rust - 用async-std大块读取

Question

我正在尝试实现类似于使用AsynchronousByteChannel在Java中读取文件的操作

   AsynchronousFileChannel channel = AsynchronousFileChannel.open(path...

   channel.read(buffer,... new CompletionHandler<Integer, ByteBuffer>() {
      @Override
      public void completed(Integer result) {
          ...use buffer         
      }

也就是说，请阅读操作系统提供的内容，进行处理，要求更多的内容等等。
用async_std实现此目的最直接的方法是什么？

Answer 1

您可以使用read特性的 async_std::io::Read 方法:

use async_std::prelude::*;

let mut reader = obtain_read_somehow();
let mut buf = [0; 4096]; // or however large you want it

// read returns a Poll<Result> so you have to handle the result
loop {
    let byte_count = reader.read(&mut buf).await?;
    if byte_count == 0 {
        // 0 bytes read means we're done
        break;
    }
    // call whatever handler function on the bytes read
    handle(&buf[..byte_count]);
}