Rust:如何逐块读取文件 [英] Rust: How to read a file block by block

问题描述

我完全不生锈.我想按块/块(每个块应包含16个字节)读取一个文件块，并将其写入此文件(对于此测试方案)到另一个文件f2中.所以我首先在这里用此代码尝试了它:

i am totally new to rust. I want to read a file block by block/Chunks (every block should contain 16 Bytes) and write it - for this test scenario - into another file, f2. So i i tried it first with this code here:

let mut buf = [0;16];
let mut count = 0;

     for byte in f1.bytes() {

            if count  == 16 {
                do_smth(&mut f2, &mut buf);
                count = 0;
                let data = byte?;
                buf[count] = data;

            } else {
                let data = byte?;
                buf[count] = data;
                count +=1;
            }

    }

文件f1中的测试字节为:

The test bytes in the file f1 were:

0123456789abcdef-hello world, hello world!

文件f2中的结果为

0123456789abcdefhello world, hel

是否有一种高效的方法可以在每次迭代时增加文件光标. 我阅读了关于seek函数的信息，并对其进行了一些尝试，但并未找到解决方案.也许可以通过每次交互增加文件光标来解决此问题?

Is there a performant way to increment the file cursor each iteration. I read about the seek function and experimented a little with it but didn't come to a solution. Maybe this could be solved with an increment of the file cursor each interation?

推荐答案

为了提高性能，您可以考虑两件事:

There are two thing you could consider in order to improve performance:

1. 将File包裹在BufReader中，以减少系统调用的次数，并从本质上对您的文件访问进行分块.
2. 您可能想查看内存映射包，以使用内存映射文件.
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1. Wrapping File in a BufReader to reduce the number of system calls and essentially chunking your file access.
2. You might want to check out the memmap crate, to use a memory mapped file.

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