netcdf-c/libnczarr/zdispatch.c
Dennis Heimbigner 11fe00ea05 Add filter support to NCZarr
Filter support has three goals:

1. Use the existing HDF5 filter implementations,
2. Allow filter metadata to be stored in the NumCodecs metadata format used by Zarr,
3. Allow filters to be used even when HDF5 is disabled

Detailed usage directions are define in docs/filters.md.

For now, the existing filter API is left in place. So filters
are defined using ''nc_def_var_filter'' using the HDF5 style
where the id and parameters are unsigned integers.

This is a big change since filters affect many parts of the code.

In the following, the terms "compressor" and "filter" and "codec" are generally
used synonomously.

### Filter-Related Changes:
* In order to support dynamic loading of shared filter libraries, a new library was added in the libncpoco directory; it helps to isolate dynamic loading across multiple platforms.
* Provide a json parsing library for use by plugins; this is created by merging libdispatch/ncjson.c with include/ncjson.h.
* Add a new _Codecs attribute to allow clients to see what codecs are being used; let ncdump -s print it out.
* Provide special headers to help support compilation of HDF5 filters when HDF5 is not enabled: netcdf_filter_hdf5_build.h and netcdf_filter_build.h.
* Add a number of new test to test the new nczarr filters.
* Let ncgen parse _Codecs attribute, although it is ignored.

### Plugin directory changes:
* Add support for the Blosc compressor; this is essential because it is the most common compressor used in Zarr datasets. This also necessitated adding a CMake FindBlosc.cmake file
* Add NCZarr support for the big-four filters provided by HDF5: shuffle, fletcher32, deflate (zlib), and szip
* Add a Codec defaulter (see docs/filters.md) for the big four filters.
* Make plugins work with windows by properly adding __declspec declaration.

### Misc. Non-Filter Changes
* Replace most uses of USE_NETCDF4 (deprecated) with USE_HDF5.
* Improve support for caching
* More fixes for path conversion code
* Fix misc. memory leaks
* Add new utility -- ncdump/ncpathcvt -- that does more or less the same thing as cygpath.
* Add a number of new test to test the non-filter fixes.
* Update the parsers
* Convert most instances of '#ifdef _MSC_VER' to '#ifdef _WIN32'
2021-09-02 17:04:26 -06:00

165 lines
3.1 KiB
C

/* Copyright 2005-2018 University Corporation for Atmospheric
Research/Unidata. */
/**
* @file
* @internal This header file contains prototypes and initialization
* for the ZARR dispatch layer.
*
* @author Dennis Heimbigner, Ed Hartnett
*/
#include "zincludes.h"
/* Forward */
static int NCZ_var_par_access(int ncid, int varid, int par_access);
static int NCZ_show_metadata(int ncid);
static const NC_Dispatch NCZ_dispatcher = {
NC_FORMATX_NCZARR,
NC_DISPATCH_VERSION,
NCZ_create,
NCZ_open,
NCZ_redef,
NCZ__enddef,
NCZ_sync,
NCZ_abort,
NCZ_close,
NCZ_set_fill,
NC4_inq_format,
NCZ_inq_format_extended,
NCZ_inq,
NC4_inq_type,
NCZ_def_dim,
NC4_inq_dimid,
NCZ_inq_dim,
NC4_inq_unlimdim,
NCZ_rename_dim,
NCZ_inq_att,
NCZ_inq_attid,
NC4_inq_attname,
NCZ_rename_att,
NCZ_del_att,
NCZ_get_att,
NCZ_put_att,
NCZ_def_var,
NC4_inq_varid,
NCZ_rename_var,
NCZ_get_vara,
NCZ_put_vara,
NCZ_get_vars,
NCZ_put_vars,
NCDEFAULT_get_varm,
NCDEFAULT_put_varm,
NCZ_inq_var_all,
NCZ_var_par_access,
NCZ_def_var_fill,
NCZ_show_metadata,
NCZ_inq_unlimdims,
NC4_inq_ncid,
NC4_inq_grps,
NC4_inq_grpname,
NC4_inq_grpname_full,
NC4_inq_grp_parent,
NC4_inq_grp_full_ncid,
NC4_inq_varids,
NC4_inq_dimids,
NC4_inq_typeids,
NCZ_inq_type_equal,
NCZ_def_grp,
NCZ_rename_grp,
NC4_inq_user_type,
NC4_inq_typeid,
NC_NOTNC4_def_compound,
NC_NOTNC4_insert_compound,
NC_NOTNC4_insert_array_compound,
NC_NOTNC4_inq_compound_field,
NC_NOTNC4_inq_compound_fieldindex,
NC_NOTNC4_def_vlen,
NC_NOTNC4_put_vlen_element,
NC_NOTNC4_get_vlen_element,
NC_NOTNC4_def_enum,
NC_NOTNC4_insert_enum,
NC_NOTNC4_inq_enum_member,
NC_NOTNC4_inq_enum_ident,
NC_NOTNC4_def_opaque,
NCZ_def_var_deflate,
NCZ_def_var_fletcher32,
NCZ_def_var_chunking,
NCZ_def_var_endian,
NCZ_def_var_filter,
NCZ_set_var_chunk_cache,
NC4_get_var_chunk_cache,
NCZ_inq_var_filter_ids,
NCZ_inq_var_filter_info,
};
const NC_Dispatch* NCZ_dispatch_table = NULL; /* moved here from ddispatch.c */
#ifdef ZTRACING
#include "ztracedispatch.h"
#endif
/**
* @internal Initialize the ZARR dispatch layer.
*
* @return ::NC_NOERR No error.
* @author Dennis Heimbigner, Ed Hartnett
*/
int ncz_initialized = 0; /**< True if initialization has happened. */
int
NCZ_initialize(void)
{
int stat;
#ifdef ZTRACING
NCZ_dispatch_table = &NCZ_dispatcher_trace;
#else
NCZ_dispatch_table = &NCZ_dispatcher;
#endif
if (!ncz_initialized)
NCZ_initialize_internal();
stat = NCZ_provenance_init();
if(stat) ncz_initialized = 1;
return stat;
}
/**
* @internal Finalize the ZARR dispatch layer.
*
* @return ::NC_NOERR No error.
* @author Dennis Heimbigner
*/
int
NCZ_finalize(void)
{
NCZ_finalize_internal();
NCZ_provenance_finalize();
return NC_NOERR;
}
static int
NCZ_var_par_access(int ncid, int varid, int par_access)
{
return NC_NOERR; /* no-op */
}
static int
NCZ_show_metadata(int ncid)
{
return NC_NOERR;
}