perf: only try to create directory if parent is not already a directory (isFile -> throws, null -> creates)

Signed-off-by: Caleb Hulbert <cmhulbert@gmail.com>

Author: cmhulbert

src/main/java/org/janelia/saalfeldlab/n5/FsIoPolicy.java

@@ -42,7 +42,8 @@ static FileChannel openFileChannel(final Path path, final boolean forWriting) th
 
         if (forWriting) {
             final Path parent = path.getParent();
-            if (parent != null) {
+            /* if not null and not directory, it will call `createDirectories` but we expect it to throw an IOException */
+            if (parent != null && !parent.toFile().isDirectory()) {
                 Files.createDirectories(parent);
             }
             return FileChannel.open(path, StandardOpenOption.READ, StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);