Lazily call IrregularUnmountCleaner from (and only from!) TemporaryMountPointChooser

main/commons/src/main/java/org/cryptomator/common/mountpoint/IrregularUnmountCleaner.java

@@ -10,7 +10,7 @@ import java.nio.file.LinkOption;
 import java.nio.file.Path;
 import java.nio.file.attribute.BasicFileAttributes;
 
-public class IrregularUnmountCleaner {
+class IrregularUnmountCleaner {
 
 	public static Logger LOG = LoggerFactory.getLogger(IrregularUnmountCleaner.class);
 
@@ -48,7 +48,6 @@ public class IrregularUnmountCleaner {
 	private static void deleteEmptyDir(Path dir) throws IOException {
 		assert Files.isDirectory(dir, LinkOption.NOFOLLOW_LINKS);
 		try {
-			checkEmpty(dir);
 			Files.delete(dir); // attempt to delete dir non-recursively (will fail, if there are contents)
 		} catch (DirectoryNotEmptyException e) {
 			LOG.info("Found non-empty directory in mountpoint dir: {}", dir);
@@ -62,10 +61,4 @@ public class IrregularUnmountCleaner {
 		}
 	}
 
-	private static void checkEmpty(Path dir) throws IOException {
-		if(Files.newDirectoryStream(dir).iterator().hasNext()) {
-			throw new DirectoryNotEmptyException(dir.toString());
-		}
-	}
-
 }

main/commons/src/main/java/org/cryptomator/common/mountpoint/TemporaryMountPointChooser.java

@@ -11,9 +11,11 @@ import javax.inject.Inject;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.LinkOption;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 class TemporaryMountPointChooser implements MountPointChooser {
 
@@ -22,6 +24,7 @@ class TemporaryMountPointChooser implements MountPointChooser {
 
 	private final VaultSettings vaultSettings;
 	private final Environment environment;
+	private volatile boolean clearedDebris;
 
 	@Inject
 	public TemporaryMountPointChooser(VaultSettings vaultSettings, Environment environment) {
@@ -40,9 +43,24 @@ class TemporaryMountPointChooser implements MountPointChooser {
 
 	@Override
 	public Optional<Path> chooseMountPoint(Volume caller) {
+		clearDebrisIfNeeded();
 		return this.environment.getMountPointsDir().map(this::choose);
 	}
 
+	//clean leftovers of not-regularly unmounted vaults
+	//see https://github.com/cryptomator/cryptomator/issues/1013 and https://github.com/cryptomator/cryptomator/issues/1061
+	private synchronized void clearDebrisIfNeeded() {
+		assert environment.getMountPointsDir().isPresent();
+		if (clearedDebris) {
+			return; // already cleared
+		}
+		Path mountPointDir = environment.getMountPointsDir().get();
+		if (Files.exists(mountPointDir, LinkOption.NOFOLLOW_LINKS)) {
+			IrregularUnmountCleaner.removeIrregularUnmountDebris(mountPointDir);
+		}
+		clearedDebris = true;
+	}
+
 	private Path choose(Path parent) {
 		String basename = this.vaultSettings.mountName().get();
 		//regular
@@ -51,13 +69,13 @@ class TemporaryMountPointChooser implements MountPointChooser {
 			return mountPoint;
 		}
 		//with id
-		mountPoint = parent.resolve(basename + " (" +vaultSettings.getId() + ")");
+		mountPoint = parent.resolve(basename + " (" + vaultSettings.getId() + ")");
 		if (Files.notExists(mountPoint)) {
 			return mountPoint;
 		}
 		//with id and count
 		for (int i = 1; i < MAX_TMPMOUNTPOINT_CREATION_RETRIES; i++) {
-			mountPoint = parent.resolve(basename + "_(" +vaultSettings.getId() + ")_"+i);
+			mountPoint = parent.resolve(basename + "_(" + vaultSettings.getId() + ")_" + i);
 			if (Files.notExists(mountPoint)) {
 				return mountPoint;
 			}

main/ui/src/main/java/org/cryptomator/ui/launcher/UiLauncher.java

@@ -1,7 +1,6 @@
 package org.cryptomator.ui.launcher;
 
 import org.cryptomator.common.Environment;
-import org.cryptomator.common.mountpoint.IrregularUnmountCleaner;
 import org.cryptomator.common.settings.Settings;
 import org.cryptomator.common.vaults.Vault;
 import org.cryptomator.integrations.tray.TrayIntegrationProvider;
@@ -16,8 +15,6 @@ import javafx.collections.ObservableList;
 import java.awt.Desktop;
 import java.awt.SystemTray;
 import java.awt.desktop.AppReopenedListener;
-import java.nio.file.Files;
-import java.nio.file.LinkOption;
 import java.util.Collection;
 import java.util.Optional;
 
@@ -65,10 +62,6 @@ public class UiLauncher {
 		// register app reopen listener
 		Desktop.getDesktop().addAppEventListener((AppReopenedListener) e -> showMainWindowAsync(hasTrayIcon));
 
-		//clean leftovers of not-regularly unmounted vaults
-		//see https://github.com/cryptomator/cryptomator/issues/1013 and https://github.com/cryptomator/cryptomator/issues/1061
-		env.getMountPointsDir().filter(path -> Files.exists(path, LinkOption.NOFOLLOW_LINKS)).ifPresent(IrregularUnmountCleaner::removeIrregularUnmountDebris);
-
 		// auto unlock
 		Collection<Vault> vaultsToAutoUnlock = vaults.filtered(this::shouldAttemptAutoUnlock);
 		if (!vaultsToAutoUnlock.isEmpty()) {