比特币交易系统升级：UTXO集合与Merkle树
UTXO集合优化
1. 为什么需要UTXO集合？
传统方式下，查找未花费输出需要遍历整个区块链，这种方式效率低下。通过引入UTXO集合，我们可以直接查询当前所有未花费输出，大大提高效率。
2. UTXO集合实现
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pub struct UTXOSet {
blockchain: Blockchain,
}
impl UTXOSet {
pub fn reindex(&self) -> Result<()> {
let db = self.blockchain.db.clone();
db.drop_bucket(UTXO_BUCKET)?;
let utxos = self.blockchain.find_all_utxo()?;
let bucket = db.create_bucket(UTXO_BUCKET)?;
for (txid, outs) in utxos {
bucket.put(txid, serialize(&outs)?)?;
}
Ok(())
}
pub fn update(&self, block: &Block) -> Result<()> {
let db = self.blockchain.db.clone();
let bucket = db.get_bucket(UTXO_BUCKET)?;
for tx in &block.transactions {
for input in &tx.vin {
let mut outs = deserialize::<TXOutputs>(&bucket.get(&input.txid)?)?;
outs.outputs.remove(input.vout as usize);
if outs.outputs.is_empty() {
bucket.delete(&input.txid)?;
} else {
bucket.put(&input.txid, serialize(&outs)?)?;
}
}
let mut new_outputs = TXOutputs { outputs: vec![] };
for output in &tx.vout {
new_outputs.outputs.push(output.clone());
}
bucket.put(&tx.id, serialize(&new_outputs)?)?;
}
Ok(())
}
}
|
Merkle树实现
1. Merkle树的作用
Merkle树允许轻节点（SPV节点）在不下载整个区块的情况下验证交易，只需要：
2. 数据结构
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pub struct MerkleNode {
left: Option<Box<MerkleNode>>,
right: Option<Box<MerkleNode>>,
data: Vec<u8>,
}
pub struct MerkleTree {
root: Option<MerkleNode>,
}
|
3. 核心实现
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| impl MerkleNode {
pub fn new(left: Option<MerkleNode>, right: Option<MerkleNode>, data: Vec<u8>) -> Self {
let mut combined = Vec::new();
combined.extend(&data);
if let Some(left) = &left {
combined.extend(&left.data);
}
if let Some(right) = &right {
combined.extend(&right.data);
}
let hash = crypto::sha256(&combined);
MerkleNode {
left: left.map(Box::new),
right: right.map(Box::new),
data: hash,
}
}
}
impl MerkleTree {
pub fn new(data: Vec<Vec<u8>>) -> Self {
let mut nodes = Vec::new();
for d in data {
nodes.push(MerkleNode::new(None, None, d));
}
while nodes.len() > 1 {
let mut new_level = Vec::new();
for i in (0..nodes.len()).step_by(2) {
let left = nodes[i].clone();
let right = if i + 1 < nodes.len() {
nodes[i + 1].clone()
} else {
nodes[i].clone()
};
new_level.push(MerkleNode::new(
Some(left),
Some(right),
Vec::new(),
));
}
nodes = new_level;
}
MerkleTree {
root: if nodes.is_empty() {
None
} else {
Some(nodes.remove(0))
},
}
}
}
|
4. 区块哈希计算优化
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| impl Block {
pub fn hash(&self) -> Vec<u8> {
let txs_data: Vec<Vec<u8>> = self.transactions
.iter()
.map(|tx| tx.hash())
.collect();
let tree = MerkleTree::new(txs_data);
tree.root.unwrap().data
}
}
|
比特币交易系统升级：UTXO集合与Merkle树实现
