consensus

Documentation

Index

• type Chain
• type Consenter
• type ConsenterSupport

Types

type Chain

type Chain interface {
	// Order accepts a message which has been processed at a given configSeq.
	// If the configSeq advances, it is the responsibility of the consenter
	// to revalidate and potentially discard the message
	// The consenter may return an error, indicating the message was not accepted
	Order(env *cb.Envelope, configSeq uint64) error

	// Configure accepts a message which reconfigures the channel and will
	// trigger an update to the configSeq if committed.  The configuration must have
	// been triggered by a ConfigUpdate message. If the config sequence advances,
	// it is the responsibility of the consenter to recompute the resulting config,
	// discarding the message if the reconfiguration is no longer valid.
	// The consenter may return an error, indicating the message was not accepted
	Configure(config *cb.Envelope, configSeq uint64) error

	// WaitReady blocks waiting for consenter to be ready for accepting new messages.
	// This is useful when consenter needs to temporarily block ingress messages so
	// that in-flight messages can be consumed. It could return error if consenter is
	// in erroneous states. If this blocking behavior is not desired, consenter could
	// simply return nil.
	WaitReady() error

	// 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()

	// Status provides access to the consensus-type migration status of the underlying chain.
	MigrationStatus() migration.Status
}

Chain defines a way to inject messages for ordering. Note, that in order to allow flexibility in the implementation, it is the responsibility of the implementer to take the ordered messages, send them through the blockcutter.Receiver supplied via HandleChain to cut blocks, and ultimately write the ledger also supplied via HandleChain. This design allows for two primary flows 1. Messages are ordered into a stream, the stream is cut into blocks, the blocks are committed (solo, kafka) 2. Messages are cut into blocks, the blocks are ordered, then the blocks are committed (sbft)

type Consenter

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)
}

Consenter defines the backing ordering mechanism.

type ConsenterSupport

type ConsenterSupport interface {
	crypto.LocalSigner
	msgprocessor.Processor

	// VerifyBlockSignature verifies a signature of a block with a given optional
	// configuration (can be nil).
	VerifyBlockSignature([]*cb.SignedData, *cb.ConfigEnvelope) error

	// BlockCutter returns the block cutting helper for this channel.
	BlockCutter() blockcutter.Receiver

	// SharedConfig provides the shared config from the channel's current config block.
	SharedConfig() channelconfig.Orderer

	// CreateNextBlock takes a list of messages and creates the next block based on the block with highest block number committed to the ledger
	// Note that either WriteBlock or WriteConfigBlock must be called before invoking this method a second time.
	CreateNextBlock(messages []*cb.Envelope) *cb.Block

	// Block returns a block with the given number,
	// or nil if such a block doesn't exist.
	Block(number uint64) *cb.Block

	// WriteBlock commits a block to the ledger.
	WriteBlock(block *cb.Block, encodedMetadataValue []byte)

	// WriteConfigBlock commits a block to the ledger, and applies the config update inside.
	WriteConfigBlock(block *cb.Block, encodedMetadataValue []byte)

	// Sequence returns the current config squence.
	Sequence() uint64

	// ChainID returns the channel ID this support is associated with.
	ChainID() string

	// Height returns the number of blocks in the chain this channel is associated with.
	Height() uint64

	// IsSystemChannel returns true if this is the system channel.
	// The chain needs to know if it is system or standard for consensus-type migration.
	IsSystemChannel() bool

	// Append appends a new block to the ledger in its raw form,
	// unlike WriteBlock that also mutates its metadata.
	Append(block *cb.Block) error
}

ConsenterSupport provides the resources available to a Consenter implementation.