前置

mongodb分片集群想要使用事务,需要对应分片没有仲裁节点

代码

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-mongodb</artifactId><version>2.1.0.RELEASE</version></dependency>

如果是单个mongos

import org.springframework.context.annotation.Bean;
import org.springframework.data.mongodb.MongoDbFactory;
import org.springframework.data.mongodb.MongoTransactionManager;
import org.springframework.stereotype.Component;/*** @author kittlen* @date 2024-04-09 17:20* @description*/@Component
public class MongodbConfig {@Beanpublic MongoTransactionManager transactionManager(MongoDbFactory factory) {return new MongoTransactionManager(factory);}
}

使用

@Autowiredprivate MongoTemplate mongoTemplate;@Autowiredprivate MongoTransactionManager mongoTransactionManager;public int dbFunc(){TransactionTemplate transactionTemplate = new TransactionTemplate(mongoTransactionManager);return transactionTemplate.execute(status -> {try {UpdateResult updateResult = mongoTemplate.updateFirst(query, update, collection1);long l = updateResult.getUpsertedId() == null ? updateResult.getModifiedCount() : 1;if (l > 0) {mongoTemplate.insert(saveEntity, collection2);}return 1;} catch (Exception e) {// 如果发生异常，事务将在此处回滚,通过status.setRollbackOnly();或者抛出异常都可回滚status.setRollbackOnly();return 0;}});
}

如果连接是多mongos,则需要重写BaseCluster类

多mongos时使用的是随机获取的方式获取mongosClient,通过记录第一次调用的client使后续事务内的请求都通过同一个client请求,防止出现不同mongos导致事务失败情况

事务记录类

import com.mongodb.connection.Server;import java.util.function.Supplier;/*** @author kittlen* @date 2024-04-29 12:08* @description*/public class MultiServiceTransactionConfig {/*** mongodb多实例事务使用*/private static ThreadLocal<Server> mongoMultiServerTransactionUserService = new ThreadLocal<>();/*** 是否开启多实例事务*/private static ThreadLocal<Boolean> mongoMultiServerTransactionCanUser = new ThreadLocal<>();/*** 获取service** @param supplier 如果该service不存在,则获取新service的方法* @return*/public static Server getService(Supplier<Server> supplier) {Server server = mongoMultiServerTransactionUserService.get();if (server != null) {return server;} else {Server saveServer = supplier.get();mongoMultiServerTransactionUserService.set(saveServer);return saveServer;}}/*** 开启事务记录*/public static void openMultiServerTransaction() {mongoMultiServerTransactionCanUser.set(true);}/*** 是否开启多实例事务** @return*/public static boolean canOpenMultiServerTransaction() {Boolean b = mongoMultiServerTransactionCanUser.get();return Boolean.TRUE.equals(b);}/*** 清除事务配置信息*/public static void clean() {mongoMultiServerTransactionCanUser.remove();mongoMultiServerTransactionUserService.remove();}
}

重写mongodb的类com.mongodb.internal.connection.BaseCluster的selectServer方法

@Overridepublic Server selectServer(final ServerSelector serverSelector) {isTrue("open", !isClosed());try {CountDownLatch currentPhase = phase.get();ClusterDescription curDescription = description;ServerSelector compositeServerSelector = getCompositeServerSelector(serverSelector);Server server;if (this instanceof MultiServerCluster) {server = MultiServiceTransactionConfig.canOpenMultiServerTransaction() ? MultiServiceTransactionConfig.getService(() -> selectRandomServer(compositeServerSelector, description)) : selectRandomServer(compositeServerSelector, curDescription);} else {server = selectRandomServer(compositeServerSelector, curDescription);}boolean selectionFailureLogged = false;long startTimeNanos = System.nanoTime();long curTimeNanos = startTimeNanos;long maxWaitTimeNanos = getMaxWaitTimeNanos();while (true) {throwIfIncompatible(curDescription);if (server != null) {return server;}if (curTimeNanos - startTimeNanos > maxWaitTimeNanos) {throw createTimeoutException(serverSelector, curDescription);}if (!selectionFailureLogged) {logServerSelectionFailure(serverSelector, curDescription);selectionFailureLogged = true;}connect();currentPhase.await(Math.min(maxWaitTimeNanos - (curTimeNanos - startTimeNanos), getMinWaitTimeNanos()), NANOSECONDS);curTimeNanos = System.nanoTime();currentPhase = phase.get();curDescription = description;server = selectRandomServer(compositeServerSelector, curDescription);}} catch (InterruptedException e) {throw new MongoInterruptedException(format("Interrupted while waiting for a server that matches %s", serverSelector), e);}}

重点为:

			Server server;if (this instanceof MultiServerCluster) {server = MultiServiceTransactionConfig.canOpenMultiServerTransaction() ? MultiServiceTransactionConfig.getService(() -> selectRandomServer(compositeServerSelector, description)) : selectRandomServer(compositeServerSelector, curDescription);} else {server = selectRandomServer(compositeServerSelector, curDescription);}

使用

			try {TransactionTemplate transactionTemplate = new TransactionTemplate(mongoTransactionManager);MultiServiceTransactionConfig.openMultiServerTransaction();return transactionTemplate.execute(status -> {try {UpdateResult updateResult = mongoTemplate.updateFirst(query, update,ollection1);long l = updateResult.getUpsertedId() == null ? updateResult.getModifiedCount() : 1;if (l > 0) {mongoTemplate.insert(historyDetailsEntity, collection2);}return 1;} catch (Exception e) {// 如果发生异常，事务将在此处回滚,通过status.setRollbackOnly();或者抛出异常都可回滚status.setRollbackOnly();return 0;}});} finally {MultiServiceTransactionConfig.clean();}