How to use Redis and Dart to develop cache penetration defense functions

How to use Redis and Dart to develop cache penetration defense functions

In modern web applications, caching is a common performance optimization technology. However, caching systems may be vulnerable to cache penetration attacks. Cache penetration refers to requesting data that does not exist in the cache. When requests are frequent, it will cause a large number of invalid requests to directly access the database or other back-end services, thus affecting the performance of the system.

In order to solve the problem of cache penetration, we can use Redis and Dart language to develop a cache penetration defense function. The following are the specific implementation steps and sample code:

1. Import the Redis library in the Dart project

First, use the pubspec.yaml file to import the redis library in the Dart project, As shown below:

dependencies:
  redis: ^4.0.0

Then, run the pub get command to get the required dependencies.

2. Connect to the Redis server

Use the following code to connect to the Redis server:

import 'package:redis/redis.dart';

Future<void> main() async {
  final redis = await RedisConnection.connect('localhost', 6379);
}

Please make sure to replace localhost with # Replace ##6379 with the correct hostname and port number of your Redis server.

Create cache key

When defending against cache penetration, we need to create a unique cache key that can represent the request. This can be achieved by combining the key parameters of the request. For example, for a request with the URL

/api/data?id=123, we can use data_123 as the cache key.

String createCacheKey(String dataType, String id) {
  return '$dataType_$id';
}

Implementation of cache penetration defense function

The following is an example of using Redis and Dart to implement cache penetration defense function:

import 'package:redis/redis.dart';

class Cache {
  final RedisConnection _redis;

  Cache(this._redis);

  Future<String?> get(String key) async {
    final value = await _redis.get(key);

    if (value == null) {
      return null;
    } else if (value.isEmpty) {
      // 如果值为空字符串，则表示请求结果为空
      return '';
    } else {
      return value;
    }
  }

  Future<void> set(String key, String value, {Duration? expiration}) async {
    await _redis.set(key, value);

    if (expiration != null) {
      await _redis.expire(key, expiration.inSeconds);
    }
  }
}

class DataService {
  final Cache _cache;

  DataService(this._cache);

  Future<String> getData(String id) async {
    final cacheKey = createCacheKey('data', id);
    final cachedValue = await _cache.get(cacheKey);

    if (cachedValue != null) {
      return cachedValue;
    }

    // 从后端服务获取数据
    final data = await fetchDataFromBackendService(id);

    // 如果数据不存在，则将空字符串存储到缓存中，避免重复查询
    final expiration = data.isNotEmpty ? Duration(minutes: 5) : Duration(seconds: 30);
    await _cache.set(cacheKey, data, expiration: expiration);

    return data;
  }

  Future<String> fetchDataFromBackendService(String id) async {
    // 从后端服务获取数据的实现代码
  }
}

Future<void> main() async {
  final redis = await RedisConnection.connect('localhost', 6379);
  final cache = Cache(redis);
  final dataService = DataService(cache);

  final data = await dataService.getData('123');
  print('Data: $data');
}

On top In the example, we first encapsulate the interaction with Redis by creating the

Cache class. Then, implement the data acquisition logic by creating the DataService class. In the getData method, we first try to get the requested data from the cache, if the data does not exist, then get the data from the backend service and store the result into the cache.

Through the above steps and sample code, we can use Redis and Dart to develop a simple and effective cache penetration defense function. This will greatly improve the performance and security of the system and avoid invalid database or backend service access.

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