netcdf-c/include/netcdf_aux.h
Dennis Heimbigner 59e04ae071 This PR adds EXPERIMENTAL support for accessing data in the
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.
2020-06-28 18:02:47 -06:00

89 lines
2.6 KiB
C

/*********************************************************************
* Copyright 2018, UCAR/Unidata
* See netcdf/COPYRIGHT file for copying and redistribution conditions.
* $Id$
* $Header$
*********************************************************************/
/*
* In order to use any of the netcdf_XXX.h files, it is necessary
* to include netcdf.h followed by any netcdf_XXX.h files.
* Various things (like EXTERNL) are defined in netcdf.h
* to make them available for use by the netcdf_XXX.h files.
*/
#ifndef NCAUX_H
#define NCAUX_H
#define NCAUX_ALIGN_C 0
#define NCAUX_ALIGN_UNIFORM 1
#if defined(__cplusplus)
extern "C" {
#endif
/**
Reclaim the output tree of data from a call
to e.g. nc_get_vara or the input to e.g. nc_put_vara.
This recursively walks the top-level instances to
reclaim any nested data such as vlen or strings or such.
Assumes it is passed a pointer to count instances of xtype.
Reclaims any nested data.
WARNING: does not reclaim the top-level memory because
we do not know how it was allocated.
Should work for any netcdf format.
*/
EXTERNL int ncaux_reclaim_data(int ncid, int xtype, void* memory, size_t count);
EXTERNL int ncaux_begin_compound(int ncid, const char *name, int alignmode, void** tag);
EXTERNL int ncaux_end_compound(void* tag, nc_type* typeid);
EXTERNL int ncaux_abort_compound(void* tag);
EXTERNL int ncaux_add_field(void* tag, const char *name, nc_type field_type,
int ndims, const int* dimsizes);
/* Takes any type */
EXTERNL size_t ncaux_type_alignment(int xtype, int ncid);
/* Takes type classes only */
EXTERNL size_t ncaux_class_alignment(int ncclass);
/**************************************************/
#define NCAUX_FILTERSPEC_VERSION 1
/* String specific filter info */
typedef struct NC_Filterspec {
int version;
char* filterid; /**< ID for arbitrary filter. */
size_t nparams;
char** params; /**< Params for arbitrary filter. */
} NC_Filterspec;
/* HDF5 specific filter info */
typedef struct NC_H5_Filterspec {
unsigned int filterid; /**< ID for arbitrary filter. */
size_t nparams; /**< nparams for arbitrary filter. */
unsigned int* params; /**< Params for arbitrary filter. */
} NC_H5_Filterspec;
EXTERNL void ncaux_filterfix8(unsigned char* mem, int decode);
EXTERNL int ncaux_filterspec_parselist(const char* listspec, char** formatp, size_t* nfilters, NC_Filterspec*** filtersp);
EXTERNL int ncaux_filterspec_parse(const char* txt, NC_Filterspec** specp);
EXTERNL void ncaux_filterspec_free(NC_Filterspec*);
EXTERNL int ncaux_filterspec_cvt(const NC_Filterspec* spec, NC_H5_Filterspec** spech5p);
#if defined(__cplusplus)
}
#endif
#endif /*NCAUX_H*/