* feat(ecstore): add stripe-advance handles for deferred bitrot readers
Give DeferredObjectReader a shared pending state and expose a
DeferredReaderStripeHandle that advances the still-unopened source by whole
bitrot blocks using the same bitrot_encoded_range geometry the reader was
created with (identity mapping when hash_size == 0). This lets the GET decode
path open a parity shard aligned to the stripe where a data shard failed
instead of reading every parity shard on every stripe (backlog#923).
An already-opened (or failed) reader rejects the advance so callers retire it
rather than engage it out of alignment; bitrot verification after an advance
checks the advanced stripe's block against that stripe's stored hash.
Co-Authored-By: heihutu <heihutu@gmail.com>
* perf(ecstore): read only data shards on healthy lockstep GET behind opt-in gate
PR #4289's lockstep fix made every reconstruction-verifying GET read all
data+parity shards per stripe; the parity blocks are read, bitrot-hashed and
then discarded, a deterministic 2x read-bytes/IOPS/hash-CPU amplification on
healthy 2+2 objects (backlog#923). With the new opt-in gate
RUSTFS_GET_LOCKSTEP_DATA_SHARDS_ONLY_ENABLE=true (default: false, behavior
identical to main):
- read_lockstep keeps only the data slots engaged while the object is
healthy; parity slots stay unopened deferred readers.
- When a data shard is missing or dies at stripe k, parity readers are
engaged mid-object by advancing their deferred stripe handle to stripe k,
preserving the lockstep alignment invariant from backlog#832.
- Degraded stripes engage one parity beyond the decode quorum so
reconstruction verification keeps an extra source to check against
(erasure.rs only verifies when available > data shards); an engaged parity
reader that errors is retired for the rest of the object like any other,
and a parity reader that cannot be realigned is retired instead of being
read out of position.
- fill_deferred_bitrot_readers records stripe handles for deferred slots and,
gate-on only, swaps eagerly opened parity readers for unopened deferred
ones so they remain engageable mid-object; ready/error bookkeeping used by
quorum decisions is untouched.
- Both GET paths (legacy duplex via Erasure::decode_with_stripe_handles,
codec streaming via ParallelReader::with_deferred_parity_handles) carry the
handles from reader setup.
Short-read -> UnexpectedEof -> whole-object retirement and the
inconsistent-source rejection are unchanged in both gate modes; tests lock
the healthy-path data-shards-only call counts, the default read-all-shards
behavior, mid-object parity engagement for streaming and hash_size==0
formats, and mid-stream inconsistent-parity rejection.
Co-Authored-By: heihutu <heihutu@gmail.com>
---------
Co-authored-by: heihutu <heihutu@gmail.com>
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