db-connect.clj

;; make sure you have c3p0 jar in classpath

(def *c3p0-datasource*
  (let [db-config (org.ho.yaml.Yaml/load (java.io.File. "../../config/database.yml"))
        env-config (get db-config rails-env) ]
    (doto (com.mchange.v2.c3p0.ComboPooledDataSource.)
      (.setDriverClass "com.mysql.jdbc.Driver")
      (.setJdbcUrl (str "jdbc:mysql://" (get env-config "host") "/" (get env-config "database")))
      (.setConnectionTesterClassName "com.mysql.jdbc.integration.c3p0.MysqlConnectionTester")
      (.setIdleConnectionTestPeriod 120)
      (.setUser (get env-config "username"))
      (.setPassword (get env-config "username")))))

; and then ...

 (with-connection {:datasource *c3p0-datasource*}
    ...)