plume-db

Plume Database

The main goal of this module is to expose a HikariCP DataSource through dependency injection.

Moreover this module contains an API to simplify the use of a transaction over a JDBC connection. This API is available in the TransactionManager class.

Configuration

The configuration is based on the Plume Config module and more specificaly the com.typesafe.config.Config object.

By default, all keys right under db.hikari are directly passed to Hikari. For example:

db.hikari.dataSourceClassName="oracle.jdbc.pool.OracleDataSource"
db.hikari."dataSource.url"="jdbc:oracle:thin:@localhost:1521:orcl"
db.hikari."dataSource.user"=login
db.hikari."dataSource.password"=password
db.hikari.minimumIdle=1
db.hikari.maximumPoolSize=4
db.hikari.leakDetectionThreshold=30000
db.hikari.idleTimeout=20000

Do note that subkeys should be wrapped inside quotes, so db.hikari.minimumIdle=1 is ok but db.hikari.dataSource.user=login is not ok, instead it should be written db.hikari."dataSource.user"=login.

Multiple databases

To connect to several databases, you have to extend TransactionManager and configure which Config prefix should be read.

Extending TransactionManager

For example, if you have 2 databases stats and product, you will need to create 2 classes:

@Singleton
public class StatsTransactionManager extends TransactionManager {

	@Inject
	public StatsTransactionManager(Config config) {
		super(config, "db.stats");
	}

}

and

@Singleton
public class ProductTransactionManager extends TransactionManager {

	@Inject
	public ProductTransactionManager(Config config) {
		super(config, "db.product");
	}

}

Config Properties

This way you can configure your 2 connections with:

# stats database
db.stats.hikari.dataSourceClassName="oracle.jdbc.pool.OracleDataSource"
db.stats.hikari."dataSource.url"="jdbc:oracle:thin:@localhost:1521:orcl"
db.stats.hikari."dataSource.user"=login
db.stats.hikari."dataSource.password"=password

# product database
db.product.hikari.dataSourceClassName="com.mysql.jdbc.jdbc2.optional.MysqlDataSource"
db.product.hikari."dataSource.url"="jdbc:mysql://localhost/product"
db.product.hikari."dataSource.user"=login
db.product.hikari."dataSource.password"=password

Usage example

Now when you want to use the stats database, just reference the StatsTransactionManager:

@Singleton
public class VisitDao {

	private final StatsTransactionManager transactionManager;

	@Inject
	public VisitDao(StatsTransactionManager transactionManager) {
		this.transactionManager = transactionManager;
	}

	public long countVisits(LocalDate day) {
		return transactionManager.executeAndReturn(connection -> {
			try(PreparedStatement statement
					= connection.prepareStatement("SELECT COUNT(*) FROM VISIT WHERE DAY = ?")) {
				// ...
			}
		});
	}

}

With Plume Querydsl

If you are using Plume Querydsl, you should extend TransactionManagerQuerydsl instead of TransactionManager:

@Singleton
public class StatsTransactionManager extends TransactionManagerQuerydsl {

	@Inject
	public StatsTransactionManager(Config config) {
		super(config, "db.stats");
	}

}