use an executor to download tracks

app/src/main/java/ru/vtosters/lite/concurrent/VTExecutors.java

@@ -3,10 +3,14 @@ package ru.vtosters.lite.concurrent;
 import com.vk.core.concurrent.VkExecutors;
 
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 import io.reactivex.Scheduler;
 
 public class VTExecutors {
+    public static ExecutorService getMusicDownloadExecutor() {
+        return VTMusicDownloadExecutor.getInstance();
+    }
 
     public static ExecutorService getIoExecutor() {
         return VkExecutors.x.e();
@@ -19,4 +23,16 @@ public class VTExecutors {
     public static Scheduler getSlowTasksScheduler() {
         return VkExecutors.x.q();
     }
+
+    static class VTMusicDownloadExecutor {
+        private VTMusicDownloadExecutor() {}
+
+        private static class LazyHolder {
+            public static final ExecutorService INSTANCE = Executors.newSingleThreadExecutor();
+        }
+
+        public static ExecutorService getInstance() {
+            return LazyHolder.INSTANCE;
+        }
+    }
 }

app/src/main/java/ru/vtosters/lite/hooks/ui/MusicBottomSheetHook.java

@@ -19,15 +19,11 @@ import com.vk.music.common.MusicPlaybackLaunchContext;
 import com.vtosters.lite.R;
 
 import java.util.ArrayList;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 
 import bruhcollective.itaysonlab.libvkx.client.LibVKXClientImpl;
 import ru.vtosters.lite.downloaders.AudioDownloader;
 
 public class MusicBottomSheetHook {
-    private static final ExecutorService executor = Executors.newCachedThreadPool();
-
     public static ArrayList<MusicAction> hook(ArrayList<MusicAction> actions, MusicTrack musicTrack) {
         if (musicTrack.F1()) return actions;
 
@@ -149,7 +145,7 @@ public class MusicBottomSheetHook {
             return tryPlayInVKX(null, null, playlist);
 
         if (actionId == R.id.add_to_cache) {
-            executor.submit(() -> AudioDownloader.cachePlaylist(playlist));
+            AudioDownloader.cachePlaylist(playlist);
             return true;
         }
 
@@ -183,7 +179,7 @@ public class MusicBottomSheetHook {
                     }
                 });
             } else {
-                executor.submit(() -> AudioDownloader.downloadPlaylist(playlist));
+                AudioDownloader.downloadPlaylist(playlist);
             }
             return true;
         }

app/src/main/java/ru/vtosters/lite/music/M3UDownloader.java

@@ -10,8 +10,6 @@ import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.crypto.NoSuchPaddingException;
@@ -28,7 +26,6 @@ import ru.vtosters.lite.utils.IOUtils;
 
 public class M3UDownloader implements ITrackDownloader {
     private static final OkHttpClient client = new OkHttpClient();
-    private ExecutorService executorService = Executors.newSingleThreadExecutor();
 
     public static M3UDownloader getInstance() {
         return Holder.INSTANCE;

app/src/main/java/ru/vtosters/lite/music/downloader/TrackDownloader.java

@@ -7,6 +7,7 @@ import com.vk.dto.music.MusicTrack;
 import java.io.File;
 
 import bruhcollective.itaysonlab.libvkx.client.LibVKXClient;
+import ru.vtosters.lite.concurrent.VTExecutors;
 import ru.vtosters.lite.music.Callback;
 import ru.vtosters.lite.music.M3UDownloader;
 import ru.vtosters.lite.music.cache.CacheDatabaseDelegate;
@@ -36,6 +37,9 @@ public class TrackDownloader {
                 Log.v("TrackDownloader", "Directory created");
             else
                 Log.e("TrackDownloader", "Directory creation failed");
-        downloader.downloadTrack(track, outDir, callback, cache);
+
+        VTExecutors.getMusicDownloadExecutor().execute(
+                () -> downloader.downloadTrack(track, outDir, callback, cache)
+        );
     }
 }