github.com/linapex/ethereum-go-chinese@v0.0.0-20190316121929-f8b7a73c3fa1/swarm/storage/feed/id.go (about)

     1  
     2  //<developer>
     3  //    <name>linapex 曹一峰</name>
     4  //    <email>linapex@163.com</email>
     5  //    <wx>superexc</wx>
     6  //    <qqgroup>128148617</qqgroup>
     7  //    <url>https://jsq.ink</url>
     8  //    <role>pku engineer</role>
     9  //    <date>2019-03-16 19:16:44</date>
    10  //</624450119026085888>
    11  
    12  
    13  package feed
    14  
    15  import (
    16  	"fmt"
    17  	"hash"
    18  	"strconv"
    19  
    20  	"github.com/ethereum/go-ethereum/common"
    21  	"github.com/ethereum/go-ethereum/swarm/storage/feed/lookup"
    22  
    23  	"github.com/ethereum/go-ethereum/swarm/storage"
    24  )
    25  
    26  //ID唯一标识网络上的更新。
    27  type ID struct {
    28  	Feed         `json:"feed"`
    29  	lookup.Epoch `json:"epoch"`
    30  }
    31  
    32  //ID布局：
    33  //进纸长度字节
    34  //时代纪元
    35  const idLength = feedLength + lookup.EpochLength
    36  
    37  //addr计算与此ID对应的源更新块地址
    38  func (u *ID) Addr() (updateAddr storage.Address) {
    39  	serializedData := make([]byte, idLength)
    40  	var cursor int
    41  	u.Feed.binaryPut(serializedData[cursor : cursor+feedLength])
    42  	cursor += feedLength
    43  
    44  	eid := u.Epoch.ID()
    45  	copy(serializedData[cursor:cursor+lookup.EpochLength], eid[:])
    46  
    47  	hasher := hashPool.Get().(hash.Hash)
    48  	defer hashPool.Put(hasher)
    49  	hasher.Reset()
    50  	hasher.Write(serializedData)
    51  	return hasher.Sum(nil)
    52  }
    53  
    54  //BinaryPut将此实例序列化到提供的切片中
    55  func (u *ID) binaryPut(serializedData []byte) error {
    56  	if len(serializedData) != idLength {
    57  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to serialize ID. Expected %d, got %d", idLength, len(serializedData))
    58  	}
    59  	var cursor int
    60  	if err := u.Feed.binaryPut(serializedData[cursor : cursor+feedLength]); err != nil {
    61  		return err
    62  	}
    63  	cursor += feedLength
    64  
    65  	epochBytes, err := u.Epoch.MarshalBinary()
    66  	if err != nil {
    67  		return err
    68  	}
    69  	copy(serializedData[cursor:cursor+lookup.EpochLength], epochBytes[:])
    70  	cursor += lookup.EpochLength
    71  
    72  	return nil
    73  }
    74  
    75  //BinaryLength返回序列化时此结构的预期大小
    76  func (u *ID) binaryLength() int {
    77  	return idLength
    78  }
    79  
    80  //binaryget从传递的切片中包含的信息还原当前实例
    81  func (u *ID) binaryGet(serializedData []byte) error {
    82  	if len(serializedData) != idLength {
    83  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to read ID. Expected %d, got %d", idLength, len(serializedData))
    84  	}
    85  
    86  	var cursor int
    87  	if err := u.Feed.binaryGet(serializedData[cursor : cursor+feedLength]); err != nil {
    88  		return err
    89  	}
    90  	cursor += feedLength
    91  
    92  	if err := u.Epoch.UnmarshalBinary(serializedData[cursor : cursor+lookup.EpochLength]); err != nil {
    93  		return err
    94  	}
    95  	cursor += lookup.EpochLength
    96  
    97  	return nil
    98  }
    99  
   100  //FromValues从字符串键值存储中反序列化此实例
   101  //用于分析查询字符串
   102  func (u *ID) FromValues(values Values) error {
   103  	level, _ := strconv.ParseUint(values.Get("level"), 10, 32)
   104  	u.Epoch.Level = uint8(level)
   105  	u.Epoch.Time, _ = strconv.ParseUint(values.Get("time"), 10, 64)
   106  
   107  	if u.Feed.User == (common.Address{}) {
   108  		return u.Feed.FromValues(values)
   109  	}
   110  	return nil
   111  }
   112  
   113  //AppendValues将此结构序列化到提供的字符串键值存储区中
   114  //用于生成查询字符串
   115  func (u *ID) AppendValues(values Values) {
   116  	values.Set("level", fmt.Sprintf("%d", u.Epoch.Level))
   117  	values.Set("time", fmt.Sprintf("%d", u.Epoch.Time))
   118  	u.Feed.AppendValues(values)
   119  }
   120