consensus.go

// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Package consensus implements different Ethereum consensus engines.
package consensus

import (
	"context"
	"time"

	"github.com/gochain-io/gochain/accounts"
	"github.com/gochain-io/gochain/common"
	"github.com/gochain-io/gochain/core/state"
	"github.com/gochain-io/gochain/core/types"
	"github.com/gochain-io/gochain/params"
	"github.com/gochain-io/gochain/rpc"
)

// ChainReader defines a small collection of methods needed to access the local
// blockchain during header and/or uncle verification.
type ChainReader interface {
	// Config retrieves the blockchain's chain configuration.
	Config() *params.ChainConfig

	// CurrentHeader retrieves the current header from the local chain.
	CurrentHeader() *types.Header

	// GetHeader retrieves a block header from the database by hash and number.
	GetHeader(hash common.Hash, number uint64) *types.Header

	// GetHeaderByNumber retrieves a block header from the database by number.
	GetHeaderByNumber(number uint64) *types.Header

	// GetHeaderByHash retrieves a block header from the database by its hash.
	GetHeaderByHash(hash common.Hash) *types.Header

	// GetBlock retrieves a block from the database by hash and number.
	GetBlock(hash common.Hash, number uint64) *types.Block
}

// Engine is an algorithm agnostic consensus engine.
type Engine interface {
	// Author retrieves the GoChain address of the account that minted the given
	// block, which may be different from the header's coinbase if a consensus
	// engine is based on signatures.
	Author(ctx context.Context, header *types.Header) (common.Address, error)

	// VerifyHeader checks whether a header conforms to the consensus rules of a
	// given engine. Verifying the seal may be done optionally here, or explicitly
	// via the VerifySeal method.
	VerifyHeader(ctx context.Context, chain ChainReader, header *types.Header) error

	// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
	// concurrently. The method returns a quit channel to abort the operations and
	// a results channel to retrieve the async verifications (the order is that of
	// the input slice).
	VerifyHeaders(ctx context.Context, chain ChainReader, headers []*types.Header) (chan<- struct{}, <-chan error)

	// Prepare initializes the consensus fields of a block header according to the
	// rules of a particular engine. The changes are executed inline.
	// Returns a deadline for block finalization, if applicable.
	Prepare(ctx context.Context, chain ChainReader, header *types.Header) (*time.Time, error)

	// Finalize runs any post-transaction state modifications (e.g. block rewards)
	// and assembles the final block (if block is true).
	// Note: The block header and state database might be updated to reflect any
	// consensus rules that happen at finalization (e.g. block rewards).
	Finalize(ctx context.Context, chain ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction,
		receipts []*types.Receipt, block bool) *types.Block

	// Seal generates a new block for the given input block with the local miner's
	// seal place on top.
	Seal(ctx context.Context, chain ChainReader, block *types.Block, stop <-chan struct{}) (*types.Block, error)

	// APIs returns the RPC APIs this consensus engine provides.
	APIs(chain ChainReader) []rpc.API

	// Authorize injects a private key into the consensus engine for minting new blocks.
	Authorize(common.Address, SignerFn)
}

// SignerFn is a signer callback function to request a hash to be signed by a
// backing account.
type SignerFn func(accounts.Account, []byte) ([]byte, error)