perf: parallel lrclib requests + in-memory cache for lyrics

- Android + web: fire exact/artist-search/title-search in parallel so
  total wait = slowest single request instead of sum of all three
- Android: HashMap cache keyed by artist|title, cleared on app restart
- Web: Map cache (session lifetime), cache hit is instant re-open
- Web: extract _showLyricsResult helper, safeJson wrapper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

android/app/src/main/kotlin/com/novasonic/app/api/LrcLibClient.kt

@@ -7,6 +7,8 @@ import io.ktor.client.plugins.*
 import io.ktor.client.plugins.contentnegotiation.*
 import io.ktor.client.request.*
 import io.ktor.serialization.kotlinx.json.*
+import kotlinx.coroutines.async
+import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.withTimeoutOrNull
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
@@ -24,15 +26,11 @@ data class LrcLibResponse(
 )
 
 @Serializable
-private data class NetEaseSearchResp(
-    val result: NetEaseResult? = null,
-    val code: Int = 0,
-)
+private data class NetEaseSearchResp(val result: NetEaseResult? = null, val code: Int = 0)
 @Serializable
 private data class NetEaseResult(val songs: List<NetEaseSong> = emptyList())
 @Serializable
 private data class NetEaseSong(val id: Long = 0, val duration: Long = 0)
-
 @Serializable
 private data class NetEaseLyricsResp(val lrc: NetEaseLrc? = null, val code: Int = 0)
 @Serializable
@@ -63,20 +61,27 @@ object LrcLibClient {
             json(Json { ignoreUnknownKeys = true; isLenient = true })
         }
         install(HttpTimeout) {
-            requestTimeoutMillis = 6_000
+            requestTimeoutMillis = 7_000
             connectTimeoutMillis = 5_000
-            socketTimeoutMillis  = 6_000
+            socketTimeoutMillis  = 7_000
         }
     }
 
+    // Simple in-memory cache — avoids re-fetching when reopening lyrics for the same song
+    private val cache = HashMap<String, LrcLibResponse?>()
+
     suspend fun getLyrics(
         artist: String,
         title: String,
         album: String?,
         durationSecs: Int?,
     ): LrcLibResponse? {
-        // 1. lrclib exact match
-        val exact = withTimeoutOrNull(6_000) {
+        val cacheKey = "$artist|$title"
+        if (cache.containsKey(cacheKey)) return cache[cacheKey]
+
+        // Fire all three lrclib requests in parallel — total wait = slowest single request
+        val lrclibResult = coroutineScope {
+            val exactDef = async {
                 runCatching {
                     client.get("https://lrclib.net/api/get") {
                         parameter("artist_name", artist)
@@ -86,10 +91,7 @@ object LrcLibClient {
                     }.body<LrcLibResponse>()
                 }.getOrNull()
             }
-        if (exact != null) return exact
-
-        // 2. lrclib artist+title search — handles metadata mismatches
-        val byArtist = withTimeoutOrNull(6_000) {
+            val artistDef = async {
                 runCatching {
                     client.get("https://lrclib.net/api/search") {
                         parameter("track_name", title)
@@ -97,46 +99,54 @@ object LrcLibClient {
                     }.body<List<LrcLibResponse>>()
                 }.getOrNull()
             }
-        bestMatch(byArtist, durationSecs)?.let { return it }
-
-        // 3. lrclib title-only search — catches artist name mismatches like "Utada" vs "Hikaru Utada"
-        val byTitle = withTimeoutOrNull(6_000) {
+            val titleDef = async {
                 runCatching {
                     client.get("https://lrclib.net/api/search") {
                         parameter("track_name", title)
                     }.body<List<LrcLibResponse>>()
                 }.getOrNull()
             }
-        bestMatch(byTitle, durationSecs)?.let { return it }
 
-        // 4. NetEase fallback — good coverage for Asian/Japanese music
+            val exact = exactDef.await()
+            if (exact != null) {
+                artistDef.cancel()
+                titleDef.cancel()
+                exact
+            } else {
+                bestMatch(artistDef.await(), durationSecs)
+                    ?: bestMatch(titleDef.await(), durationSecs)
+            }
+        }
+        if (lrclibResult != null) {
+            cache[cacheKey] = lrclibResult
+            return lrclibResult
+        }
+
+        // NetEase fallback — good for Asian/Japanese music
         val neLrc = withTimeoutOrNull(8_000) {
             runCatching { netEaseLyrics(artist, title, durationSecs) }.getOrNull()
         }
-        if (!neLrc.isNullOrBlank()) return LrcLibResponse(syncedLyrics = neLrc)
-
-        return null
+        val result = if (!neLrc.isNullOrBlank()) LrcLibResponse(syncedLyrics = neLrc) else null
+        cache[cacheKey] = result
+        return result
     }
 
     private fun bestMatch(candidates: List<LrcLibResponse>?, durationSecs: Int?): LrcLibResponse? {
         if (candidates.isNullOrEmpty()) return null
-        return if (durationSecs != null && durationSecs > 0) {
         val synced = candidates.filter { !it.syncedLyrics.isNullOrBlank() }
         val pool   = synced.ifEmpty { candidates }
-            pool.minByOrNull { kotlin.math.abs(it.duration - durationSecs) }
-                ?.takeIf { kotlin.math.abs(it.duration - durationSecs) <= 5.0 }
-                ?: synced.firstOrNull()
-                ?: candidates.firstOrNull()
+        return if (durationSecs != null && durationSecs > 0) {
+            val best = pool.minByOrNull { kotlin.math.abs(it.duration - durationSecs) }!!
+            if (kotlin.math.abs(best.duration - durationSecs) <= 5.0) best
+            else synced.firstOrNull() ?: candidates.firstOrNull()
         } else {
-            candidates.firstOrNull { !it.syncedLyrics.isNullOrBlank() }
-                ?: candidates.firstOrNull()
+            pool.firstOrNull()
         }
     }
 
     private suspend fun netEaseLyrics(artist: String, title: String, durationSecs: Int?): String? {
-        val query  = "$artist $title".trim()
         val search = client.get("https://music.163.com/api/search/get") {
-            parameter("s", query)
+            parameter("s", "$artist $title".trim())
             parameter("type", 1)
             parameter("limit", 5)
             header("Referer", "https://music.163.com")
@@ -148,18 +158,14 @@ object LrcLibClient {
             songs.minByOrNull { kotlin.math.abs(it.duration - durMs) }
                 ?.takeIf { kotlin.math.abs(it.duration - durMs) <= 5000L }
                 ?: songs.firstOrNull()
-        } else {
-            songs.firstOrNull()
-        } ?: return null
+        } else songs.firstOrNull() ?: return null
 
-        val lyricsResp = client.get("https://music.163.com/api/song/lyric") {
-            parameter("id", song.id)
+        return client.get("https://music.163.com/api/song/lyric") {
+            parameter("id", song!!.id)
             parameter("lv", 1)
             parameter("kv", 1)
             parameter("tv", -1)
             header("Referer", "https://music.163.com")
-        }.body<NetEaseLyricsResp>()
-
-        return lyricsResp.lrc?.lyric?.takeIf { it.isNotBlank() }
+        }.body<NetEaseLyricsResp>().lrc?.lyric?.takeIf { it.isNotBlank() }
     }
 }

src/player/nowplaying.js

@@ -100,6 +100,7 @@ export function switchNpTab(tab) {
 let _lyricsLines = [];
 let _lyricsSongId = null;
 let _lyricsLoadToken = 0;
+const _lyricsCache = new Map(); // "artist|title" → result object (null = not found)
 
 const LYRICS_LOOKAHEAD_MS = 200;
 
@@ -152,84 +153,78 @@ async function _loadNpLyrics(songId) {
   const title  = s?.title || '';
   const album  = s?.album || '';
   const dur    = s?.duration || 0;
+  const cacheKey = `${artist}|${title}`;
 
-  const SIG = () => AbortSignal.timeout(5000);
+  const SIG = () => AbortSignal.timeout(6000);
+  const safeJson = async (promise) => { try { const r = await promise; return r.ok ? r.json() : null; } catch { return null; } };
   const bestMatch = (candidates, durSecs) => {
     if(!candidates?.length) return null;
     const synced = candidates.filter(c => c.syncedLyrics);
     const pool   = synced.length ? synced : candidates;
     if(!durSecs) return pool[0];
-    const pick = pool.sort((a, b) => Math.abs(a.duration - durSecs) - Math.abs(b.duration - durSecs))[0];
+    const pick = [...pool].sort((a, b) => Math.abs(a.duration - durSecs) - Math.abs(b.duration - durSecs))[0];
     return Math.abs(pick.duration - durSecs) <= 5 ? pick : (synced[0] || candidates[0]);
   };
 
-  // 1. Exact match (fast path)
-  let result = null;
-  try {
-    const p = new URLSearchParams({ artist_name: artist, track_name: title });
-    if(album) p.set('album_name', album);
-    if(dur)   p.set('duration', dur);
-    const r = await fetch(`https://lrclib.net/api/get?${p}`, { signal: SIG() });
-    if(r.ok) result = await r.json();
-  } catch {}
-
-  // 2. lrclib artist+title search
-  if(token !== _lyricsLoadToken) return;
-  if(!result?.syncedLyrics && !result?.plainLyrics) {
-    try {
-      const p = new URLSearchParams({ track_name: title });
-      if(artist) p.set('artist_name', artist);
-      const r = await fetch(`https://lrclib.net/api/search?${p}`, { signal: SIG() });
-      if(r.ok) result = bestMatch(await r.json(), dur);
-    } catch {}
+  // Cache hit — instant
+  if(_lyricsCache.has(cacheKey)) {
+    const cached = _lyricsCache.get(cacheKey);
+    content.innerHTML = '';
+    _showLyricsResult(content, cached);
+    return;
   }
 
-  // 3. lrclib title-only search — catches "Utada" vs "Hikaru Utada" type mismatches
-  if(token !== _lyricsLoadToken) return;
-  if(!result?.syncedLyrics && !result?.plainLyrics) {
-    try {
-      const p = new URLSearchParams({ track_name: title });
-      const r = await fetch(`https://lrclib.net/api/search?${p}`, { signal: SIG() });
-      if(r.ok) result = bestMatch(await r.json(), dur);
-    } catch {}
-  }
+  // Fire all three lrclib requests in parallel — total wait = slowest single request
+  const exactP  = new URLSearchParams({ artist_name: artist, track_name: title });
+  if(album) exactP.set('album_name', album);
+  if(dur)   exactP.set('duration', dur);
+  const artistP = new URLSearchParams({ track_name: title });
+  if(artist) artistP.set('artist_name', artist);
+  const titleP  = new URLSearchParams({ track_name: title });
+
+  const [exactData, artistData, titleData] = await Promise.all([
+    safeJson(fetch(`https://lrclib.net/api/get?${exactP}`,    { signal: SIG() })),
+    safeJson(fetch(`https://lrclib.net/api/search?${artistP}`, { signal: SIG() })),
+    safeJson(fetch(`https://lrclib.net/api/search?${titleP}`,  { signal: SIG() })),
+  ]);
 
-  // 4. NetEase fallback — good coverage for Asian/Japanese music
   if(token !== _lyricsLoadToken) return;
+
+  let result = (exactData?.syncedLyrics || exactData?.plainLyrics ? exactData : null)
+    ?? bestMatch(artistData, dur)
+    ?? bestMatch(titleData, dur);
+
+  // NetEase fallback — good for Asian/Japanese music
   if(!result?.syncedLyrics && !result?.plainLyrics) {
     try {
       const q    = encodeURIComponent(`${artist} ${title}`.trim());
-      const sr  = await fetch(`https://music.163.com/api/search/get?s=${q}&type=1&limit=5`, {
-        headers: { Referer: 'https://music.163.com' },
-        signal: SIG(),
-      });
-      if(sr.ok) {
-        const sd    = await sr.json();
+      const sd   = await safeJson(fetch(`https://music.163.com/api/search/get?s=${q}&type=1&limit=5`, {
+        headers: { Referer: 'https://music.163.com' }, signal: SIG(),
+      }));
       const songs = sd?.result?.songs || [];
       const durMs = dur * 1000;
       const song  = dur
-          ? songs.sort((a, b) => Math.abs(a.duration - durMs) - Math.abs(b.duration - durMs))
+        ? [...songs].sort((a, b) => Math.abs(a.duration - durMs) - Math.abs(b.duration - durMs))
                     .find(s => Math.abs(s.duration - durMs) <= 5000)
         : songs[0];
-        if(song) {
-          if(token !== _lyricsLoadToken) return;
-          const lr = await fetch(
+      if(song && token === _lyricsLoadToken) {
+        const ld  = await safeJson(fetch(
           `https://music.163.com/api/song/lyric?id=${song.id}&lv=1&kv=1&tv=-1`,
           { headers: { Referer: 'https://music.163.com' }, signal: SIG() },
-          );
-          if(lr.ok) {
-            const ld = await lr.json();
+        ));
         const lrc = ld?.lrc?.lyric;
         if(lrc) result = { syncedLyrics: lrc };
       }
-        }
-      }
     } catch {}
   }
 
   if(token !== _lyricsLoadToken) return;
+  _lyricsCache.set(cacheKey, result ?? null);
   content.innerHTML = '';
+  _showLyricsResult(content, result);
+}
 
+function _showLyricsResult(content, result) {
   if(result?.syncedLyrics) {
     const parsed = _parseLrc(result.syncedLyrics);
     if(parsed.length) { _renderSyncedLines(content, parsed); return; }