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quak/src/library/index.ts
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Plain-record library snapshot and change subscription (closes #43)
Adds a synchronous, key-free snapshot() returning LibrarySnapshot (one PhotoRecord per fileID, deduped, newest first) with edited-name/time precedence (pubMagicMetadata over basic metadata) in milliseconds, plus AlbumRecord (favorites identified by type). subscribe({onChange}) delivers LibraryChange (changed/removed albums and files, refreshedAt) only when a refresh changes something; unsubscribe stops delivery. Built on the existing refresh loop; served from RAM, safe to send over IPC.

Model: opus-4-8
2026-09-22 15:22:52 +02:00

387 lines
15 KiB
TypeScript

// The library surface over the local cache.
//
// `Library.open()` loads the on-disk metadata store (issue #41), then starts
// the refresh loop. When the cache loaded empty it awaits the first refresh,
// so the library never opens onto an empty store it could have filled; when an
// existing copy loaded, that first refresh runs in the background and `open()`
// returns as soon as the cached data is ready to serve — a slow or unreachable
// server no longer stalls opening. A background timer then refreshes every
// `refreshIntervalSeconds`. Every read is answered from RAM — no read touches
// the network. There is deliberately no `sync()`, no `refresh()`, no
// `serverReachable` flag, and no "before each read" mode (design #36): the
// only ways state changes are the refreshes above.
//
// A refresh stages all of its network work first and only mutates the store
// once every fetch has succeeded. A refresh that fails partway therefore never
// becomes visible to reads: the last good snapshot stays in place, and the
// failure surfaces through `onProgress` and `status()` instead. A commit that
// mutates RAM but then fails to persist keeps `status().lastError` set and the
// store marked unsaved until a later save actually lands, so a stuck disk is
// never masked by a subsequent empty refresh.
import { join } from "node:path";
import envPaths from "env-paths";
import { MetadataStore } from "./store.js";
import {
deriveRecords,
snapshotFrom,
diffRecords,
type DerivedRecords,
type LibrarySnapshot,
type LibraryChange,
} from "./records.js";
import type { CollectionsPage, FilesPage } from "../client.js";
import type { Collection, EnteFile } from "../model/types.js";
export const DEFAULT_REFRESH_INTERVAL_SECONDS = 3;
// The slice of `Client` the library depends on. Narrowing to an interface lets
// tests drive a mock with no crypto or network; the real `Client` satisfies it
// structurally.
export interface LibraryClient {
whoami(): { email: string; userID: number };
collectionsSince(args: { sinceTime: number }): Promise<CollectionsPage>;
filesSince(args: {
collectionID: number;
collectionKey: Uint8Array;
sinceTime: number;
}): Promise<FilesPage>;
}
// A single refresh cycle's progress. "started" fires before the network work,
// then exactly one of "done" or "failed"; "failed" carries the error message.
export interface RefreshEvent {
operation: "refresh";
status: "started" | "done" | "failed";
error?: string;
}
export type RefreshProgressCallback = (event: RefreshEvent) => void;
export interface LibraryOptions {
client: LibraryClient;
// Where `metadata.json` lives. Defaults to the env-paths cache directory
// plus the user id, so each account has its own cache.
cacheDirectory?: string;
// Persistent backup destination for later phases (backup, thumbnails); the
// refresh loop does not use it.
downloadDirectory?: string;
refreshIntervalSeconds?: number;
onProgress?: RefreshProgressCallback;
}
export interface LibraryStatus {
userID: number;
collections: number;
files: number;
// Wall-clock ms of the last refresh that succeeded, or undefined if none
// has yet.
lastRefreshAt?: number;
// The message from the most recent refresh, set only while that refresh
// failed; cleared by the next success.
lastError?: string;
closed: boolean;
}
export class Library {
readonly cacheDirectory: string;
readonly downloadDirectory?: string;
private readonly client: LibraryClient;
private readonly store: MetadataStore;
private readonly userID: number;
private readonly intervalMs: number;
private readonly onProgress?: RefreshProgressCallback;
private timer?: ReturnType<typeof setTimeout>;
private refreshing = false;
private closed = false;
private lastRefreshAt?: number;
private lastError?: string;
// The plain-record projection as of the last refresh, and the GUI change
// subscribers. A refresh that alters the projection notifies each with the
// delta; `lastRecords` is kept current every refresh so a subscriber that
// joins later diffs against the state its own `snapshot()` already returned.
private readonly subscribers = new Set<(change: LibraryChange) => void>();
private lastRecords: DerivedRecords;
// RAM holds changes disk has not yet accepted (an earlier save failed).
// Cleared only when a save actually succeeds; keeps the store trying to
// persist and the failure visible in `status()` until then.
private unsaved = false;
private constructor(args: {
client: LibraryClient;
store: MetadataStore;
userID: number;
cacheDirectory: string;
downloadDirectory?: string;
intervalMs: number;
onProgress?: RefreshProgressCallback;
}) {
this.client = args.client;
this.store = args.store;
this.userID = args.userID;
this.cacheDirectory = args.cacheDirectory;
this.downloadDirectory = args.downloadDirectory;
this.intervalMs = args.intervalMs;
this.onProgress = args.onProgress;
this.lastRecords = this.deriveNow();
}
// Load the cache and start the refresh loop. With an empty cache the first
// refresh is awaited, so `open()` resolves onto populated data whenever the
// server is reachable; that awaited refresh may still fail, and the library
// then opens empty with the failure recorded in `status()`. With an
// existing cache the first refresh runs in the background and `open()`
// returns as soon as the cached data is ready — an unreachable server does
// not block opening.
static async open(opts: LibraryOptions): Promise<Library> {
const { userID } = opts.client.whoami();
const cacheDirectory =
opts.cacheDirectory ??
join(envPaths("quak", { suffix: "" }).cache, String(userID));
const store = await MetadataStore.load(
join(cacheDirectory, "metadata.json"),
);
const intervalMs =
(opts.refreshIntervalSeconds ?? DEFAULT_REFRESH_INTERVAL_SECONDS) *
1000;
const lib = new Library({
client: opts.client,
store,
userID,
cacheDirectory,
downloadDirectory: opts.downloadDirectory,
intervalMs,
onProgress: opts.onProgress,
});
if (store.loadedFromDisk) {
// An existing copy already answers reads; refresh in the background
// and start the interval once that first cycle settles.
void lib.runRefresh().then(() => lib.scheduleNext());
} else {
// Nothing was cached: wait for the first refresh to fill the store
// (or fail) rather than resolve onto an empty library.
await lib.runRefresh();
lib.scheduleNext();
}
return lib;
}
listCollections(): Collection[] {
return this.store.listCollections();
}
getCollection(id: number): Collection | undefined {
return this.store.getCollection(id);
}
listFiles(collectionID: number): EnteFile[] {
return this.store.listFiles(collectionID);
}
getFile(collectionID: number, fileID: number): EnteFile | undefined {
return this.store.getFile(collectionID, fileID);
}
// A synchronous, RAM-only projection of the whole library into plain
// records (no keys), the surface the GUI reads across IPC. Photos are
// deduplicated to one record per file and ordered newest first.
snapshot(): LibrarySnapshot {
return snapshotFrom(this.deriveNow(), Date.now());
}
// Deliver a `LibraryChange` whenever a refresh alters the projection. A
// refresh that changes nothing delivers nothing. The returned handle's
// `unsubscribe` stops delivery.
subscribe(args: { onChange: (change: LibraryChange) => void }): {
unsubscribe: () => void;
} {
const { onChange } = args;
this.subscribers.add(onChange);
return {
unsubscribe: () => {
this.subscribers.delete(onChange);
},
};
}
status(): LibraryStatus {
let files = 0;
const collections = this.store.listCollections();
for (const c of collections) {
files += this.store.listFiles(c.id).length;
}
return {
userID: this.store.userID,
collections: collections.length,
files,
lastRefreshAt: this.lastRefreshAt,
lastError: this.lastError,
closed: this.closed,
};
}
// Stop the background timer. Idempotent. An in-flight refresh is left to
// finish; it will not schedule another cycle once closed.
close(): void {
this.closed = true;
if (this.timer !== undefined) {
clearTimeout(this.timer);
this.timer = undefined;
}
}
private scheduleNext(): void {
if (this.closed) return;
this.timer = setTimeout(() => {
void this.runRefresh().then(() => this.scheduleNext());
}, this.intervalMs);
// Do not keep the process alive for the sake of the timer.
this.timer.unref?.();
}
// One refresh cycle, guarded so a failure never escapes and overlapping
// cycles never run. Errors are reported, not thrown.
private async runRefresh(): Promise<void> {
if (this.closed || this.refreshing) return;
this.refreshing = true;
this.emit({ operation: "refresh", status: "started" });
try {
await this.refreshOnce();
this.lastRefreshAt = Date.now();
this.lastError = undefined;
this.emit({ operation: "refresh", status: "done" });
} catch (err) {
const error = err instanceof Error ? err.message : String(err);
this.lastError = error;
this.emit({ operation: "refresh", status: "failed", error });
} finally {
this.refreshing = false;
}
}
// Fetch every change since the stored cursor, then commit. All network
// reads happen before any store mutation, so a fetch that throws leaves the
// store untouched and the previous snapshot intact.
private async refreshOnce(): Promise<void> {
const page = await this.client.collectionsSince({
sinceTime: this.store.collectionsSinceTime,
});
// Stage per-collection file diffs. A collection's files are
// re-enumerated only when its updationTime has advanced past the cached
// copy; an unchanged album's file list cannot have changed. New
// collections enumerate from the beginning of time.
const filePages: { collectionID: number; page: FilesPage }[] = [];
for (const collection of page.collections) {
const known = this.store.getCollection(collection.id);
if (known && collection.updationTime <= known.updationTime)
continue;
const filePage = await this.client.filesSince({
collectionID: collection.id,
collectionKey: collection.key,
sinceTime: known ? known.updationTime : 0,
});
filePages.push({ collectionID: collection.id, page: filePage });
}
// Network work done; commit to the store and persist only if something
// actually changed.
let changed = false;
if (this.store.userID !== this.userID) {
this.store.userID = this.userID;
changed = true;
}
for (const id of page.deleted) {
if (this.store.getCollection(id)) {
this.store.deleteCollection(id);
changed = true;
}
}
for (const collection of page.collections) {
this.store.putCollection(collection);
changed = true;
}
for (const { collectionID, page: filePage } of filePages) {
for (const id of filePage.deleted) {
if (this.store.getFile(collectionID, id)) {
this.store.deleteFile(collectionID, id);
changed = true;
}
}
for (const f of filePage.files) {
this.store.putFile(f);
changed = true;
}
}
if (page.cursor !== this.store.collectionsSinceTime) {
this.store.collectionsSinceTime = page.cursor;
changed = true;
}
if (changed) this.unsaved = true;
// Reproject and notify subscribers of the delta. This tracks RAM (what
// reads see), so it fires whether or not the save below succeeds; a
// save failure surfaces separately through `status().lastError`.
// `lastRecords` advances every changed refresh so the next diff is
// against current state.
if (changed) {
const next = this.deriveNow();
if (this.subscribers.size > 0) {
const change = diffRecords(this.lastRecords, next, Date.now());
if (change) this.notify(change);
}
this.lastRecords = next;
}
// Persist whenever RAM holds changes disk has not accepted — including
// changes an earlier cycle staged whose save failed. `unsaved` clears
// only once a save lands, so a save failure both stays visible through
// `status().lastError` (the throw below records it) and keeps being
// retried, instead of a later empty refresh silently clearing it while
// the on-disk cache is still behind RAM.
if (this.unsaved) {
await this.store.save();
this.unsaved = false;
}
}
// Gather every file membership and project the store into by-id records.
private deriveNow(): DerivedRecords {
const collections = this.store.listCollections();
const files: EnteFile[] = [];
for (const c of collections) files.push(...this.store.listFiles(c.id));
return deriveRecords(collections, files);
}
private notify(change: LibraryChange): void {
for (const onChange of this.subscribers) {
// A misbehaving subscriber must not break the loop or its peers.
try {
onChange(change);
} catch {
// ignore
}
}
}
private emit(event: RefreshEvent): void {
if (!this.onProgress) return;
// A misbehaving callback must not break the refresh loop.
try {
this.onProgress(event);
} catch {
// ignore
}
}
}