以太坊区块设计分析(下) - 教学文档<\/h1>

1. 链条构建<\/h2>

1.1 区块链初始化流程<\/h3>
以太坊启动时通过NewBlockChain<\/code>函数创建区块链，调用流程如下：<\/p>
geth → makeFullNode → RegisterEthService → eth.New → core.NewBlockChain
<\/code><\/pre>
1.2 关键初始化步骤<\/h3>


创世区块加载<\/strong>：<\/p>

使用SetupGenesisBlockWithOverride<\/code>加载创世区块并获取链基本配置<\/li>
调用ReadDatabaseVersion<\/code>获取DB版本<\/li>
<\/ul>
<\/li>

核心组件创建<\/strong>：<\/p>

NewBlockChain<\/code>构建区块链<\/li>
NewTxPool<\/code>创建交易池<\/li>
NewOracle<\/code>进行价格预言<\/li>
<\/ul>
<\/li>

缓存配置<\/strong>：<\/p>

创建各种LRU缓存(最近最少使用算法)<\/li>
初始化triegc<\/code>(用于垃圾回收的区块number优先级队列)<\/li>
初始化stateCache<\/code><\/li>
<\/ul>
<\/li>
<\/ol>
1.3 NewBlockChain函数详解<\/h3>
func<\/span> NewBlockChain<\/span>(db<\/span> ethdb<\/span>.Database<\/span>, cacheConfig<\/span> *<\/span>CacheConfig<\/span>, chainConfig<\/span> *<\/span>params<\/span>.ChainConfig<\/span>, 
<\/span><\/span>    engine<\/span> consensus<\/span>.Engine<\/span>, vmConfig<\/span> vm<\/span>.Config<\/span>, shouldPreserve<\/span> func<\/span>(block<\/span> *<\/span>types<\/span>.Block<\/span>) bool<\/span>, 
<\/span><\/span>    txLookupLimit<\/span> *<\/span>uint64<\/span>) (*<\/span>BlockChain<\/span>, error<\/span>) {
<\/span><\/span>    \/\/ 初始化缓存
<\/span><\/span><\/span><\/span>    bodyCache<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(bodyCacheLimit<\/span>)
<\/span><\/span>    bodyRLPCache<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(bodyCacheLimit<\/span>)
<\/span><\/span>    receiptsCache<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(receiptsCacheLimit<\/span>)
<\/span><\/span>    blockCache<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(blockCacheLimit<\/span>)
<\/span><\/span>    txLookupCache<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(txLookupCacheLimit<\/span>)
<\/span><\/span>    futureBlocks<\/span>, _<\/span> :=<\/span> lru<\/span>.New<\/span>(maxFutureBlocks<\/span>)
<\/span><\/span>    
<\/span><\/span>    \/\/ 创建区块链实例
<\/span><\/span><\/span><\/span>    bc<\/span> :=<\/span> &<\/span>BlockChain<\/span>{
<\/span><\/span>        chainConfig<\/span>: chainConfig<\/span>,
<\/span><\/span>        cacheConfig<\/span>: cacheConfig<\/span>,
<\/span><\/span>        db<\/span>:          db<\/span>,
<\/span><\/span>        triegc<\/span>:      prque<\/span>.New<\/span>(nil<\/span>),
<\/span><\/span>        stateCache<\/span>: state<\/span>.NewDatabaseWithConfig<\/span>(db<\/span>, &<\/span>trie<\/span>.Config<\/span>{
<\/span><\/span>            Cache<\/span>:     cacheConfig<\/span>.TrieCleanLimit<\/span>,
<\/span><\/span>            Journal<\/span>:   cacheConfig<\/span>.TrieCleanJournal<\/span>,
<\/span><\/span>            Preimages<\/span>: cacheConfig<\/span>.Preimages<\/span>,
<\/span><\/span>        }),
<\/span><\/span>        \/\/ ...其他字段初始化
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 初始化验证器、预取器和处理器
<\/span><\/span><\/span><\/span>    bc<\/span>.validator<\/span> = NewBlockValidator<\/span>(chainConfig<\/span>, bc<\/span>, engine<\/span>)
<\/span><\/span>    bc<\/span>.prefetcher<\/span> = newStatePrefetcher<\/span>(chainConfig<\/span>, bc<\/span>, engine<\/span>)
<\/span><\/span>    bc<\/span>.processor<\/span> = NewStateProcessor<\/span>(chainConfig<\/span>, bc<\/span>, engine<\/span>)
<\/span><\/span>    
<\/span><\/span>    \/\/ 初始化区块头链
<\/span><\/span><\/span><\/span>    bc<\/span>.hc<\/span>, err<\/span> = NewHeaderChain<\/span>(db<\/span>, chainConfig<\/span>, engine<\/span>, bc<\/span>.insertStopped<\/span>)
<\/span><\/span>    
<\/span><\/span>    \/\/ 获取创世区块
<\/span><\/span><\/span><\/span>    bc<\/span>.genesisBlock<\/span> = bc<\/span>.GetBlockByNumber<\/span>(0<\/span>)
<\/span><\/span>    if<\/span> bc<\/span>.genesisBlock<\/span> ==<\/span> nil<\/span> {
<\/span><\/span>        return<\/span> nil<\/span>, ErrNoGenesis<\/span>
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 加载最新状态
<\/span><\/span><\/span><\/span>    if<\/span> err<\/span> :=<\/span> bc<\/span>.loadLastState<\/span>(); err<\/span> !=<\/span> nil<\/span> {
<\/span><\/span>        return<\/span> nil<\/span>, err<\/span>
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 启动后台任务
<\/span><\/span><\/span><\/span>    go<\/span> bc<\/span>.update<\/span>() \/\/ 定时处理future block
<\/span><\/span><\/span><\/span>    if<\/span> txLookupLimit<\/span> !=<\/span> nil<\/span> {
<\/span><\/span>        go<\/span> bc<\/span>.maintainTxIndex<\/span>(txIndexBlock<\/span>)
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    return<\/span> bc<\/span>, nil<\/span>
<\/span><\/span>}
<\/span><\/span><\/code><\/pre>1.4 状态加载机制<\/h3>
loadLastState<\/code>函数加载最新区块链状态：<\/p>

获取最新区块及其hash<\/li>
检查DB是否为空或损坏，必要时调用bc.Reset<\/code>重置区块链<\/li>
确定区块头的可用性<\/li>
获取最新区块<\/li>
通过日志记录状态信息<\/li>
<\/ol>
func<\/span> (bc<\/span> *<\/span>BlockChain<\/span>) loadLastState<\/span>() error<\/span> {
<\/span><\/span>    head<\/span> :=<\/span> rawdb<\/span>.ReadHeadBlockHash<\/span>(bc<\/span>.db<\/span>)
<\/span><\/span>    if<\/span> head<\/span> ==<\/span> (common<\/span>.Hash<\/span>{}) {
<\/span><\/span>        return<\/span> bc<\/span>.Reset<\/span>() \/\/ 空数据库时重置
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    currentBlock<\/span> :=<\/span> bc<\/span>.GetBlockByHash<\/span>(head<\/span>)
<\/span><\/span>    if<\/span> currentBlock<\/span> ==<\/span> nil<\/span> {
<\/span><\/span>        return<\/span> bc<\/span>.Reset<\/span>() \/\/ 头块缺失时重置
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    bc<\/span>.currentBlock<\/span>.Store<\/span>(currentBlock<\/span>)
<\/span><\/span>    currentHeader<\/span> :=<\/span> currentBlock<\/span>.Header<\/span>()
<\/span><\/span>    
<\/span><\/span>    \/\/ 设置当前头部和快速区块
<\/span><\/span><\/span><\/span>    bc<\/span>.hc<\/span>.SetCurrentHeader<\/span>(currentHeader<\/span>)
<\/span><\/span>    bc<\/span>.currentFastBlock<\/span>.Store<\/span>(currentBlock<\/span>)
<\/span><\/span>    
<\/span><\/span>    \/\/ 记录状态信息
<\/span><\/span><\/span><\/span>    log<\/span>.Info<\/span>("Loaded most recent local header"<\/span>, "number"<\/span>, currentHeader<\/span>.Number<\/span>, ...<\/span>)
<\/span><\/span>    log<\/span>.Info<\/span>("Loaded most recent local full block"<\/span>, "number"<\/span>, currentBlock<\/span>.Number<\/span>(), ...<\/span>)
<\/span><\/span>    log<\/span>.Info<\/span>("Loaded most recent local fast block"<\/span>, "number"<\/span>, currentFastBlock<\/span>.Number<\/span>(), ...<\/span>)
<\/span><\/span>    
<\/span><\/span>    return<\/span> nil<\/span>
<\/span><\/span>}
<\/span><\/span><\/code><\/pre>1.5 区块回滚机制<\/h3>
SetHead<\/code>函数用于回滚本地链到新的头部：<\/p>
func<\/span> (bc<\/span> *<\/span>BlockChain<\/span>) SetHead<\/span>(head<\/span> uint64<\/span>) error<\/span> {
<\/span><\/span>    _<\/span>, err<\/span> :=<\/span> bc<\/span>.SetHeadBeyondRoot<\/span>(head<\/span>, common<\/span>.Hash<\/span>{})
<\/span><\/span>    return<\/span> err<\/span>
<\/span><\/span>}
<\/span><\/span>
<\/span><\/span>func<\/span> (bc<\/span> *<\/span>BlockChain<\/span>) SetHeadBeyondRoot<\/span>(head<\/span> uint64<\/span>, root<\/span> common<\/span>.Hash<\/span>) (uint64<\/span>, error<\/span>) {
<\/span><\/span>    \/\/ 更新函数：处理区块回滚逻辑
<\/span><\/span><\/span><\/span>    updateFn<\/span> :=<\/span> func<\/span>(db<\/span> ethdb<\/span>.KeyValueWriter<\/span>, header<\/span> *<\/span>types<\/span>.Header<\/span>) (uint64<\/span>, bool<\/span>) {
<\/span><\/span>        \/\/ 回滚逻辑实现...
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 删除函数：清除中间区块头所有数据和缓存
<\/span><\/span><\/span><\/span>    delFn<\/span> :=<\/span> func<\/span>(db<\/span> ethdb<\/span>.KeyValueWriter<\/span>, hash<\/span> common<\/span>.Hash<\/span>, num<\/span> uint64<\/span>) {
<\/span><\/span>        \/\/ 删除逻辑实现...
<\/span><\/span><\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 执行回滚操作
<\/span><\/span><\/span><\/span>    bc<\/span>.hc<\/span>.SetHead<\/span>(head<\/span>, updateFn<\/span>, delFn<\/span>)
<\/span><\/span>    
<\/span><\/span>    \/\/ 清除缓存
<\/span><\/span><\/span><\/span>    bc<\/span>.bodyCache<\/span>.Purge<\/span>()
<\/span><\/span>    bc<\/span>.bodyRLPCache<\/span>.Purge<\/span>()
<\/span><\/span>    bc<\/span>.receiptsCache<\/span>.Purge<\/span>()
<\/span><\/span>    bc<\/span>.blockCache<\/span>.Purge<\/span>()
<\/span><\/span>    bc<\/span>.txLookupCache<\/span>.Purge<\/span>()
<\/span><\/span>    bc<\/span>.futureBlocks<\/span>.Purge<\/span>()
<\/span><\/span>    
<\/span><\/span>    \/\/ 重新加载状态
<\/span><\/span><\/span><\/span>    return<\/span> rootNumber<\/span>, bc<\/span>.loadLastState<\/span>()
<\/span><\/span>}
<\/span><\/span><\/code><\/pre>2. 分叉处理<\/h2>
2.1 reorg函数分析<\/h3>
reorg<\/code>函数处理分叉，将原来的分叉链设置为规范链：<\/p>
func<\/span> (bc<\/span> *<\/span>BlockChain<\/span>) reorg<\/span>(oldBlock<\/span>, newBlock<\/span> *<\/span>types<\/span>.Block<\/span>) error<\/span> {
<\/span><\/span>    var<\/span> (
<\/span><\/span>        newChain<\/span>    types<\/span>.Blocks<\/span>
<\/span><\/span>        oldChain<\/span>    types<\/span>.Blocks<\/span>
<\/span><\/span>        commonBlock<\/span> *<\/span>types<\/span>.Block<\/span>
<\/span><\/span>        deletedTxs<\/span>  types<\/span>.Transactions<\/span>
<\/span><\/span>        addedTxs<\/span>    types<\/span>.Transactions<\/span>
<\/span><\/span>        deletedLogs<\/span> [][]*<\/span>types<\/span>.Log<\/span>
<\/span><\/span>        rebirthLogs<\/span> [][]*<\/span>types<\/span>.Log<\/span>
<\/span><\/span>    )
<\/span><\/span>    
<\/span><\/span>    \/\/ 步骤1：找到共同祖先
<\/span><\/span><\/span><\/span>    \/\/ 如果老链比新链长，减少老链高度
<\/span><\/span><\/span><\/span>    if<\/span> oldBlock<\/span>.NumberU64<\/span>() > newBlock<\/span>.NumberU64<\/span>() {
<\/span><\/span>        for<\/span> ; oldBlock<\/span> !=<\/span> nil<\/span> &&<\/span> oldBlock<\/span>.NumberU64<\/span>() !=<\/span> newBlock<\/span>.NumberU64<\/span>(); oldBlock<\/span> = bc<\/span>.GetBlock<\/span>(oldBlock<\/span>.ParentHash<\/span>(), oldBlock<\/span>.NumberU64<\/span>()-<\/span>1<\/span>) {
<\/span><\/span>            oldChain<\/span> = append(oldChain<\/span>, oldBlock<\/span>)
<\/span><\/span>            deletedTxs<\/span> = append(deletedTxs<\/span>, oldBlock<\/span>.Transactions<\/span>()...<\/span>)
<\/span><\/span>            collectLogs<\/span>(oldBlock<\/span>.Hash<\/span>(), true<\/span>)
<\/span><\/span>        }
<\/span><\/span>    } else<\/span> {
<\/span><\/span>        \/\/ 新链比老链长，暂存新链区块
<\/span><\/span><\/span><\/span>        for<\/span> ; newBlock<\/span> !=<\/span> nil<\/span> &&<\/span> newBlock<\/span>.NumberU64<\/span>() !=<\/span> oldBlock<\/span>.NumberU64<\/span>(); newBlock<\/span> = bc<\/span>.GetBlock<\/span>(newBlock<\/span>.ParentHash<\/span>(), newBlock<\/span>.NumberU64<\/span>()-<\/span>1<\/span>) {
<\/span><\/span>            newChain<\/span> = append(newChain<\/span>, newBlock<\/span>)
<\/span><\/span>        }
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 步骤2：找到共同祖先
<\/span><\/span><\/span><\/span>    for<\/span> {
<\/span><\/span>        if<\/span> oldBlock<\/span>.Hash<\/span>() ==<\/span> newBlock<\/span>.Hash<\/span>() {
<\/span><\/span>            commonBlock<\/span> = oldBlock<\/span>
<\/span><\/span>            break<\/span>
<\/span><\/span>        }
<\/span><\/span>        oldChain<\/span> = append(oldChain<\/span>, oldBlock<\/span>)
<\/span><\/span>        deletedTxs<\/span> = append(deletedTxs<\/span>, oldBlock<\/span>.Transactions<\/span>()...<\/span>)
<\/span><\/span>        collectLogs<\/span>(oldBlock<\/span>.Hash<\/span>(), true<\/span>)
<\/span><\/span>        
<\/span><\/span>        newChain<\/span> = append(newChain<\/span>, newBlock<\/span>)
<\/span><\/span>        
<\/span><\/span>        oldBlock<\/span> = bc<\/span>.GetBlock<\/span>(oldBlock<\/span>.ParentHash<\/span>(), oldBlock<\/span>.NumberU64<\/span>()-<\/span>1<\/span>)
<\/span><\/span>        newBlock<\/span> = bc<\/span>.GetBlock<\/span>(newBlock<\/span>.ParentHash<\/span>(), newBlock<\/span>.NumberU64<\/span>()-<\/span>1<\/span>)
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 步骤3：插入新链到规范链中
<\/span><\/span><\/span><\/span>    for<\/span> i<\/span> :=<\/span> len(newChain<\/span>) -<\/span> 1<\/span>; i<\/span> >=<\/span> 1<\/span>; i<\/span>--<\/span> {
<\/span><\/span>        bc<\/span>.writeHeadBlock<\/span>(newChain<\/span>[i<\/span>])
<\/span><\/span>        collectLogs<\/span>(newChain<\/span>[i<\/span>].Hash<\/span>(), false<\/span>)
<\/span><\/span>        addedTxs<\/span> = append(addedTxs<\/span>, newChain<\/span>[i<\/span>].Transactions<\/span>()...<\/span>)
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 步骤4：清理无用索引
<\/span><\/span><\/span><\/span>    indexesBatch<\/span> :=<\/span> bc<\/span>.db<\/span>.NewBatch<\/span>()
<\/span><\/span>    for<\/span> _<\/span>, tx<\/span> :=<\/span> range<\/span> types<\/span>.TxDifference<\/span>(deletedTxs<\/span>, addedTxs<\/span>) {
<\/span><\/span>        rawdb<\/span>.DeleteTxLookupEntry<\/span>(indexesBatch<\/span>, tx<\/span>.Hash<\/span>())
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    \/\/ 步骤5：发送事件通知
<\/span><\/span><\/span><\/span>    if<\/span> len(deletedLogs<\/span>) > 0<\/span> {
<\/span><\/span>        bc<\/span>.rmLogsFeed<\/span>.Send<\/span>(RemovedLogsEvent<\/span>{mergeLogs<\/span>(deletedLogs<\/span>, true<\/span>)})
<\/span><\/span>    }
<\/span><\/span>    if<\/span> len(rebirthLogs<\/span>) > 0<\/span> {
<\/span><\/span>        bc<\/span>.logsFeed<\/span>.Send<\/span>(mergeLogs<\/span>(rebirthLogs<\/span>, false<\/span>))
<\/span><\/span>    }
<\/span><\/span>    if<\/span> len(oldChain<\/span>) > 0<\/span> {
<\/span><\/span>        for<\/span> i<\/span> :=<\/span> len(oldChain<\/span>) -<\/span> 1<\/span>; i<\/span> >=<\/span> 0<\/span>; i<\/span>--<\/span> {
<\/span><\/span>            bc<\/span>.chainSideFeed<\/span>.Send<\/span>(ChainSideEvent<\/span>{Block<\/span>: oldChain<\/span>[i<\/span>]})
<\/span><\/span>        }
<\/span><\/span>    }
<\/span><\/span>    
<\/span><\/span>    return<\/span> nil<\/span>
<\/span><\/span>}
<\/span><\/span><\/code><\/pre>2.2 分叉处理关键点<\/h3>


共同祖先查找<\/strong>：<\/p>

比较两条链的高度，将较长链回退到与较短链相同高度<\/li>
然后同时回退两条链直到找到共同祖先<\/li>
<\/ul>
<\/li>

数据清理<\/strong>：<\/p>

删除不再属于规范链的交易索引<\/li>
清理规范哈希映射<\/li>
<\/ul>
<\/li>

事件通知<\/strong>：<\/p>

发送日志删除事件(rmLogsFeed<\/code>)<\/li>
发送新日志事件(logsFeed<\/code>)<\/li>
发送被替换的侧链区块事件(chainSideFeed<\/code>)<\/li>
<\/ul>
<\/li>
<\/ol>
3. 关键安全考量<\/h2>


区块验证<\/strong>：<\/p>

区块头验证(共识引擎的VerifyHeader<\/code>)<\/li>
交易执行验证(StateProcessor<\/code>)<\/li>
<\/ul>
<\/li>

状态一致性<\/strong>：<\/p>

确保区块状态可用(state.New<\/code>)<\/li>
处理状态缺失时的恢复逻辑<\/li>
<\/ul>
<\/li>

异常处理<\/strong>：<\/p>

数据库损坏检测与恢复<\/li>
硬分叉处理机制<\/li>
坏块(bad block)检测与回滚<\/li>
<\/ul>
<\/li>

性能优化<\/strong>：<\/p>

缓存策略(LRU缓存)<\/li>
并行处理(future block处理)<\/li>
批量写入(索引清理)<\/li>
<\/ul>
<\/li>
<\/ol>
4. 总结<\/h2>
本教学文档详细分析了以太坊区块设计的核心机制，包括：<\/p>

区块链初始化流程和关键组件<\/li>
状态加载和回滚机制<\/li>
分叉处理的核心算法<\/li>
关键安全考量和性能优化点<\/li>
<\/ol>
这些机制共同构成了以太坊区块链稳定运行的基础，理解这些底层原理对于区块链开发和安全审计至关重要。<\/p>