I have an application, which "messes" with files in different ways. It can modify, move, copy, even delete them. So far all file operations were performed directly, without any checking if affected files were already busy or locked by other processes (or even the same application). So, in case a locked file is encountered and the operation failed, an appropriate error was reported.
Now I want to enhance this behaviour and ensure two things:
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make sure all files to be performed on are available for the operation in question (not busy/locked by other processes)
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before the operation starts, inform other processes, so they can act accordingly if necessary.
The most obvious solution to me is using NSFileCoordinator class and its reading/writing options. And even though documentation for this class is quite descriptive and helpful, I have some unanswered questions. So before doing my own tests (and perhaps even coming to potentially wrong conclusions), I'd like to ask here if someone has already had experience with this class and what I want to achieve with it.
The basic question is: if I start coordinated operation (reading or writing) on a directory identified by an URL, does that operation intent automatically spans to all files and folders in the directory, all the way down the whole directory hierarchy?
Or let me try to me more specific; I want to read all files in a certain directory, but then also list all its subfolders and read their (sub)files and go on like that down the directory hierarchy. While doing so, I don't want any other process to mess (modify, delete…) with any of those subfiles and subdirectories in the hierarchy. Is it enough to request coordinated reading to the root directory only, or do I still need to require coordinating reading to subfiles and subfolders? Or to put it another way, if I start coordinated reading on the root directory only, will other processes still be allowed to mess with subfiles and subdirectories?
Or does this behaviour depend on the read/write option I actually want to perform? For example, requesting NSFileCoordinatorReadingWithoutChanges on a directory doesn't necessarily imply reading intent to all its subfolders and subfiles down the hierarchy. But requesting e.g. NSFileCoordinatorWritingForDeleting on a directory certainly implies the deletion will also affect all its subfiles and subfolders.
I hope I was clear enough about what I want to achieve. Thanks for any insights.
-- Dragan