Backend shutdowner interface

Dev Discussions
1

I'm looking for a way to run some code at the end of the backend's lifecycle. I've read the discussion at The end of use of a backend . Was going to use lib/atexit , but stumbled upon the Shutdowner interface, which seems to be a much cleaner way to solve my task. Unfortunately, my backend's Shutdown() function do not being called. Related code:

func (f *Fs) Shutdown(ctx context.Context) error {
	panic("SHUTDOWN")
}

var (
	_ fs.Fs         = (*Fs)(nil)
	_ fs.Shutdowner = (*Fs)(nil)
)

Any suggestions?

2

I don't actually think the Shutdown method is being called at the moment.

The intention was it would be called when a backend dropped out of the backend cache, or possibly on program exit.

What do you need it for in your backend?

3

I'm working on the backend, which allows storing files directly in Tar archives. I need to write an archive footer (2x zero blocks) after the sync or copy session ends.

PS:
Also, I've noticed some other methods in my backend are not being called at all:

  • (f *Fs) Mkdir
  • (f *Fs) Rmdir
  • (f *Fs) NewObject

Are they reserved for future use too?

4

I wrote a similar backend (unreleased) which writes into zip files. For that I used libatexit.

The backend life-cycle isn't fixed yet.

What it would be nice to happen is that the Shutdown method gets called whenever a backend is no longer used, so at the end of the program or when a backend is removed from the backend cache...

I made an issue about this

Those should be called definitely depending on exactly what you are doing.

5

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