Redis rate limiter in Spring Boot

plugins {
	id 'org.springframework.boot' version '2.3.1.RELEASE'
	id 'io.spring.dependency-management' version '1.0.9.RELEASE'
	id 'java'
}

group = 'com.carvia'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

repositories {
	mavenCentral()
}

dependencies {
	implementation 'org.springframework.boot:spring-boot-starter-data-redis'
	implementation 'org.springframework.boot:spring-boot-starter-web'
	implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.10'
	testImplementation('org.springframework.boot:spring-boot-starter-test') {
		exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
	}
}

test {
	useJUnitPlatform()
}

spring.redis.host=localhost
spring.redis.database=0
spring.redis.password=

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.dao.DataAccessException;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.SessionCallback;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;

import java.time.Instant;
import java.time.LocalDateTime;
import java.util.List;
import java.util.concurrent.TimeUnit;

@Service
public class RedisRateLimiter {

    private static final Logger logger = LoggerFactory.getLogger(RedisRateLimiter.class);

    @Autowired
    private StringRedisTemplate stringTemplate;

    private static final int REQUESTS_PER_HOUR = 10;

    public boolean isAllowed(String username) {
        final int hour = LocalDateTime.now().getHour(); (1)
        String key = username + ":" + hour;
        ValueOperations<String, String> operations = stringTemplate.opsForValue();
        String requests = operations.get(key);
        if (StringUtils.isNotBlank(requests) && Integer.parseInt(requests) >= REQUESTS_PER_HOUR) {
            return false;
        }
        List<Object> txResults = stringTemplate.execute(new SessionCallback<>() {
            @Override
            public <K, V> List<Object> execute(RedisOperations<K, V> operations) throws DataAccessException {
                final StringRedisTemplate redisTemplate = (StringRedisTemplate) operations;
                final ValueOperations<String, String> valueOperations = redisTemplate.opsForValue();
                operations.multi();
                valueOperations.increment(key);
                redisTemplate.expire(key, 2, TimeUnit.HOURS);
                // This will contain the results of all operations in the transaction
                return operations.exec();
            }
        });
        logger.info("Current request count: " + txResults.get(0));
        return true;
    }

    public void service() {
        for (int i=0; i<20; i++) {
            boolean allowed = isAllowed("carvia");
            if(!allowed)
                break;
        }
    }
}