vertx实例的fileSystem文件系统模块

初始化

//根据OS区分实现　System.getProperty("os.name").toLowerCase();
 Utils.isWindows() ? new WindowsFileSystem(this) : new FileSystemImpl(this);

异步操作实现

FileSystemImpl 内部类 BlockingAction, 使用internalBlocking Pool 执行文件阻塞操作, xxxBlocking相关方法在当前主线程操作造成阻塞，尽量避免

protected abstract class BlockingAction<T> implements Action<T> {

    private final Handler<AsyncResult<T>> handler;//回调　handler
    protected final ContextImpl context;//上下文，作用:处理完成回调到同一线程

    public BlockingAction(Handler<AsyncResult<T>> handler) {
      this.handler = handler;
      this.context = vertx.getOrCreateContext();
    }

    /**
     *  Run the blocking action using a thread from the worker pool.
     */
    public void run() {
      context.executeBlocking(this, handler);　//使用　internalBlocking　Pool执行任务
    }
 }

AsyncFileImpl

FileSystemImpl 的open方法返回的AsyncFileImpl，记住调用close方法，防止文件句柄泄露, linux可使用 lsof 工具查看当前file descriptor情况

AsyncFileImpl(VertxInternal vertx, String path, OpenOptions options, ContextImpl context) {
    if (!options.isRead() && !options.isWrite()) {
      throw new FileSystemException("Cannot open file for neither reading nor writing");
    }
    this.vertx = vertx;
    Path file = Paths.get(path);
    /**定义open属性*/
    HashSet<OpenOption> opts = new HashSet<>();
    if (options.isRead()) opts.add(StandardOpenOption.READ);
    if (options.isWrite()) opts.add(StandardOpenOption.WRITE);
    if (options.isCreate()) opts.add(StandardOpenOption.CREATE);
    if (options.isCreateNew()) opts.add(StandardOpenOption.CREATE_NEW);
    if (options.isSync()) opts.add(StandardOpenOption.SYNC);
    if (options.isDsync()) opts.add(StandardOpenOption.DSYNC);
    if (options.isDeleteOnClose()) opts.add(StandardOpenOption.DELETE_ON_CLOSE);
    if (options.isSparse()) opts.add(StandardOpenOption.SPARSE);
    if (options.isTruncateExisting())   opts.add(StandardOpenOption.TRUNCATE_EXISTING);
    try {
    　//获取文件权限字符　linux 下 ls -al　文件权限标识 rwx
      if (options.getPerms() != null) {
        //将权限字符转化为FileAttribute属性
        FileAttribute<?> attrs = PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString(options.getPerms()));

        /**使用worker　Pool,而不是用默认的Executors.newCachedThreadPool(threadFactory),
            原则:vertx使用少量线程处理大并发,吞吐量优先*/
        ch = AsynchronousFileChannel.open(file, opts, vertx.getWorkerPool(), attrs);
      } else {
        ch = AsynchronousFileChannel.open(file, opts, vertx.getWorkerPool());
      }
      //属性为"追加"获取大小做为　write index
      if (options.isAppend()) writePos = ch.size();
    } catch (IOException e) {
      throw new FileSystemException(e);
    }
    //上下文，作用:处理完成回调到同一线程
    this.context = context;
}