The per-file report now separates a tree view (open, every group's
entries, every dataset's shape and type) from reading the largest
dataset under 64 MiB, and checks the budget the design's testing section
asks for: listing the IMERG file (file A of docs/design/range-reads.md
section 2) takes at most 3 requests when CLAWHDF5_REMOTE_CORPUS includes
it. The test server now counts a response's bytes before sending it: a
client could read a body and reset the counters before the server thread
had added it, so the counts of the next file were occasionally too high.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Range-read milestone M3, first half: a new crate with the block cache the
design makes mandatory for remote files and an HTTP backend, so
open_url("http://...") gives a clawhdf5::File over File::open_storage.
BlockCache wraps any Storage: aligned blocks (1 MiB by default, the size
docs/design/range-reads.md section 2 measured), LRU with a byte budget,
the missing blocks of one read_at/read_ranges fetched with one backend
read_ranges call as runs of consecutive blocks (a one-block gap filled to
merge runs, each request at most 8 MiB), and reads that miss more than
half the budget not kept. Thread-safe without holding the lock across a
fetch: a block being fetched is in flight, a second reader waits for it
instead of fetching it again, and a failed fetch fails its waiters and is
not cached. A backend holding the file in memory passes through.
HttpStorage (ureq, no TLS by default; `https` adds rustls with ring):
opening is one ranged GET of the first block, whose Content-Range gives
the length (the cache keeps the bytes). The file is pinned by a strong
ETag (If-Match), else Last-Modified (If-Unmodified-Since), and its length,
checked on every response: a change is RemoteError::FileChanged, never
mixed data. A server that ignores Range is refused without reading the
body unless a full download is allowed. Connection errors, timeouts,
408/429/5xx and short bodies are retried with exponential backoff;
Accept-Encoding: identity, and an encoded body is refused. read_ranges
fetches its ranges in parallel.
Tests (a std-only HTTP/1.1 server in tests/common/server.rs, also the
range_server example): every fixture read over HTTP gives File::open's
transcript (CLAWHDF5_REMOTE_CORPUS adds the conformance corpus), with
request counts per file with and without the cache; an h5py-written file
against libhdf5's values; a multi-block file fetched in whole blocks, each
once; a server ignoring Range; a file replaced mid-read (ETag,
Last-Modified, length only); truncated bodies and 503s (retried, then an
error, never cached); a slow server with 8 concurrent readers (no block
fetched twice); bad URLs, 404, encoded bodies, non-HDF5 data. The cache
has unit tests for coalescing, splitting, LRU order, large reads,
failures and concurrent in-flight dedup.
ci-test.sh: clawhdf5-remote joins the no-C default-build check, and its
https feature is linted.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
