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:

dart

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:

dart

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

code

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

dart

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:

dart

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:

dart

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:

dart

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

dart

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

dart

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

dart

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

dart

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

Feature	First Call	Subsequent Calls	Best For
Throttle	Executes immediately	Blocked until period ends	Refresh, scroll, rate limits
Debounce	Waits for inactivity	Reset timer	Search, validation
Fresh	Executes if stale	Skipped if fresh	Caching loaded data

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:

dart

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

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

Complete Example

dart

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:

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