synchronized DataSource ds() {
if (ds == null) {
String providerClass = config.getString("provider_class");
if (providerClass == null) {
providerClass = DEFAULT_PROVIDER_CLASS;
}
try {
Class clazz = getClassLoader().loadClass(providerClass);
provider = (DataSourceProvider) clazz.newInstance();
ds = provider.getDataSource(config);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
return ds;
}
