This commit adds three new tests:
- a test documenting the limitation originally reported in #350 (in
general modifying an attribute about 2^16 times makes it impossible
to modify this file in ways requiring nc_redef() and nc_enddef() calls).
- a test ensuring that a scalar attribute can be modified 2^16 times
as long as its type and size remain the same
- a test ensuring that a text attribute can be modified 2^16 times as
long as its size remains the same
This version uses the nc_redef(), nc_put_att_...(), nc_enddef()
sequence. One could also use nc_open(), nc_put_att_...(), nc_close()
but that would make these tests significantly slower.
The file docs/indexing.dox tries to provide design
information for the refactoring.
The primary change is to replace all walking of linked
lists with the use of the NCindex data structure.
Ncindex is a combination of a hash table (for name-based
lookup) and a vector (for walking the elements in the index).
Additionally, global vectors are added to NC_HDF5_FILE_INFO_T
to support direct mapping of an e.g. dimid to the NC_DIM_INFO_T
object. These global vectors exist for dimensions, types, and groups
because they have globally unique id numbers.
WARNING:
1. since libsrc4 and libsrchdf4 share code, there are also
changes in libsrchdf4.
2. Any outstanding pull requests that change libsrc4 or libhdf4
are likely to cause conflicts with this code.
3. The original reason for doing this was for performance improvements,
but as noted elsewhere, this may not be significant because
the meta-data read performance apparently is being dominated
by the hdf5 library because we do bulk meta-data reading rather
than lazy reading.
(I hope) metadata mechanism. This mostly just adds new pieces of
code (e.g. nclistmap) and does some minor fixes.
It should be transparent to everything else.
The next set of changes will be the big step.
