TransactionSynchronizationManager.isCurrentTransactionReadOnly() is always false - spring

Question

I want to implement a hibernate-based approach for developing read-only DB.
I have implemented the following code but when it comes to executing the
protected Object determineCurrentLookupKey() {
event though the request comes from the #Transactional(read-only=true) it always return "read-only=false" , Why transaction does not successfully process this ? Thanks.
DatabaseContextHolder.java
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class DatabaseContextHolder {
private static final Log log = LogFactory.getLog(DatabaseContextHolder.class);
private static final ThreadLocal<DatabaseEnvironment> CONTEXT = new ThreadLocal<>();
public static void set(DatabaseEnvironment databaseEnvironment) {
CONTEXT.set(databaseEnvironment);
}
public static DatabaseEnvironment getEnvironment() {
log.info("DB Environment : " + CONTEXT.get());
return CONTEXT.get();
}
public static void reset() {
CONTEXT.set(DatabaseEnvironment.WRITABLE);
}
}
DatabaseEnvironment.java
public enum DatabaseEnvironment {
WRITABLE,
READONLY
}
TransactionRoutingDataSource.java
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.lang.Nullable;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import io.api.readWriteRoutingHibernate.DataSourceConfiguration;
import io.api.readWriteRoutingHibernate.context.DatabaseEnvironment;
public class TransactionRoutingDataSource
extends AbstractRoutingDataSource {
private static final Log log = LogFactory.getLog(DataSourceConfiguration.class);
#Nullable
#Override
protected Object determineCurrentLookupKey() {
log.info("DatabaseEnvironment.READONLY : " + TransactionSynchronizationManager
.isCurrentTransactionReadOnly() );
return TransactionSynchronizationManager
.isCurrentTransactionReadOnly() ?
DatabaseEnvironment.READONLY :
DatabaseEnvironment.WRITABLE;
}
}
DataSourceConfiguration.java
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import com.zaxxer.hikari.HikariDataSource;
import io.api.readWriteRoutingHibernate.context.DatabaseEnvironment;
import io.api.readWriteRoutingHibernate.datasource.TransactionRoutingDataSource;
#Configuration
public class DataSourceConfiguration {
private static final Log log = LogFactory.getLog(DataSourceConfiguration.class);
#Value("${spring.datasource.master.url}")
private String mstUrl;
#Value("${spring.datasource.master.username}")
private String mstUsername;
#Value("${spring.datasource.master.password}")
private String mstPassword;
#Value("${spring.datasource.slave.url}")
private String slaveUrl;
#Value("${spring.datasource.slave.username}")
private String slaveUsername;
#Value("${spring.datasource.slave.password}")
private String slavePassword;
#Bean
public DataSource dataSource() {
TransactionRoutingDataSource masterSlaveRoutingDataSource = new TransactionRoutingDataSource();
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(DatabaseEnvironment.WRITABLE, masterDataSource());
targetDataSources.put(DatabaseEnvironment.READONLY, slaveDataSource());
masterSlaveRoutingDataSource.setTargetDataSources(targetDataSources);
// Set as all transaction point to master
masterSlaveRoutingDataSource.setDefaultTargetDataSource(masterDataSource());
return masterSlaveRoutingDataSource;
}
public DataSource slaveDataSource() {
HikariDataSource hikariDataSource = new HikariDataSource();
hikariDataSource.setJdbcUrl(slaveUrl);
hikariDataSource.setUsername(slaveUsername);
hikariDataSource.setPassword(slavePassword);
return hikariDataSource;
}
public DataSource masterDataSource() {
HikariDataSource hikariDataSource = new HikariDataSource();
hikariDataSource.setJdbcUrl(mstUrl);
hikariDataSource.setUsername(mstUsername);
hikariDataSource.setPassword(mstPassword);
return hikariDataSource;
}
protected Properties additionalProperties() {
Properties properties = new Properties();
properties.setProperty(
"hibernate.connection.provider_disables_autocommit",
Boolean.TRUE.toString()
);
return properties;
}
}