Fix tile-saving errors after reloading bluemap with sql storage

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/map/lowres/LowresLayer.java

@@ -84,6 +84,12 @@ public class LowresLayer {
     private void saveTile(Vector2i tilePos, @Nullable LowresTile tile, RemovalCause removalCause) {
         if (tile == null) return;
 
+        // check if storage is closed
+        if (mapStorage.getStorage().isClosed()){
+            Logger.global.logDebug("Tried to save tile " + tilePos + " (lod: " + lod + ") but storage is already closed.");
+            return;
+        }
+
         // save the tile
         try (OutputStream out = mapStorage.write(lod, tilePos)) {
             tile.save(out);

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/storage/Storage.java

@@ -59,6 +59,8 @@ public abstract class Storage implements Closeable {
         return new TileStorage(mapId, lod);
     }
 
+    public abstract boolean isClosed();
+
     public class MapStorage {
 
         private final String mapId;
@@ -79,6 +81,10 @@ public abstract class Storage implements Closeable {
             deleteMapTile(mapId, lod, tile);
         }
 
+        public Storage getStorage() {
+            return Storage.this;
+        }
+
     }
 
     public class TileStorage {
@@ -103,6 +109,10 @@ public abstract class Storage implements Closeable {
             deleteMapTile(mapId, lod, tile);
         }
 
+        public Storage getStorage() {
+            return Storage.this;
+        }
+
     }
 
 }

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/storage/file/FileStorage.java

@@ -57,6 +57,11 @@ public class FileStorage extends Storage {
     @Override
     public void initialize() {}
 
+    @Override
+    public boolean isClosed() {
+        return false;
+    }
+
     @Override
     public void close() throws IOException {}
 

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/storage/sql/SQLStorage.java

@@ -61,7 +61,11 @@ public class SQLStorage extends Storage {
             .executor(BlueMap.THREAD_POOL)
             .build(this::loadMapTileCompressionFK);
 
+    private volatile boolean closed;
+
     public SQLStorage(SQLStorageSettings config) throws MalformedURLException, SQLDriverException {
+        this.closed = false;
+
         try {
             if (config.getDriverClass().isPresent()) {
                 if (config.getDriverJar().isPresent()) {
@@ -478,8 +482,14 @@ public class SQLStorage extends Storage {
         }
     }
 
+    @Override
+    public boolean isClosed() {
+        return closed;
+    }
+
     @Override
     public void close() throws IOException {
+        this.closed = true;
         if (dataSource instanceof AutoCloseable) {
             try {
                 ((AutoCloseable) dataSource).close();