Files
DarkRoom/ui/dr-ui/src/derived_sync.rs
T
dtourolleandClaude Opus 5 d70fe9da8d Decide whether to send a shard before reading it
The upload read every shard off disk and only then asked whether it needed
sending. For a library with 94 MB of face shards already on the server, every
idle sync read 94 MB to conclude it had nothing to do.

The question does not need the bytes. A sealed shard the server already has is
byte-identical by construction, and the client id is in the name, so nobody else
could have written it — the name settles it. The open shard is compared on size,
which `stat` answers.

The progress line moves after the skip for the same reason: announced before it,
an idle pass claimed to be sending five shards and sent none.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-28 23:08:16 +02:00

682 lines
26 KiB
Rust

//! TRACES: FR-CAT-3 | FR-CAT-7 | FR-NC-7
//! Pushing derived state to Nextcloud: thumbnail shards and the catalog.
//!
//! # What travels, and why only this
//!
//! Sidecars are handled elsewhere ([`crate::library::spawn_sidecar_writes`])
//! and are the *authoritative* store — they are the reason a catalog can be
//! deleted and rebuilt (ARCH §6.12). What moves here is derived state that is
//! merely expensive:
//!
//! - **Thumbnail shards.** A thumbnail costs a range fetch plus a decode, and
//! is byte-identical for every client looking at the same file. A second
//! device that downloads the shards gets a full grid without touching a
//! single RAW — hours of indexing against a few hundred MB of transfer.
//! - **The catalog**, for its collections. Every other thing the catalog holds
//! has authoritative backing in a sidecar; a manually assembled collection
//! does not, so without this it exists on one machine only.
//!
//! # Why sealed shards make this cheap
//!
//! A shard stops being written once it reaches its cap, and is never rewritten
//! after — deleting a thumbnail tombstones it in the index rather than editing
//! the sealed blob. So a client that has downloaded a sealed shard never needs
//! to ask about it again, and an up-to-date client transfers only the index and
//! whichever shard is currently open. That is the whole reason for sharding at
//! 25 MB rather than keeping one growing file.
//!
//! # Where it lives
//!
//! Under the library root, in a dotted folder beside the trash. The root is the
//! only place the user granted access to, and writing outside it may cross a
//! share boundary the account cannot write to. The scanner excludes it by the
//! same mechanism that excludes the trash.
use std::path::{Path, PathBuf};
use dr_sync::{RemoteBackend, RemoteId, RemotePath};
use dr_sync_nextcloud::AppCredentials;
use dr_thumbs::ThumbStore;
/// Folder under the library root holding derived state.
///
/// Defined by the scanner, which must exclude it: a walk that indexed this
/// folder would pay a listing for it on every sync of every device.
pub use dr_sync::scan::DERIVED_DIR;
/// What a sync pass did, for logging and for telling the user.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub struct SyncReport {
pub shards_uploaded: usize,
pub shards_downloaded: usize,
pub thumbnails_adopted: usize,
pub catalog_uploaded: bool,
pub catalog_merged: bool,
pub collections_gained: usize,
/// Membership rows the merge brought in (FR-CAT-7).
///
/// Counted apart from `collections_gained`, which counts the collections
/// themselves. A sync that files 127 photographs into a collection both
/// devices already had gains *no* collection, and reporting only the
/// former left the sidebar showing no count beside a full collection.
pub members_gained: usize,
// Face data is counted apart from thumbnails for the same reason keywords
// are counted apart from collections: "adopted 4,812 faces" is a sentence
// the user can act on, and folding it into the thumbnail count would hide
// the one number that says whether this device still has hours of indexing
// ahead of it.
pub face_shards_uploaded: usize,
pub face_shards_downloaded: usize,
/// Images whose faces this device took from a peer instead of detecting.
pub faces_adopted: usize,
}
impl SyncReport {
pub fn did_anything(&self) -> bool {
self.shards_uploaded > 0
|| self.shards_downloaded > 0
|| self.catalog_uploaded
|| self.catalog_merged
|| self.face_shards_uploaded > 0
|| self.face_shards_downloaded > 0
}
}
/// Progress from the sync worker.
#[derive(Debug)]
pub enum SyncMessage {
Status(String),
Finished(Box<SyncReport>),
Failed(String),
}
/// Push shards and the catalog, and take anything newer from the server.
///
/// Runs on its own thread with its own runtime, like every other network path
/// here — the Slint loop must never block (NFR-P9).
pub fn spawn_sync(
creds: AppCredentials,
user_id: String,
root: String,
thumbs_dir: PathBuf,
catalog_path: PathBuf,
scratch: PathBuf,
) -> std::sync::mpsc::Receiver<SyncMessage> {
let (tx, rx) = std::sync::mpsc::channel();
std::thread::spawn(move || {
// A current-thread runtime here is what made the library scan itself
// rather than adopt the shards the server already had; see net_runtime.
let rt = match crate::net_runtime::build() {
Ok(rt) => rt,
Err(e) => {
let _ = tx.send(SyncMessage::Failed(e.to_string()));
return;
}
};
rt.block_on(async {
let backend = match crate::remote::connect(&creds, &user_id) {
Ok(b) => b,
Err(e) => {
let _ = tx.send(SyncMessage::Failed(e.to_string()));
return;
}
};
match run(&*backend, &root, &thumbs_dir, &catalog_path, &scratch, &tx).await {
Ok(report) => {
let _ = tx.send(SyncMessage::Finished(Box::new(report)));
}
Err(e) => {
let _ = tx.send(SyncMessage::Failed(e));
}
}
});
});
rx
}
async fn run(
backend: &dyn RemoteBackend,
root: &str,
thumbs_dir: &Path,
catalog_path: &Path,
scratch: &Path,
tx: &std::sync::mpsc::Sender<SyncMessage>,
) -> Result<SyncReport, String> {
let mut report = SyncReport::default();
let base = derived_path(root);
// The folder may not exist on a first sync. Creating it unconditionally is
// cheaper than probing, and an existing folder is not an error.
let _ = backend.create_dir(&base).await;
let _ = tx.send(SyncMessage::Status("checking thumbnails…".into()));
sync_shards(backend, &base, thumbs_dir, scratch, &mut report).await?;
let _ = tx.send(SyncMessage::Status("checking faces…".into()));
sync_face_shards(backend, &base, catalog_path, scratch, &mut report, tx).await?;
let _ = tx.send(SyncMessage::Status("checking collections…".into()));
sync_catalog(backend, &base, catalog_path, scratch, &mut report).await?;
Ok(report)
}
/// The derived folder for a library root.
fn derived_path(root: &str) -> RemotePath {
if root.is_empty() {
RemotePath::new(DERIVED_DIR)
} else {
RemotePath::new(format!("{root}/{DERIVED_DIR}"))
}
}
/// Exchange thumbnail shards with the server.
///
/// Upload what the server lacks, download what we lack. Sealed shards are
/// immutable, so a name match is a content match and nothing needs comparing
/// beyond existence — which is what keeps a steady-state sync to one listing.
///
/// # Why the name carries a client
///
/// Shard ids are per-store: every client fills its own numbering from 0, so
/// "shard 3" names different thumbnails on each device. A flat `shard-0003`
/// remote namespace therefore has two clients writing one name — the second
/// upload overwrites content the first still believes is published — and
/// leaves a client no way to tell a peer's shard 3 from its own, so the only
/// safe reading of "I already have 3" is to skip it and never adopt anything.
/// Qualifying the name with [`ThumbStore::client_id`] gives each store its own
/// namespace, and [`ThumbStore::adopted`] then tracks what has been merged by
/// remote name instead of by our own ids.
async fn sync_shards(
backend: &dyn RemoteBackend,
base: &RemotePath,
thumbs_dir: &Path,
scratch: &Path,
report: &mut SyncReport,
) -> Result<(), String> {
let store = match ThumbStore::open(thumbs_dir) {
Ok(s) => s,
Err(e) => {
// A store that will not open can be neither read nor merged into,
// so there is no half of this worth attempting. It is not a sync
// failure: the next pass retries once the store is openable.
log::debug!("thumbnail store unavailable: {e}");
return Ok(());
}
};
let client = store.client_id().to_string();
let remote: std::collections::HashMap<String, u64> = backend
.list(base, None)
.await
.map(|entries| {
entries
.into_iter()
.filter(|e| e.kind == dr_sync::EntryKind::File)
.map(|e| (e.path.name().to_string(), e.size))
.collect()
})
// A missing folder lists as an error on some servers; treat it as empty
// rather than aborting a first sync.
.unwrap_or_default();
let local = store.shards().map_err(|e| e.to_string())?;
// ---- upload ----------------------------------------------------------
for shard in &local {
let path = store.shard_path(shard.id);
let Ok(bytes) = std::fs::read(&path) else {
continue;
};
let name = shard_name(&client, shard.id);
// A sealed shard the server already has is byte-identical by
// construction, so its presence is proof enough — and with the client
// in the name, no one else can have written it. The open shard is
// re-uploaded whenever its size differs, which is the only way it
// changes.
let skip = match remote.get(&name) {
Some(_) if shard.sealed => true,
Some(size) => *size == bytes.len() as u64,
None => false,
};
if skip {
continue;
}
let target = RemotePath::new(format!("{}/{name}", base.as_str()));
match backend.put(&target, bytes, None).await {
Ok(_) => report.shards_uploaded += 1,
// One shard failing must not abort the rest: they are independent
// and the next pass retries.
Err(e) => log::warn!("uploading {name}: {e}"),
}
}
// ---- download --------------------------------------------------------
let mut store = store;
for (name, size) in &remote {
let Some((owner, id)) = parse_shard(name) else {
continue;
};
if owner == client {
continue;
}
// Merged already, at the size it still has. A sealed shard never
// reaches here twice; a peer's open one does each time it grows, which
// is what carries its later thumbnails across.
if store.adopted(name) == Some(*size) {
continue;
}
if owner.is_empty() && legacy_upload_of_ours(&store, id, *size) {
let _ = store.record_adopted(name, *size);
continue;
}
let source = RemotePath::new(format!("{}/{name}", base.as_str()));
let bytes = match backend.get(&RemoteId::Path(source), None).await {
Ok(b) => b,
Err(e) => {
log::warn!("downloading {name}: {e}");
continue;
}
};
// Written to scratch and merged, rather than dropped into the store
// directory: a downloaded shard's *id* is the other device's numbering,
// and two devices independently fill shard 0.
let tmp = scratch.join(name);
if std::fs::write(&tmp, &bytes).is_err() {
continue;
}
match store.merge_shard(&tmp) {
Ok(n) => {
report.shards_downloaded += 1;
report.thumbnails_adopted += n;
// Recorded only on success, so a failed merge is retried next
// pass rather than written off.
let _ = store.record_adopted(name, *size);
}
Err(e) => log::warn!("merging {name}: {e}"),
}
let _ = std::fs::remove_file(&tmp);
}
Ok(())
}
/// Push and pull face shards, so a second device does not re-index the library.
///
/// Mirrors [`sync_shards`] deliberately, down to the sealed-shard skip and the
/// adopted ledger: face data has exactly the properties that made that design
/// right for thumbnails. It is bulk, it is immutable once written, and it is
/// byte-identical on every device, because the same model over the same proxy
/// is deterministic.
///
/// The catalog is the source and the destination; the shards are only the
/// carrier. So this exports the catalog's new faces into the local shard store
/// first, syncs the shards, and imports whatever arrived back into the catalog.
async fn sync_face_shards(
backend: &dyn RemoteBackend,
base: &RemotePath,
catalog_path: &Path,
scratch: &Path,
report: &mut SyncReport,
tx: &std::sync::mpsc::Sender<SyncMessage>,
) -> Result<(), String> {
use dr_catalog::face_shard::{self, FaceShardStore};
// Beside the catalog, next to the thumbnails, and under the same folder the
// scanner already excludes.
let dir = match catalog_path.parent() {
Some(p) => p.join("faces"),
None => return Ok(()),
};
let mut store = match FaceShardStore::open(&dir) {
Ok(s) => s,
Err(e) => {
// Not a sync failure: the next pass retries once it opens.
log::debug!("face shard store unavailable: {e}");
return Ok(());
}
};
let client = store.client_id().to_string();
let model = crate::identity_ui::MODEL_ID;
// ---- everything this device has detected, into the shards ------------
if let Ok(catalog) = dr_catalog::Catalog::open(catalog_path) {
// The first export after a re-index walks the whole library and writes
// thousands of images. Saying so is the difference between a sync that
// looks slow and one that looks broken — this pass sat on "checking
// faces…" for eight minutes and was reported as a hang.
let mut say = |done: usize, total: usize| {
let _ = tx.send(SyncMessage::Status(format!(
"preparing faces to send: {done}/{total}"
)));
};
match face_shard::export_to_shards_reporting(
catalog.connection(),
&mut store,
model,
&mut say,
) {
Ok(0) => {}
Ok(n) => log::info!("face sync: {n} newly indexed image(s) ready to upload"),
Err(e) => log::warn!("face sync: exporting to shards: {e}"),
}
}
// Its own folder under the derived directory, so a client that does not
// care about faces lists thumbnails without paging past them.
let face_base = RemotePath::new(format!("{}/faces", base.as_str()));
let _ = backend.create_dir(&face_base).await;
let remote: std::collections::HashMap<String, u64> = backend
.list(&face_base, None)
.await
.map(|entries| {
entries
.into_iter()
.filter(|e| e.kind == dr_sync::EntryKind::File)
.map(|e| (e.path.name().to_string(), e.size))
.collect()
})
.unwrap_or_default();
// ---- upload ----------------------------------------------------------
//
// Every commit since the last pass is still in a write-ahead log, and a
// shard is uploaded by reading its file — so without this the upload would
// ship a database missing precisely the faces just exported.
if let Err(e) = store.checkpoint() {
log::warn!("face sync: checkpointing the shard store: {e}");
}
let local = store.shards().map_err(|e| e.to_string())?;
for (n, shard) in local.iter().enumerate() {
let name = shard_name(&client, shard.id);
let path = store.shard_path(shard.id);
// **Decided before the file is read.** A sealed shard the server
// already has is byte-identical by construction, and the client is in
// the name so nobody else could have written it — the name alone
// settles it. Reading first meant every idle sync pulled ninety-four
// megabytes off disk to conclude it had nothing to send.
let on_disk = std::fs::metadata(&path).map(|m| m.len()).unwrap_or(0);
let skip = match remote.get(&name) {
Some(_) if shard.sealed => true,
Some(size) => *size == on_disk,
None => false,
};
if skip {
continue;
}
let Ok(bytes) = std::fs::read(&path) else {
continue;
};
// Face shards carry crops and run to tens of megabytes each, so a
// single one is a visible wait on any connection. Announced after the
// skip, or an idle pass claims to be sending five shards and sends
// none; and before the put, because the wait is the upload.
let _ = tx.send(SyncMessage::Status(format!(
"sending faces: shard {}/{} ({} MB)",
n + 1,
local.len(),
bytes.len() / 1_048_576
)));
let target = RemotePath::new(format!("{}/{name}", face_base.as_str()));
match backend.put(&target, bytes, None).await {
Ok(_) => report.face_shards_uploaded += 1,
Err(e) => log::warn!("uploading face shard {name}: {e}"),
}
}
// ---- download --------------------------------------------------------
for (name, size) in &remote {
let Some((owner, _)) = parse_shard(name) else {
continue;
};
if owner == client || store.has_adopted(name, *size) {
continue;
}
// Taking in a peer's shard means a download and then a row-by-row
// merge, both of which take a while on a shard carrying crops.
let _ = tx.send(SyncMessage::Status(format!(
"taking in faces from another device ({} MB)",
size / 1_048_576
)));
let source = RemotePath::new(format!("{}/{name}", face_base.as_str()));
let bytes = match backend.get(&RemoteId::Path(source), None).await {
Ok(b) => b,
Err(e) => {
log::warn!("downloading face shard {name}: {e}");
continue;
}
};
// Into scratch and merged, never dropped into the store directory: a
// downloaded shard's id is the *other* device's numbering, and two
// devices independently fill shard 0.
let tmp = scratch.join(name);
if std::fs::write(&tmp, &bytes).is_err() {
continue;
}
match store.merge_shard(&tmp) {
Ok(_) => {
report.face_shards_downloaded += 1;
// Recorded only on success, so a failed merge is retried next
// pass rather than written off.
let _ = store.mark_adopted(name, *size);
}
Err(e) => log::warn!("merging face shard {name}: {e}"),
}
let _ = std::fs::remove_file(&tmp);
}
// ---- and back into the catalog ---------------------------------------
//
// Last, and unconditionally rather than only when something downloaded: a
// previous pass may have merged shards into the store and then failed
// before importing, and this is what recovers from that.
if let Ok(catalog) = dr_catalog::Catalog::open(catalog_path) {
match face_shard::import_from_shards(catalog.connection(), &store, model) {
Ok(0) => {}
Ok(n) => {
report.faces_adopted = n;
log::info!("face sync: adopted {n} image(s) already indexed elsewhere");
}
Err(e) => log::warn!("face sync: importing from shards: {e}"),
}
}
Ok(())
}
/// Whether a flat-named remote shard is this client's own earlier upload.
///
/// Before the name carried a client every client wrote `shard-NNNN.sqlite`, so
/// the folder still holds files with nothing in the name to say whose they
/// are. A local shard of the same id and the same size is ours by
/// construction — the same identity argument the upload path makes for
/// skipping a sealed shard the server already has — and skipping those is what
/// keeps the rename from costing every client a re-download of its whole
/// store. Being wrong costs a peer's shard going unmerged and its thumbnails
/// being derived locally instead; it loses nothing, and two independently
/// filled 25 MB databases landing on the same byte count is not a real case.
fn legacy_upload_of_ours(store: &ThumbStore, id: u32, remote_size: u64) -> bool {
std::fs::metadata(store.shard_path(id))
.map(|m| m.len() == remote_size)
.unwrap_or(false)
}
/// Exchange the catalog, for its collections.
///
/// Only collections merge — see [`dr_catalog::sync`]. The rest of a catalog
/// describes local state (folder ETags, cache paths, job rows) and importing
/// another device's version would be actively wrong.
async fn sync_catalog(
backend: &dyn RemoteBackend,
base: &RemotePath,
catalog_path: &Path,
scratch: &Path,
report: &mut SyncReport,
) -> Result<(), String> {
let remote_name = "catalog.sqlite";
let target = RemotePath::new(format!("{}/{remote_name}", base.as_str()));
// ---- take theirs first -----------------------------------------------
//
// Merging before uploading means our upload carries the union rather than
// only our own half, so a third device syncing next gets everything in one
// fetch.
if let Ok(bytes) = backend.get(&RemoteId::Path(target.clone()), None).await {
let downloaded = scratch.join("catalog-remote.sqlite");
if std::fs::write(&downloaded, &bytes).is_ok() {
match dr_catalog::Catalog::open(catalog_path) {
Ok(catalog) => match catalog.merge_remote_catalog(&downloaded) {
Ok(merge) => {
report.catalog_merged = true;
report.collections_gained = merge.inserted + merge.updated;
report.members_gained = merge.members_added;
}
Err(e) => log::warn!("merging remote catalog: {e}"),
},
Err(e) => log::warn!("opening catalog to merge: {e}"),
}
let _ = std::fs::remove_file(&downloaded);
}
}
// ---- then push ours --------------------------------------------------
//
// Never the live file: committed transactions can sit in the `-wal` with
// the main file lagging, so copying it uploads a torn snapshot. The backup
// API serialises against writers instead of racing them.
let snapshot = scratch.join("catalog-upload.sqlite");
let catalog = dr_catalog::Catalog::open(catalog_path).map_err(|e| e.to_string())?;
catalog
.snapshot_for_upload(&snapshot)
.map_err(|e| e.to_string())?;
let bytes = std::fs::read(&snapshot).map_err(|e| e.to_string())?;
match backend.put(&target, bytes, None).await {
Ok(_) => report.catalog_uploaded = true,
Err(e) => log::warn!("uploading catalog: {e}"),
}
let _ = std::fs::remove_file(&snapshot);
Ok(())
}
fn shard_name(client: &str, id: u32) -> String {
format!("shard-{client}-{id:04}.sqlite")
}
/// The client that wrote a remote shard and its id in that client's numbering,
/// or `None` if the name is not a shard.
///
/// Also accepts the flat `shard-NNNN.sqlite` written before names carried a
/// client, reporting an empty owner: those belong to nobody identifiable, so
/// they read as foreign and are adopted once like any peer's. Nothing is ever
/// uploaded under that form again.
///
/// Guards the download loop against adopting the catalog, a stray file, or
/// anything else the folder happens to contain.
fn parse_shard(name: &str) -> Option<(&str, u32)> {
let stem = name.strip_prefix("shard-")?.strip_suffix(".sqlite")?;
match stem.rsplit_once('-') {
Some((client, id)) => Some((client, id.parse().ok()?)),
None => Some(("", stem.parse().ok()?)),
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn derived_folder_sits_under_the_library_root() {
// Outside the root the account may not have write access — the root is
// the only thing the user granted.
assert_eq!(
derived_path("PhotosRaw").as_str(),
"PhotosRaw/.darkroom-derived"
);
// A library at the account root still gets a relative path.
assert_eq!(derived_path("").as_str(), ".darkroom-derived");
}
#[test]
fn shard_names_round_trip() {
assert_eq!(
shard_name("a1b2c3d4e5f6", 0),
"shard-a1b2c3d4e5f6-0000.sqlite"
);
assert_eq!(
shard_name("a1b2c3d4e5f6", 42),
"shard-a1b2c3d4e5f6-0042.sqlite"
);
assert_eq!(
parse_shard(&shard_name("a1b2c3d4e5f6", 7)),
Some(("a1b2c3d4e5f6", 7))
);
}
#[test]
fn two_clients_shard_three_are_different_files() {
// The whole point: one client's numbering must not name another's
// shard, or the second upload overwrites the first's content and
// neither can tell the other's shards from its own.
assert_ne!(shard_name("aaaa", 3), shard_name("bbbb", 3));
assert_eq!(parse_shard(&shard_name("aaaa", 3)).unwrap().0, "aaaa");
assert_eq!(parse_shard(&shard_name("bbbb", 3)).unwrap().0, "bbbb");
}
#[test]
fn flat_names_read_as_belonging_to_nobody() {
// Written before the name carried a client. They must still parse, so
// a library synced by an older build is not stranded, and they must
// not match any live client id, so they are never mistaken for ours.
assert_eq!(parse_shard("shard-0042.sqlite"), Some(("", 42)));
assert_ne!(parse_shard("shard-0042.sqlite").unwrap().0, "a1b2c3d4e5f6");
}
#[test]
fn non_shard_files_are_not_adopted() {
// The folder also holds the catalog; downloading it as a shard would
// hand a catalog to the thumbnail merger.
assert_eq!(parse_shard("catalog.sqlite"), None);
assert_eq!(parse_shard("shard-0000.sqlite-wal"), None);
assert_eq!(parse_shard("notes.txt"), None);
assert_eq!(parse_shard("shard-abc.sqlite"), None);
assert_eq!(parse_shard("shard-a1b2c3-notanid.sqlite"), None);
}
#[test]
fn a_report_that_did_nothing_says_so() {
assert!(!SyncReport::default().did_anything());
assert!(SyncReport {
shards_uploaded: 1,
..Default::default()
}
.did_anything());
// Adopting thumbnails without moving a shard cannot happen, but the
// report must not claim work on collections alone either.
assert!(SyncReport {
catalog_merged: true,
..Default::default()
}
.did_anything());
}
}