if target blob already exists, migration will check the blob
if header is already with the targeted key (or no key if not ciphered) no need write
otherwise write the blob (that will convert any blob with no header into the correct version)
Round 3 of benchmark-gated optimizations (benches/ROUND3.md; every change
gated by a before/after benchmark — an AFTER that did not beat its BEFORE
was to be rolled back; none needed it. Equivalence gates assert identical
row sequences / byte-identical output on every behavior-preserving rewrite):
DB hot paths (local PG16, EXPLAIN-verified):
- Web-UI listing (list_resources_paged): cursor pushed INSIDE the
folders/files UNION-ALL branches as sargable row-value comparisons with
per-branch ORDER/LIMIT + two partial expression indexes
(folder_id, LOWER(name), id). 20k-entry folder: 26.6 -> 1.3 ms/page
(19.5x); other sort modes at parity or better. New migration
20260918000000. [benches/LISTING-KEYSET.md section in ROUND3]
- Photos timeline (list_media_files): per-drive CROSS JOIN LATERAL top-N
on the timeline index, joins moved above the top-N. 50k-photo library:
97.4 -> 1.6 ms/page (55.7x). The old "LIMIT stops the scan early"
comment was refuted by EXPLAIN.
- PROPFIND sub-folders (both DAV surfaces): keyset list_folders_batch off
idx_folders_unique_name replaces COUNT(*) OVER() + LIMIT/OFFSET
(5k dirs: 79.7 -> 17.9 ms full walk, 4.5x).
Concurrency:
- Basic-auth cache single-flight (moka try_get_with): 8 concurrent DAV
connections at TTL expiry paid 8 Argon2id runs (2.6 s CPU + 8x64 MiB);
now 1 (300 ms). Failed verifications remain uncached.
- CachedBlobBackend per-hash single-flight + unique tmp names: 16
concurrent cold readers = 16 full remote downloads racing truncating
writes on ONE deterministic .tmp (corruptible cache); now 1 download
(16x less egress, 2.8x wall on a shared link) and torn files can never
be renamed into the cache.
I/O and allocations:
- Chunk-assembly reads 64K -> 512K buffers (2.3x, 8x fewer syscalls);
chunk-spool writes via BufWriter 512K (5.6x, 32x fewer syscalls).
- S3/Azure put_blob_from_bytes_unsynced overrides: dedup settle no longer
pays a HEAD probe per new chunk (2 RTT -> 1, 1.8x); Azure stops copying
every chunk (Bytes -> Body, -0.44 ms - 4 MiB alloc per 4 MiB chunk).
- Entity->DTO mapping: Arc<str> interning of closed-set display fields +
common MIMEs, 1-alloc etag/size formatting, FolderDto moves instead of
clones. File row: 11 -> 4 allocs; folder row: 11.8 -> 1 (2.1x faster).
- CardDAV REPORT: deleted dead per-contact vCard pre-generation and the
O(N^2) uid scan whose result was discarded (5k contacts: 55.7 -> 5.7 ms,
9.8x); byte-identical XML asserted.
- Search-results cache: byte weigher + 32 MiB budget
(OXICLOUD_SEARCH_CACHE_MAX_BYTES) replaces the 1000-ENTRY cap that let
~300 MiB of enriched rows sit in RSS; read latency parity.
- Dropped aws-config + aws-smithy-types (zero references; -82 dep-graph
nodes, three SDK stacks gone from every build). tokio "process" is now
an explicit feature (was enabled transitively by aws-config).
Frontend:
- Cached Intl.DateTimeFormat keyed by (locale, options) in formatDate and
4 sibling callsites: 20k dates 2612 -> 51 ms (51.6x); vitest gate
asserts output identity across locales and a 3x floor.
Validation: cargo fmt + clippy --all-features --all-targets -D warnings
clean; 518 unit + 548 integration-cfg tests green; new-shape endpoints
smoke-tested end-to-end over HTTP (all 5 listing sort modes with cursor
walks, WebDAV PROPFIND Depth-1, photos timeline, Basic-auth DAV login);
frontend npm run check clean, new vitest gates green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EBsU2qEzny3A8WQUEuMNCr
read_blob_stream / read_blob_range_stream reassembled a CDC file by fetching
its chunks with `buffered(1)` — strictly sequential, so the next chunk's
backend fetch (a file `open` locally; a full request round-trip on S3/Azure)
only started after the current chunk was fully drained.
A benchmark of the exact pipeline (stream::iter(chunks).map(get).buffered(K)
.try_flatten()) showed a blind `buffered(4)` is the WRONG fix: on a local
disk it is neutral on a warm page cache and ~37% SLOWER cold, because
concurrent opens turn one sequential read into several competing random-I/O
streams over content-addressed (scattered) chunk files. The win is entirely
on remote backends, where per-chunk request latency dominates and overlapping
fetches hide it (≈ linear in K).
So the read-ahead depth is now a backend hint, not a constant:
- BlobStorageBackend::read_prefetch() default 1 (sequential; safe for local).
- S3 / Azure override to 8 (overlap GETs to hide TTFB).
- cached / encrypted / retry / migration delegate to the backend that serves
the bytes.
- Both CDC read paths use `self.backend.read_prefetch().max(1)`.
Net: local backend unchanged (no regression); remote reassembly ~4-8x faster.
Ordered `buffered` (not buffer_unordered) keeps chunks in sequence.
Bench (per-chunk fetch-latency model): buffered(1)->(4)/(8) = x3.9 / x7.8
@1ms, x4.0 / x8.1 @5ms, x4.0 / x8.0 @20ms. Local warm: 230ms@1 vs 227ms@4
(noise); local cold: 425ms@1 vs 585ms@4 (why local stays at 1).
https://claude.ai/code/session_01DCszkkU11LYxMEUWr4setK
Edouard Vanbelle