Logging Active Transaction Manager in a Spring Application Using AOP

In scenarios where multiple DataSourceTransactionManager beans are used in a Spring application (e.g., one for read operations and another for write operations), it's often useful to log which transaction manager is active during a transaction. This solution uses Spring AOP to log the active PlatformTransactionManager based on whether a transaction is read-only or not.

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Step 1: Define Two DataSourceTransactionManager Beans

You will define two separate DataSourceTransactionManager beans—one for read operations (read-only) and another for write operations (default). This allows Spring to use the correct transaction manager based on the transaction context.

java
@Configuration
public class TransactionManagerConfig {

    // DataSource for write operations (default)
    @Bean
    @Primary
    public PlatformTransactionManager writeTransactionManager(DataSource writeDataSource) {
        return new DataSourceTransactionManager(writeDataSource);
    }

    // DataSource for read operations
    @Bean
    @Qualifier("readTxManager")
    public PlatformTransactionManager readTransactionManager(DataSource readDataSource) {
        return new DataSourceTransactionManager(readDataSource);
    }
}

• @Primary: Marks writeTransactionManager as the default.
• @Qualifier("readTxManager"): Differentiates the read-only transaction manager (readTxManager) from the write transaction manager.

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Step 2: Define AOP to Log Active Transaction Manager

An AOP aspect will intercept @Transactional methods and log which PlatformTransactionManager is being used. The aspect checks if the transaction is read-only and logs the appropriate manager.

java
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.stereotype.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Aspect
@Component
public class TransactionManagerLoggingAspect {

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

    // Inject both transaction managers
    @Autowired
    private PlatformTransactionManager writeTransactionManager;

    @Autowired
    @Qualifier("readTxManager")
    private PlatformTransactionManager readTransactionManager;

    // Pointcut to target methods with @Transactional annotation
    @Pointcut("@annotation(org.springframework.transaction.annotation.Transactional)")
    public void transactionalMethods() {}

    // Before the transactional method is executed, log the active transaction manager
    @Before("transactionalMethods()")
    public void logTransactionManager() {
        if (TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
            logger.info("Read-only transaction is being used with the Read Transaction Manager: {}", readTransactionManager.getClass().getName());
        } else {
            logger.info("Write transaction is being used with the Write Transaction Manager: {}", writeTransactionManager.getClass().getName());
        }
        
        // Additional logging to show active transaction context
        String currentTransactionName = TransactionSynchronizationManager.getCurrentTransactionName();
        boolean isReadOnly = TransactionSynchronizationManager.isCurrentTransactionReadOnly();
        logger.debug("Current Transaction: {}, Is Read-Only: {}", currentTransactionName, isReadOnly);
    }
}

Explanation:

• @Pointcut: Defines the AOP pointcut to intercept methods annotated with @Transactional.
• logTransactionManager(): Logs the active transaction manager before the method executes. It checks if the transaction is read-only using TransactionSynchronizationManager.isCurrentTransactionReadOnly().

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Step 3: Configure @Transactional to Use Read/Write Transaction Managers

Using the @Transactional annotation, you can specify which transaction manager to use for different operations. If readOnly = true, Spring will automatically use the read transaction manager.

java
@Service
public class MyTransactionalService {

    // This will use the readTxManager (read-only transaction)
    @Transactional(readOnly = true)
    public void performReadOperation() {
        // Your read operation logic here
        System.out.println("Executing read operation");
    }

    // This will use the default writeTxManager (write transaction)
    @Transactional
    public void performWriteOperation() {
        // Your write operation logic here
        System.out.println("Executing write operation");
    }
}

• @Transactional(readOnly = true): This triggers the use of readTxManager for read operations.
• @Transactional (without readOnly): This uses the default writeTxManager for write operations.

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Step 4: Enable AOP in Your Configuration

Ensure that AOP support is enabled in your Spring configuration by using the @EnableAspectJAutoProxy annotation.

java
@Configuration
@EnableAspectJAutoProxy // Enables AOP support in the Spring context
public class AopConfig {
    // This class enables AOP functionality
}

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Step 5: Configure Logging and Monitoring (Optional)

For better insight, you can configure the log levels in your application.properties to capture detailed logs from your aspect.

properties
# Set log level for the aspect logging
logging.level.com.example.kafka.aspect.TransactionManagerLoggingAspect=DEBUG
logging.level.org.springframework.transaction=INFO

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Summary of Flow

1. Two DataSourceTransactionManager Beans:

   • writeTransactionManager: Default transaction manager for write operations.
   • readTransactionManager: For read-only operations.

2. AOP Aspect:

   • Intercepts methods annotated with @Transactional.
   • Logs which PlatformTransactionManager is being used based on the transaction's read-only status.

3. @Transactional Configuration:

   • readOnly = true: Forces the use of the read-only transaction manager.
   • Default behavior uses the write transaction manager.

4. AOP Configuration:

   • Enables AOP to intercept @Transactional methods and log the active transaction manager.

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Conclusion

With this setup, you can efficiently log which PlatformTransactionManager (read or write) is active during the execution of each transaction. This is especially useful for debugging, monitoring, and ensuring that your system correctly handles read and write transactions separately.