Restartable iterators

Hdf-forum archives
1

Hi,

I'm wondering whether HDF5 supports restartable iterators? H5Giterate
seems to provide for what I need, but has been deprecated in favor of
H5Literate which doesn't seem to mention how the user provided
function can stop the iteration.

Thanks,
James

···

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2

Hi James,

Yes, the new H5L and H5O iterate and visit functions are also restartable.
Description of that functionality was overlooked in the initial 1.8 user
docs, but was recently added to the HDF5 Reference Manual; your query has
prompted me to upload the revisions to the HDF5 website.

The discussion of the operator callback function in the updated H5Ovisit
entry should answer your questions:

  http://hdfgroup.org/HDF5/doc/RM/RM_H5O.html#Object-Visit

(Since it uses the same operator callback function, H5Lvisit simply
references this discussion.)

If this does not answer your question, please let me know.

Regards,
-- Frank

···

======================
Frank Baker
HDF Documentation
The HDF Group

At 12:59 +0100 2008-08-18, James Philbin wrote:

Hi,

I'm wondering whether HDF5 supports restartable iterators? H5Giterate
seems to provide for what I need, but has been deprecated in favor of
H5Literate which doesn't seem to mention how the user provided
function can stop the iteration.

Thanks,
James

----------------------------------------------------------------------
This mailing list is for HDF software users discussion.
To subscribe to this list, send a message to hdf-forum-subscribe@hdfgroup.org.
To unsubscribe, send a message to hdf-forum-unsubscribe@hdfgroup.org.

3

Hi Frank,

Thanks for the reply, but the documentation seems misleading for
H5Ovisit, as there doesn't seem to be a way to actually restart the
iteration (i.e. the function doesn't take a hsize_t *idx to start
from). I assume one can only restart the *iterate functions. Is this
correct?

Thanks,
James

···

On Mon, Aug 18, 2008 at 6:09 PM, Frank Baker <fbaker@hdfgroup.org> wrote:

Hi James,

Yes, the new H5L and H5O iterate and visit functions are also restartable.
Description of that functionality was overlooked in the initial 1.8 user
docs, but was recently added to the HDF5 Reference Manual; your query has
prompted me to upload the revisions to the HDF5 website.

The discussion of the operator callback function in the updated H5Ovisit
entry should answer your questions:

       http://hdfgroup.org/HDF5/doc/RM/RM_H5O.html#Object-Visit

(Since it uses the same operator callback function, H5Lvisit simply
references this discussion.)

If this does not answer your question, please let me know.

Regards,
-- Frank

======================
Frank Baker
HDF Documentation
The HDF Group

At 12:59 +0100 2008-08-18, James Philbin wrote:

Hi,

I'm wondering whether HDF5 supports restartable iterators? H5Giterate
seems to provide for what I need, but has been deprecated in favor of
H5Literate which doesn't seem to mention how the user provided
function can stop the iteration.

Thanks,
James

----------------------------------------------------------------------
This mailing list is for HDF software users discussion.
To subscribe to this list, send a message to hdf-forum-subscribe@hdfgroup.org.
To unsubscribe, send a message to hdf-forum-unsubscribe@hdfgroup.org.

4

Hi James,

Hi Frank,

Thanks for the reply, but the documentation seems misleading for
H5Ovisit, as there doesn't seem to be a way to actually restart the
iteration (i.e. the function doesn't take a hsize_t *idx to start
from). I assume one can only restart the *iterate functions. Is this
correct?

  Yes, you are correct, you can only restart the *iterate routines. We considered adding some way to restart the iteration for the *visit routines, but they are more complex because they are traversing the full group hierarchy. We'd have to return some "visitation ID" for the internal state of the visitation and it didn't seem like a great idea at the time.

  What we generally recommend for more complex situations is that the application's iterate/visit callback use the "op_data" parameter for storing the information desired from the entire iterate/visit operation and then process the [filtered] information in their "op_data" data structure after the iterate/visit operation concludes. Or, you can make the callback routine smart enough to take whatever action is necessary (passing information to it through the "op_data" parameter).

  Quincey

···

On Aug 19, 2008, at 6:17 AM, James Philbin wrote:

Thanks,
James

On Mon, Aug 18, 2008 at 6:09 PM, Frank Baker <fbaker@hdfgroup.org> > wrote:

Hi James,

Yes, the new H5L and H5O iterate and visit functions are also restartable.
Description of that functionality was overlooked in the initial 1.8 user
docs, but was recently added to the HDF5 Reference Manual; your query has
prompted me to upload the revisions to the HDF5 website.

The discussion of the operator callback function in the updated H5Ovisit
entry should answer your questions:

      http://hdfgroup.org/HDF5/doc/RM/RM_H5O.html#Object-Visit

(Since it uses the same operator callback function, H5Lvisit simply
references this discussion.)

If this does not answer your question, please let me know.

Regards,
-- Frank

======================
Frank Baker
HDF Documentation
The HDF Group

At 12:59 +0100 2008-08-18, James Philbin wrote:

Hi,

I'm wondering whether HDF5 supports restartable iterators? H5Giterate
seems to provide for what I need, but has been deprecated in favor of
H5Literate which doesn't seem to mention how the user provided
function can stop the iteration.

Thanks,
James

----------------------------------------------------------------------
This mailing list is for HDF software users discussion.
To subscribe to this list, send a message to hdf-forum-subscribe@hdfgroup.org.
To unsubscribe, send a message to hdf-forum-unsubscribe@hdfgroup.org.

----------------------------------------------------------------------
This mailing list is for HDF software users discussion.
To subscribe to this list, send a message to hdf-forum-subscribe@hdfgroup.org.
To unsubscribe, send a message to hdf-forum-unsubscribe@hdfgroup.org.