Question

I setup a FsWatcher on a local filesystem directory. I only want to know when files are added to the directory so they can be moved to another filesystem. I seem to be able to detect when the first file is in, but actually I want to know when all files from a given copy operation are done.

If I used Windows Explorer to copy files from one directory to another, Explorer would tell me that there are n seconds left in the transfer, so while there is some activity for the begin-transfer and end-transfer for each file, it appears that there is something for the begin-transfer and end-transfer for all files.

I wonder if there is something similar that I can do just with the .NET Framework. I would like to know when “all” files are in and not just a single file in a “transaction”. If there is nothing baked in, maybe I should come up with some kind of waiting/countering in order to only do my activity when a job is “done”.

Not sure if I’m making 100% sense on this one, please anyone comment.

Thanks.

Answer 1

The way I have implemented this in the past is to have a ‘marker’ file with a special name, e.g. ‘end’. This file is always the last file written and serves as an indicator for when a multi file transaction is complete. This would work just fine if there is only one thread which is writing these sets of files.

If there are many threads, each of which may be writing a set of files, then you’d need to somehow associate each ‘end’ file with the set of files it is marking. One way to do this would be to include a GUID (or some other unique identifier) in the filenames, e.g.

{ GUID1.file1.bin, GUID1.file2.bin, GUID1.end }

{ GUID2.file1.bin, GUID2.file2.bin, GUID2.end }

Another way to do it is to zip all the files from each set into a single ZIP file so you only have to watch for single files.