I have a bunch of files on a local file system. My server will serve those files. In some cases the server will receive an instruction to delete a file.
At the moment I'm using FileChannel.lock() to acquire a lock on the file, this is mostly to make sure that some other process isn't editing the file when I try to delete it.
If I successfully acquire the lock, can I delete the file straight away, or do I need to release the lock first?
like this:
FileOutputStream out = new FileOutputStream(file);
FileChannel channel = out.getChannel();
FileLock lock = channel.lock();
if(lock.isValid() && !lock.isShared()){
Path filePath = Paths.get(file.getPath());
Files.delete(filePath);
}
Do I need to release the lock after I've deleted the file?
Or should it be like this (lock.release() added):
FileOutputStream out = new FileOutputStream(file);
FileChannel channel = out.getChannel();
FileLock lock = channel.lock();
if(lock.isValid() && !lock.isShared()){
lock.release();
Path filePath = Paths.get(file.getPath());
Files.delete(filePath);
}
EDIT:
So it turns out the code above wouldn't work anyway, because you can't modify the file with a FileInputStream because, of course, it's read only. I've modified the code above to use FileOutputStream instead, but it still doesn't quite work, because even though I release the lock from the channel, the file object still has a lock. So I modified the code like so:
FileOutputStream out = new FileOutputStream(file);
FileChannel channel = out.getChannel();
FileLock lock = channel.lock();
if(lock.isValid() && !lock.isShared()){
channel.close();
boolean deleted = file.delete();
logger.info("{} @{} File {} deleted: {}", id, type, file.getName(), deleted);
}
This seems to work as expected. I'd still like to know if this is safe, or if there's a better way to do this?
