Move file caching logic to new FileCache service

Also: removes the -re ffmpeg option.
If this option is passed, ffmpeg won't write to fs-capacitor (and the cache file) as fast as possible.
In other words, the cache file won't finish writing until the entire stream has been played.

.env.example

@@ -3,3 +3,6 @@ DATA_DIR=
 YOUTUBE_API_KEY=
 SPOTIFY_CLIENT_ID=
 SPOTIFY_CLIENT_SECRET=
+
+# Optional
+# CACHE_LIMIT=2GB

README.md

@@ -69,3 +69,7 @@ services:
 5. `yarn start` (or `npm run start`)
 
 **Note**: if you're on Windows, you may need to manually set the ffmpeg path. See [#345](https://github.com/codetheweb/muse/issues/345) for details.
+
+#### Advanced
+
+By default, Muse limits the total cache size to around 2 GB. If you want to change this, set the environment variable `CACHE_LIMIT`. For example, `CACHE_LIMIT=512MB` or `CACHE_LIMIT=10GB`.

src/index.ts

@@ -5,6 +5,7 @@ import {TYPES} from './types.js';
 import Bot from './bot.js';
 import {sequelize} from './utils/db.js';
 import Config from './services/config.js';
+import FileCacheProvider from './services/file-cache.js';
 
 const bot = container.get<Bot>(TYPES.Bot);
 
@@ -18,5 +19,7 @@ const bot = container.get<Bot>(TYPES.Bot);
 
   await sequelize.sync({alter: true});
 
+  await container.get<FileCacheProvider>(TYPES.FileCache).cleanup();
+
   await bot.listen();
 })();

src/inversify.config.ts

@@ -28,6 +28,7 @@ import Shuffle from './commands/shuffle.js';
 import Skip from './commands/skip.js';
 import Unskip from './commands/unskip.js';
 import ThirdParty from './services/third-party.js';
+import FileCacheProvider from './services/file-cache.js';
 import KeyValueCacheProvider from './services/key-value-cache.js';
 
 const container = new Container();
@@ -76,6 +77,7 @@ container.bind(TYPES.Config).toConstantValue(new ConfigProvider());
 // Static libraries
 container.bind(TYPES.ThirdParty).to(ThirdParty);
 
+container.bind(TYPES.FileCache).to(FileCacheProvider);
 container.bind(TYPES.KeyValueCache).to(KeyValueCacheProvider);
 
 export default container;

src/managers/player.ts

@@ -2,25 +2,25 @@ import {inject, injectable} from 'inversify';
 import {Client} from 'discord.js';
 import {TYPES} from '../types.js';
 import Player from '../services/player.js';
-import Config from '../services/config.js';
+import FileCacheProvider from '../services/file-cache.js';
 
 @injectable()
 export default class {
   private readonly guildPlayers: Map<string, Player>;
-  private readonly cacheDir: string;
   private readonly discordClient: Client;
+  private readonly fileCache: FileCacheProvider;
 
-  constructor(@inject(TYPES.Config) config: Config, @inject(TYPES.Client) client: Client) {
+  constructor(@inject(TYPES.FileCache) fileCache: FileCacheProvider, @inject(TYPES.Client) client: Client) {
     this.guildPlayers = new Map();
-    this.cacheDir = config.CACHE_DIR;
     this.discordClient = client;
+    this.fileCache = fileCache;
   }
 
   get(guildId: string): Player {
     let player = this.guildPlayers.get(guildId);
 
     if (!player) {
-      player = new Player(this.cacheDir, this.discordClient);
+      player = new Player(this.discordClient, this.fileCache);
 
       this.guildPlayers.set(guildId, player);
     }

src/models/file-cache.ts

@@ -1,13 +1,13 @@
 import {Table, Column, PrimaryKey, Model} from 'sequelize-typescript';
 
 @Table
-export default class FileCache extends Model<FileCache> {
+export default class FileCache extends Model {
   @PrimaryKey
   @Column
   hash!: string;
 
   @Column
-  kbits!: number;
+  bytes!: number;
 
   @Column
   accessedAt!: Date;

src/models/key-value-cache.ts

@@ -2,7 +2,7 @@ import {Table, Column, PrimaryKey, Model} from 'sequelize-typescript';
 import sequelize from 'sequelize';
 
 @Table
-export default class KeyValueCache extends Model<KeyValueCache> {
+export default class KeyValueCache extends Model {
   @PrimaryKey
   @Column
   key!: string;

src/models/settings.ts

@@ -1,7 +1,7 @@
 import {Table, Column, PrimaryKey, Model, Default} from 'sequelize-typescript';
 
 @Table
-export default class Settings extends Model<Settings> {
+export default class Settings extends Model {
   @PrimaryKey
   @Column
   guildId!: string;

src/models/shortcut.ts

@@ -1,7 +1,7 @@
 import {Table, Column, PrimaryKey, Model, AutoIncrement, Index} from 'sequelize-typescript';
 
 @Table
-export default class Shortcut extends Model<Shortcut> {
+export default class Shortcut extends Model {
   @PrimaryKey
   @AutoIncrement
   @Column

src/services/config.ts

@@ -1,6 +1,8 @@
 import dotenv from 'dotenv';
 import {injectable} from 'inversify';
 import path from 'path';
+import xbytes from 'xbytes';
+import {ConditionalKeys} from 'type-fest';
 dotenv.config();
 
 export const DATA_DIR = path.resolve(process.env.DATA_DIR ? process.env.DATA_DIR : './data');
@@ -12,6 +14,7 @@ const CONFIG_MAP = {
   SPOTIFY_CLIENT_SECRET: process.env.SPOTIFY_CLIENT_SECRET,
   DATA_DIR,
   CACHE_DIR: path.join(DATA_DIR, 'cache'),
+  CACHE_LIMIT_IN_BYTES: xbytes.parseSize(process.env.CACHE_LIMIT ?? '2GB'),
 } as const;
 
 @injectable()
@@ -22,6 +25,7 @@ export default class Config {
   readonly SPOTIFY_CLIENT_SECRET!: string;
   readonly DATA_DIR!: string;
   readonly CACHE_DIR!: string;
+  readonly CACHE_LIMIT_IN_BYTES!: number;
 
   constructor() {
     for (const [key, value] of Object.entries(CONFIG_MAP)) {
@@ -30,7 +34,13 @@ export default class Config {
         process.exit(1);
       }
 
-      this[key as keyof typeof CONFIG_MAP] = value;
+      if (typeof value === 'number') {
+        this[key as ConditionalKeys<typeof CONFIG_MAP, number>] = value;
+      } else if (typeof value === 'string') {
+        this[key as ConditionalKeys<typeof CONFIG_MAP, string>] = value;
+      } else {
+        throw new Error(`Unsupported type for ${key}`);
+      }
     }
   }
 }

src/services/file-cache.ts

@@ -0,0 +1,109 @@
+import {inject, injectable} from 'inversify';
+import sequelize from 'sequelize';
+import {FileCache} from '../models/index.js';
+import {TYPES} from '../types.js';
+import Config from './config.js';
+import {promises as fs, createWriteStream} from 'fs';
+import path from 'path';
+
+@injectable()
+export default class FileCacheProvider {
+  private readonly config: Config;
+
+  constructor(@inject(TYPES.Config) config: Config) {
+    this.config = config;
+  }
+
+  /**
+   * Returns path to cached file if it exists, otherwise throws an error.
+   * Updates the `accessedAt` property of the cached file.
+   * @param hash lookup key
+   */
+  async getPathFor(hash: string): Promise<string> {
+    const model = await FileCache.findByPk(hash);
+
+    if (!model) {
+      throw new Error('File is not cached');
+    }
+
+    const resolvedPath = path.join(this.config.CACHE_DIR, hash);
+
+    try {
+      await fs.access(resolvedPath);
+    } catch (_: unknown) {
+      await FileCache.destroy({where: {hash}});
+
+      throw new Error('File is not cached');
+    }
+
+    await model.update({accessedAt: new Date()});
+
+    return resolvedPath;
+  }
+
+  /**
+   * Returns a write stream for the given hash key.
+   * The stream handles saving a new file and will
+   * update the database after the stream is finished.
+   * @param hash lookup key
+   */
+  createWriteStream(hash: string) {
+    const tmpPath = path.join(this.config.CACHE_DIR, 'tmp', hash);
+    const finalPath = path.join(this.config.CACHE_DIR, hash);
+
+    const stream = createWriteStream(tmpPath);
+
+    stream.on('finish', async () => {
+      // Only move if size is non-zero (may have errored out)
+      const stats = await fs.stat(tmpPath);
+
+      if (stats.size !== 0) {
+        await fs.rename(tmpPath, finalPath);
+      }
+
+      await FileCache.create({hash, bytes: stats.size, accessedAt: new Date()});
+
+      await this.evictOldestIfNecessary();
+    });
+
+    return stream;
+  }
+
+  /**
+   * Deletes orphaned cache files and evicts files if
+   * necessary. Should be run on program startup so files
+   * will be evicted if the cache limit has changed.
+   */
+  async cleanup() {
+    await this.removeOrphans();
+    await this.evictOldestIfNecessary();
+  }
+
+  private async evictOldestIfNecessary() {
+    const [{dataValues: {totalSizeBytes}}] = await FileCache.findAll({
+      attributes: [
+        [sequelize.fn('sum', sequelize.col('bytes')), 'totalSizeBytes'],
+      ],
+    }) as unknown as [{dataValues: {totalSizeBytes: number}}];
+
+    if (totalSizeBytes > this.config.CACHE_LIMIT_IN_BYTES) {
+      const oldest = await FileCache.findOne({
+        order: [
+          ['accessedAt', 'ASC'],
+        ],
+      });
+
+      if (oldest) {
+        await oldest.destroy();
+        await fs.unlink(path.join(this.config.CACHE_DIR, oldest.hash));
+      }
+
+      // Continue to evict until we're under the limit
+      await this.evictOldestIfNecessary();
+    }
+  }
+
+  private async removeOrphans() {
+    // TODO
+  }
+}

src/services/player.ts

@@ -1,7 +1,5 @@
 import {VoiceChannel, Snowflake, Client, TextChannel} from 'discord.js';
-import {promises as fs, createWriteStream} from 'fs';
-import {Readable, PassThrough} from 'stream';
-import path from 'path';
+import {Readable} from 'stream';
 import hasha from 'hasha';
 import ytdl from 'ytdl-core';
 import {WriteStream} from 'fs-capacitor';
@@ -9,6 +7,7 @@ import ffmpeg from 'fluent-ffmpeg';
 import shuffle from 'array-shuffle';
 import errorMsg from '../utils/error-msg.js';
 import {AudioPlayer, AudioPlayerStatus, createAudioPlayer, createAudioResource, joinVoiceChannel, StreamType, VoiceConnection, VoiceConnectionStatus} from '@discordjs/voice';
+import FileCacheProvider from './file-cache.js';
 
 export interface QueuedPlaylist {
   title: string;
@@ -35,7 +34,6 @@ export default class {
   public voiceConnection: VoiceConnection | null = null;
   private queue: QueuedSong[] = [];
   private queuePosition = 0;
-  private readonly cacheDir: string;
   private audioPlayer: AudioPlayer | null = null;
   private nowPlaying: QueuedSong | null = null;
   private playPositionInterval: NodeJS.Timeout | undefined;
@@ -44,10 +42,11 @@ export default class {
   private positionInSeconds = 0;
 
   private readonly discordClient: Client;
+  private readonly fileCache: FileCacheProvider;
 
-  constructor(cacheDir: string, client: Client) {
-    this.cacheDir = cacheDir;
+  constructor(client: Client, fileCache: FileCacheProvider) {
     this.discordClient = client;
+    this.fileCache = fileCache;
   }
 
   async connect(channel: VoiceChannel): Promise<void> {
@@ -283,40 +282,24 @@ export default class {
     return this.queueSize() === 0;
   }
 
-  private getCachedPath(url: string): string {
-    return path.join(this.cacheDir, hasha(url));
-  }
-
-  private getCachedPathTemp(url: string): string {
-    return path.join(this.cacheDir, 'tmp', hasha(url));
-  }
-
-  private async isCached(url: string): Promise<boolean> {
-    try {
-      await fs.access(this.getCachedPath(url));
-
-      return true;
-    } catch (_: unknown) {
-      return false;
-    }
+  private getHashForCache(url: string): string {
+    return hasha(url);
   }
 
   private async getStream(url: string, options: {seek?: number} = {}): Promise<Readable> {
-    const cachedPath = this.getCachedPath(url);
-
     let ffmpegInput = '';
     const ffmpegInputOptions: string[] = [];
     let shouldCacheVideo = false;
 
     let format: ytdl.videoFormat | undefined;
 
-    if (await this.isCached(url)) {
-      ffmpegInput = cachedPath;
+    try {
+      ffmpegInput = await this.fileCache.getPathFor(this.getHashForCache(url));
 
       if (options.seek) {
         ffmpegInputOptions.push('-ss', options.seek.toString());
       }
-    } else {
+    } catch {
       // Not yet cached, must download
       const info = await ytdl.getInfo(url);
 
@@ -367,7 +350,6 @@ export default class {
         '1',
         '-reconnect_delay_max',
         '5',
-        '-re',
       ]);
 
       if (options.seek) {
@@ -386,8 +368,7 @@ export default class {
         .on('error', error => {
           console.error(error);
           reject(error);
-        })
-        .pipe() as PassThrough;
+        });
 
       const capacitor = new WriteStream();
 
@@ -395,17 +376,7 @@ export default class {
 
       // Cache video if necessary
       if (shouldCacheVideo) {
-        const cacheTempPath = this.getCachedPathTemp(url);
-        const cacheStream = createWriteStream(cacheTempPath);
-
-        cacheStream.on('finish', async () => {
-          // Only move if size is non-zero (may have errored out)
-          const stats = await fs.stat(cacheTempPath);
-
-          if (stats.size !== 0) {
-            await fs.rename(cacheTempPath, cachedPath);
-          }
-        });
+        const cacheStream = this.fileCache.createWriteStream(this.getHashForCache(url));
 
         capacitor.createReadStream().pipe(cacheStream);
       }