github.com/yinchengtsinghua/golang-Eos-dpos-Ethereum@v0.0.0-20190121132951-92cc4225ed8e/cmd/utils/cmd.go

//此源码被清华学神尹成大魔王专业翻译分析并修改
//尹成QQ77025077
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//尹成所在QQ群721929980
//尹成邮箱 yinc13@mails.tsinghua.edu.cn
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//https://mvp.microsoft.com/zh-cn/PublicProfile/4033620
//版权所有2014 Go Ethereum作者
//此文件是Go以太坊的一部分。
//
//Go以太坊是免费软件：您可以重新发布和/或修改它
//根据GNU通用公共许可证的条款
//自由软件基金会，或者许可证的第3版，或者
//（由您选择）任何更高版本。
//
//Go以太坊的分布希望它会有用，
//但没有任何保证；甚至没有
//适销性或特定用途的适用性。见
//GNU通用公共许可证了解更多详细信息。
//
//你应该已经收到一份GNU通用公共许可证的副本
//一起去以太坊吧。如果没有，请参见<http://www.gnu.org/licenses/>。

//
package utils

import (
	"compress/gzip"
	"fmt"
	"io"
	"os"
	"os/signal"
	"runtime"
	"strings"
	"syscall"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/rawdb"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/internal/debug"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/node"
	"github.com/ethereum/go-ethereum/rlp"
)

const (
	importBatchSize = 2500
)

//fatalf将消息格式化为标准错误并退出程序。
//如果标准错误，消息也会打印到标准输出。
//已重定向到其他文件。
func Fatalf(format string, args ...interface{}) {
	w := io.MultiWriter(os.Stdout, os.Stderr)
	if runtime.GOOS == "windows" {
//
//
		w = os.Stdout
	} else {
		outf, _ := os.Stdout.Stat()
		errf, _ := os.Stderr.Stat()
		if outf != nil && errf != nil && os.SameFile(outf, errf) {
			w = os.Stderr
		}
	}
	fmt.Fprintf(w, "Fatal: "+format+"\n", args...)
	os.Exit(1)
}

func StartNode(stack *node.Node) {
	if err := stack.Start(); err != nil {
		Fatalf("Error starting protocol stack: %v", err)
	}
	go func() {
		sigc := make(chan os.Signal, 1)
		signal.Notify(sigc, syscall.SIGINT, syscall.SIGTERM)
		defer signal.Stop(sigc)
		<-sigc
		log.Info("Got interrupt, shutting down...")
		go stack.Stop()
		for i := 10; i > 0; i-- {
			<-sigc
			if i > 1 {
				log.Warn("Already shutting down, interrupt more to panic.", "times", i-1)
			}
		}
debug.Exit() //确保刷新跟踪和CPU配置文件数据。
		debug.LoudPanic("boom")
	}()
}

func ImportChain(chain *core.BlockChain, fn string) error {
//当导入正在运行时，请注意ctrl-c。
//如果收到信号，导入将在下一批停止。
	interrupt := make(chan os.Signal, 1)
	stop := make(chan struct{})
	signal.Notify(interrupt, syscall.SIGINT, syscall.SIGTERM)
	defer signal.Stop(interrupt)
	defer close(interrupt)
	go func() {
		if _, ok := <-interrupt; ok {
			log.Info("Interrupted during import, stopping at next batch")
		}
		close(stop)
	}()
	checkInterrupt := func() bool {
		select {
		case <-stop:
			return true
		default:
			return false
		}
	}

	log.Info("Importing blockchain", "file", fn)

//打开文件句柄并可能打开gzip流
	fh, err := os.Open(fn)
	if err != nil {
		return err
	}
	defer fh.Close()

	var reader io.Reader = fh
	if strings.HasSuffix(fn, ".gz") {
		if reader, err = gzip.NewReader(reader); err != nil {
			return err
		}
	}
	stream := rlp.NewStream(reader, 0)

//实际运行导入。
	blocks := make(types.Blocks, importBatchSize)
	n := 0
	for batch := 0; ; batch++ {
//加载一批RLP块。
		if checkInterrupt() {
			return fmt.Errorf("interrupted")
		}
		i := 0
		for ; i < importBatchSize; i++ {
			var b types.Block
			if err := stream.Decode(&b); err == io.EOF {
				break
			} else if err != nil {
				return fmt.Errorf("at block %d: %v", n, err)
			}
//不导入第一个块
			if b.NumberU64() == 0 {
				i--
				continue
			}
			blocks[i] = &b
			n++
		}
		if i == 0 {
			break
		}
//
		if checkInterrupt() {
			return fmt.Errorf("interrupted")
		}
		missing := missingBlocks(chain, blocks[:i])
		if len(missing) == 0 {
			log.Info("Skipping batch as all blocks present", "batch", batch, "first", blocks[0].Hash(), "last", blocks[i-1].Hash())
			continue
		}
		if _, err := chain.InsertChain(missing); err != nil {
			return fmt.Errorf("invalid block %d: %v", n, err)
		}
	}
	return nil
}

func missingBlocks(chain *core.BlockChain, blocks []*types.Block) []*types.Block {
	head := chain.CurrentBlock()
	for i, block := range blocks {
//
		if head.NumberU64() > block.NumberU64() {
			if !chain.HasBlock(block.Hash(), block.NumberU64()) {
				return blocks[i:]
			}
			continue
		}
//如果我们在链头之上，状态可用性是必须的
		if !chain.HasBlockAndState(block.Hash(), block.NumberU64()) {
			return blocks[i:]
		}
	}
	return nil
}

//exportchain将区块链导出到指定文件中，截断任何数据
//
func ExportChain(blockchain *core.BlockChain, fn string) error {
	log.Info("Exporting blockchain", "file", fn)

//
	fh, err := os.OpenFile(fn, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.ModePerm)
	if err != nil {
		return err
	}
	defer fh.Close()

	var writer io.Writer = fh
	if strings.HasSuffix(fn, ".gz") {
		writer = gzip.NewWriter(writer)
		defer writer.(*gzip.Writer).Close()
	}
//遍历块并导出它们
	if err := blockchain.Export(writer); err != nil {
		return err
	}
	log.Info("Exported blockchain", "file", fn)

	return nil
}

//
//文件中已存在数据。
func ExportAppendChain(blockchain *core.BlockChain, fn string, first uint64, last uint64) error {
	log.Info("Exporting blockchain", "file", fn)

//打开文件句柄并可能使用gzip流进行包装
	fh, err := os.OpenFile(fn, os.O_CREATE|os.O_APPEND|os.O_WRONLY, os.ModePerm)
	if err != nil {
		return err
	}
	defer fh.Close()

	var writer io.Writer = fh
	if strings.HasSuffix(fn, ".gz") {
		writer = gzip.NewWriter(writer)
		defer writer.(*gzip.Writer).Close()
	}
//遍历块并导出它们
	if err := blockchain.ExportN(writer, first, last); err != nil {
		return err
	}
	log.Info("Exported blockchain to", "file", fn)
	return nil
}

//importpreimages将一批导出的哈希预映像导入数据库。
func ImportPreimages(db *ethdb.LDBDatabase, fn string) error {
	log.Info("Importing preimages", "file", fn)

//打开文件句柄并可能打开gzip流
	fh, err := os.Open(fn)
	if err != nil {
		return err
	}
	defer fh.Close()

	var reader io.Reader = fh
	if strings.HasSuffix(fn, ".gz") {
		if reader, err = gzip.NewReader(reader); err != nil {
			return err
		}
	}
	stream := rlp.NewStream(reader, 0)

//批量导入预映像以防止磁盘损坏
	preimages := make(map[common.Hash][]byte)

	for {
//阅读下一个条目并确保它不是垃圾
		var blob []byte

		if err := stream.Decode(&blob); err != nil {
			if err == io.EOF {
				break
			}
			return err
		}
//积累预映像并在收集足够的WS时刷新
		preimages[crypto.Keccak256Hash(blob)] = common.CopyBytes(blob)
		if len(preimages) > 1024 {
			rawdb.WritePreimages(db, 0, preimages)
			preimages = make(map[common.Hash][]byte)
		}
	}
//刷新上一批预映像数据
	if len(preimages) > 0 {
		rawdb.WritePreimages(db, 0, preimages)
	}
	return nil
}

//exportpreimages将所有已知的哈希preimages导出到指定的文件中，
//
func ExportPreimages(db *ethdb.LDBDatabase, fn string) error {
	log.Info("Exporting preimages", "file", fn)

//打开文件句柄并可能使用gzip流进行包装
	fh, err := os.OpenFile(fn, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.ModePerm)
	if err != nil {
		return err
	}
	defer fh.Close()

	var writer io.Writer = fh
	if strings.HasSuffix(fn, ".gz") {
		writer = gzip.NewWriter(writer)
		defer writer.(*gzip.Writer).Close()
	}
//迭代预映像并导出它们
	it := db.NewIteratorWithPrefix([]byte("secure-key-"))
	for it.Next() {
		if err := rlp.Encode(writer, it.Value()); err != nil {
			return err
		}
	}
	log.Info("Exported preimages", "file", fn)
	return nil
}