configuration - Configuring Grails to use own DataSource implementation or to proxy the standard DataSource

Question

In an application I want to use my own implementation of javax.sql.DataSource that extends the standard org.apache.commons.dbcp.BasicDataSource used by Grails and adds the functionality to set the client identifier based on the currently logged in user at the Grails application.

What is the best way to change the underlying javax.sql.DataSource implementation in a Grails application?

At the moment I see two possibilities:

• change the implementation of the DataSource that is used by Grails
• proxy the DataSource that is used by Grails and add the functionality with AOP

Any hints on how to deal with this requirement?

Answer 1

here is my resources.groovy

import org.codehaus.groovy.grails.commons.ConfigurationHolder as CH

// Place your Spring DSL code here
beans = {

    /**
     * c3P0 pooled data source that forces renewal of DB connections of certain age 
     * to prevent stale/closed DB connections and evicts excess idle connections
     * Still using the JDBC configuration settings from DataSource.groovy
     * to have easy environment specific setup available
     */
    dataSource(com.mchange.v2.c3p0.ComboPooledDataSource) { bean ->
        bean.destroyMethod = 'close'
        //use grails' datasource configuration for connection user, password, driver and JDBC url
        user = CH.config.dataSource.username 
        password = CH.config.dataSource.password
        driverClass = CH.config.dataSource.driverClassName
        jdbcUrl = CH.config.dataSource.url
        //force connections to renew after 2 hours
        maxConnectionAge = 2 * 60 * 60
        //get rid too many of idle connections after 30 minutes 
        maxIdleTimeExcessConnections = 30 * 60
    }

}

i'm using c3p0 ComboPooledDataSource