Check Flock Status on File

[Matt]

I have a daemon that is checking files as they are uploaded by FTP and
processing them accordingly.
I noticed that occasionally the files are truncated, and have put this
down to the file currently being written by the FTP server as im
reading it.
I would like to check the lock status on the file, so I will only
process the file if it is not write-locked.
How can I check the lock status on a given filename?

 

[ara.t.howard]

I have a daemon that is checking files as they are uploaded by FTP and
processing them accordingly.
I noticed that occasionally the files are truncated, and have put this
down to the file currently being written by the FTP server as im
reading it.
I would like to check the lock status on the file, so I will only
process the file if it is not write-locked.
How can I check the lock status on a given filename?

fcntl/posix (see posixlock gem) locks export that information but
flock, afaik, does not. this seems workable though

http://drawohara.tumblr.com/post/5891548





-a

 

[barjunk]

fcntl/posix (see posixlock gem) locks export that information but
flock, afaik, does not. this seems workable though

http://drawohara.tumblr.com/post/5891548

-a

So the code above modifies the File class so that an instance will
include a flocked? method, right?

Is it a good assumption that something like this would eventually make
it into File?

Mike B.

 

[ara.t.howard]

So the code above modifies the File class so that an instance will
include a flocked? method, right?
indeed.


Is it a good assumption that something like this would eventually make
it into File?

hmmm. i wouldn't hold my breath - but you could put in an rcr ;-)

a @ http://drawohara.com/

 

[barjunk]

hmmm. i wouldn't hold my breath - but you could put in an rcr ;-)

OK. I'll keep it lying about then, cause it seems very usefull.

One last thing. So I assume then, that multiple process as well as
multiple threads will maintain the lock properly.

Mike B.

 

[ara.t.howard]

One last thing. So I assume then, that multiple process as well as
multiple threads will maintain the lock properly.

no - just processes. it's easy to extend ruby's flock to support
processes though: just keep state in thread local vars - i think i
actually have code lying around that does just that.... (goes
hunting...)

a @ http://drawohara.com/