DatabaseWrapper.java 文件源码

/**
 * Send a notifications with Postgres' LISTEN/NOTIFY feature.
 * See https://www.postgresql.org/docs/current/static/sql-notify.html for more info.
 * <p>
 * See {@link NotificationService} for a listener implementation provided by this package.
 */
public void notif(@Nonnull String channel, @Nullable String payload) {
    final EntityManager em = this.databaseConnection.getEntityManager();
    try {
        em.getTransaction().begin();
        //the cast is necessary otherwise hibernate chokes on the void return type
        em.createNativeQuery("SELECT cast(pg_notify(:channel, :payload) AS TEXT);")
                .setParameter("channel", channel)
                .setParameter("payload", payload != null ? payload : "")
                .getSingleResult();
        em.getTransaction().commit();
    } catch (final PersistenceException e) {
        final String message = String.format("Failed to execute notification for channel %s with payload %s on DB %s",
                channel, payload, this.databaseConnection.getName());
        throw new DatabaseException(message, e);
    } finally {
        em.close();
    }
}