ff6c313bab26746c5f820f139d589ebd1b951a88
4
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 dtourolle
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4168d67cfa |
Do not push a catalog over one we could not read
`sync_catalog` is a read-modify-write over a file another device also
writes: take theirs, merge, push the union. It was shaped
if let Ok(bytes) = backend.get(&RemoteId::Path(target), None).await {
which folds *every* failure into "there is no remote catalog" and carries
straight on to the upload. On a placeholder library the snapshot in
`.darkroom-derived/` is dehydrated like anything else, so the read failed
every time and each sync pushed our catalog over theirs unmerged —
taking the other device's collections and their members with it.
The same shape as the sidecar bug, and the same fix: a read that fails
for anything other than `NotFound` stops the upload and says why. An
unreadable or unopenable snapshot stops it too — "will not parse" is not
"is not there". This is what `NotFound` and `NotMaterialised` being
separate errors is *for*: one means ours is the whole truth, the other
means do not dare.
Shard downloads go through the same fetch-on-demand read. They logged
and skipped before, which on a library the client keeps dehydrated is
every shard, every pass, and a peer's thumbnails and faces silently
never arriving.
And `put` over a placeholder now replaces it rather than refusing.
Refusing was over-cautious of me: derived state lives inside the library
folder, so a folder the client had dehydrated could never be written to
again. An unconditional write replaces the whole file, so there is
nothing in the stub to keep — content first, then the placeholder, since
in a synced tree an absence is a deletion that propagates. `IfMatch`
still refuses, because a stub's validator describes the stub; `IfAbsent`
fails, because the file is there and only its content is not.
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dtourolle
|
5768100816 |
Borrow the library to index it, and give it back
The passes that need every photograph's bytes — thumbnails, face indexing — now borrow each one and release it at the end. On a placeholder library that is the difference between peak disk being the working set and being the whole library. Including on cancellation, which was nearly missed: the face sweep returns mid-loop when the user presses Stop, and without releasing there the disk is spent and nothing is delivered for it. `materialise` now answers whether *it* fetched the content. The pool used to work that out by listing a file's parent directory — one listing per file across a library — when the backend already had to `stat` it to decide whether to ask. One syscall instead of a directory walk, and it removes the bug class the tests found earlier: a file at the library root has no `parent()`, so every one of them read as already-downloaded. **Pinning is the retention control**, and it drives the model the catalog already had rather than a second one. `tier_desired` is what the user asked to keep hydrated, `pending_pins` is the resumable work list, and a pinned collection is never dehydrated for the same reason it was never evicted. It was in fact *broken* here before: `get` on a stub failed, and the pin worker logged "one unreadable file must not abandon the whole pin" and silently did nothing. Pinned originals on such a library are recorded with `path = NULL` (`Cache::record_in_place`) rather than copied under `originals/`. Two reasons, and the second is the important one. A copy would hold every pinned photograph twice, with the budget able to evict the half that was not costing the disk. And `release` deletes the file a row names — so a row that names none cannot delete anything, which puts the one catastrophic operation out of reach by construction rather than by remembering not to call it. Deleting a materialised file inside a synced tree removes the photograph from the server and every other device. Handing disk back is `spawn_dehydrate`, which asks the client. Two gaps written down rather than papered over (docs/storage.md §7): a hydrating pass cannot yet quote its cost, because a stub reports no size; and the two sweeps hold separate pools, so a library indexed for both fetches twice. |
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|
dtourolle
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c102ba9df2 |
Treat a placeholder as the photograph, not as a one-byte file
The folder connector was pointed at a Nextcloud VFS tree and got three things wrong, the first of which loses work. **A dehydrated sidecar read as absent.** `a.drsc` does not exist when the client has dehydrated it — only `a.drsc.nextcloud` does — so `get` missed, `.ok()` swallowed the `NotFound`, and the sidecar writer took that for "there is no sidecar yet" and wrote a fresh document over the existing one. Every edit another device had put there went with it. That function's own doc comment calls this the exact loss the format's unknown-key preservation exists to prevent. **A stub was catalogued as a 1-byte image**, and ARCH §9.0 measured this machine at 121,785 placeholders against 10,267 real files — so a folder library on a synced tree was ~92% broken rows. **Identity changed on hydration**, so downloading a photograph looked like a delete and an add, orphaning its thumbnail and its face rows. Entries now carry the photograph's own name and a `materialised` flag; `get` on a stub returns the new `RemoteError::NotMaterialised`, which is distinct from `NotFound` precisely because the sidecar writer must treat them differently — it fetches the sidecar and merges, or leaves the entry queued. Hydration is a **borrow**. `BorrowPool` records what was on disk before it asked, so `release_all` dehydrates only what a pass brought and leaves what the user already had. Reference counted: the thumbnail pass and the face pass meet on the same RAW, and without counting the first to finish dehydrates the file the second is reading. A borrow against a plain folder or a server does nothing, so a pass written for VFS runs everywhere. Releasing means asking the client to dehydrate and never deleting: a deletion inside a synced tree propagates to the server and removes the photograph from every device. Not a second backend — the capability is per *connection*, not per type, since the same folder hydrates only while the client runs. The convention arrives through a detector the registry supplies, so `dr-sync-folder` still knows nothing about any client's protocol. ARCH §9.0a records this as an amendment: finding 3 rejected hydration because it costs 100× a range read, and that comparison assumed a connector was available. A folder library has none. |
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dtourolle
|
f12aece07e |
Make storage pluggable, and prove it with a folder backend
`RemoteBackend` existed from the first release and bought nothing it was
designed for. Seven files in `dr-ui` constructed a `NextcloudBackend`
directly, an account *was* a server URL beside a DAV user id, the local
cache directory was named after a hostname, and the launch screen knew
that signing in meant a browser handshake. The trait was real; the seam
was documentation.
A trait over operations is only a quarter of it. Pluggable storage needs
four things, and this adds the other three:
- **Capabilities** — already there, and the reason the engine can drive
two backends at the speed each actually runs at.
- **Configuration** — `dr_sync::Account`: where a library lives, in
whatever form its connector addresses, with no server in it. Loads
every existing config unchanged (`backend` defaults to `nextcloud`,
`endpoint` is stored under its historical `server` key), and
`Account::namespace()` reproduces the old catalog directory byte for
byte, because changing it would abandon a catalog, its thumbnail
shards, and the sidecars holding unsynced offline work.
- **Registration** — `BackendProvider` and `BackendRegistry`.
`ui/dr-ui/src/remote.rs` is now the only file above `dr-sync` that
names a connector.
`Connection` (an account plus an optional `Secret`) replaces the
credentials-and-user-id pair that was threaded through fifteen
signatures in an order that could be swapped. `Secret`'s inner string is
reachable only through `expose()` and its `Debug` prints `Secret(***)`,
so the indirect leak — a `{:?}` on anything holding one — no longer
compiles into a leak.
Nextcloud is unchanged and keeps every peculiarity: propagating ETags,
chunked upload v2, `oc:fileid`, the `oc:permissions` probe on a refused
PUT, the 423 retry classification, Login Flow v2. Those are what the
capability model exists to serve, not something to hide.
`dr-sync-folder` is the second connector: a local disk, a network mount,
an external drive, or a folder a Nextcloud client already syncs. No
account, no credential — the route that works where no secrets daemon
does. It declares `LocalEtags` rather than claiming propagation a POSIX
directory cannot provide, which costs nothing because 50k `stat` calls
are not 50k PROPFINDs. Identity is a path hash, not an inode: an inode
survives a rename but differs between devices and is reused after a
delete, so two machines would disagree about which photograph a
thumbnail belonged to. Re-deriving a thumbnail is a cost; showing the
wrong one is a bug.
docs/storage.md is the contract — the traits, the four steps to add a
backend, and what each connector declares. ARCH §8.0 and §8.4a, and
FR-NC-13, say why.
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