path: root/core/headerchain.go

// Copyright 2015 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 core

import (
	crand "crypto/rand"
	"errors"
	"fmt"
	"math"
	"math/big"
	mrand "math/rand"
	"sync/atomic"
	"time"

	"github.com/ava-labs/coreth/consensus"
	"github.com/ava-labs/coreth/core/rawdb"
	"github.com/ava-labs/coreth/core/types"
	"github.com/ava-labs/coreth/params"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/log"
	lru "github.com/hashicorp/golang-lru"
)

const (
	headerCacheLimit = 512
	tdCacheLimit     = 1024
	numberCacheLimit = 2048
)

// HeaderChain implements the basic block header chain logic that is shared by
// core.BlockChain and light.LightChain. It is not usable in itself, only as
// a part of either structure.
//
// HeaderChain is responsible for maintaining the header chain including the
// header query and updating.
//
// The components maintained by headerchain includes: (1) total difficult
// (2) header (3) block hash -> number mapping (4) canonical number -> hash mapping
// and (5) head header flag.
//
// It is not thread safe either, the encapsulating chain structures should do
// the necessary mutex locking/unlocking.
type HeaderChain struct {
	config *params.ChainConfig

	chainDb       ethdb.Database
	genesisHeader *types.Header

	currentHeader     atomic.Value // Current head of the header chain (may be above the block chain!)
	currentHeaderHash common.Hash  // Hash of the current head of the header chain (prevent recomputing all the time)

	headerCache *lru.Cache // Cache for the most recent block headers
	tdCache     *lru.Cache // Cache for the most recent block total difficulties
	numberCache *lru.Cache // Cache for the most recent block numbers

	procInterrupt func() bool

	rand   *mrand.Rand
	engine consensus.Engine
}

// NewHeaderChain creates a new HeaderChain structure. ProcInterrupt points
// to the parent's interrupt semaphore.
func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine consensus.Engine, procInterrupt func() bool) (*HeaderChain, error) {
	headerCache, _ := lru.New(headerCacheLimit)
	tdCache, _ := lru.New(tdCacheLimit)
	numberCache, _ := lru.New(numberCacheLimit)

	// Seed a fast but crypto originating random generator
	seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
	if err != nil {
		return nil, err
	}

	hc := &HeaderChain