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/*
Copyright IBM Corp. 2017 All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package consensus
import (
"github.com/hyperledger/fabric/common/channelconfig"
"github.com/hyperledger/fabric/common/crypto"
"github.com/hyperledger/fabric/orderer/common/blockcutter"
"github.com/hyperledger/fabric/orderer/common/msgprocessor"
cb "github.com/hyperledger/fabric/protos/common"
)
// Consenter defines the backing ordering mechanism.
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)
}
// 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 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// discarding the message if the reconfiguration is no longer valid.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()
}
//go:generate counterfeiter -o mocks/mock_consenter_support.go . ConsenterSupport
// ConsenterSupport provides the resources available to a Consenter implementation.
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
}