song cache

src/lib/music-song-cache.ts

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+// 音乐歌曲信息缓存模块 - 基于 platform+id 的全局缓存
+
+// 歌曲信息接口
+export interface SongInfo {
+  id: string;
+  name: string;
+  artist: string;
+  album?: string;
+  pic?: string;
+}
+
+// 缓存条目接口
+export interface SongCacheEntry {
+  expiresAt: number;
+  data: SongInfo;
+}
+
+// 缓存配置
+const SONG_CACHE_TTL_MS = 24 * 60 * 60 * 1000; // 24小时
+const CACHE_CLEANUP_INTERVAL_MS = 60 * 60 * 1000; // 1小时清理一次
+const MAX_CACHE_SIZE = 5000; // 最大缓存条目数量
+const SONG_CACHE: Map<string, SongCacheEntry> = new Map();
+
+// 惰性清理时间戳
+let lastCleanupTime = 0;
+
+/**
+ * 生成歌曲缓存键：platform+id
+ */
+function makeSongCacheKey(platform: string, id: string): string {
+  return `${platform}+${id}`;
+}
+
+/**
+ * 获取缓存的歌曲信息
+ */
+export function getCachedSong(platform: string, id: string): SongInfo | null {
+  const key = makeSongCacheKey(platform, id);
+  const entry = SONG_CACHE.get(key);
+  if (!entry) return null;
+
+  // 检查是否过期
+  if (entry.expiresAt <= Date.now()) {
+    SONG_CACHE.delete(key);
+    return null;
+  }
+
+  return entry.data;
+}
+
+/**
+ * 设置缓存的歌曲信息
+ */
+export function setCachedSong(platform: string, id: string, songInfo: SongInfo): void {
+  // 惰性清理：每次写入时检查是否需要清理
+  const now = Date.now();
+  if (now - lastCleanupTime > CACHE_CLEANUP_INTERVAL_MS) {
+    performCacheCleanup();
+  }
+
+  const key = makeSongCacheKey(platform, id);
+  SONG_CACHE.set(key, {
+    expiresAt: now + SONG_CACHE_TTL_MS,
+    data: songInfo,
+  });
+}
+
+/**
+ * 批量获取缓存的歌曲信息
+ */
+export function getCachedSongs(keys: Array<{ platform: string; id: string }>): Map<string, SongInfo> {
+  const result = new Map<string, SongInfo>();
+  const now = Date.now();
+
+  for (const { platform, id } of keys) {
+    const key = makeSongCacheKey(platform, id);
+    const entry = SONG_CACHE.get(key);
+
+    if (entry && entry.expiresAt > now) {
+      result.set(key, entry.data);
+    }
+  }
+
+  return result;
+}
+
+/**
+ * 批量设置缓存的歌曲信息
+ */
+export function setCachedSongs(songs: Array<{ platform: string; id: string; songInfo: SongInfo }>): void {
+  const now = Date.now();
+
+  // 惰性清理
+  if (now - lastCleanupTime > CACHE_CLEANUP_INTERVAL_MS) {
+    performCacheCleanup();
+  }
+
+  for (const { platform, id, songInfo } of songs) {
+    const key = makeSongCacheKey(platform, id);
+    SONG_CACHE.set(key, {
+      expiresAt: now + SONG_CACHE_TTL_MS,
+      data: songInfo,
+    });
+  }
+}
+
+/**
+ * 智能清理过期的缓存条目
+ */
+function performCacheCleanup(): { expired: number; total: number; sizeLimited: number } {
+  const now = Date.now();
+  const keysToDelete: string[] = [];
+  let sizeLimitedDeleted = 0;
+
+  // 1. 清理过期条目
+  SONG_CACHE.forEach((entry, key) => {
+    if (entry.expiresAt <= now) {
+      keysToDelete.push(key);
+    }
+  });
+
+  const expiredCount = keysToDelete.length;
+  keysToDelete.forEach(key => SONG_CACHE.delete(key));
+
+  // 2. 如果缓存大小超限，清理最老的条目（LRU策略）
+  if (SONG_CACHE.size > MAX_CACHE_SIZE) {
+    const entries = Array.from(SONG_CACHE.entries());
+    // 按照过期时间排序，最早过期的在前面
+    entries.sort((a, b) => a[1].expiresAt - b[1].expiresAt);
+
+    const toRemove = SONG_CACHE.size - MAX_CACHE_SIZE;
+    for (let i = 0; i < toRemove; i++) {
+      SONG_CACHE.delete(entries[i][0]);
+      sizeLimitedDeleted++;
+    }
+  }
+
+  lastCleanupTime = now;
+
+  return {
+    expired: expiredCount,
+    total: SONG_CACHE.size,
+    sizeLimited: sizeLimitedDeleted
+  };
+}
+
+/**
+ * 清除所有歌曲缓存
+ */
+export function clearSongCache(): { cleared: number } {
+  const size = SONG_CACHE.size;
+  SONG_CACHE.clear();
+  return { cleared: size };
+}
+
+/**
+ * 获取缓存统计信息
+ */
+export function getSongCacheStats(): {
+  size: number;
+  maxSize: number;
+  ttlMs: number;
+} {
+  return {
+    size: SONG_CACHE.size,
+    maxSize: MAX_CACHE_SIZE,
+    ttlMs: SONG_CACHE_TTL_MS,
+  };
+}