improve: refactor error handling and optimize key

Author: 1Lucas1apk

src/playback/hls/HLSHandler.js

@@ -245,7 +245,7 @@ export default class HLSHandler extends PassThrough {
       if (this.stop) return null
       const isRecoverable = err.message === 'aborted' || err.code === 'ECONNRESET' || err.code === 'ETIMEDOUT'
       if (isRecoverable && attempt <= 3) {
-        const delay = Math.pow(2, attempt) * 500
+        const delay = 2 ** attempt * 500
         logger('warn', 'HLSHandler', `Segment fetch failed (attempt ${attempt}/3): ${err.message}. Retrying in ${delay}ms...`)
         await new Promise(r => setTimeout(r, delay))
         return this._fetchWithRetry(segment, attempt + 1)
@@ -255,6 +255,23 @@ export default class HLSHandler extends PassThrough {
     }
   }
 
+  async _waitForDrain() {
+    if (this.destroyed || this.stop) return
+    return new Promise((resolve) => {
+      const cleanup = () => {
+        this.removeListener('drain', onDrain)
+        this.removeListener('close', onFinish)
+        this.removeListener('error', onFinish)
+        resolve()
+      }
+      const onDrain = cleanup
+      const onFinish = cleanup
+      this.once('drain', onDrain)
+      this.once('close', onFinish)
+      this.once('error', onFinish)
+    })
+  }
+
   async _fetchSegments() {
     if (this.isFetching || this.stop) return
     this.isFetching = true
@@ -296,20 +313,20 @@ export default class HLSHandler extends PassThrough {
         if (segment.map && segment.map.uri !== this.lastMapUri) {
           const mapData = await this.fetcher.fetchMap(segment.map, segment.key)
           if (mapData && !this.stop) {
-            if (!this.write(mapData)) await new Promise(r => this.once('drain', r))
+            if (!this.write(mapData)) await this._waitForDrain()
             this.lastMapUri = segment.map.uri
           }
         }
 
         if (this.strategy === 'segmented') {
           if (!this.stop && data) {
-            if (!this.write(data)) await new Promise(r => this.once('drain', r))
+            if (!this.write(data)) await this._waitForDrain()
           }
         } else if (stream) {
           this.activeSegmentStreams.set(key, stream)
           for await (const chunk of stream) {
             if (this.stop) break
-            if (!this.write(chunk)) await new Promise(r => this.once('drain', r))
+            if (!this.write(chunk)) await this._waitForDrain()
           }
           this.activeSegmentStreams.delete(key)
         }

src/playback/hls/SegmentFetcher.js

@@ -8,7 +8,7 @@ class DecryptTransform extends Transform {
     this.decipher = crypto.createDecipheriv(algorithm, key, iv)
     this.decipher.setAutoPadding(false)
   }
-  _transform(chunk, encoding, callback) {
+  _transform(chunk, _encoding, callback) {
     try { this.push(this.decipher.update(chunk)); callback() }
     catch (err) { callback(err) }
   }
@@ -44,6 +44,10 @@ export default class SegmentFetcher {
           logger('error', 'SegmentFetcher', `Key fetch failed for ${keyInfo.uri}: Status ${statusCode}, Error: ${error?.message || 'Empty Body'}`)
           throw new Error(`Key fetch failed: ${statusCode}`)
         }
+        if (this.keyMap.size >= 20) {
+          const firstKey = this.keyMap.keys().next().value
+          this.keyMap.delete(firstKey)
+        }
         this.keyMap.set(keyInfo.uri, body)
     return body
   }
@@ -54,7 +58,7 @@ export default class SegmentFetcher {
       headers: this.headers, responseType: 'buffer', localAddress: this.localAddress
     })
     if (error || statusCode !== 200) throw new Error(`Map fetch failed: ${statusCode}`)
-    if (keyInfo && keyInfo.iv && body.length % 16 === 0) {
+    if (keyInfo?.iv && body.length % 16 === 0) {
       const keyData = await this.fetchKey(keyInfo)
       const algorithm = keyInfo.method === 'AES-128' ? 'aes-128-cbc' : 'aes-256-cbc'
       const decipher = crypto.createDecipheriv(algorithm, keyData, keyInfo.iv)