikoo.regionerator.hooks.PluginHook;
+import com.github.jikoo.regionerator.listeners.DebugListener;
 import com.github.jikoo.regionerator.listeners.FlaggingListener;
 import com.github.jikoo.regionerator.listeners.HookListener;
 import com.github.jikoo.regionerator.util.yaml.Config;
@@ -44,6 +45,7 @@ public class Regionerator extends JavaPlugin {
 	private Config config;
 	private MiscData miscData;
 	private BukkitTask flagging;
+	private DebugListener debugListener;
 
 	@Override
 	public void onEnable() {
@@ -68,6 +70,7 @@ public void onEnable() {
 		miscData.checkWorldValidity();
 
 		chunkFlagger = new ChunkFlagger(this);
+		debugListener = new DebugListener(this);
 
 		PluginCommand command = getCommand("regionerator");
 		RegioneratorExecutor executor = new RegioneratorExecutor(this, deletionRunnables);
@@ -176,6 +179,10 @@ public void run() {
 				}
 			}.runTaskTimer(this, 0L, 1200L);
 		}
+
+		if (debug(DebugLevel.HIGH)) {
+			getServer().getPluginManager().registerEvents(debugListener, this);
+		}
 	}
 
 	public Config config() {
@@ -277,6 +284,10 @@ public ChunkFlagger getFlagger() {
 		return this.chunkFlagger;
 	}
 
+	DebugListener getDebugListener() {
+		return debugListener;
+	}
+
 	public boolean isPaused() {
 		return this.paused.get();
 	}

src/main/java/com/github/jikoo/regionerator/listeners/DebugListener.java

@@ -0,0 +1,52 @@
+package com.github.jikoo.regionerator.listeners;
+
+import com.github.jikoo.regionerator.DebugLevel;
+import com.github.jikoo.regionerator.Regionerator;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.logging.Level;
+import org.bukkit.Chunk;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.world.ChunkLoadEvent;
+
+/**
+ * Listener used for additional debugging info.
+ *
+ * @author Jikoo
+ */
+public class DebugListener implements Listener {
+
+	private final Regionerator plugin;
+	private final Set<Long> badChunkHashes;
+
+	public DebugListener(Regionerator plugin) {
+		this.plugin = plugin;
+		this.badChunkHashes = new HashSet<>();
+	}
+
+	@EventHandler
+	public void onChunkLoad(ChunkLoadEvent event) {
+		if (badChunkHashes.contains(getHash(event.getChunk()))) {
+			plugin.debug(DebugLevel.HIGH, () -> String.format("Chunk loaded while being checked at %s, %s", event.getChunk().getX(), event.getChunk().getZ()));
+			plugin.debug(DebugLevel.EXTREME, () -> plugin.getLogger().log(Level.INFO, "Chunk load trace", new Throwable()));
+		}
+	}
+
+	public void monitorChunk(int chunkX, int chunkZ) {
+		badChunkHashes.add(getHash(chunkX, chunkZ));
+	}
+
+	public void ignoreChunk(int chunkX, int chunkZ) {
+		badChunkHashes.remove(getHash(chunkX, chunkZ));
+	}
+
+	private long getHash(Chunk chunk) {
+		return getHash(chunk.getX(), chunk.getZ());
+	}
+
+	private long getHash(long x, long z) {
+		return z ^ (x << 32);
+	}
+
+}