Dear Werner:
Thanks for the suggestions. I'll keep these suggestions as last
resort because my program is cross-platform, so I'm trying to avoid
such low-level functions.
I'm thinking now of using an md5 hash of the file instead of the
size. Do you think that would suffice and work? The only problem
with that is that it could be a little expensive, but that's still
OK if that's the only problem because the files aren't really that
big (a few megabytes).
All the best,
Samer
On 19.07.2015 16:37, Werner Benger
wrote:
Hi Samer,
if those applications are linking dynamically with HDF5, you
could interface there by providing a "patched" version of HDF5
that is binary compatible, but still performs some file locking,
possibly via a modified VFD.
Just checking the file sizes won't be a sure check, in particular
it would not work for and application that does not append data
but modifies existing ones. You should be able to check the "last
modified" date on the file as well, and if the HDF5 file cannot be
opened by another application, then it's either corrupted or still
open and data written to it.
It should also be possible to find out which process has file
handles to a specific file open, both Linux and Windows seem to
allow that, just in an OS-specific way:
http://stackoverflow.com/questions/6583158/finding-open-file-descriptors-for-a-process-linux-c-code
https://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
It may require your program to run under admin rights though.
Cheers,
Werner
On 19.07.2015 12:32, Samer Afach
wrote:
Dear Werner:
Unfortunately I don't have the source of the writing program. It
could be anything actually; labview, C, C++, etc... . I'm
working on a collaborative program for collecting data, and my
software is supposed to upload the data to the main storage
server for backup and data analysis. Everyone is free to use any
tools they want for data acquisition.
Is there any solution to my problem that doesn't involve me
having authority on the writing program? Currently I'm using a
method that I invented, where I measure the size of the file
multiple times, and if the size doesn't change for some time,
then that decide that the file isn't being written... that's the
only way I could come up with, but this has nothing to do with
HDF5.
All the best,
Samer
On 19.07.2015 12:23, Werner Benger
wrote:
Hi Samer,
do you have full source code access to both programs, the one
writing the file and the one uploading it?
If so, would adding some file locking mechanism ( https://en.wikipedia.org/wiki/File_locking
) help your case?
Cheers,
Werner
On 19.07.2015 02:50, Samer Afach
wrote:
Dear Werner:
Thank you for your response and your time.
I tried modifying the source code of h5check, but it's very
complicated and returns strings instead of error codes.
Besides, I tried to compile it by including the three files
in the main c file and it gave errors that don't seem to be
easily trackable. It'll take me lots of time to prepare
something reliable out of it with full testing. I wonder why
the hdf group didn't implement such a functionality in low
language, I thought it exists and I can't find it. :(
About my second question, apparently I wasn't clear on what
I really need and I was misunderstood. What I need is to
check whether the file I want to read is being accessed by
some other program. My problem is that the file I wanna deal
with is being written by some other program, and I want to
initiate an upload after it's done writing. So I would like
to check whether the other program is finished writing and
closed it before I send it to my upload queue.
All the best,
Samer
On 18.07.2015 23:11, Werner
Benger wrote:
Hi Samer,
On 18.07.2015 16:23, Samer
Afach wrote:
Dear pros:
I have two similar issues I would like to ask about, and
I'd be grateful if you could help me:
1- How can I check HDF5 file integrity in C/C++ (I
prefer low level C)? I know there's a software called
h5check, but I need a function to do that, not a
software. In my application, it's not an option to
execute h5check from my system.
Is there any objection against you taking the source code
of h5check, rename the main function to h5check_main() and
then call it as C function from your code?
2- How can I do a quick check in C/C++ to
see whether the file is being written/modified/open for
write? I looked in
this link which discusses metadata, but there
doesn't seem to be a clear way through the C/C++
interface for me a to read the first two bits that give
me that information. Could you please help with that
with a simple example?
This sounds as if you want to know what the HDF5 library
is currently doing with a file? Well what you could do is
to modify the virtual file driver that you want to use,
and let it keep track of that happens with the file. It's
the VFD that does the actual writing of a file content, so
you can trace its write() call to keep track what exactly
happens when. It's some effort of course.
Cheers,
Werner
All the best,
Samer
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
--
___________________________________________________________________________
Dr. Werner Benger Visualization Research
Center for Computation & Technology at Louisiana State University (CCT/LSU)
2019 Digital Media Center, Baton Rouge, Louisiana 70803
Tel.: +1 225 578 4809 Fax.: +1 225 578-5362
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
--
___________________________________________________________________________
Dr. Werner Benger Visualization Research
Center for Computation & Technology at Louisiana State University (CCT/LSU)
2019 Digital Media Center, Baton Rouge, Louisiana 70803
Tel.: +1 225 578 4809 Fax.: +1 225 578-5362
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
--
___________________________________________________________________________
Dr. Werner Benger Visualization Research
Center for Computation & Technology at Louisiana State University (CCT/LSU)
2019 Digital Media Center, Baton Rouge, Louisiana 70803
Tel.: +1 225 578 4809 Fax.: +1 225 578-5362
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
|
