SingletonHolder.java 文件源码

/**
 * @deprecated This method is only used from configuration modules and thus callers of it
 *             should use service injection to make the executor configurable.
 */
@Deprecated
public static synchronized ListeningExecutorService getDefaultCommitExecutor() {
    if (COMMIT_EXECUTOR == null) {
        final ThreadFactory factory = new ThreadFactoryBuilder().setDaemon(true).setNameFormat("md-sal-binding-commit-%d").build();
        /*
         * FIXME: this used to be newCacheThreadPool(), but MD-SAL does not have transaction
         *        ordering guarantees, which means that using a concurrent threadpool results
         *        in application data being committed in random order, potentially resulting
         *        in inconsistent data being present. Once proper primitives are introduced,
         *        concurrency can be reintroduced.
         */
        final ExecutorService executor = Executors.newSingleThreadExecutor(factory);
        COMMIT_EXECUTOR = MoreExecutors.listeningDecorator(executor);
    }

    return COMMIT_EXECUTOR;
}