dtourolle
a1d511fd4b
library.rs was 7,729 lines wiring together everything "open a remote library" touches: scanning, pulling other devices' judgements out of sidecars found along the way, writing local edits back out to the sidecar outbox, pushing/reloading XMP by hand, fetching and prefetching thumbnails and originals, generating thumbnails locally, the metadata and thumbnail background sweeps, on-disk paths for the catalog and model files, and reading the grid's cells, spans and rating filter. Same motivation as the develop.rs split (docs/dev/code-health.md CH-1): a pure, no-behaviour-change move into one file per area, each under about 1,500 lines. Tracing actual call sites rather than trusting the file's physical layout mattered here: `persist`, `load_folder_etags`, `pull_sidecars`, `load_sidecar_etags`, `record_sidecar_read` and `apply_judgement` sit textually beside the XMP push/reload functions but are called only from `run_scan` (pulling a device's own past judgements out of the sidecars a scan just walked), so they went to scan.rs and not xmp.rs. `cells` came out at over 1,800 lines once its tests moved with it and split further into cells.rs (windowed reads, trash, ordinals) and spans.rs (collection scope, manual reordering, the capture-time histogram) -- ten submodules rather than the nine first planned. Previously-private items reached from a sibling module became `pub(super)`, narrower than the whole-crate reachability one file gave them. Tests moved with the code they test; the two test fixtures used across more than one file (`scanned`, and develop.rs's `session_with_a_left_half_subject` in the matching commit) joined the shared `test_support` module alongside the existing `entry`/ `with_images`/`image_ids` helpers. `mod.rs` re-exports every module's public items under `library::`, including the `pub(crate)` `test_support` module `repairs.rs` reads its fixtures from, so no file outside `library` needed a change. The previous commit split develop.rs the same way; taken alone it left dr-ui without library.rs, so that intermediate commit does not build on its own. This one restores it.
966 lines
36 KiB
Rust
966 lines
36 KiB
Rust
//! Fetching thumbnails, previews and originals from the remote: the pin
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//! cache, dehydration, and the prefetcher that keeps the grid ahead of
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//! scrolling.
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use crate::sidecar_cache::SidecarCache;
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use dr_catalog::Catalog;
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#[cfg(test)]
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use dr_sync::Account;
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use dr_sync::{Connection, RemoteId, RemotePath};
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use std::path::PathBuf;
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use std::sync::mpsc::{Receiver, Sender};
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use super::scan::now_secs;
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use super::sidecar::sidecar_path;
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/// Largest preview worth fetching whole.
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///
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/// A located preview above this is skipped rather than transferred: past a few
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/// MB the saving over the full file stops justifying the wait, and a 256px
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/// thumbnail needs nothing like that much detail.
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pub(super) const MAX_PREVIEW_BYTES: u64 = 8 * 1024 * 1024;
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/// What the grid wants a thumbnail for.
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///
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/// Carries the `oc:fileid` as well as the path, because that is what the
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/// shared store keys on — stable across a server-side move, and the same id
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/// every other client sees (FR-NC-5).
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#[derive(Debug, Clone)]
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pub struct ThumbnailRequest {
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pub row: usize,
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pub path: String,
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/// `None` where the scan found no stable id; such an image is fetched but
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/// not stored, since there is no durable key to store it under.
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pub file_id: Option<u64>,
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/// File length, needed to reject a preview range that points past the end
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/// of the file (NFR-SEC-1).
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pub size: u64,
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/// Catalog row, so EXIF read from the header can be written back.
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pub image_id: i64,
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/// Which resolution this cell needs, from how large it is drawn. A zoomed
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/// grid asks for the large class; a wall of small cells does not.
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///
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/// Named apart from `size`, which is the file's length in bytes — the two
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/// are unrelated and confusing them would fetch the wrong thing.
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pub thumb_size: dr_thumbs::ThumbSize,
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/// Whether this image still needs its EXIF read. Where false the header is
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/// still fetched — the preview needs it — but nothing is parsed or written.
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pub needs_metadata: bool,
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/// Keep the preview at the resolution it was decoded at, ignoring
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/// `thumb_size`.
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///
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/// For face indexing, which wants the pixels a thumbnail throws away: a
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/// face 2% across the frame is 5 px on a grid thumbnail and 120 px on the
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/// embedded preview, and 112 is what the embedder samples. Capped by
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/// [`FACE_SOURCE_EDGE`] rather than truly unbounded, because a 24 MP buffer
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/// converted to `f32` RGB is ~288 MB and several lanes hold one at once.
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pub full_resolution: bool,
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}
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/// Why a full fetch failed, keeping the one bit the UI cannot re-derive.
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///
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/// The same reasoning as [`ScanFailure`]: the typed error cannot cross the
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/// channel, and "offline" versus "refused" decides whether develop shows
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/// "you are offline — this image is not stored locally" or a real error.
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#[derive(Debug)]
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pub struct FetchFailure {
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pub message: String,
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pub offline: bool,
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}
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impl FetchFailure {
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fn local(message: impl std::fmt::Display) -> Self {
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Self {
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message: message.to_string(),
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offline: false,
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}
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}
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}
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impl From<dr_sync::RemoteError> for FetchFailure {
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fn from(e: dr_sync::RemoteError) -> Self {
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Self {
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offline: e.indicates_offline(),
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message: e.to_string(),
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}
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}
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}
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impl std::fmt::Display for FetchFailure {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.write_str(&self.message)
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}
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}
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/// TRACES: FR-NC-6a
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/// Progress from the pin worker.
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#[derive(Debug)]
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pub enum PinMessage {
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/// How many originals the pin still needs. Sent once, before any transfer.
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Planned {
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total: usize,
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},
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/// One original landed.
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Stored {
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done: usize,
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},
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/// The pin is fully downloaded.
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Done {
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stored: usize,
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bytes: u64,
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},
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Failed {
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message: String,
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offline: bool,
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},
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}
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/// TRACES: FR-NC-6a
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/// Download every original a pin has asked for.
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///
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/// Whole files, deliberately: a pin exists so the photographs can be *edited*
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/// away from the server, and develop needs every photosite. This is the one
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/// place in the app that fetches originals in bulk, which is why FR-NC-6
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/// makes it opt-in rather than something sync does on its own.
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///
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/// Sequential rather than parallel. The lanes that make the thumbnail sweep
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/// fast are wrong here: these are tens of megabytes each, so concurrency buys
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/// little against a single connection's bandwidth and costs a great deal of
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/// memory — and it is the same contention that produced 423 Locked in the
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/// sweep.
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pub fn spawn_pin_fetch(
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conn: Connection,
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catalog_path: PathBuf,
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cache_dir: PathBuf,
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budget: dr_catalog::Budget,
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) -> Receiver<PinMessage> {
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let (tx, rx) = std::sync::mpsc::channel();
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std::thread::spawn(move || {
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let (store, catalog) = match (
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dr_catalog::Cache::open(&cache_dir, budget),
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Catalog::open(&catalog_path),
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) {
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(Ok(s), Ok(c)) => (s, c),
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(Err(e), _) | (_, Err(e)) => {
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: false,
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});
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return;
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}
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};
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let pending = match store.pending_pins(catalog.connection()) {
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Ok(p) => p,
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Err(e) => {
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: false,
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});
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return;
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}
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};
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if tx
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.send(PinMessage::Planned {
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total: pending.len(),
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})
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.is_err()
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{
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return;
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}
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if pending.is_empty() {
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let _ = tx.send(PinMessage::Done {
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stored: 0,
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bytes: 0,
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});
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return;
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}
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let rt = match crate::net_runtime::build() {
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Ok(rt) => rt,
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Err(e) => {
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: false,
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});
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return;
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}
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};
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rt.block_on(async {
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let backend = match crate::remote::connect(&conn) {
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Ok(b) => b,
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Err(e) => {
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: false,
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});
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return;
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}
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};
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let mut stored = 0usize;
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let mut bytes_total = 0u64;
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for image in pending {
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let Some(source_ref) = source_ref_of(&catalog, image) else {
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// Catalogued and then removed while the pin was pending.
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continue;
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};
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let id = RemoteId::Path(RemotePath::new(&source_ref));
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// TRACES: FR-NC-6c
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// On a placeholder library "pin" means *keep it downloaded*,
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// not "make a second copy". The original materialises in the
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// library folder itself, so copying it under `originals/`
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// would hold every pinned photograph twice — and the copy
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// would be the half the budget could evict while the real disk
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// cost stayed. Only the bookkeeping is recorded, with no path,
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// so nothing here can ever delete a file inside a synced tree
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// (see `Cache::record_in_place`).
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if backend.capabilities().materialisation.can_materialise() {
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match backend.materialise(&id).await {
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Ok(_) => {
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let bytes = size_of(&catalog, image).unwrap_or(0);
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if let Err(e) = store.record_in_place(
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catalog.connection(),
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image,
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bytes,
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true,
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now_secs(),
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) {
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log::warn!("recording pinned {source_ref}: {e}");
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continue;
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}
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stored += 1;
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bytes_total += bytes;
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if tx.send(PinMessage::Stored { done: stored }).is_err() {
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return;
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}
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}
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Err(e) if e.indicates_offline() => {
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: true,
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});
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return;
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}
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Err(e) => log::warn!("pinning {source_ref}: {e}"),
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}
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continue;
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}
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match backend.get(&id, None).await {
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Ok(bytes) => {
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// `pinned: true` — this is the population the budget
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// must never evict, which is the entire promise the
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// user made when they pinned the collection.
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if let Err(e) = store.store(
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catalog.connection(),
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image,
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&source_ref,
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&bytes,
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true,
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now_secs(),
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) {
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log::warn!("storing pinned {source_ref}: {e}");
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continue;
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}
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stored += 1;
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bytes_total += bytes.len() as u64;
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if tx.send(PinMessage::Stored { done: stored }).is_err() {
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return;
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}
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}
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Err(e) if e.indicates_offline() => {
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// Stop rather than failing each remaining file against
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// a dead connection. What was downloaded stays
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// downloaded, and `pending_pins` resumes from there.
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let _ = tx.send(PinMessage::Failed {
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message: e.to_string(),
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offline: true,
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});
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return;
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}
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Err(e) => {
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// One unreadable file must not abandon the whole pin.
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log::warn!("pinning {source_ref}: {e}");
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}
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}
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}
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let _ = tx.send(PinMessage::Done {
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stored,
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bytes: bytes_total,
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});
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});
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});
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rx
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}
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/// TRACES: FR-NC-6c
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/// Hand a set of photographs back to the sync client, freeing their disk.
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///
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/// The other half of pinning on a placeholder library. `Cache::release` drops
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/// the bookkeeping and — correctly — deletes nothing, because the rows it
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/// holds for a library like this name no file of ours (`record_in_place`).
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/// The bytes are in the library folder, and only the client may take them
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/// back.
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///
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/// **This is a dehydration, not a deletion, and the distinction is the whole
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/// safety of the feature.** Removing a materialised file inside a synced tree
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/// propagates to the server and deletes the photograph everywhere.
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///
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/// Best effort per image: a file the client refuses to release simply stays,
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/// which costs disk and loses nothing.
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pub fn spawn_dehydrate(
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conn: Connection,
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catalog_path: PathBuf,
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images: Vec<dr_types::ImageId>,
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) -> Receiver<usize> {
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let (tx, rx) = std::sync::mpsc::channel();
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std::thread::spawn(move || {
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let Ok(catalog) = Catalog::open(&catalog_path) else {
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return;
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};
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let Ok(rt) = crate::net_runtime::build() else {
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return;
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};
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rt.block_on(async {
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let Ok(backend) = crate::remote::connect(&conn) else {
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return;
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};
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// Nothing to do where content is not a thing that can be given
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// back — a server library, or a plain folder.
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if !backend.capabilities().materialisation.can_materialise() {
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return;
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}
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let mut released = 0usize;
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for image in images {
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let Some(source_ref) = source_ref_of(&catalog, image) else {
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continue;
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};
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let id = RemoteId::Path(RemotePath::new(&source_ref));
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match backend.dematerialise(&id).await {
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Ok(()) => released += 1,
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Err(e) => log::debug!("releasing {source_ref}: {e}"),
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}
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}
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log::info!("released {released} photograph(s) back to the sync client");
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let _ = tx.send(released);
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});
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});
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rx
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}
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/// What an image occupies, as the catalog recorded it.
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///
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/// Zero where the scan could not tell — a placeholder reports no size, because
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/// a one-byte stub says nothing about what it stands for (ARCH §9.0a). A pin
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/// that cannot state its cost is better than one that states a wrong one.
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pub(super) fn size_of(catalog: &Catalog, image: dr_types::ImageId) -> Option<u64> {
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catalog
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.connection()
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.query_row(
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"SELECT file_size FROM images WHERE id = ?1",
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rusqlite::params![image.0 as i64],
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|r| r.get::<_, Option<i64>>(0),
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)
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.ok()
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.flatten()
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.map(|v| v.max(0) as u64)
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}
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/// The remote path for a catalogued image.
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pub(super) fn source_ref_of(catalog: &Catalog, image: dr_types::ImageId) -> Option<String> {
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catalog
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.connection()
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.query_row(
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"SELECT source_ref FROM images WHERE id = ?1",
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rusqlite::params![image.0 as i64],
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|r| r.get(0),
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)
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.ok()
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}
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/// TRACES: FR-NC-6a | FR-CAT-9
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/// Where a cached original is kept and how much may be kept.
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///
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/// Passed in rather than derived here so the caller owns the policy: the
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/// budget is a user setting, and this function is on a worker thread with no
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/// access to one.
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pub struct CacheContext {
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pub dir: PathBuf,
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pub catalog_path: PathBuf,
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pub image: dr_types::ImageId,
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pub budget: dr_catalog::Budget,
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/// Whether a downloaded original is kept.
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///
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/// Only the write. A cache is always *read*, because bytes already on disk
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/// cost nothing to use and declining them would re-download an image that
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/// is present — including every pinned one, which would leave a pinned
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/// collection unopenable offline the moment this was switched off.
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pub store: bool,
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}
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/// TRACES: FR-CAT-8 | FR-DEV-6
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/// Fetch and parse the sidecar beside one image.
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///
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/// # Why the edit is read from the file rather than the catalog
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///
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/// The catalog carries a `graph_hash` and no parameters, and it is
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/// *disposable* (ARCH §6.12) — a rebuild would silently return every
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/// photograph to neutral. The sidecar is the authoritative store, so it is
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/// what an open reads, and that is also what makes an edit pasted on the
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/// desktop appear when the same frame is opened on the phone.
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///
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/// # Why absence and failure are the same answer here
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///
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/// `None` means "open this image at its defaults", which is right for a
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/// photograph that has never been edited — the overwhelmingly common case on a
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/// fresh library — and equally right when the network is down. The alternative,
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/// refusing to open the image because its sidecar could not be read, would make
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/// an unreachable server also mean an unviewable library.
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///
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/// The one case that is *not* harmless is a sidecar that exists but does not
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/// parse. That still opens at defaults, but the write path
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/// ([`write_one_sidecar`]) independently refuses to overwrite a file it could
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/// not read, so an edit this build failed to understand is never destroyed by
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/// having been opened.
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pub fn spawn_sidecar_fetch(
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conn: Connection,
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image_path: String,
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cache_dir: PathBuf,
|
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offline: bool,
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|
) -> Receiver<Option<dr_pipeline::Sidecar>> {
|
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let (tx, rx) = std::sync::mpsc::channel();
|
|
|
|
std::thread::spawn(move || {
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let cache = SidecarCache::open(cache_dir);
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let path_str = sidecar_path(&image_path);
|
|
|
|
// TRACES: FR-CAT-9 | FR-NC-10
|
|
// The cache wins outright when it is holding work the server has not
|
|
// seen. Fetching in that state would answer with a document *older*
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|
// than the edit sitting in the outbox, and opening the photograph
|
|
// would silently show it without the change the user just made —
|
|
// which the next save would then write back over the top of.
|
|
if cache.is_pending(&path_str) {
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log::debug!("{path_str} has queued local edits; opening from the cache");
|
|
let _ = tx.send(cache.load(&path_str));
|
|
return;
|
|
}
|
|
|
|
// Offline there is nothing to ask, and the cache is the whole answer.
|
|
let rt = if offline {
|
|
None
|
|
} else {
|
|
match crate::net_runtime::build() {
|
|
Ok(e) => Some(e),
|
|
Err(e) => {
|
|
log::debug!("sidecar fetch runtime: {e}");
|
|
None
|
|
}
|
|
}
|
|
};
|
|
let Some(rt) = rt else {
|
|
let _ = tx.send(cache.load(&path_str));
|
|
return;
|
|
};
|
|
|
|
rt.block_on(async {
|
|
let backend = match crate::remote::connect(&conn) {
|
|
Ok(b) => b,
|
|
Err(e) => {
|
|
log::debug!("sidecar fetch backend: {e}");
|
|
let _ = tx.send(cache.load(&path_str));
|
|
return;
|
|
}
|
|
};
|
|
|
|
let path = RemotePath::new(path_str.clone());
|
|
let id = RemoteId::Path(path.clone());
|
|
|
|
// A 404 is the normal case on a library that has never been
|
|
// edited, so this is `ok()` rather than an error path.
|
|
let Ok(bytes) = backend.get(&id, None).await else {
|
|
// Unreachable, or no such file. The cache cannot tell those
|
|
// apart and does not need to: either way it holds the best
|
|
// answer this device has.
|
|
let _ = tx.send(cache.load(&path_str));
|
|
return;
|
|
};
|
|
|
|
let text = String::from_utf8_lossy(&bytes).into_owned();
|
|
let parsed = match dr_pipeline::Sidecar::parse(&text) {
|
|
Ok(mut s) => {
|
|
// TRACES: FR-NC-8 | FR-NC-9
|
|
// Opening a photograph must show everything that has been
|
|
// done to it, not whichever of two split default versions
|
|
// happens to win. Fused in memory with no canonical uuid
|
|
// to impose — this is a read, and the write path is where
|
|
// the identity is decided.
|
|
//
|
|
// The fused document is what gets cached below, so the
|
|
// next offline open sees the union too.
|
|
s.fuse_default_versions(None);
|
|
Some(s)
|
|
}
|
|
Err(e) => {
|
|
log::warn!("sidecar at {} is unreadable ({e})", path.as_str());
|
|
None
|
|
}
|
|
};
|
|
|
|
// Populate the cache from what the server said, so the *next*
|
|
// open of this photograph works with no connection. Clean rather
|
|
// than pending: this content came from the server, so there is
|
|
// nothing to send back.
|
|
if let Some(sidecar) = parsed.as_ref() {
|
|
if let Err(e) = cache.store(&path_str, sidecar, false) {
|
|
log::debug!("caching {path_str}: {e}");
|
|
}
|
|
}
|
|
|
|
let _ = tx.send(parsed);
|
|
});
|
|
});
|
|
|
|
rx
|
|
}
|
|
|
|
/// Fetch one file in full, for opening it in develop.
|
|
///
|
|
/// Deliberately *not* the preview path. Browsing fetches a range and decodes
|
|
/// an embedded JPEG (FR-NC-3); develop needs every byte, because demosaic
|
|
/// needs every photosite. On a RAW file that is tens of megabytes, which is
|
|
/// why this is a click-triggered download and not something the grid does.
|
|
///
|
|
/// # Read-through
|
|
///
|
|
/// With a `cache`, this checks disk before the network and stores what it
|
|
/// downloads. That is what makes opening the same photograph twice cost one
|
|
/// transfer, and what leaves a working session's images openable offline
|
|
/// without anyone having pinned anything.
|
|
///
|
|
/// A cache miss is not an error and a cache failure is not fatal: both fall
|
|
/// through to the network, which is exactly the behaviour that existed before
|
|
/// the cache did.
|
|
///
|
|
/// Returns the bytes on a channel rather than blocking: the download runs on
|
|
/// its own thread and the UI stays live, exactly as thumbnail fetching does.
|
|
/// The work itself is [`fetch_original`], which is also what the
|
|
/// [`Prefetcher`] runs — one transfer path, so a photograph fetched ahead is
|
|
/// stored exactly as one fetched on a click.
|
|
pub fn spawn_full_fetch(
|
|
conn: Connection,
|
|
path: String,
|
|
cache: Option<CacheContext>,
|
|
) -> Receiver<Result<Vec<u8>, FetchFailure>> {
|
|
let (tx, rx) = std::sync::mpsc::channel();
|
|
std::thread::spawn(move || {
|
|
let _ = tx.send(fetch_original(conn, &path, cache.as_ref()));
|
|
});
|
|
rx
|
|
}
|
|
|
|
/// TRACES: FR-NC-6a
|
|
/// Every original transfer that is under way right now, by remote path.
|
|
///
|
|
/// **One file, one transfer.** The [`Prefetcher`] fetches the photographs
|
|
/// beside the open one before they are asked for, and the whole point is that
|
|
/// the user then asks for one of them — often while it is still coming down.
|
|
/// Without this the click would miss the cache, start a second download of
|
|
/// the same file, and the two would halve each other's bandwidth for the rest
|
|
/// of the transfer. With it, the click finds the path claimed, waits for the
|
|
/// prefetch to store its bytes, and reads them from disk.
|
|
///
|
|
/// Process-wide rather than passed in, because the property it enforces is
|
|
/// process-wide: there is no caller for whom two concurrent downloads of one
|
|
/// file is the right answer. Keyed on the path rather than the image id
|
|
/// because that is the one name every caller has.
|
|
static IN_FLIGHT: std::sync::LazyLock<InFlight> = std::sync::LazyLock::new(InFlight::default);
|
|
|
|
#[derive(Default)]
|
|
pub(super) struct InFlight {
|
|
busy: std::sync::Mutex<std::collections::HashSet<String>>,
|
|
freed: std::sync::Condvar,
|
|
}
|
|
|
|
impl InFlight {
|
|
/// Take `path` for this thread, or wait for whoever holds it.
|
|
///
|
|
/// `Some` is a claim, released when the guard drops. `None` means another
|
|
/// thread held the path and has now let it go — so the caller's cache
|
|
/// check is worth repeating, because that thread has very probably just
|
|
/// stored what the caller was about to download.
|
|
fn claim(&self, path: &str) -> Option<InFlightGuard<'_>> {
|
|
let mut busy = self.busy.lock().unwrap_or_else(|e| e.into_inner());
|
|
if busy.insert(path.to_string()) {
|
|
return Some(InFlightGuard {
|
|
of: self,
|
|
path: path.to_string(),
|
|
});
|
|
}
|
|
while busy.contains(path) {
|
|
busy = self.freed.wait(busy).unwrap_or_else(|e| e.into_inner());
|
|
}
|
|
None
|
|
}
|
|
|
|
fn release(&self, path: &str) {
|
|
self.busy
|
|
.lock()
|
|
.unwrap_or_else(|e| e.into_inner())
|
|
.remove(path);
|
|
self.freed.notify_all();
|
|
}
|
|
}
|
|
|
|
/// A claim on a path, dropped on every exit from the fetch — a failed
|
|
/// download must free the path too, or the click waiting on it never wakes.
|
|
pub(super) struct InFlightGuard<'a> {
|
|
of: &'a InFlight,
|
|
path: String,
|
|
}
|
|
|
|
impl Drop for InFlightGuard<'_> {
|
|
fn drop(&mut self) {
|
|
self.of.release(&self.path);
|
|
}
|
|
}
|
|
|
|
/// The blocking body of [`spawn_full_fetch`]: cache, then in-flight registry,
|
|
/// then network, storing what it downloads when the cache says to.
|
|
pub(super) fn fetch_original(
|
|
conn: Connection,
|
|
path: &str,
|
|
cache: Option<&CacheContext>,
|
|
) -> Result<Vec<u8>, FetchFailure> {
|
|
// Opened on this thread: `rusqlite::Connection` is not `Send`, and the
|
|
// UI thread's handle cannot be borrowed across the spawn.
|
|
let cached = cache.and_then(|c| {
|
|
let store = dr_catalog::Cache::open(&c.dir, c.budget).ok()?;
|
|
let conn = Catalog::open(&c.catalog_path).ok()?;
|
|
Some((store, conn))
|
|
});
|
|
|
|
let from_cache = || {
|
|
let (c, (store, conn)) = (cache?, cached.as_ref()?);
|
|
match store.load(conn.connection(), c.image, now_secs()) {
|
|
Ok(Some(bytes)) => {
|
|
log::info!("{path}: {} bytes from the local cache", bytes.len());
|
|
Some(bytes)
|
|
}
|
|
Ok(None) => None,
|
|
// A cache that cannot be read is a cache miss, not a failure
|
|
// to open the photograph.
|
|
Err(e) => {
|
|
log::debug!("cache lookup for {path}: {e}");
|
|
None
|
|
}
|
|
}
|
|
};
|
|
|
|
// Miss, claim, and if the claim had to wait, look again: the thread that
|
|
// held the path has finished with it, and what it fetched is on disk.
|
|
let _claim = loop {
|
|
if let Some(bytes) = from_cache() {
|
|
return Ok(bytes);
|
|
}
|
|
if let Some(claim) = IN_FLIGHT.claim(path) {
|
|
break claim;
|
|
}
|
|
};
|
|
|
|
let rt = crate::net_runtime::build().map_err(FetchFailure::local)?;
|
|
|
|
rt.block_on(async {
|
|
let backend = crate::remote::connect(&conn).map_err(FetchFailure::local)?;
|
|
|
|
let id = RemoteId::Path(RemotePath::new(path));
|
|
let bytes = backend.get(&id, None).await?;
|
|
|
|
// Store before returning, so the bytes are on disk by the time the
|
|
// image is on screen. Doing it after would leave a window where
|
|
// closing the app immediately lost the download.
|
|
if let (Some(c), Some((store, conn))) = (cache.filter(|c| c.store), cached.as_ref()) {
|
|
// `pinned: false` — this is the passive population. A pin is
|
|
// something the user asks for explicitly; opening an image is
|
|
// not that, and treating it as one would make the pinned set
|
|
// grow silently and never be evicted.
|
|
if let Err(e) = store.store(conn.connection(), c.image, path, &bytes, false, now_secs())
|
|
{
|
|
log::debug!("caching {path}: {e}");
|
|
} else if let Err(e) = store.enforce(conn.connection()) {
|
|
log::debug!("enforcing the cache budget: {e}");
|
|
}
|
|
}
|
|
|
|
Ok(bytes)
|
|
})
|
|
}
|
|
|
|
/// TRACES: FR-NC-6a | FR-UI-4
|
|
/// One original to fetch ahead of its being asked for.
|
|
pub struct PrefetchJob {
|
|
pub path: String,
|
|
pub cache: CacheContext,
|
|
}
|
|
|
|
/// What the [`Prefetcher`] is doing, for the activity list.
|
|
pub enum PrefetchEvent {
|
|
/// A transfer has started for this path.
|
|
Started(String),
|
|
/// And has ended — stored, or not; either way the row can go.
|
|
Ended(String),
|
|
}
|
|
|
|
/// TRACES: FR-NC-6a | FR-UI-4
|
|
/// Fetches the photographs beside the open one into the cache, ahead of the
|
|
/// step that asks for them.
|
|
///
|
|
/// **Why this exists.** Walking the photo roll is one click per frame, and
|
|
/// without this every click is a download of tens of megabytes with a
|
|
/// "Downloading…" line over an empty canvas. A photographer moving between a
|
|
/// pair of near-identical frames does that a dozen times. Fetching the two
|
|
/// neighbours while the current photograph is being looked at turns the next
|
|
/// step into a disk read, which is what makes stepping feel like stepping.
|
|
///
|
|
/// **One worker, one wish.** A single thread serves the *latest* request and
|
|
/// nothing older. Each open replaces the previous wish outright, so a fast
|
|
/// walk along the roll does not leave a trail of stale downloads competing
|
|
/// with the one the user is actually waiting on; a job already under way is
|
|
/// finished rather than abandoned, because the bytes are mostly here. Jobs
|
|
/// run in the order given — next before previous, since that is the way a
|
|
/// roll is mostly walked — and one at a time, so two neighbours never halve
|
|
/// each other's bandwidth.
|
|
///
|
|
/// **What it never does.** It never fetches into a cache that would not keep
|
|
/// the bytes: the caller only hands it jobs whose cache stores, because a
|
|
/// prefetch that is discarded on arrival is pure transfer for nothing — and
|
|
/// "keep opened originals" being off is the user saying this device is
|
|
/// metered or small (FR-NC-6). It never starts while offline, for the same
|
|
/// reason. And it fetches only the immediate neighbours: originals are
|
|
/// "explicit pin or on-demand open only", and ±1 is as far as "on demand"
|
|
/// honestly stretches.
|
|
pub struct Prefetcher {
|
|
shared: std::sync::Arc<PrefetchShared>,
|
|
events: Receiver<PrefetchEvent>,
|
|
}
|
|
|
|
#[derive(Default)]
|
|
pub(super) struct PrefetchShared {
|
|
wanted: std::sync::Mutex<Wanted>,
|
|
changed: std::sync::Condvar,
|
|
}
|
|
|
|
/// The latest wish, and a generation so the worker can tell it has been
|
|
/// replaced mid-list.
|
|
#[derive(Default)]
|
|
pub(super) struct Wanted {
|
|
generation: u64,
|
|
conn: Option<Connection>,
|
|
jobs: Vec<PrefetchJob>,
|
|
}
|
|
|
|
impl Wanted {
|
|
/// Replace whatever was wanted with `jobs`.
|
|
fn replace(&mut self, conn: Connection, jobs: Vec<PrefetchJob>) {
|
|
self.generation += 1;
|
|
self.conn = Some(conn);
|
|
self.jobs = jobs;
|
|
}
|
|
|
|
/// Whether a wish taken at `generation` is still the current one.
|
|
fn is_current(&self, generation: u64) -> bool {
|
|
self.generation == generation
|
|
}
|
|
}
|
|
|
|
impl Default for Prefetcher {
|
|
fn default() -> Self {
|
|
Self::new()
|
|
}
|
|
}
|
|
|
|
impl Prefetcher {
|
|
/// Start the worker. It sleeps until the first [`Self::want`].
|
|
pub fn new() -> Self {
|
|
let shared = std::sync::Arc::new(PrefetchShared::default());
|
|
let (tx, events) = std::sync::mpsc::channel();
|
|
let worker = shared.clone();
|
|
std::thread::Builder::new()
|
|
.name("prefetch".into())
|
|
.spawn(move || serve_prefetches(&worker, &tx))
|
|
.expect("spawning the prefetch worker");
|
|
Self { shared, events }
|
|
}
|
|
|
|
/// Fetch these, in this order, instead of whatever was asked for before.
|
|
///
|
|
/// An empty list is a valid wish: it cancels the rest of the previous
|
|
/// one, and is what a photograph with no neighbours in the window asks.
|
|
pub fn want(&self, conn: Connection, jobs: Vec<PrefetchJob>) {
|
|
self.shared
|
|
.wanted
|
|
.lock()
|
|
.unwrap_or_else(|e| e.into_inner())
|
|
.replace(conn, jobs);
|
|
self.shared.changed.notify_one();
|
|
}
|
|
|
|
/// Everything the worker has reported since the last poll.
|
|
pub fn poll(&self) -> Vec<PrefetchEvent> {
|
|
std::iter::from_fn(|| self.events.try_recv().ok()).collect()
|
|
}
|
|
}
|
|
|
|
/// The worker: take the current wish, serve it job by job, stop the moment it
|
|
/// is superseded, sleep until the next one.
|
|
pub(super) fn serve_prefetches(shared: &PrefetchShared, events: &Sender<PrefetchEvent>) {
|
|
loop {
|
|
let (generation, conn, jobs) = {
|
|
let mut wanted = shared.wanted.lock().unwrap_or_else(|e| e.into_inner());
|
|
while wanted.jobs.is_empty() {
|
|
wanted = shared
|
|
.changed
|
|
.wait(wanted)
|
|
.unwrap_or_else(|e| e.into_inner());
|
|
}
|
|
let jobs = std::mem::take(&mut wanted.jobs);
|
|
let Some(conn) = wanted.conn.clone() else {
|
|
continue;
|
|
};
|
|
(wanted.generation, conn, jobs)
|
|
};
|
|
|
|
for job in jobs {
|
|
let current = shared
|
|
.wanted
|
|
.lock()
|
|
.unwrap_or_else(|e| e.into_inner())
|
|
.is_current(generation);
|
|
if !current {
|
|
break;
|
|
}
|
|
if holds_original(&job.cache) {
|
|
continue;
|
|
}
|
|
|
|
// A closed channel means the window is gone: nothing to fetch
|
|
// for any more.
|
|
if events
|
|
.send(PrefetchEvent::Started(job.path.clone()))
|
|
.is_err()
|
|
{
|
|
return;
|
|
}
|
|
match fetch_original(conn.clone(), &job.path, Some(&job.cache)) {
|
|
Ok(bytes) => log::info!("{}: {} bytes fetched ahead", job.path, bytes.len()),
|
|
// Not a failure anyone needs to hear about now: the click
|
|
// that wants this photograph will try again and say so.
|
|
Err(e) => log::debug!("fetching {} ahead: {}", job.path, e.message),
|
|
}
|
|
if events.send(PrefetchEvent::Ended(job.path)).is_err() {
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Whether the cache already has this original — a row check, not a read,
|
|
/// so asking costs nothing and touches no `last_used`.
|
|
pub(super) fn holds_original(cache: &CacheContext) -> bool {
|
|
let Ok(store) = dr_catalog::Cache::open(&cache.dir, cache.budget) else {
|
|
return false;
|
|
};
|
|
let Ok(catalog) = Catalog::open(&cache.catalog_path) else {
|
|
return false;
|
|
};
|
|
store.holds_original(catalog.connection(), cache.image)
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
/// The whole reason the registry exists: a click on a photograph that is
|
|
/// being fetched ahead waits for that transfer rather than starting its
|
|
/// own, and is told so — `None` — so it looks in the cache again.
|
|
#[test]
|
|
fn a_second_claim_waits_for_the_first_to_be_released() {
|
|
let registry = std::sync::Arc::new(InFlight::default());
|
|
let first = registry.claim("shoot/one.CR2");
|
|
assert!(first.is_some(), "an unclaimed path is claimed outright");
|
|
|
|
let (tx, rx) = std::sync::mpsc::channel();
|
|
let waiter = {
|
|
let registry = registry.clone();
|
|
std::thread::spawn(move || {
|
|
tx.send(()).unwrap();
|
|
registry.claim("shoot/one.CR2").is_some()
|
|
})
|
|
};
|
|
rx.recv().unwrap();
|
|
// The waiter is blocked on the first claim. Not provable without a
|
|
// sleep, but a release that reaches it proves the wait ended there.
|
|
assert!(
|
|
!waiter.is_finished(),
|
|
"the second claim must not return while the first is held"
|
|
);
|
|
|
|
drop(first);
|
|
let claimed = waiter.join().unwrap();
|
|
assert!(
|
|
!claimed,
|
|
"after waiting, the caller is told to recheck the cache"
|
|
);
|
|
|
|
assert!(
|
|
registry.claim("shoot/one.CR2").is_some(),
|
|
"and once nobody holds the path it can be claimed again"
|
|
);
|
|
}
|
|
|
|
/// Different photographs never wait on each other.
|
|
#[test]
|
|
fn distinct_paths_are_claimed_independently() {
|
|
let registry = InFlight::default();
|
|
let _a = registry.claim("a.CR2");
|
|
assert!(registry.claim("b.CR2").is_some());
|
|
}
|
|
|
|
/// A newer wish supersedes an older one mid-list; the worker checks this
|
|
/// between jobs, and it is what keeps a fast walk along the roll from
|
|
/// queueing every neighbour it passed.
|
|
#[test]
|
|
fn a_new_wish_supersedes_the_one_being_served() {
|
|
let mut wanted = Wanted::default();
|
|
let conn = test_connection();
|
|
wanted.replace(conn.clone(), Vec::new());
|
|
let taken = wanted.generation;
|
|
assert!(wanted.is_current(taken));
|
|
|
|
wanted.replace(conn, Vec::new());
|
|
assert!(
|
|
!wanted.is_current(taken),
|
|
"the list taken before the replacement is stale"
|
|
);
|
|
}
|
|
|
|
fn test_connection() -> Connection {
|
|
Connection::new(
|
|
Account::new("nextcloud", "https://cloud.example").with_login("d", "d"),
|
|
None,
|
|
)
|
|
}
|
|
}
|