les fetcher

lesfetcher.go

// Copyright 2019 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 main

import (
	"context"
	"flag"
	"math/big"
	"math/rand"
	"os"
	"strconv"
	"time"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params"
)

var (
	r = rand.New(rand.NewSource(int64(time.Now().Nanosecond())))
)

func main() {
	log.Root().SetHandler(log.LvlFilterHandler(log.LvlInfo, log.StreamHandler(os.Stderr, log.TerminalFormat(true))))
	flag.Parse()

	// Establish a connect with local **light client** via JSON RPC
	client, err := ethclient.Dial("http://127.0.0.1:8545")
	if err != nil {
		panic(err)
	}
	number, err := strconv.Atoi(flag.Args()[0])
	if err != nil {
		panic(err)
	}
	var t time.Time

	// If the requested block before the checkpoint, 2 underlying network
	// requests will be made:
	// (1) GetHeaderByNumber: validate by local CHT root
	// (2) GetBodyRLP: validate by retrieved header
	t = time.Now()
	old := r.Intn(params.CHTFrequency) + 1
	block, err := client.BlockByNumber(context.Background(), big.NewInt(int64(old)))
	if err != nil {
		log.Crit("Failed to retrieve block", "error", err)
	}
	log.Info("Retrieved specified block", "number", old, "hash", block.Hash(), "elapsed", common.PrettyDuration(time.Since(t)))

	// Request balance of a specified account, 1 underlying network request
	// will be made:
	// (1) TrieRequest: validate by local header
	t = time.Now()
	oracle := params.GoerliCheckpointOracle
	balance, err := client.BalanceAt(context.Background(), oracle.Address, big.NewInt(int64(number)))
	if err != nil {
		log.Crit("Failed to retrieve balance", "error", err)
	}
	log.Info("Retrieved balance of oracle", "balance", balance, "elapsed", common.PrettyDuration(time.Since(t)))

	// Request code of a specified account, 1 underlying network request
	// will be made:
	// (1) CodeRequest: validate by local header
	t = time.Now()
	code, err := client.CodeAt(context.Background(), oracle.Address, big.NewInt(int64(number)))
	if err != nil {
		log.Crit("Failed to retrieve code", "error", err)
	}
	log.Info("Retrieved code of oracle", "code", common.Bytes2Hex(code), "elapsed", common.PrettyDuration(time.Since(t)))

	// Filter all logs of oracle in the past blockchain history
	//
	// 2 types of underlying network requests will be made
	// (1) BloomRequest
	// (2) GetBlockReceipts
	t = time.Now()
	query := ethereum.FilterQuery{
		Addresses: []common.Address{oracle.Address},
	}
	logs, err := client.FilterLogs(context.Background(), query)
	if err != nil {
		log.Crit("Failed to filter logs of oracle", "error", err)
	}
	log.Info("Retrieved logs of oracle", "number", len(logs), "elapsed", common.PrettyDuration(time.Since(t)))
}