实现用例分析
上篇基于Kafka消息驱动最终一致事务（一）介绍BASE的理论，接着我们引入一个实例看如何实现BASE，我们会用图7显示的算法实现BASE。
首先介绍使用技术栈
JDK：1.8
Spring：spring-boot，spring-data-jpa
数据库：Mysql
消息服务器：Kafka
数据表
用户库user创建用户表user，更新应用表updates_applied
CREATE TABLE `user` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(50) NOT NULL, `amt_sold` INT(11) NOT NULL DEFAULT '0', `amt_bought` INT(11) NOT NULL DEFAULT '0', PRIMARY KEY (`id`) ); CREATE TABLE `updates_applied` ( `trans_id` INT(11) NOT NULL, `balance` VARCHAR(50) NOT NULL, `user_id` INT(11) NOT NULL );
交易库transaction创建交易库表transaction
CREATE TABLE `transaction` ( `xid` INT(11) NOT NULL AUTO_INCREMENT, `seller_id` INT(11) NOT NULL, `buyer_id` INT(11) NOT NULL, `amount` INT(11) NOT NULL, PRIMARY KEY (`xid`) );
配置两个数据源
使用JavaConfig方式。其它damain类，repository类，service类请看源码github地址：https://github.com/birdstudiocn/spring-sample/tree/master/Message-Driven-Sample
package cn.birdstudio.user.domain;
import javax.sql.DataSource;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
@Configuration
@EnableJpaRepositories(basePackageClasses = User.class, entityManagerFactoryRef = "userEntityManagerFactory", transactionManagerRef = "userTransactionManager")
class UserDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource.user")
DataSourceProperties userDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@ConfigurationProperties("app.datasource.user")
DataSource userDataSource() {
return userDataSourceProperties().initializeDataSourceBuilder().build();
}
@Bean
LocalContainerEntityManagerFactoryBean userEntityManagerFactory() {
HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
vendorAdapter.setGenerateDdl(false);
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setJpaVendorAdapter(vendorAdapter);
factory.setPackagesToScan(User.class.getPackage().getName());
factory.setDataSource(userDataSource());
factory.setPersistenceUnitName("user");
return factory;
}
@Bean
PlatformTransactionManager userTransactionManager() {
JpaTransactionManager txManager = new JpaTransactionManager();
txManager.setEntityManagerFactory(userEntityManagerFactory().getObject());
return txManager;
}
}
TransactionDataSourceConfiguration
package cn.birdstudio.transaction.domain;
import javax.sql.DataSource;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
@Configuration
@EnableJpaRepositories(basePackageClasses = Transaction.class, entityManagerFactoryRef = "transactionEntityManagerFactory", transactionManagerRef = "transactionManager")
class TransactionDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource.transaction")
DataSourceProperties transactionDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@ConfigurationProperties("app.datasource.transaction")
DataSource transactionDataSource() {
return transactionDataSourceProperties().initializeDataSourceBuilder().build();
}
@Bean
LocalContainerEntityManagerFactoryBean transactionEntityManagerFactory() {
HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
vendorAdapter.setGenerateDdl(false);
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setJpaVendorAdapter(vendorAdapter);
factory.setPackagesToScan(Transaction.class.getPackage().getName());
factory.setDataSource(transactionDataSource());
factory.setPersistenceUnitName("transaction");
return factory;
}
@Bean
PlatformTransactionManager transactionManager() {
JpaTransactionManager txManager = new JpaTransactionManager();
txManager.setEntityManagerFactory(transactionEntityManagerFactory().getObject());
return txManager;
}
}
配置Kafka消息服务
生产者配置类KafkaProducerConfig.java，配置KafkaTransactionManager必须设置producerFactory.setTransactionIdPrefix("trans");
Configuration
public class KafkaProducerConfig {
@Bean
public ProducerFactory<String, Map<String, Object>> producerFactory() {
DefaultKafkaProducerFactory<String, Map<String, Object>> producerFactory = new DefaultKafkaProducerFactory<>(
producerConfigs());
producerFactory.setTransactionIdPrefix("trans");
return producerFactory;
}
@Bean
public Map<String, Object> producerConfigs() {
Map<String, Object> props = new HashMap<>();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "172.16.1.168:9092");
props.put(ProducerConfig.RETRIES_CONFIG, 2);
props.put(ProducerConfig.BATCH_SIZE_CONFIG, 16384);
props.put(ProducerConfig.LINGER_MS_CONFIG, 1);
props.put(ProducerConfig.BUFFER_MEMORY_CONFIG, 33554432);
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class);
return props;
}
@Bean
public KafkaTemplate<String, Map<String, Object>> kafkaTemplate() {
return new KafkaTemplate<>(producerFactory());
}
}
消费者配置类KafkaConsumerConfig.java，配置KafkaTransactionManager
@Configuration
@EnableKafka
public class KafkaConsumerConfig {
@Bean
public KafkaListenerContainerFactory<?> kafkaListenerContainerFactory(
ProducerFactory<String, Map<String, Object>> producerFactory) {
ConcurrentKafkaListenerContainerFactory<String, TransactionMessage> factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory());
//factory.setMessageConverter(new StringJsonMessageConverter());
//factory.setConcurrency(3);
factory.getContainerProperties().setPollTimeout(3000);
factory.getContainerProperties().setTransactionManager(new KafkaTransactionManager<>(producerFactory));
return factory;
}
@Bean
public ConsumerFactory<String, TransactionMessage> consumerFactory() {
JsonDeserializer<TransactionMessage> jd = new JsonDeserializer<>(TransactionMessage.class);
return new DefaultKafkaConsumerFactory<>(consumerConfigs(), new StringDeserializer(), jd);
}
@Bean
public Map<String, Object> consumerConfigs() {
Map<String, Object> propsMap = new HashMap<>();
propsMap.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "172.16.1.168:9092");
propsMap.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false);
propsMap.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "100");
propsMap.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, "15000");
propsMap.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
propsMap.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
propsMap.put(ConsumerConfig.GROUP_ID_CONFIG, "group1");
propsMap.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
return propsMap;
}
}
Kafka消息监听接口实现UserServiceImpl。@KafkaListener(groupId = "group1", topics = "transaction")注释监听事件接口，@Transactional("userTransactionManager")注释数据库事务。事件接口被调用KafkaTransactionManager事务开始，然后JpaTransactionManager事务开始，如果事务提交则调用producer.sendOffsetsToTransaction()，最后KafkaTransactionManager事务提交。如果JpaTransactionManager事务有异常则不调用producer.sendOffsetsToTransaction()。如果JpaTransactionManager事务提交后KafkaTransactionManager事务有异常也不调用producer.sendOffsetsToTransaction()。int processed = updatesAppliedRepository.find(trans_id, id, type.toString())语句来判断是否已经更新了User。producer.sendOffsetsToTransaction()作用与删除队列消息相当。
@Component("userService")
public class UserServiceImpl implements UserService {
private static final Logger logger = LoggerFactory.getLogger(UserServiceImpl.class);
private final UserRepository userRepository;
@Resource
private UpdatesAppliedRepository updatesAppliedRepository;
public UserServiceImpl(UserRepository userRepository) {
this.userRepository = userRepository;
}
private void sold(TransactionMessage msg) {
Type type = msg.getType();
int id = msg.getId();
int amount = msg.getAmount();
int trans_id = msg.getXid();
int processed = updatesAppliedRepository.find(trans_id, id, type.toString());
if (processed == 0) {
switch (type) {
case SELLER:
userRepository.updateAmtSold(id, amount);
break;
case BUYER:
userRepository.updateAmtBought(id, amount);
break;
}
//throwException();
UpdatesApplied updatesApplied = new UpdatesApplied();
updatesApplied.setTrans_id(trans_id);
updatesApplied.setUser_id(id);
updatesApplied.setBalance(type.toString());
updatesAppliedRepository.save(updatesApplied);
}
}
@Override
@Transactional("userTransactionManager")
@KafkaListener(groupId = "group1", topics = "transaction")
//@KafkaListener(groupId = "group1", topicPartitions = @TopicPartition(topic = "", partitionOffsets = @PartitionOffset(partition = "0", initialOffset = "5")))
public void receivekafka(TransactionMessage msg) {
logger.info("receive kafka message {}", msg);
sold(msg);
}
private void throwException() {
throw new RuntimeException("throw exception in test");
}
}
参考资料
1，http://queue.acm.org/detail.cfm?id=1394128
2，Spring Data JPA - Multiple datasources exam
3，JMS
5，http://www.kennybastani.com/2016/04/event-sourcing-microservices-spring-cloud.html
6，使用Spring Cloud和Reactor在微服务中实现Event Sourcing
7，Spring Kafka Tutorial – Getting Started with the Spring for Apache Kafka
8，碧桂园旺生活平台解决分布式事务方案之tcc开源框架 https://github.com/yu199195/happylifeplat-tcc