// 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))