use sha2::{Digest, Sha256};

fn main() {
    let blobs = Blobs::new(128 * 1024);
    for blob in blobs.take(10) {
        println!("{}", sha256(&blob));
    }
}

struct Blobs {
    size: usize,
}

impl Blobs {
    fn new(size: usize) -> Self {
        Self { size }
    }
}

impl Iterator for Blobs {
    type Item = Vec<u8>;

    fn next(&mut self) -> Option<Self::Item> {
        Some(vec![0; self.size])
    }
}

fn sha256(data: &[u8]) -> String {
    let mut hasher = Sha256::new();
    hasher.update(data);
    let hash = hasher.finalize();
    format!("{:x}", hash)
}