Add Throttle

Add Throttle Rate Limiting

This skill rate-limits method execution to prevent too-frequent calls.

What This Skill Does

Adds the throttle parameter to a mix() call so that:

• The first call executes immediately
• Subsequent calls within the throttle period are ignored
• After the period expires, the next call executes

Instructions

Step 1: Identify the Method

Ask the user which Cubit method needs throttling, or identify methods that:

• Could be triggered rapidly (scroll events, button spam)
• Should not execute too frequently (refresh, sync)
• Need rate limiting for performance or API limits

Step 2: Add Throttle

Add throttle: throttle to the mix() call:

import 'package:bloc_superpowers/bloc_superpowers.dart';

class DataCubit extends Cubit<DataState> {
  DataCubit() : super(const DataState());

  void refresh() => mix(
    key: this,
    throttle: throttle,  // Add this line (default: 1 second)
    () async {
      final data = await api.fetchData();
      emit(state.copyWith(data: data));
    },
  );
}

Step 3: Configure Duration

The default throttle duration is 1 second. Customize as needed:

void refresh() => mix(
  key: this,
  throttle: throttle(duration: 5.sec),  // Rate limit to once per 5 seconds
  () async {
    final data = await api.fetchData();
    emit(state.copyWith(data: data));
  },
);

How Throttle Works

User taps refresh rapidly: tap → tap → tap → tap → tap
                           ↓     ✗     ✗     ✗     ✗
                        executes (ignored until 1 second passes)
                           ↓
                     1 second later...
                           ↓
                        tap → executes

First call runs immediately, subsequent calls are blocked for the throttle period.

Configuration Options

Duration Examples

throttle                              // 1 second (default)
throttle(duration: 500.millis)        // 500ms
throttle(duration: 5.sec)             // 5 seconds
throttle(duration: 1.minutes)         // 1 minute

Remove Lock on Error

Allow immediate retry if the method fails:

void refresh() => mix(
  key: this,
  throttle: throttle(
    duration: 5.sec,
    removeLockOnError: true,  // Allow retry after failure
  ),
  () async {
    final data = await api.fetchData();
    emit(state.copyWith(data: data));
  },
);

Force Bypass Throttle

Allow bypassing the throttle with a parameter:

void refresh({bool force = false}) => mix(
  key: this,
  throttle: throttle(
    duration: 5.sec,
    ignoreThrottle: force,  // When true, ignores throttle
  ),
  () async {
    final data = await api.fetchData();
    emit(state.copyWith(data: data));
  },
);

// Normal call - respects throttle
cubit.refresh();

// Force refresh - ignores throttle
cubit.refresh(force: true);

Per-Item Throttle with Custom Key

Different items can have separate throttle timers:

void refreshFeed(String feedId) => mix(
  key: this,
  throttle: throttle(key: (FeedCubit, feedId)),
  () async {
    final posts = await api.fetchFeed(feedId);
    emit(state.copyWith(feeds: {...state.feeds, feedId: posts}));
  },
);

With this setup:

• Refreshing feed "A" has its own throttle timer
• Refreshing feed "B" has its own throttle timer
• You can refresh different feeds independently

Common Patterns

Pull-to-Refresh

void refresh({bool force = false}) => mix(
  key: this,
  throttle: throttle(
    duration: 5.sec,
    ignoreThrottle: force,
    removeLockOnError: true,
  ),
  () async {
    final data = await api.getData();
    emit(state.copyWith(data: data));
  },
);

// In widget
RefreshIndicator(
  onRefresh: () async {
    context.read<DataCubit>().refresh(force: true);
  },
  child: DataList(),
)

Scroll-Based Loading

void loadMore() => mix(
  key: LoadMore,
  throttle: throttle(duration: 500.millis),
  () async {
    final nextPage = await api.getNextPage(state.currentPage + 1);
    emit(state.copyWith(
      items: [...state.items, ...nextPage.items],
      currentPage: state.currentPage + 1,
    ));
  },
);

Like/Favorite Button

void toggleLike(String itemId) => mix(
  key: (ToggleLike, itemId),
  throttle: throttle(duration: 1.sec),
  () async {
    await api.toggleLike(itemId);
    emit(state.copyWith(
      likedItems: state.likedItems.contains(itemId)
          ? state.likedItems.remove(itemId)
          : state.likedItems.add(itemId),
    ));
  },
);

API with Rate Limits

void fetchData() => mix(
  key: this,
  throttle: throttle(duration: 1.sec),  // Match API rate limit
  retry: retry,
  () async {
    final data = await rateLimitedApi.getData();
    emit(data);
  },
);

Throttle vs Debounce vs Fresh

Throttle: "Execute now, then wait before allowing again" Debounce: "Wait until user stops, then execute" Fresh: "Skip if we already have recent data"

Manual Lock Control

Clear throttle locks manually when needed:

// Clear throttle for a specific key
Superpowers.removeThrottleLock(DataCubit);
Superpowers.removeThrottleLock((FeedCubit, feedId));

// Clear all throttle locks
Superpowers.removeAllThrottleLocks();

Complete Example

class FeedCubit extends Cubit<FeedState> {
  FeedCubit() : super(const FeedState());

  // Throttle refresh to once per 5 seconds
  void refresh({bool force = false}) => mix(
    key: this,
    throttle: throttle(
      duration: 5.sec,
      ignoreThrottle: force,
      removeLockOnError: true,
    ),
    retry: retry,
    () async {
      final posts = await api.getPosts();
      emit(state.copyWith(posts: posts));
    },
  );

  // Throttle scroll-based loading
  void loadMore() => mix(
    key: LoadMore,
    throttle: throttle(duration: 500.millis),
    () async {
      if (state.hasMore) {
        final nextPage = await api.getPosts(page: state.page + 1);
        emit(state.copyWith(
          posts: [...state.posts, ...nextPage.posts],
          page: state.page + 1,
          hasMore: nextPage.hasMore,
        ));
      }
    },
  );
}

// Widget
class FeedScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return RefreshIndicator(
      onRefresh: () async {
        context.read<FeedCubit>().refresh(force: true);
      },
      child: NotificationListener<ScrollNotification>(
        onNotification: (notification) {
          if (notification.metrics.pixels >=
              notification.metrics.maxScrollExtent - 200) {
            context.read<FeedCubit>().loadMore();
          }
          return false;
        },
        child: PostsList(),
      ),
    );
  }
}

User Preferences

Ask the user:

1. What duration? (depends on use case and API limits)
2. Allow force bypass? (for pull-to-refresh)
3. Remove lock on error? (allow retry after failure)
4. Per-item throttle? (separate limits by ID)

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