In case HDF5 adds more storage specifications, netcdf4 should be able to
cope with them by default. Further specializations could be added
nonetheless.
cloud using a variant of the Zarr protocol and storage
format. This enhancement is generically referred to as "NCZarr".
The data model supported by NCZarr is netcdf-4 minus the user-defined
types and the String type. In this sense it is similar to the CDF-5
data model.
More detailed information about enabling and using NCZarr is
described in the document NUG/nczarr.md and in a
[Unidata Developer's blog entry](https://www.unidata.ucar.edu/blogs/developer/en/entry/overview-of-zarr-support-in).
WARNING: this code has had limited testing, so do use this version
for production work. Also, performance improvements are ongoing.
Note especially the following platform matrix of successful tests:
Platform | Build System | S3 support
------------------------------------
Linux+gcc | Automake | yes
Linux+gcc | CMake | yes
Visual Studio | CMake | no
Additionally, and as a consequence of the addition of NCZarr,
major changes have been made to the Filter API. NOTE: NCZarr
does not yet support filters, but these changes are enablers for
that support in the future. Note that it is possible
(probable?) that there will be some accidental reversions if the
changes here did not correctly mimic the existing filter testing.
In any case, previously filter ids and parameters were of type
unsigned int. In order to support the more general zarr filter
model, this was all converted to char*. The old HDF5-specific,
unsigned int operations are still supported but they are
wrappers around the new, char* based nc_filterx_XXX functions.
This entailed at least the following changes:
1. Added the files libdispatch/dfilterx.c and include/ncfilter.h
2. Some filterx utilities have been moved to libdispatch/daux.c
3. A new entry, "filter_actions" was added to the NCDispatch table
and the version bumped.
4. An overly complex set of structs was created to support funnelling
all of the filterx operations thru a single dispatch
"filter_actions" entry.
5. Move common code to from libhdf5 to libsrc4 so that it is accessible
to nczarr.
Changes directly related to Zarr:
1. Modified CMakeList.txt and configure.ac to support both C and C++
-- this is in support of S3 support via the awd-sdk libraries.
2. Define a size64_t type to support nczarr.
3. More reworking of libdispatch/dinfermodel.c to
support zarr and to regularize the structure of the fragments
section of a URL.
Changes not directly related to Zarr:
1. Make client-side filter registration be conditional, with default off.
2. Hack include/nc4internal.h to make some flags added by Ed be unique:
e.g. NC_CREAT, NC_INDEF, etc.
3. cleanup include/nchttp.h and libdispatch/dhttp.c.
4. Misc. changes to support compiling under Visual Studio including:
* Better testing under windows for dirent.h and opendir and closedir.
5. Misc. changes to the oc2 code to support various libcurl CURLOPT flags
and to centralize error reporting.
6. By default, suppress the vlen tests that have unfixed memory leaks; add option to enable them.
7. Make part of the nc_test/test_byterange.sh test be contingent on remotetest.unidata.ucar.edu being accessible.
Changes Left TO-DO:
1. fix provenance code, it is too HDF5 specific.
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
nc4internal.c contains code to free the format_XXX_info
fields. Since these are format specific, this code
was moved to the dispatch code (libhdf5 and libhdf4
in the current case).
Additionally, there are some fields in nc4internal.h (e.g.
dimscale fields) that are specific to HDF5 and have been moved
to the corresponding HDF5 data structures and code.
Misc. other changes:
1. NC_VAR_INFO_T->hdf5_name renamed to alt_name to avoid
implying it is necessarily HDF5 specific.
2. prefix NC_FILE_INFO_T with an instance of NC_OBJ for consistency.
this also requires wrapping move_in_NCList() to keep
hdr.id consistent.
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.
* For URL paths, the new approach essentially centralizes all information
in the URL into the "#mode=" fragment key and uses that value
to determine the dispatcher for (most) URLs.
* The new approach has the following steps:
1. canonicalize the path if it is a URL.
2. use the mode= fragment key to determine the dispatcher
3. if dispatcher still not determined, then use the mode flags
argument to nc_open/nc_create to determine the dispatcher.
4. if the path points to something readable, attempt to read the
magic number at the front, and use that to determine the dispatcher.
this case may override all previous cases.
* Misc changes.
1. Update documentation
2. Moved some unit tests from libdispatch to unit_test directory.
3. Fixed use of wrong #ifdef macro in test_filter_reg.c
[I think this may fix an previously reported esupport query].
Anyway, I repaired it as follows:
1. Created NC4_write_provenance as parallel to NC4_read_provenance
2. Modified hdf5file.c to use NC4_write_provenance
3. Modified hdf5open.c to use NC4_read_provenance (was NC4_read_ncproperties).
4. The creation of the _NCProperties string was seriously hosed:
was using all the wrong fields.
re: https://github.com/Unidata/netcdf-c/issues/1373 (partial)
* Mark some global constants be const to indicate to make them easier to track.
* Hide direct access to the ncrc_globalstate behind a function call.
* Convert dispatch tables to constants (except the user defined ones)
This has some consequences in terms of function arguments needing to be marked
as const also.
* Remove some no longer needed global fields
* Aggregate all the globals in nclog.c
* Uniformly replace nc_sizevector{0,1} with NC_coord_{zero,one}
* Uniformly replace nc_ptrdffvector1 with NC_stride_one
* Remove some obsolete code
re: https://github.com/Unidata/netcdf-c/issues/1352
When nc4info.c encounters an _NCProperties attribute
with a version number it does not recognize, it does not
show it correctly.
Solution chosen is to arrange so that accessing the attribute
returns the raw value of the Attribute from the file. This way,
even if the version is unrecognized, it will return something
usable.
The changes were primarily to never attempt to parse the value
of _NCProperties until actually required. Which since they
are currently not used means that parsing never occurs.
Also modified ncdump/tst_fileinfo.sh to include some extra testing
I tested the original failure by changing the value of NCPROPS to 3.
However, there is no way to test this at build time.
Misc. Changes
* Inlined the provenance info in the NC_FILE_INFO_T structure
* Centralized stuff from elsewhere into include/nc_provenance.h
Misc. Unrelated Changes
* Removed/turned off some misc debug output left on by accident
* Fix CPPFLAGS name error in libhdf5/Makefile.am
re: issue https://github.com/Unidata/netcdf-c/issues/1251
Assume that you have the URL to a remote dataset
which is a normal netcdf-3 or netcdf-4 file.
This PR allows the netcdf-c to read that dataset's
contents as a netcdf file using HTTP byte ranges
if the remote server supports byte-range access.
Originally, this PR was set up to access Amazon S3 objects,
but it can also access other remote datasets such as those
provided by a Thredds server via the HTTPServer access protocol.
It may also work for other kinds of servers.
Note that this is not intended as a true production
capability because, as is known, this kind of access to
can be quite slow. In addition, the byte-range IO drivers
do not currently do any sort of optimization or caching.
An additional goal here is to gain some experience with
the Amazon S3 REST protocol.
This architecture and its use documented in
the file docs/byterange.dox.
There are currently two test cases:
1. nc_test/tst_s3raw.c - this does a simple open, check format, close cycle
for a remote netcdf-3 file and a remote netcdf-4 file.
2. nc_test/test_s3raw.sh - this uses ncdump to investigate some remote
datasets.
This PR also incorporates significantly changed model inference code
(see the superceded PR https://github.com/Unidata/netcdf-c/pull/1259).
1. It centralizes the code that infers the dispatcher.
2. It adds support for byte-range URLs
Other changes:
1. NC_HDF5_finalize was not being properly called by nc_finalize().
2. Fix minor bug in ncgen3.l
3. fix memory leak in nc4info.c
4. add code to walk the .daprc triples and to replace protocol=
fragment tag with a more general mode= tag.
Final Note:
Th inference code is still way too complicated. We need to move
to the validfile() model used by netcdf Java, where each
dispatcher is asked if it can process the file. This decentralizes
the inference code. This will be done after all the major new
dispatchers (PIO, Zarr, etc) have been implemented.
