netcdf-c/libnczarr/zcreate.c
Dennis Heimbigner 5fa2defc7e Improve fetch performance of DAP4
Prior to this PR, DAP4 always fetched the whole (constrained) dataset
This PR changes the query processing so
1. It reads data on a per-variable request (equivalent to calling nc_get_var()).
2. It tracks a response for every query.

Most of the changes reflect having to do per-variable requests.
In any case, doing all this significantly reduces the amount of data transmitted and hence speeds up DAP4 requests.
2023-10-08 19:59:28 -06:00

133 lines
3.7 KiB
C

/* Copyright 2003-2018, University Corporation for Atmospheric
* Research. See COPYRIGHT file for copying and redistribution
* conditions. */
/**
* @file
* @internal The netCDF-4 file functions relating to file creation.
*
* @author Dennis Heimbigner, Ed Hartnett
*/
#include "zincludes.h"
/** @internal These flags may not be set for create. */
static const int ILLEGAL_CREATE_FLAGS = (NC_NOWRITE|NC_MMAP|NC_DISKLESS|NC_64BIT_OFFSET|NC_CDF5);
/**
* @internal Create a netCDF-4/NCZ file.
*
* @param path The file name of the new file.
* @param cmode The creation mode flag.
* @param initialsz The proposed initial file size (advisory)
* @param nc Pointer to an instance of NC.
*
* @return ::NC_NOERR No error.
* @return ::NC_EINVAL Invalid input (check cmode).
* @return ::NC_EEXIST File exists and NC_NOCLOBBER used.
* @return ::NC_EHDFERR ZARR returned error.
* @ingroup netcdf4
* @author Dennis Heimbigner, Ed Hartnett
*/
static int
ncz_create_file(const char *path, int cmode, size_t initialsz, NClist* controls, int ncid)
{
int retval = NC_NOERR;
NC_FILE_INFO_T* h5 = NULL;
assert(path);
LOG((3, "%s: path %s mode 0x%x", __func__, path, cmode));
/* Add necessary structs to hold netcdf-4 file data. */
if ((retval = nc4_file_list_add(ncid, path, cmode, (void**)&h5)))
BAIL(retval);
assert(h5 && h5->root_grp);
h5->root_grp->atts_read = 1;
h5->mem.inmemory = ((cmode & NC_INMEMORY) == NC_INMEMORY);
h5->mem.diskless = ((cmode & NC_DISKLESS) == NC_DISKLESS);
h5->mem.persist = ((cmode & NC_PERSIST) == NC_PERSIST);
/* Do format specific setup */
if((retval = ncz_create_dataset(h5,h5->root_grp,controls)))
BAIL(retval);
/* Define mode gets turned on automatically on create. */
h5->flags |= NC_INDEF;
/* Set provenance. */
if ((retval = NCZ_new_provenance(h5)))
BAIL(retval);
return NC_NOERR;
exit: /*failure exit*/
if(retval && h5)
ncz_closeorabort(h5, NULL, 1); /* treat like abort */
return retval;
}
/**
* @internal Create a netCDF-4/NCZ file.
*
* @param path The file name of the new file.
* @param cmode The creation mode flag.
* @param initialsz Ignored by this function.
* @param basepe Ignored by this function.
* @param chunksizehintp Ignored by this function.
* @param parameters pointer to struct holding extra data (e.g. for
* parallel I/O) layer. Ignored if NULL.
* @param dispatch Pointer to the dispatch table for this file.
* @param nc_file Pointer to an instance of NC.
*
* @return ::NC_NOERR No error.
* @return ::NC_EINVAL Invalid input (check cmode).
* @ingroup netcdf4
* @author Dennis Heimbigner, Ed Hartnett
*/
int
NCZ_create(const char* path, int cmode, size_t initialsz, int basepe,
size_t *chunksizehintp, void *parameters,
const NC_Dispatch *dispatch, int ncid)
{
int stat = NC_NOERR;
NCURI* uri = NULL;
ZTRACE(0,"path=%s,cmode=%d,initialsz=%ld,ncid=%d)",path,cmode,initialsz,ncid);
NC_UNUSED(parameters);
assert(path);
LOG((1, "%s: path %s cmode 0x%x ncid %d",
__func__, path, cmode ,ncid));
/* If this is our first file, initialize */
if (!ncz_initialized) NCZ_initialize();
#ifdef LOGGING
/* If nc logging level has changed, see if we need to turn on
* NCZ's error messages. */
NCZ_set_log_level();
#endif /* LOGGING */
/* Check the cmode for validity. */
if((cmode & ILLEGAL_CREATE_FLAGS) != 0)
{stat = NC_EINVAL; goto done;}
/* Turn on NC_WRITE */
cmode |= NC_WRITE;
/* Get the controls */
ncuriparse(path,&uri);
if(uri == NULL) goto done;
/* Create the file */
stat = ncz_create_file(path, cmode, initialsz, ncurifragmentparams(uri), ncid);
done:
ncurifree(uri);
return ZUNTRACE(stat);
}