read_string, read_string_bytes, read_string_selection, read_vlen and
read_vlen_selection now retry as a whole, the global-heap decoding after the
read included; so do File::decode_strings / decode_string_bytes /
decode_vlen, Group::datasets / groups / attrs / attr, Dataset::attrs / attr,
the typed full reads (read_f64 ...), the header messages behind shape() and
dtype() (a shared message is read from another header), and
verify_provenance. Before, a transient failure on those reached the caller.
Attribute reads leave out an attribute they cannot read (or return a
variable-length string one as AttrValue::Raw) instead of failing, which hid
a transient error as a missing or raw attribute: on a live file such an
error of a retried kind now runs the read again too, and after the last
attempt the last result is returned as before. The format crate gains
find_attribute_reporting_in, which returns the errors find_attribute_in
skips (dense name-index lookups dropped them). The zero-copy reads need the
file in memory, which a live file never is, so they have nothing to retry.
Test: a storage that fails one read with a checksum mismatch; for 14 read
paths over a new fixture (tests/fixtures/swmr_strings_attrs.h5, an h5py
copy with the SWMR-write flag: vlen strings, vlen int32, dense attributes),
each read the path makes fails once in turn and the path must return the
same result with exactly one retry. It fails on the previous commit
(root.attrs, read 0). Dataset::attr on dense attributes returned None
before find_attribute_reporting_in.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
The README example looped while swmr_writer_active(), which never ends when
the writer crashed or was killed: libhdf5 clears the SWMR-write flag only on
close (the mid-write fixture keeps it set for good). The loop now also stops
after a minute without growth, and the README, the swmr_writer_active docs
(with the same loop as a compiled no_run doctest) and the design say why.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
is_transient_format counted every format error but a handful as transient,
so on an open_swmr handle a permanent failure (a file that is not HDF5, an
unsupported version or message, a truncated file) was retried 100 times,
about 0.9 s of pauses per failing operation. Now only these are retried:
a checksum mismatch; a read past the file's current end (UnexpectedEof;
libhdf5 reads zeros there, which fail the checksum); and an object header
prefix whose signature or version does not decode, which libhdf5's
H5C__load_entry also retries (a header garbled whole fails there before its
checksum). Everything else is returned at once.
Tests: a unit test that every permanent kind returns after one call within
50 ms and every transient kind is retried to the limit; open_storage_swmr
of a non-HDF5 buffer returns SignatureNotFound within 100 ms (0.87 s before)
and a missing name on a live file fails without retries. The torn-read and
live h5py-writer tests still pass.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
A file opened with open_swmr whose superblock does not have the SWMR-write
flag (its writer has closed it) is now read exactly as File::open reads it:
bounded by its recorded end of file, through the chunk cache, each
operation tried once, and is_swmr_read() is false. Before, every file opened
with open_swmr ignored its recorded end of file, so a closed file whose end
of file is below its length (h5clear_fsm_persist_less.h5, or the mid-write
fixture with its flags cleared) listed and read objects that File::open and
libhdf5's plain reader refuse. Opening such a file is not retried once the
superblock has been read.
libhdf5's SWMR reader is looser than either (it reads the fixture's chunk
index past the end of file even with the flags cleared); a test pins what
h5py does and docs/design/swmr.md says why we follow the plain reader.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
libhdf5's SWMR semantics as they matter to a reader (superblock v3 with
the SWMR-write flag and a stale EOF, append-only writer, flush
dependencies, refresh, 100 metadata read attempts), what clawhdf5 did
with such files, and the plan: data_end bounded by the file length for
SWMR-flagged files, a live File::open_swmr over positioned reads without
the chunk cache, Dataset::refresh, and bounded whole-operation retries.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
