multichain

type Chain interface {
	// Enqueue accepts a message and returns true on acceptance, or false on failure
	Enqueue(env *cb.Envelope) bool

	// Errored returns a channel which will close when an error has occurred
	// This is especially useful for the Deliver client, who must terminate waiting
	// clients when the consenter is not up to date
	Errored() <-chan struct{}

	// Start should allocate whatever resources are needed for staying up to date with the chain
	// Typically, this involves creating a thread which reads from the ordering source, passes those
	// messages to a block cutter, and writes the resulting blocks to the ledger
	Start()

	// Halt frees the resources which were allocated for this Chain
	Halt()
}

type ChainSupport interface {

	// PolicyManager returns the current policy manager as specified by the chain config
	// 背书策略，读取相关的策略配置
	PolicyManager() policies.Manager

	// Reader returns the chain Reader for the chain
	// 读取账本的对象接口
	Reader() ledger.Reader

	// Errored returns whether the backing consenter has errored
	// 是否有错误发生?
	Errored() <-chan struct{}

	broadcast.Support // 处理交易输入
	ConsenterSupport  // 共识机制的帮助方法

	// Sequence returns the current config sequence number
	// 和配置相关对链的配置更改，则会加1
	Sequence() uint64

	// ProposeConfigUpdate applies a CONFIG_UPDATE to an existing config to produce a *cb.ConfigEnvelope
	// 将一个交易转换成配置交易
	// Envelope本意是信封(orderer从客户端处获取交易，但不会对交易做有效性的验证，就是指他从客户端获取的交易只是一个信封)
	// 交易的具体内容是被封装在信封里的 orderer节点是不会展开Envepole，不会对交易进行处理，只会对交易进行转发
	ProposeConfigUpdate(env *cb.Envelope) (*cb.ConfigEnvelope, error)
}

type Consenter interface {
	// HandleChain should create and return a reference to a Chain for the given set of resources
	// It will only be invoked for a given chain once per process.  In general, errors will be treated
	// as irrecoverable and cause system shutdown.  See the description of Chain for more details
	// The second argument to HandleChain is a pointer to the metadata stored on the `ORDERER` slot of
	// the last block committed to the ledger of this Chain.  For a new chain, this metadata will be
	// nil, as this field is not set on the genesis block
	HandleChain(support ConsenterSupport, metadata *cb.Metadata) (Chain, error)
}

type ConsenterSupport interface {
	crypto.LocalSigner                                                                                // 签名
	BlockCutter() blockcutter.Receiver                                                                // 区块切割对象(将fabric交易切割成区块)
	SharedConfig() config.Orderer                                                                     // 配置
	CreateNextBlock(messages []*cb.Envelope) *cb.Block                                                // 将切割好的交易，打包成区块
	WriteBlock(block *cb.Block, committers []filter.Committer, encodedMetadataValue []byte) *cb.Block // 写入临时区块
	// 链ID
	ChainID() string // ChainID returns the chain ID this specific consenter instance is associated with
	// 链当前高度
	Height() uint64 // Returns the number of blocks on the chain this specific consenter instance is associated with
}

type Manager interface {
	// GetChain retrieves the chain support for a chain (and whether it exists)
	// 获取链对象，不是直接对链对象操作，而是对ChainSupport操作
	GetChain(chainID string) (ChainSupport, bool)

	// SystemChannelID returns the channel ID for the system channel
	// 系统链名
	SystemChannelID() string

	// NewChannelConfig returns a bare bones configuration ready for channel
	// creation request to be applied on top of it
	// 链的配置 (可能是新生成 也有可能是更新)
	NewChannelConfig(envConfigUpdate *cb.Envelope) (configtxapi.Manager, error)
}