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.
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/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
Looks like extra comment begin and a missing comment end resulted in nested comments. Results in warning on at least the ibm compiler:
```
In file included from /g/g16/TPL/netcdf/netcdf-c/include/nc4internal.h:24:0,
from /g/g16/TPL/netcdf/netcdf-c/ncgen/includes.h:50,
from /g/g16/TPL/netcdf/netcdf-c/ncgen/genc.c:7:
/g/g16/TPL/netcdf/netcdf-c/include/nc_provenance.h:4:1: warning: "/*" within comment [-Wcomment]
/**
^
```
re: issue https://github.com/Unidata/netcdf-c/issues/1233
Changes:
1. remove exit that was there for testing.
2. the program tst_open_mem must be netcdf-4 only.
3. fix some diff problems
- Change dataset name for tst_inmemory4_create to tst_inmemory4
- Modify tst_inmemory.c to reorder the variables (somewhat major rewrite)
Minor Unrelated Fixes:
1. fix comment problem in nc_provenance.h
2. Fix memory leak in tst_open_mem.c
3. fix ncdump/bindata.c to properly compile if netcdf4 is disabled.
4. minor changes to ncgen.l
