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
<https://www.hdfgroup.org/HDF5/doc/H5.format.html#FileMetaData>
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]
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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
