feat(flutter/cache): AudioCacheManager — pin/unpin/evict + tiered LRU

API:
  - isCached(trackId), pathFor(trackId)
  - pin(trackId, source) — dio.download → drift index entry
  - unpin(trackId), clearAll()
  - usageBytes(), evict(targetBytes)

Eviction order: incidental → autoPrefetch → autoPlaylist → autoLiked.
'manual' never evicts via cap-driven eviction; only clearAll() removes
operator-pinned tracks.

Two providers:
  - appDbProvider — singleton AppDb per run
  - audioCacheManagerProvider — wraps the AppDb + dioProvider

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-05-09 23:17:14 -04:00
parent 2bcbb53c49
commit 16669a0365
2 changed files with 291 additions and 0 deletions
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import 'dart:io';
import 'package:dio/dio.dart';
import 'package:drift/drift.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:path_provider/path_provider.dart';
import '../library/library_providers.dart' show dioProvider;
import 'db.dart';
/// Owns the audio cache directory + drift index.
/// API:
/// - isCached(trackId)
/// - pathFor(trackId)
/// - pin(trackId, source) — downloads + indexes
/// - unpin(trackId)
/// - evict(targetBytes) — tiered LRU
/// - usageBytes()
/// - clearAll()
class AudioCacheManager {
AudioCacheManager({
required AppDb db,
required Future<Dio> Function() dioFactory,
Future<Directory> Function()? cacheDirFactory,
}) : _db = db,
_dioFactory = dioFactory,
_cacheDirFactory = cacheDirFactory ?? getApplicationCacheDirectory;
final AppDb _db;
final Future<Dio> Function() _dioFactory;
final Future<Directory> Function() _cacheDirFactory;
Future<String> _tracksDir() async {
final base = await _cacheDirFactory();
final d = Directory('${base.path}/audio_cache');
if (!await d.exists()) await d.create(recursive: true);
return d.path;
}
/// True if the trackId has a complete file on disk.
Future<bool> isCached(String trackId) async {
final row = await (_db.select(_db.audioCacheIndex)
..where((t) => t.trackId.equals(trackId)))
.getSingleOrNull();
if (row == null) return false;
return File(row.path).existsSync();
}
/// Returns the local file path if cached, else null.
Future<String?> pathFor(String trackId) async {
final row = await (_db.select(_db.audioCacheIndex)
..where((t) => t.trackId.equals(trackId)))
.getSingleOrNull();
if (row == null) return null;
return File(row.path).existsSync() ? row.path : null;
}
/// Downloads the track's stream to disk and indexes it. Idempotent —
/// returns the existing path if already cached.
Future<String?> pin(String trackId, {required CacheSource source}) async {
final existing = await pathFor(trackId);
if (existing != null) return existing;
final dir = await _tracksDir();
final path = '$dir/$trackId.mp3';
final dio = await _dioFactory();
try {
await dio.download('/api/tracks/$trackId/stream', path);
} catch (_) {
final f = File(path);
if (f.existsSync()) await f.delete();
return null;
}
final size = await File(path).length();
await _db.into(_db.audioCacheIndex).insertOnConflictUpdate(
AudioCacheIndexCompanion.insert(
trackId: trackId,
path: path,
sizeBytes: size,
source: source,
),
);
return path;
}
/// Removes a track from the index AND deletes the file.
Future<void> unpin(String trackId) async {
final row = await (_db.select(_db.audioCacheIndex)
..where((t) => t.trackId.equals(trackId)))
.getSingleOrNull();
if (row == null) return;
final f = File(row.path);
if (f.existsSync()) await f.delete();
await (_db.delete(_db.audioCacheIndex)
..where((t) => t.trackId.equals(trackId)))
.go();
}
/// Total bytes used by the cache.
Future<int> usageBytes() async {
final result = await _db.customSelect(
'SELECT COALESCE(SUM(size_bytes), 0) AS total FROM audio_cache_index',
readsFrom: {_db.audioCacheIndex},
).getSingle();
return result.read<int>('total');
}
/// Evicts files until usage ≤ targetBytes. Eviction order:
/// incidental → autoPrefetch → autoPlaylist → autoLiked.
/// `manual` never evicts via this path; only clearAll() removes them.
Future<void> evict({required int targetBytes}) async {
final used = await usageBytes();
if (used <= targetBytes) return;
final order = [
CacheSource.incidental,
CacheSource.autoPrefetch,
CacheSource.autoPlaylist,
CacheSource.autoLiked,
];
int remaining = used - targetBytes;
for (final src in order) {
if (remaining <= 0) break;
final rows = await (_db.select(_db.audioCacheIndex)
..where((t) => t.source.equalsValue(src))
..orderBy([(t) => OrderingTerm.asc(t.cachedAt)]))
.get();
for (final row in rows) {
if (remaining <= 0) break;
final f = File(row.path);
if (f.existsSync()) await f.delete();
await (_db.delete(_db.audioCacheIndex)
..where((t) => t.trackId.equals(row.trackId)))
.go();
remaining -= row.sizeBytes;
}
}
}
/// Clears EVERY row + EVERY file. Wired to the operator's "Clear cache"
/// button — `manual` source rows are removed here but only here.
Future<void> clearAll() async {
final dir = await _tracksDir();
final d = Directory(dir);
if (d.existsSync()) {
for (final entity in d.listSync()) {
if (entity is File) await entity.delete();
}
}
await _db.delete(_db.audioCacheIndex).go();
}
}
/// AppDb singleton. One per app run; ref.onDispose closes it.
final appDbProvider = Provider<AppDb>((ref) {
final db = AppDb();
ref.onDispose(db.close);
return db;
});
final audioCacheManagerProvider = Provider<AudioCacheManager>((ref) {
final db = ref.watch(appDbProvider);
return AudioCacheManager(
db: db,
dioFactory: () async => ref.read(dioProvider.future),
);
});
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import 'dart:io';
import 'package:dio/dio.dart';
import 'package:drift/native.dart' show NativeDatabase;
import 'package:flutter_test/flutter_test.dart';
import 'package:minstrel/cache/audio_cache_manager.dart';
import 'package:minstrel/cache/db.dart';
AppDb _testDb() => AppDb(NativeDatabase.memory());
void main() {
test('isCached returns false when no row exists', () async {
final db = _testDb();
addTearDown(db.close);
final mgr = AudioCacheManager(
db: db,
dioFactory: () async => Dio(),
cacheDirFactory: () async => Directory.systemTemp.createTempSync(),
);
expect(await mgr.isCached('nonexistent'), false);
expect(await mgr.pathFor('nonexistent'), null);
});
test('usageBytes sums sizeBytes across rows', () async {
final db = _testDb();
addTearDown(db.close);
final tmp = Directory.systemTemp.createTempSync();
final mgr = AudioCacheManager(
db: db,
dioFactory: () async => Dio(),
cacheDirFactory: () async => tmp,
);
await db.into(db.audioCacheIndex).insertAll([
AudioCacheIndexCompanion.insert(
trackId: 'a', path: 'p', sizeBytes: 100, source: CacheSource.manual),
AudioCacheIndexCompanion.insert(
trackId: 'b', path: 'p', sizeBytes: 250, source: CacheSource.incidental),
]);
expect(await mgr.usageBytes(), 350);
});
test('eviction order: incidental first, manual never', () async {
final db = _testDb();
addTearDown(db.close);
final tmp = Directory.systemTemp.createTempSync();
final mgr = AudioCacheManager(
db: db,
dioFactory: () async => Dio(),
cacheDirFactory: () async => tmp,
);
final f1 = File('${tmp.path}/audio_cache/inc.mp3');
await f1.create(recursive: true);
await f1.writeAsBytes(List.filled(100, 0));
final f2 = File('${tmp.path}/audio_cache/man.mp3');
await f2.create(recursive: true);
await f2.writeAsBytes(List.filled(100, 0));
await db.into(db.audioCacheIndex).insertAll([
AudioCacheIndexCompanion.insert(
trackId: 'inc',
path: f1.path,
sizeBytes: 100,
source: CacheSource.incidental),
AudioCacheIndexCompanion.insert(
trackId: 'man',
path: f2.path,
sizeBytes: 100,
source: CacheSource.manual),
]);
expect(await mgr.usageBytes(), 200);
await mgr.evict(targetBytes: 100);
expect(await mgr.isCached('inc'), false);
expect(await mgr.isCached('man'), true);
});
test('clearAll removes everything including manual', () async {
final db = _testDb();
addTearDown(db.close);
final tmp = Directory.systemTemp.createTempSync();
final mgr = AudioCacheManager(
db: db,
dioFactory: () async => Dio(),
cacheDirFactory: () async => tmp,
);
final f = File('${tmp.path}/audio_cache/man.mp3');
await f.create(recursive: true);
await f.writeAsBytes(List.filled(50, 0));
await db.into(db.audioCacheIndex).insertOnConflictUpdate(
AudioCacheIndexCompanion.insert(
trackId: 'man',
path: f.path,
sizeBytes: 50,
source: CacheSource.manual),
);
expect(await mgr.usageBytes(), 50);
await mgr.clearAll();
expect(await mgr.usageBytes(), 0);
expect(await mgr.isCached('man'), false);
});
test('unpin removes index row + deletes file', () async {
final db = _testDb();
addTearDown(db.close);
final tmp = Directory.systemTemp.createTempSync();
final mgr = AudioCacheManager(
db: db,
dioFactory: () async => Dio(),
cacheDirFactory: () async => tmp,
);
final f = File('${tmp.path}/audio_cache/x.mp3');
await f.create(recursive: true);
await f.writeAsBytes(List.filled(10, 0));
await db.into(db.audioCacheIndex).insertOnConflictUpdate(
AudioCacheIndexCompanion.insert(
trackId: 'x',
path: f.path,
sizeBytes: 10,
source: CacheSource.autoPrefetch),
);
expect(await mgr.isCached('x'), true);
await mgr.unpin('x');
expect(await mgr.isCached('x'), false);
expect(f.existsSync(), false);
});
}