> 之前学习比特币和以太坊，必先学习其区块结构，当时在银行做Hyperledger相关项目时，我却对结构很忽略，只关心智能合约，居然也能初步掌握并开始项目相关的开发。这说明超级账本的区块属性其实比较弱，重要的是智能合约的属性。性能也不错。从这个意义上讲Hyperledger用来做存证是大材小用的。
问题1：交易是怎么存入区块的？
Transactions are collected into blocks/batches on the ordering service first. Blocks are cut either when the BatchSize is met, or when BatchTimeout elapses (provided a non-empty block).
也就是说，满足这2个条件，区块生成了：
交易数量够了
超时时间到了
所以Hyperledger的区块生成不是定时的，高峰时间，区块生成速度明显加快
configtx.yaml in the common/configtx/tool/ directory for more info on the block-cutting criteria.
The Block type definition in protos/common/common.proto
和以太坊一样，hyperledger的区别，也有区块号、指向前一个区块的指针、指向数据的指针，因为没有挖矿，头部简洁了很多
// This is finalized block structure to be shared among the orderer and peer
// Note that the BlockHeader chains to the previous BlockHeader, and the BlockData hash is embedded
// in the BlockHeader. This makes it natural and obvious that the Data is included in the hash, but
// the Metadata is not.
message Block {
BlockHeader header = 1;
BlockData data = 2;
BlockMetadata metadata = 3;
}
// BlockHeader is the element of the block which forms the block chain
// The block header is hashed using the configured chain hashing algorithm
// over the ASN.1 encoding of the BlockHeader
message BlockHeader {
**uint64 number = 1;** // The position in the blockchain
**bytes previous_hash = 2;** // The hash of the previous block header
**bytes data_hash = 3;** // The hash of the BlockData, by MerkleTree
}
message BlockData {
repeated bytes data = 1;
}
message BlockMetadata {
repeated bytes metadata = 1;
}
问题2：怎么存入LevelDB
These blocks are stored locally to disk on every ordering service node along with a LevelDB to index these blocks by number – see orderer/ledger/file
// Append a new block to the ledger
func (fl *fileLedger) Append(block *cb.Block) error {
err := fl.blockStore.AddBlock(block)
if err == nil {
close(fl.signal)
fl.signal = make(chan struct{})
}
return err
}