70 lines
2.0 KiB
TypeScript
70 lines
2.0 KiB
TypeScript
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import type { SftpFileEntry } from "../../../domain/models";
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export interface DirectoryListingCacheEntry {
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files: SftpFileEntry[];
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timestamp: number;
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}
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export type DirectoryListingCache = Map<string, DirectoryListingCacheEntry>;
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export const MAX_DIRECTORY_CACHE_ENTRIES = 128;
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export const MAX_DIRECTORY_CACHE_FILES = 20_000;
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function removeExpiredEntries(
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cache: DirectoryListingCache,
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now: number,
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ttlMs: number,
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): void {
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for (const [key, entry] of cache) {
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if (now - entry.timestamp >= ttlMs) cache.delete(key);
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}
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}
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export function getDirectoryCacheEntry(
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cache: DirectoryListingCache,
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key: string,
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now: number,
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ttlMs: number,
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): DirectoryListingCacheEntry | undefined {
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removeExpiredEntries(cache, now, ttlMs);
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const entry = cache.get(key);
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if (!entry) return undefined;
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cache.delete(key);
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cache.set(key, entry);
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return entry;
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}
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export function setDirectoryCacheEntry(
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cache: DirectoryListingCache,
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key: string,
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entry: DirectoryListingCacheEntry,
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options: {
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now?: number;
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ttlMs?: number;
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maxEntries?: number;
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maxFiles?: number;
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} = {},
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): void {
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const now = options.now ?? Date.now();
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const ttlMs = options.ttlMs ?? 10_000;
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const maxEntries = options.maxEntries ?? MAX_DIRECTORY_CACHE_ENTRIES;
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const maxFiles = options.maxFiles ?? MAX_DIRECTORY_CACHE_FILES;
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removeExpiredEntries(cache, now, ttlMs);
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cache.delete(key);
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// A cache budget must remain a hard bound. Truncating a directory listing
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// would be incorrect, so oversized listings are served to the caller but
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// deliberately not retained.
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if (entry.files.length > maxFiles || maxEntries < 1) return;
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cache.set(key, entry);
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let totalFiles = 0;
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for (const value of cache.values()) totalFiles += value.files.length;
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while (cache.size > 1 && (cache.size > maxEntries || totalFiles > maxFiles)) {
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const oldestKey = cache.keys().next().value as string | undefined;
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if (!oldestKey) break;
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const oldest = cache.get(oldestKey);
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cache.delete(oldestKey);
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totalFiles -= oldest?.files.length ?? 0;
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}
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}
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