CODEWITHSUNDEEP
javaspringspring-bootcachingspring-cache
Federico Piazza
Federico Piazza

Reputation: 30985

Spring cache all elements in list separately

I'm trying to add caching to a CRUD app, I started doing something like this:

@Cacheable("users")
List<User> list() {
    return userRepository.findAll()
}
@CachePut(value = "users", key = "#user.id") 
void create(User user) {
    userRepository.create(user)
}
@CachePut(value = "users", key = "#user.id") 
void update(User user) {
    userRepository.update(user)
}
@CacheEvict(value = "users", key = "#user.id") 
void delete(User user) {
    userRepository.delete(user)
}

The problem I have is that I would like that create/update/delete operations can update the elements already stored in the cache for the list() operation (note that list() is not pulling from database but an data engine), but I am not able to do it.

I would like to cache all elements returned by list() individually so all other operations can update the cache by using #user.id. Or perhaps, make all operations to update the list already stored in cache.

I read that I could evict the whole cache when it is updated, but I want to avoid something like:

@CacheEvict(value = "users", allEntries=true) 
void create(User user) {
    userRepository.create(user)
}

Is there any way to create/update/remove values within a cached collection? Or to cache all values from a collection as individual keys?

Upvotes: 29

Views: 41435

Answers (3)

xtreme
xtreme

Reputation: 21

Try below given solution:

  @Caching(put = @CachePut(cacheNames = "product", key = "#result.id"),
            evict = @CacheEvict(cacheNames = "products", allEntries = true))
    public Product create(ProductCreateDTO dto) {
        return repository.save(mapper.asProduct(dto));
    }
    
    @Caching(put = @CachePut(cacheNames = "product", key = "#result.id"),
            evict = @CacheEvict(cacheNames = "products", allEntries = true))
    public Product update(long id, ProductCreateDTO dto) {
        return repository.save(mapper.merge(dto, get(id)));
    }

    @Caching(evict = {
            @CacheEvict(cacheNames = "product", key = "#result.id"),
            @CacheEvict(cacheNames = "products", allEntries = true)
    })
    public void delete(long id) {
        repository.delete(get(id));
    }

    @Cacheable(cacheNames = "product", key = "#id")
    public Product get(long id) {
        return repository.findById(id).orElseThrow(() -> new RuntimeException("product not found"));
    }

    @Cacheable(cacheNames = "products", key = "#pageable")
    public Page<Product> getAll(Pageable pageable) {
        return repository.findAll(pageable);
    }

Upvotes: 1

Sandeep Lakdawala
Sandeep Lakdawala

Reputation: 492

Not Sure if, using Spring's @Cacheable is a hard constraint for you, but this essentially worked for me.

I tried using Spring's RedisTemplate and Redis HasMap data-structure for storing the list elements.

Store a single User:

redisTemplate.opsForHash().put("usersRedisKey" ,user.id,user);

Storing List of Users:

Need to map this with user.id first

Map<Long, User> userMap = users.stream()
                .collect(Collectors.toMap(User::getId, Function.identity()));

    redisTemplate.opsForHash().putAll("usersRedisKey", userMap);

Get single user from Cache:

redisTemplate.opsForHash().get("usersRedisKey",user.id);

Get list of users:

redisTemplate.opsForHash().multiGet("usersRedisKey", userIds); //userIds is List of ids

Delete user from List:

redisTemplate.opsForHash().delete("usersRedisKey",user.id);

Similarly you could try using other operations from Redis HashMap to update individual objects based on ids.

I understand I am quite late to the party here, but do let me know if this works for you.

Upvotes: 3

Federico Piazza
Federico Piazza

Reputation: 30985

I'll self answer my question since no one gave any and could help others.

The problem I had when dealing with this issue was a problem of misconception of Cache usage. My need posted on this question was related to how to update members of a cached list (method response). This problem cannot be solved with cache, because the cached value was the list itself and we cannot update a cached value partially.

The way I wanted to tackle this problem is related to a "map" or a distributed map, but I wanted to use the @Cacheable annotation. By using a distributed map would have achieved what I asked in my question without using @Cacheable. So, the returned list could have been updated.

So, I had (wanted) to tackle this problem using @Cacheable from other angle. Anytime the cache needed to update I refreshed it with this code.

I used below code to fix my problem:

@Cacheable("users")
List<User> list() {
    return userRepository.findAll()
}
// Refresh cache any time the cache is modified
@CacheEvict(value = "users", allEntries = true") 
void create(User user) {
    userRepository.create(user)
}
@CacheEvict(value = "users", allEntries = true") 
void update(User user) {
    userRepository.update(user)
}
@CacheEvict(value = "users", allEntries = true") 
void delete(User user) {
    userRepository.delete(user)
}

In addition, I have enabled the logging output for spring cache to ensure/learn how the cache is working:

# Log Spring Cache output
logging.level.org.springframework.cache=TRACE

Upvotes: 12

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