优化

app/src/main/java/io/legado/app/service/CacheBookService.kt

@@ -140,13 +140,12 @@ class CacheBookService : BaseService() {
             cacheBook.addDownload(start, end2)
             notificationContent = CacheBook.downloadSummary
             upCacheBookNotification()
-            synchronized(this) {
+        }.onFinally {
             if (downloadJob == null) {
                 download()
             }
         }
     }
-    }
 
     private fun removeDownload(bookUrl: String?) {
         CacheBook.cacheBookMap[bookUrl]?.stop()