fs.watch : knowing when a copy is finished ?

[Naouak]

Hi,

My aim is to do an automatic operation on files dropped into a directory over the network.

To be sure that no one try to modify that file during the execution of the operation, I want to move it from the drop area to another dir. With fs.watch I'm able to tell when a new file arrives with the rename event. The problem is when the transfer is not fast enough, I will get the event before the file has finished transfer.

So my question is : Is there a way to know if transfer is done before doing anything ?

Thanks for your answers,

Naouak, Grade 2 de Kobal.
Site web: http://www.naouak.net

[fent]

If you don't know the file size, you could use node-growing-file https://github.com/felixge/node-growing-file

It uses a timeout to determine if a file is finished growing or not.

[Naouak]

So the best way would be to check whether the file is still growing to start the process.

I will do that.

Thanks for the answer.

Naouak, Grade 2 de Kobal.
Site web: http://www.naouak.net

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[Mark Hahn]

Isn't there some way to see if the file is still open by someone else?

[Matt]

That's extremely fragile advice. Just use an atomic move/rename. i.e. copy it to <name>.tmp and then move it to <name> when done. Don't read any files with suffix .tmp (or use dot files, even better, though if things break crappy sysadmins might not "see" the files).

Matt.

[Naouak]

Matt: 

Does it mean that I would have at least the double of filesize to be able to do anything with it ?

How come does it protect me from anything ? I mean, if the copy is local won't it be done before the end of the network one ?

Naouak, Grade 2 de Kobal.
Site web: http://www.naouak.net

[Matt]

On Tue, Feb 28, 2012 at 2:56 PM, Naouak <tar...@gmail.com> wrote:

Matt: 

Does it mean that I would have at least the double of filesize to be able to do anything with it ?

No.

 

How come does it protect me from anything ?

Because you write your code to ignore those temporary files.

 

I mean, if the copy is local won't it be done before the end of the network one ?

I don't understand the question.

Matt.

[Mark Hahn]

The confusion is whether the sender or the receiver is doing the copy from .tmp.  The sender does the copy (or rename) in order to make this work right.

[Matt]

Well if the receiver was doing the copy there wouldn't be any issues, as it could just wait for itself to finish :)

On Tue, Feb 28, 2012 at 7:09 PM, Mark Hahn <ma...@hahnca.com> wrote:

The confusion is whether the sender or the receiver is doing the copy from .tmp.  The sender does the copy (or rename) in order to make this work right.

[Mark Hahn]

I was just pointing out the source of the confusion on this thread - i didn't do a very good job of it though.