re: Github Issue https://github.com/Unidata/netcdf-c/issues/1826
It turns out that the common get code (NC4_get_vars) in libhdf5
(and libnczarr) has an optimization where it does not attempt to
read from the file if the file is all fill values. Rather it
just fills the output buffer with the fill value. The problem
is that -- in that case -- it forgets that conversion might still be
needed. So the conversion never occurs and the raw bits of
the fill data are stored directly into the memory space.
Solution: move some code around to properly do the
conversion no matter how the data was obtained.
Added a test cases nc_test4/test_fillonly.sh and
nczarr_test/test_fillonlyz.sh
In commit ba6ab3, the `tst_gfs_data_1.c` file was moved from `nc_test4` to `nc_perf`, but the test/executable that uses that file was not removed from nc_test4 CMakeLists.txt
re: Github issue https://github.com/Unidata/netcdf-c/issues/1713
If nc_def_var_filter or nc_def_var_deflate or nc_def_var_szip is
called multiple times with the same filter id, but possibly with
different sets of parameters, then the first invocation is
sticky and later invocations are ignored. The desired behavior
is to have the last invocation be used.
This PR implements that desired behavior, with some special
cases. If you call nc_def_var_deflate multiple times, then the
last invocation rule applies with respect to deflate. However,
the shuffle filter, if enabled, is always applied just before
applying deflate.
Misc unrelated changes:
1. Make client-side filters be disabled by default
2. Fix the definition of uintptr_t and use in oc2 and libdap4
3. Add some test cases
4. modify filter order tests to use plugin filters rather
than client-side filters
re: https://github.com/Unidata/netcdf-c/issues/1584
Support has been added for multiple filters per variable. This
affects a number of components in netcdf. The new APIs are
documented in NUG/filters.md.
The primary changes are:
* A set of new functions are provided (see __include/netcdf_filter.h__).
- Obtain a list of the filters associated with a variable
- Obtain the parameters for a specific filter.
* The existing __nc_inq_var_filter__ function now returns info
about the first defined filter.
* The utilities (ncgen, ncdump, and nccopy) now support
an extended format for specifying a sequence of filters.
The general form is __<filter>|<filter>..._.
* The ncdump **_Filter** attribute now dumps a list of all the
filters associated with a variable using the above new format.
* Filter specifications can now use a filter name instead of number
for filters known to the netcdf library, which in turn is taken
from the HDF5 filter registration page.
* New errors are defined: NC_EFILTER and NC_ENOFILTER. The latter
is returned if an attempt is made to access an unknown filter.
* Internally, the dispatch table has been extended to add a function
to handle all of the filter functions.
* New, filter-related, tests were added to nc_test4.
* A new plugin was added to the plugins directory to help with testing.
Notes:
1. The shuffle and fletcher32 filters are not part of the multifilter system.
Misc. changes:
1. A debug module was added to libhdf5 to help catch error locations.
Priority: Low
re: issue https://github.com/Unidata/netcdf-c/issues/1329
HDF5 has the ability to programmatically define new filters,
as opposed to using HDF5_PLUGIN_PATH env variable.
This PR adds support for that feature.
Not clear how useful this is, though.
See docs/filters.md for details.
I took Ed's advice and moved the plugin stuff to its own
top-level directory. This is an attempt to solve the problem of
copying files that we have experienced. In any case, it will
serve as a place to stick additional plugins.
The file docs/indexing.dox tries to provide design
information for the refactoring.
The primary change is to replace all walking of linked
lists with the use of the NCindex data structure.
Ncindex is a combination of a hash table (for name-based
lookup) and a vector (for walking the elements in the index).
Additionally, global vectors are added to NC_HDF5_FILE_INFO_T
to support direct mapping of an e.g. dimid to the NC_DIM_INFO_T
object. These global vectors exist for dimensions, types, and groups
because they have globally unique id numbers.
WARNING:
1. since libsrc4 and libsrchdf4 share code, there are also
changes in libsrchdf4.
2. Any outstanding pull requests that change libsrc4 or libhdf4
are likely to cause conflicts with this code.
3. The original reason for doing this was for performance improvements,
but as noted elsewhere, this may not be significant because
the meta-data read performance apparently is being dominated
by the hdf5 library because we do bulk meta-data reading rather
than lazy reading.
2. Fixed plugin building (nc_test4/hdf5plugins)
to be done properly by cmake and automake.
4. Duplicated part of the nc_test4 filter test code
in examples/C
An incomplete and untested set of hooks exist
for OS-X in nc_test4/findplugins.in. They need testing.
