spring boot redis 布隆过滤器

简单实现

import com.google.common.base.Charsets;
import com.google.common.hash.Funnel;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

/**
 * 〈Redis配置〉
 *
 * @create 2019/1/22
 * @since 1.0.0
 */
@Configuration
public class RedisConfig {
    @Autowired
    private RedisTemplate redisTemplate;

    @Bean
    public RedisTemplate redisTemplateInit() {
        //设置序列化Key的实例化对象
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        //设置序列化Value的实例化对象
        redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());

        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(new StringRedisSerializer());
        return redisTemplate;
    }

	/**
     * <注册BloomFilterHelper>
     * 
     * @param 
     * @return com.zy.crawler.config.redis.BloomFilterHelper
     * @author Lifeifei
     * @date 2019/4/8 13:18 
     */
    @Bean
    public BloomFilterHelper<String> initBloomFilterHelper() {
        return new BloomFilterHelper<>((Funnel<String>) (from, into) -> into.putString(from, Charsets.UTF_8)
                .putString(from, Charsets.UTF_8), 1000000, 0.01);
    }
}

import com.zy.crawler.config.redis.BloomFilterHelper;
import com.zy.crawler.mapper.WbUserMapper;
import com.zy.crawler.model.weibo.WbUser;
import com.zy.crawler.service.redis.RedisService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

import java.util.List;

/**
 * 〈RedisRunner-用于在项目启动时加载需要的redis相关内容〉
 *
 * @create 2019/1/22
 * @since 1.0.0
 */
@Slf4j
@Component
public class RedisRunner implements CommandLineRunner {

    @Autowired
    private RedisService redisService;

    @Autowired
    private WbUserMapper wbUserMapper;

    @Autowired
    private BloomFilterHelper bloomFilterHelper;

    @Override
    public void run(String... args) throws Exception {
        log.info("**** RedisRunner ****");
        List<WbUser> wbUsers = wbUserMapper.selectListForBloom();
        // 初始化布隆过滤器内容
        for (WbUser user : wbUsers) {
            redisService.addByBloomFilter(bloomFilterHelper, "bloom", user.getName());
        }
    }
}

import com.google.common.base.Preconditions;
import com.google.common.hash.Funnel;
import com.google.common.hash.Hashing;

/**
 * <布隆过滤器>
 *
 *  算法过程：
 * 1. 首先需要k个hash函数，每个函数可以把key散列成为1个整数
 * 2. 初始化时，需要一个长度为n比特的数组，每个比特位初始化为0
 * 3. 某个key加入集合时，用k个hash函数计算出k个散列值，并把数组中对应的比特位置为1
 * 4. 判断某个key是否在集合时，用k个hash函数计算出k个散列值，并查询数组中对应的比特位，如果所有的比特位都是1，认为在集合中。
 *
 * @author Lifeifei
 * @create 2019/4/4
 * @since 1.0.0
 */
public class BloomFilterHelper<T> {

    private int numHashFunctions;

    private int bitSize;

    private Funnel<T> funnel;

    public BloomFilterHelper(Funnel<T> funnel, int expectedInsertions, double fpp) {
        Preconditions.checkArgument(funnel != null, "funnel不能为空");
        this.funnel = funnel;
        // 计算bit数组长度
        bitSize = optimalNumOfBits(expectedInsertions, fpp);
        // 计算hash方法执行次数
        numHashFunctions = optimalNumOfHashFunctions(expectedInsertions, bitSize);
    }

    public int[] murmurHashOffset(T value) {
        int[] offset = new int[numHashFunctions];

        long hash64 = Hashing.murmur3_128().hashObject(value, funnel).asLong();
        int hash1 = (int) hash64;
        int hash2 = (int) (hash64 >>> 32);
        for (int i = 1; i <= numHashFunctions; i++) {
            int nextHash = hash1 + i * hash2;
            if (nextHash < 0) {
                nextHash = ~nextHash;
            }
            offset[i - 1] = nextHash % bitSize;
        }

        return offset;
    }

    /**
     * 计算bit数组长度
     */
    private int optimalNumOfBits(long n, double p) {
        if (p == 0) {
            // 设定最小期望长度
            p = Double.MIN_VALUE;
        }
        int sizeOfBitArray = (int) (-n * Math.log(p) / (Math.log(2) * Math.log(2)));
        return sizeOfBitArray;
    }

    /**
     * 计算hash方法执行次数
     */
    private int optimalNumOfHashFunctions(long n, long m) {
        int countOfHash = Math.max(1, (int) Math.round((double) m / n * Math.log(2)));
        return countOfHash;
    }
}

import com.google.common.base.Preconditions;
import com.zy.crawler.config.redis.BloomFilterHelper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.*;
import org.springframework.stereotype.Service;

import java.io.Serializable;
import java.util.List;
import java.util.Set;
import java.util.concurrent.TimeUnit;

/**
 * 〈Redis-操作工具类〉
 *
 * @create 2019/1/22
 * @since 1.0.0
 */
@Service
public class RedisService {

    @Autowired
    private RedisTemplate redisTemplate;

    /**
     * 根据给定的布隆过滤器添加值
     */
    public <T> void addByBloomFilter(BloomFilterHelper<T> bloomFilterHelper, String key, T value) {
        Preconditions.checkArgument(bloomFilterHelper != null, "bloomFilterHelper不能为空");
        int[] offset = bloomFilterHelper.murmurHashOffset(value);
        for (int i : offset) {
//            System.out.println("key : " + key + " " + "value : " + i);
            redisTemplate.opsForValue().setBit(key, i, true);
        }
    }

    /**
     * 根据给定的布隆过滤器判断值是否存在
     */
    public <T> boolean includeByBloomFilter(BloomFilterHelper<T> bloomFilterHelper, String key, T value) {
        Preconditions.checkArgument(bloomFilterHelper != null, "bloomFilterHelper不能为空");
        int[] offset = bloomFilterHelper.murmurHashOffset(value);
        for (int i : offset) {
//            System.out.println("key : " + key + " " + "value : " + i);
            if (!redisTemplate.opsForValue().getBit(key, i)) {
                return false;
            }
        }

        return true;
    }

}

动态扩容

参考博客

• https://blog.csdn.net/qq_16234613/article/details/82798892
• https://www.cnblogs.com/liyulong1982/p/6013002.html