Refactoring removeDuplicates function and preventing concurrent calls.

Author: Jared234

app/src/main/java/org/schabi/newpipe/local/playlist/LocalPlaylistFragment.java

@@ -95,8 +95,8 @@ public class LocalPlaylistFragment extends BaseLocalListFragment<List<PlaylistSt
     private AtomicBoolean isLoadingComplete;
     /* Has the playlist been modified (e.g. items reordered or deleted) */
     private AtomicBoolean isModified;
-    /* Is the playlist currently being processed to remove watched videos */
-    private boolean isRemovingWatched = false;
+    /* Flag to prevent simultaneous rewrites of the playlist */
+    private boolean isRewritingPlaylist = false;
 
     public static LocalPlaylistFragment getInstance(final long playlistId, final String name) {
         final LocalPlaylistFragment instance = new LocalPlaylistFragment();
@@ -353,7 +353,7 @@ public boolean onOptionsItemSelected(final MenuItem item) {
         } else if (item.getItemId() == R.id.menu_item_rename_playlist) {
             createRenameDialog();
         } else if (item.getItemId() == R.id.menu_item_remove_watched) {
-            if (!isRemovingWatched) {
+            if (!isRewritingPlaylist) {
                 new AlertDialog.Builder(requireContext())
                         .setMessage(R.string.remove_watched_popup_warning)
                         .setTitle(R.string.remove_watched_popup_title)
@@ -368,7 +368,9 @@ public boolean onOptionsItemSelected(final MenuItem item) {
                         .show();
             }
         } else if (item.getItemId() == R.id.menu_item_remove_duplicates) {
-            openRemoveDuplicatesDialog();
+            if (!isRewritingPlaylist) {
+                openRemoveDuplicatesDialog();
+            }
         } else {
             return super.onOptionsItemSelected(item);
         }
@@ -390,10 +392,10 @@ public void sharePlaylist() {
     }
 
     public void removeWatchedStreams(final boolean removePartiallyWatched) {
-        if (isRemovingWatched) {
+        if (isRewritingPlaylist) {
             return;
         }
-        isRemovingWatched = true;
+        isRewritingPlaylist = true;
         showLoading();
 
         final var recordManager = new HistoryRecordManager(getContext());
@@ -469,7 +471,7 @@ public void removeWatchedStreams(final boolean removePartiallyWatched) {
                     }
 
                     hideLoading();
-                    isRemovingWatched = false;
+                    isRewritingPlaylist = false;
                 }, throwable -> showError(new ErrorInfo(throwable, UserAction.REQUESTED_BOOKMARK,
                         "Removing watched videos, partially watched=" + removePartiallyWatched))));
     }
@@ -623,7 +625,6 @@ private void updateThumbnailUrl() {
         changeThumbnailUrl(newThumbnailUrl);
     }
 
-
     private void openRemoveDuplicatesDialog() {
         final AlertDialog.Builder builder = new AlertDialog.Builder(this.getActivity());
 
@@ -638,14 +639,28 @@ private void openRemoveDuplicatesDialog() {
     }
 
     private void removeDuplicatesInPlaylist() {
-        final List<PlaylistStreamEntry> itemsToKeep = playlistManager
-                .getDistinctPlaylistStreams(playlistId).blockingFirst();
+        if (isRewritingPlaylist) {
+            return;
+        }
+        isRewritingPlaylist = true;
+        showLoading();
 
-        itemListAdapter.clearStreamItemList();
-        itemListAdapter.addItems(itemsToKeep);
-        setVideoCount(itemListAdapter.getItemsList().size());
+        final var streamsMaybe = playlistManager
+                .getDistinctPlaylistStreams(playlistId).firstElement();
 
-        saveChanges();
+
+        disposables.add(streamsMaybe.subscribeOn(Schedulers.io())
+                .observeOn(AndroidSchedulers.mainThread())
+                .subscribe(itemsToKeep -> {
+                    itemListAdapter.clearStreamItemList();
+                    itemListAdapter.addItems(itemsToKeep);
+                    setVideoCount(itemListAdapter.getItemsList().size());
+                    saveChanges();
+
+                    hideLoading();
+                    isRewritingPlaylist = false;
+                }, throwable -> showError(new ErrorInfo(throwable, UserAction.REQUESTED_BOOKMARK,
+                        "Removing duplicated streams"))));
     }
 
     private void deleteItem(final PlaylistStreamEntry item) {