Storage usage within reasonable limits

An app with no storage quotas or cleanup logic accumulates cache data indefinitely. On devices with limited storage — a real constraint on mid-range and older Android handsets — this causes the OS to terminate the app, deny further writes, or prompt the user to clear data. ISO 25010:2011 performance-efficiency.resource-utilisation requires that apps bound their resource footprint. Beyond the device-health impact, unbounded storage growth retains data that should have been evicted: stale records, orphaned queue items, and superseded cache entries that inflate the attack surface for physical device compromise.

Implement a storage quota check and an LRU or age-based eviction function. Call the eviction function on app launch and after any large batch write.

import AsyncStorage from '@react-native-async-storage/async-storage';

const SOFT_LIMIT_BYTES = 50 * 1024 * 1024; // 50 MB

export async function storageUsageBytes(): Promise<number> {
  const keys = await AsyncStorage.getAllKeys();
  const pairs = await AsyncStorage.multiGet(keys);
  return pairs.reduce((sum, [, v]) => sum + (v?.length ?? 0), 0);
}

export async function evictOldCache(maxAgeDays = 7) {
  const cutoff = Date.now() - maxAgeDays * 86_400_000;
  const keys = await AsyncStorage.getAllKeys();
  const cacheKeys = keys.filter(k => k.startsWith('cache_'));
  const stale = cacheKeys.filter(k => {
    const ts = parseInt(k.split('_').pop() ?? '0', 10);
    return ts < cutoff;
  });
  if (stale.length) await AsyncStorage.multiRemove(stale);
}

// On app launch:
const used = await storageUsageBytes();
if (used > SOFT_LIMIT_BYTES) await evictOldCache(3); // tighten window under pressure

Apply the same eviction logic to offline queue entries older than 30 days — a queued action that old is almost certainly no longer relevant.