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use bincode::Encode;
use sha2::{Digest, Sha256, digest::DynDigest};
use std::ops::Deref;
use serde::{Deserialize, Serialize};
use crate::{ZERO_PREFIX_AMOUNT, hash_chain::HashChain, transaction::Transaction};
use std::sync::{
Arc,
atomic::{AtomicBool, Ordering},
};
use tokio::sync::mpsc;
use tokio::task;
pub trait CryptoDigest {
fn digest(&self, state: &mut impl DynDigest);
}
#[derive(Debug, Deserialize, Serialize, Clone, PartialEq, Encode)]
pub struct Block {
pub prev_hash: Vec<u8>,
pub trans: Transaction,
pub pow: Option<u64>,
}
impl Block {
fn new(prev_hash: Option<&[u8]>, trans: Transaction) -> Self {
Self {
prev_hash: prev_hash
.unwrap_or(&[])
.to_vec(),
trans,
pow: None,
}
}
fn pref_zeros(hashed: &[u8]) -> Result<usize, usize> {
hashed
.iter()
.try_fold(0, |nonce, x| {
if nonce >= ZERO_PREFIX_AMOUNT {
Ok(nonce)
} else if *x == 0 {
Ok(nonce + 1)
} else {
Err(nonce)
}
})
}
pub async fn calc_pow(&self) -> u64 {
let threads = std::thread::available_parallelism()
.map(|n| n.get())
.unwrap_or(4); // TODO: config
let found = Arc::new(AtomicBool::new(false));
let (tx, mut rx) = mpsc::unbounded_channel::<u64>();
let prev_hash = Arc::new(
self.prev_hash
.clone(),
);
let trans = self.trans;
for t in 0..threads {
let tx = tx.clone();
let prev_hash = Arc::clone(&prev_hash);
let step = threads as u64;
let found = found.clone();
task::spawn_blocking(move || {
let mut i = t as u64;
while !found.load(Ordering::Relaxed) {
let mut hasher = Sha256::new();
Digest::update(&mut hasher, bincode::encode_to_vec((&*prev_hash, &trans, i), bincode::config::standard()).unwrap());
let hashed = hasher.finalize();
if Self::pref_zeros(&hashed).is_ok() {
if !found.swap(true, Ordering::Relaxed) {
_ = tx.send(i);
}
break;
}
i = i.wrapping_add(step);
}
});
}
// for h in handles {
// h.abort(); // h.join();
// }
rx.recv() // blocking
.await
.expect("miner dropped without sending")
}
pub async fn calc_set_pow(&mut self) {
self.pow = Some(
self.calc_pow()
.await,
);
}
pub fn verify_pow(&self) -> bool {
if let Some(nonce) = self.pow {
let mut hasher = Sha256::new();
Digest::update(&mut hasher, bincode::encode_to_vec((&self.prev_hash, &self.trans, nonce), bincode::config::standard()).unwrap());
Self::pref_zeros(&hasher.finalize()).is_ok()
} else {
false
}
}
}
impl CryptoDigest for Block {
fn digest(&self, state: &mut impl DynDigest) {
state.update(&bincode::encode_to_vec((&self.prev_hash, &self.trans, &self.pow), bincode::config::standard()).unwrap());
}
}
#[derive(Debug, Default, Deserialize, Serialize, Clone, PartialEq)]
pub struct BlockChain {
pub blocks: HashChain<Block>,
}
impl BlockChain {
pub fn new(blocks: Vec<Block>) -> Self {
Self {
blocks: HashChain::new(blocks),
}
}
pub fn new_block(&self, trans: Transaction) -> Block {
let prev = self
.blocks
.last();
let prev_hash = if let Some(b) = prev {
Some(HashChain::hash_o_item(b))
} else {
None
};
Block::new(prev_hash.as_deref(), trans)
}
pub fn store(&mut self, block: Block) {
// TODO: check config
if block.verify_pow() {
self.blocks
.push(block)
} else {
eprint!("Err: Failed to store unverified block")
}
}
}
impl Deref for BlockChain {
type Target = HashChain<Block>;
fn deref(&self) -> &Self::Target {
&self.blocks
}
}
|
