nc.c

一个用来实现偏微分方程中网格的计算库

static int
fill_added(NC *gnu, NC *old)
{
	NC_var ** const gnu_varpp = (NC_var **)gnu->vars.value;
	int varid = (int)old->vars.nelems;

	for(; varid < (int)gnu->vars.nelems; varid++)
	{
		const NC_var *const gnu_varp = *(gnu_varpp + varid);
		if(IS_RECVAR(gnu_varp))
		{
			/* skip record variables */
			continue;
		}
		/* else */
		{
		const int status = fill_NC_var(gnu, gnu_varp, gnu_varp->len, 0);
		if(status != NC_NOERR)
			return status;
		}
	}

	return NC_NOERR;
}


/*
 * Move the records "out". 
 * Fill as needed.
 */
static int
move_recs_r(NC *gnu, NC *old)
{
	int status;
	int recno;
	int varid;
	NC_var **gnu_varpp = (NC_var **)gnu->vars.value;
	NC_var **old_varpp = (NC_var **)old->vars.value;
	NC_var *gnu_varp;
	NC_var *old_varp;
	off_t gnu_off;
	off_t old_off;
	const size_t old_nrecs = NC_get_numrecs(old);
	
	/* Don't parallelize this loop */
	for(recno = (int)old_nrecs -1; recno >= 0; recno--)
	{
	/* Don't parallelize this loop */
	for(varid = (int)old->vars.nelems -1; varid >= 0; varid--)
	{
		gnu_varp = *(gnu_varpp + varid);
		if(!IS_RECVAR(gnu_varp))
		{
			/* skip non-record variables on this pass */
			continue;
		}
		/* else */

		/* else, a pre-existing variable */
		old_varp = *(old_varpp + varid);
		gnu_off = gnu_varp->begin + (off_t)(gnu->recsize * recno);
		old_off = old_varp->begin + (off_t)(old->recsize * recno);

		if(gnu_off == old_off)
			continue; 	/* nothing to do */

		assert(gnu_off > old_off);
	
		status = gnu->nciop->move(gnu->nciop, gnu_off, old_off,
			 old_varp->len, 0);

		if(status != NC_NOERR)
			return status;
		
	}
	}

	NC_set_numrecs(gnu, old_nrecs);

	return NC_NOERR;
}


/*
 * Move the "non record" variables "out". 
 * Fill as needed.
 */
static int
move_vars_r(NC *gnu, NC *old)
{
	int status;
	int varid;
	NC_var **gnu_varpp = (NC_var **)gnu->vars.value;
	NC_var **old_varpp = (NC_var **)old->vars.value;
	NC_var *gnu_varp;
	NC_var *old_varp;
	off_t gnu_off;
	off_t old_off;
	
	/* Don't parallelize this loop */
	for(varid = (int)old->vars.nelems -1;
		 varid >= 0; varid--)
	{
		gnu_varp = *(gnu_varpp + varid);
		if(IS_RECVAR(gnu_varp))
		{
			/* skip record variables on this pass */
			continue;
		}
		/* else */

		old_varp = *(old_varpp + varid);
		gnu_off = gnu_varp->begin;
		old_off = old_varp->begin;
	
		if(gnu_off == old_off)
			continue; 	/* nothing to do */

		assert(gnu_off > old_off);

		status = gnu->nciop->move(gnu->nciop, gnu_off, old_off,
			 old_varp->len, 0);

		if(status != NC_NOERR)
			return status;
		
	}

	return NC_NOERR;
}


/*
 * Given a valid ncp, return NC_EVARSIZE if any variable has a bad len 
 * (product of non-rec dim sizes too large), else return NC_NOERR.
 */
static int
NC_check_vlens(NC *ncp)
{
    NC_var **vpp;
    /* maximum permitted variable size (or size of one record's worth
       of a record variable) in bytes.  This is different for format 1
       and format 2. */
    size_t vlen_max;
    size_t ii;
    size_t large_vars_count;
    size_t rec_vars_count;
    int last = 0;

    if(ncp->vars.nelems == 0) 
	return NC_NOERR;

    if ((ncp->flags & NC_64BIT_OFFSET) && sizeof(off_t) > 4) {
	/* CDF2 format and LFS */
	vlen_max = X_UINT_MAX - 3; /* "- 3" handles rounded-up size */
    } else {
	/* CDF1 format */
	vlen_max = X_INT_MAX - 3;
    }
    /* Loop through vars, first pass is for non-record variables.   */
    large_vars_count = 0;
    rec_vars_count = 0;
    vpp = ncp->vars.value;
    for (ii = 0; ii < ncp->vars.nelems; ii++, vpp++) {
	if( !IS_RECVAR(*vpp) ) {
	    last = 0;
	    if( NC_check_vlen(*vpp, vlen_max) == 0 ) {
		large_vars_count++;
		last = 1;
	    }
	} else {
	  rec_vars_count++;
	}
    }
    /* OK if last non-record variable size too large, since not used to 
       compute an offset */
    if( large_vars_count > 1) { /* only one "too-large" variable allowed */
      return NC_EVARSIZE;
    }
    /* and it has to be the last one */ 
    if( large_vars_count == 1 && last == 0) { 
      return NC_EVARSIZE;
    }
    if( rec_vars_count > 0 ) {
	/* and if it's the last one, there can't be any record variables */
	if( large_vars_count == 1 && last == 1) {
	    return NC_EVARSIZE;
	}
	/* Loop through vars, second pass is for record variables.   */
	large_vars_count = 0;
	vpp = ncp->vars.value;
	for (ii = 0; ii < ncp->vars.nelems; ii++, vpp++) {
	    if( IS_RECVAR(*vpp) ) {
		last = 0;
		if( NC_check_vlen(*vpp, vlen_max) == 0 ) {
		    large_vars_count++;
		    last = 1;
		}
	    }
	}
	/* OK if last record variable size too large, since not used to 
	   compute an offset */
	if( large_vars_count > 1) { /* only one "too-large" variable allowed */
	    return NC_EVARSIZE;
	}
	/* and it has to be the last one */ 
	if( large_vars_count == 1 && last == 0) { 
	    return NC_EVARSIZE;
	}
    }
    return NC_NOERR;
}


/*
 *  End define mode.
 *  Common code for ncendef, ncclose(endef)
 *  Flushes I/O buffers.
 */
static int
NC_endef(NC *ncp,
	size_t h_minfree, size_t v_align,
	size_t v_minfree, size_t r_align)
{
	int status = NC_NOERR;

	assert(!NC_readonly(ncp));
	assert(NC_indef(ncp));

	status = NC_check_vlens(ncp);
	if(status != NC_NOERR)
	    return status;
	status = NC_begins(ncp, h_minfree, v_align, v_minfree, r_align);
	if(status != NC_NOERR)
	    return status;

	if(ncp->old != NULL)
	{
		/* a plain redef, not a create */
		assert(!NC_IsNew(ncp));
		assert(fIsSet(ncp->flags, NC_INDEF));
		assert(ncp->begin_rec >= ncp->old->begin_rec);
		assert(ncp->begin_var >= ncp->old->begin_var);

		if(ncp->vars.nelems != 0)
		{
		if(ncp->begin_rec > ncp->old->begin_rec)
		{
			status = move_recs_r(ncp, ncp->old);
			if(status != NC_NOERR)
				return status;
			if(ncp->begin_var > ncp->old->begin_var)
			{
				status = move_vars_r(ncp, ncp->old);
				if(status != NC_NOERR)
					return status;
			} 
			/* else if (ncp->begin_var == ncp->old->begin_var) { NOOP } */
		}
		else
		{	/* Even if (ncp->begin_rec == ncp->old->begin_rec)
			   and     (ncp->begin_var == ncp->old->begin_var)
			   might still have added a new record variable */
		        if(ncp->recsize > ncp->old->recsize)
			{
			        status = move_recs_r(ncp, ncp->old);
				if(status != NC_NOERR)
				      return status;
			}
		}
		}
	}

	status = write_NC(ncp);
	if(status != NC_NOERR)
		return status;

	if(NC_dofill(ncp))
	{
		if(NC_IsNew(ncp))
		{
			status = fillerup(ncp);
			if(status != NC_NOERR)
				return status;
			
		}
		else if(ncp->vars.nelems > ncp->old->vars.nelems)
		{
			status = fill_added(ncp, ncp->old);
			if(status != NC_NOERR)
				return status;
			status = fill_added_recs(ncp, ncp->old);
			if(status != NC_NOERR)
				return status;
		}
	}

	if(ncp->old != NULL)
	{
		free_NC(ncp->old);
		ncp->old = NULL;
	}

	fClr(ncp->flags, NC_CREAT | NC_INDEF);

	return ncp->nciop->sync(ncp->nciop);
}

#ifdef LOCKNUMREC
static int
NC_init_pe(NC *ncp, int basepe) {
	if (basepe < 0 || basepe >= _num_pes()) {
		return NC_EINVAL; /* invalid base pe */
	}
	/* initialize common values */
	ncp->lock[LOCKNUMREC_VALUE] = 0;
	ncp->lock[LOCKNUMREC_LOCK] = 0;
	ncp->lock[LOCKNUMREC_SERVING] = 0;
	ncp->lock[LOCKNUMREC_BASEPE] =  basepe;
	return NC_NOERR;
}
#endif


/*
 * Compute the expected size of the file.
 */
int
NC_calcsize(NC *ncp, off_t *calcsizep)
{
	NC_var **vpp = (NC_var **)ncp->vars.value;
	NC_var *const *const end = &vpp[ncp->vars.nelems];
	NC_var *last_fix = NULL;	/* last "non-record" var */
	NC_var *last_rec = NULL;	/* last "record" var */
	/*NC_var *last_var;*/
	int status;
	int numrecvars = 0;	/* number of record variables */

	if(ncp->vars.nelems == 0) { /* no non-record variables and 
				       no record variables */
	    *calcsizep = ncp->xsz; /* size of header */
	    return NC_NOERR;
	}

	for( /*NADA*/; vpp < end; vpp++) {
	    status = NC_var_shape(*vpp, &ncp->dims);
	    if(status != NC_NOERR)
		return status;
	    if(IS_RECVAR(*vpp)) {
		last_rec = *vpp;
		numrecvars++;
	    } else {
		last_fix = *vpp;
	    }
	}

	if(numrecvars == 0) {
	    assert(last_fix != NULL);
	    *calcsizep = last_fix->begin + last_fix->len;
	    /*last_var = last_fix;*/
	} else {       /* we have at least one record variable */
	    *calcsizep = ncp->begin_rec + ncp->numrecs * ncp->recsize;
	    /*last_var = last_rec;*/
	}

	return NC_NOERR;
}

/* Public */

int
nc__create(const char * path, int ioflags, size_t initialsz,
	size_t *chunksizehintp, int *ncid_ptr)
{
	return nc__create_mp(path, ioflags, initialsz, 0,
		chunksizehintp, ncid_ptr);
}

int
nc__create_mp(const char * path, int ioflags, size_t initialsz, int basepe,
	size_t *chunksizehintp, int *ncid_ptr)
{
	NC *ncp;
	int status;
	void *xp = NULL;
	int sizeof_off_t = 0;

#if ALWAYS_NC_SHARE /* DEBUG */
	fSet(ioflags, NC_SHARE);
#endif

	ncp = new_NC(chunksizehintp);
	if(ncp == NULL)
		return NC_ENOMEM;

#if defined(LOCKNUMREC) /* && _CRAYMPP */
	if (status = NC_init_pe(ncp, basepe)) {
		return status;
	}
#else
	/*
	 * !_CRAYMPP, only pe 0 is valid
	 */
	if(basepe != 0)
		return NC_EINVAL;
#endif

	assert(ncp->flags == 0);

	/* Apply default create format. */
	if (default_create_format == NC_FORMAT_64BIT)
	  ioflags |= NC_64BIT_OFFSET;

	if (fIsSet(ioflags, NC_64BIT_OFFSET)) {
	  fSet(ncp->flags, NC_64BIT_OFFSET);
	  sizeof_off_t = 8;
	} else {
	  sizeof_off_t = 4;
	}

	assert(ncp->xsz == ncx_len_NC(ncp,sizeof_off_t));
	
	status = ncio_create(path, ioflags,
		initialsz,
		0, ncp->xsz, &ncp->chunk,
		&ncp->nciop, &xp);
	if(status != NC_NOERR)
	{
		/* translate error status */
		if(status == EEXIST)
			status = NC_EEXIST;
		goto unwind_alloc;
	}

	fSet(ncp->flags, NC_CREAT);

	if(fIsSet(ncp->nciop->ioflags, NC_SHARE))
	{
		/*
		 * NC_SHARE implies sync up the number of records as well.
		 * (File format version one.)
		 * Note that other header changes are not shared
		 * automatically.  Some sort of IPC (external to this package)
		 * would be used to trigger a call to nc_sync().
		 */
		fSet(ncp->flags, NC_NSYNC);
	}

	status = ncx_put_NC(ncp, &xp, sizeof_off_t, ncp->xsz);
	if(status != NC_NOERR)
		goto unwind_ioc;

	add_to_NCList(ncp);

	if(chunksizehintp != NULL)
		*chunksizehintp = ncp->chunk;
	*ncid_ptr = ncp->nciop->fd;
	return NC_NOERR;

unwind_ioc:
	(void) ncio_close(ncp->nciop, 1); /* N.B.: unlink */
	ncp->nciop = NULL;
	/*FALLTHRU*/
unwind_alloc:
	free_NC(ncp);
	return status;
}

/* This function sets a default create flag that will be logically
   or'd to whatever flags are passed into nc_create for all future
   calls to nc_create.
   Valid default create flags are NC_64BIT_OFFSET, NC_CLOBBER,
   NC_LOCK, NC_SHARE. */
int
nc_set_default_format(int format, int *old_formatp)
{
    /* Return existing format if desired. */
    if (old_formatp)
      *old_formatp = default_create_format;

    /* Make sure only valid format is set. */
#ifdef USE_NETCDF4
    if (format != NC_FORMAT_CLASSIC && format != NC_FORMAT_64BIT &&
	format != NC_FORMAT_NETCDF4 && format != NC_FORMAT_NETCDF4_CLASSIC)
      return NC_EINVAL;
#else
    if (format != NC_FORMAT_CLASSIC && format != NC_FORMAT_64BIT)
      return NC_EINVAL;
#endif
    default_create_format = format;
    return NC_NOERR;
}

int
nc_create(const char * path, int ioflags, int *ncid_ptr)
{
	return nc__create(path, ioflags, 0, NULL, ncid_ptr);
}

int
nc__open(const char * path, int ioflags,
	size_t *chunksizehintp, int *ncid_ptr)
{
	return nc__open_mp(path, ioflags, 0,
		chunksizehintp, ncid_ptr);
}

int
nc__open_mp(const char * path, int ioflags, int basepe,
	size_t *chunksizehintp, int *ncid_ptr)
{
	NC *ncp;
	int status;

#if ALWAYS_NC_SHARE /* DEBUG */
	fSet(ioflags, NC_SHARE);
#endif

	ncp = new_NC(chunksizehintp);
	if(ncp == NULL)
		return NC_ENOMEM;

#if defined(LOCKNUMREC) /* && _CRAYMPP */
	if (status = NC_init_pe(ncp, basepe)) {
		return status;
	}
#else
	/*
	 * !_CRAYMPP, only pe 0 is valid
	 */
	if(basepe != 0)
		return NC_EINVAL;
#endif

	status = ncio_open(path, ioflags,
		0, 0, &ncp->chunk,
		&ncp->nciop, 0);
	if(status)
		goto unwind_alloc;

	assert(ncp->flags == 0);

	if(fIsSet(ncp->nciop->ioflags, NC_SHARE))