src_old/NEWS

#### H5PART 1.6 ##############################################################

Updated Documentation
---------------------

The Fortran API has been added to the doxygen documentation. Most entries have
a reference to their respective C API call.

Regression Test Suite
---------------------

The test subdirectory has been reorganized to include a systematic series
of regression tests of common use cases for the API. The goal is to have both
complete coverage of the API (every call is exercised) and testing of some
unlikely or unsuspected values and cases.

Currently, the C test covers the entire H5Part API and the Fortran test is
still in development.

Benchmark Utilities
-------------------

Two benchmarking utilities, H5PartBench and H5BlockBench, have been added to
the tools collection. Both require the parallel library and have functionality
and syntax similar to the IOR benchmark:

  http://sourceforge.net/projects/ior-sio/

File Mode Flags
---------------

Previously, the only flags used were H5PART_READ, H5PART_WRITE, and
H5PART_APPEND, and these were mutually exclusive. Additional flags have been
added to select the underlying virtual file driver (VFD) that HDF5 uses in
parallel mode and to accommodate the lustre filesystem:

H5PART_VFD_MPIPOSIX (use the MPI-POSIX driver, which bypasses MPI-IO)
H5PART_VFD_MPIIO_IND (use MPI-IO in independent mode)
H5PART_FS_LUSTRE (activate H5P tunings for the lustre stripe size)

These flags can be specified using the typical bitwise OR method, e.g.

  char flag = H5PART_WRITE | H5PART_VFD_MPIPOSIX | H5PART_FS_LUSTRE;

will select write mode with these two additional options.

The parallel library now defaults to using the MPI-IO collective mode driver
(previously it used independent mode). The collective buffering algorithm in
the Cray XT4/5 environment has been substantially improved in the last year,
and defaulting to collective mode allows us to take advantage of these
improvements automatically.

There are also new open calls H5PartOpenAlign and H5PartOpenParallelAlign that
take an additional 'alignment' value. This value is passed to HDF5 and used to
pad out objects so that they align to filesystem boundaries. For instance, it
would make sense to use the stripe size as the alignment value when writing to
a lustre filesystem.

Unified 'View' Model
--------------------

Views are now supported in both read and write mode (previously only supported
in read mode). It is possible to specify non-sensical views: you could for
instance specify a read view that is larger than the dataset on disk. Or you
could create a write view that is larger than the data in memory. In those
cases, you will encounter an error when you try to perform a read or write
operation on a dataset.

There are two new methods for selecting views. H5PartSetNumParticlesStrided
selects a view with $n$ particles per processor, but such that the data in
memory is expected to have a 'stride' factor. For instance, if you have
particle data with fields $x$ and $y$ and a single array with entries
$x1,y1,x2,y2...$, then the stride factor is 2. Striding works for both reads
and writes and only affects the view of memory: individual fields are still
stored as individual arrays on disk.

The second new method is H5PartSetViewIndices, which allows for point
selections of datasets. You can pass a list of indices for the points you
want to select. This is useful, for instance, when interfacing with FastBit
to perform queries that select a small subset of non-contiguous particles.

Because views are now supported on write, it is possible to write a dataset
using multiple 'passes' or to leave some values unwritten.

Internal Handling of Dataspaces
-------------------------------

H5PartSetNumParticles and H5PartSetNumParticlesStrided now share the same
HDF5 dataspace state in the H5PartFile struct with the calls that modify
the view (H5PartSetView etc.). Previously, the memory and disk dataspaces
were regenerated from the view on every read access, which was unnecessary.

Autogeneration of API Calls
---------------------------

Python scripts have been added to automatically generate read/write call
variants for different data types.

Renamed Fortran Include
-----------------------

The automake system no longer greps the *F90.inc files to generate an include
called 'H5Part.inc'. Instead, the *F90.inc files have been renamed to *.f90,
and awk is used to generate an 'H5PartF.h' file (the same naming convention
as in MPI's 'mpif.h').

The change to *.f90 was necessary to facilitate integration of the Fortran
API into doxygen. Note that the *.f90 files will not compile, nor can they
be included directly. Simply use

  include 'H5PartF.h'

in your Fortran code to include all the definitions for Fortran H5Part/H5Block
calls.

64 Char Limit on Dataset Names
------------------------------

Previously, a user could overrun internal buffers for dataset names. Now, a
fixed limit of 64 chars is imposed. Dataset names that are longer than this are
truncated and a warning is printed. We expect that most users are using
short canoncical names like x, px, id, etc.


#### H5PART 1.4 ##############################################################

Error Handling
--------------
 Now all functions, in which an error could occure, are returning a
value. This value is either a 64bit integer or a pointer.

 A negative 64bit integer as result indicates an error. Values >= 0
indicates successfull execution.   This is similiar to the convention
used in UNIX system calls, but we do not return -1 but the error
number (which is always negative).

 For functions returning a pointer the NULL-pointer is used to indicate
an error. You can call the function H5PartGetErrno() to get the error
number.  For the time being there is no strerror(3) or perror(3)
equivalent. 


API Changes
-----------
 There are several changes in the API of H5Part. The biggest change is
a side-effect of the implementation of strict error handling.  The
impact to the existing C/C++ code is very small.  But now you *can*
and *should* implement some kind of error handling.  The simplest
error handling is to set an error handler which aborts the program as
soon as an error occured.

 The next "biggest" change is the use of H5Part types instead of "long
long" and "double". The replacement of "long long" is "h5part_int64_t"
and for "double" "h5part_float64_t". This change has now effect in
Fortran.  

 In some functions the argument type changed from "int" to
"h5part_int64_t". Since on most systems "int" is a 32bit integer,
calls to these functions must be adapted to the new API. In C/C++ the
compiler will complain about it. But in Fortran you will *not* get an
error message.So, you must check your Fortran code carefully.

 Changes in detail (not listed are functions where only the return
type changed from any to "h5part_int64_t"):

	New API					Changes to old API

	h5part_int64_t				void
	H5PartSetNumParticles (
		H5PartFile *f,
		h5part_int64_t nparticles	long long
		);

	h5part_int64_t				int
	H5PartWriteDataFloat64 (
		H5PartFile *f,
		char *name, 
		h5part_float64_t *dta		double
		);

	h5part_int64_t				int
	H5PartWriteDataInt64 (
		H5PartFile *f,
		char *name,
		h5part_int64_t *dta		long long
		);

	h5part_int64_t				void
	H5PartSetStep (
		H5PartFile *f,
		h5part_int64_t step		int
		);

	h5part_int64_t				void
	H5PartSetView (
		H5PartFile *f,
		h5part_int64_t start,		long long
		h5part_int64_t end		long long
		);

	h5part_int64_t				int
	H5PartGetView (
		H5PartFile *f,
		h5part_int64_t *start,		long long
		h5part_int64_t *end		long long
		);

	h5part_int64_t				int
	H5PartReadDataFloat64 (
		H5PartFile *f,
		char *name,
		h5part_float64_t *dta		double
		);

	h5part_int64_t				int
	H5PartReadDataInt64 (
		H5PartFile *f,
		char *name,
		h5part_int64_t *dta		long long
		);
    
	h5part_int64_t				void
	H5PartReadParticleStep (		
		H5PartFile *f,
		h5part_int64_t step,		int
		h5part_float64_t *x,		double
		h5part_float64_t *y,		double
		h5part_float64_t *z,		double
		h5part_float64_t *px,		double
		h5part_float64_t *py,		double
		h5part_float64_t *pz,		double
		h5part_int64_t *id		long long
		);

New functions:

	h5part_int64_t
	H5PartSetVerbosityLevel (
		unsigned int
		);

	h5part_int64_t
	H5PartSetErrorHandler ( 
		h5part_error_handler handler
		);

	h5part_int64_t
	H5PartGetErrno (
		void
		);

	h5part_int64_t
	H5PartDefaultErrorHandler (
		const char *funcname,
		const h5part_int64_t eno,
		const char *fmt,
		...
		);

	h5part_int64_t
	H5PartAbortErrorHandler (
		const char *funcname,
		const h5part_int64_t eno,
		const char *fmt,
		...
		);

Removed functions:

	int
	H5PartFileIsValid (
		H5PartFile *f
		);