github.com/linapex/ethereum-go-chinese@v0.0.0-20190316121929-f8b7a73c3fa1/swarm/storage/feed/feed.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  //</624450118795399168>
    11  
    12  
    13  package feed
    14  
    15  import (
    16  	"hash"
    17  	"unsafe"
    18  
    19  	"github.com/ethereum/go-ethereum/common"
    20  	"github.com/ethereum/go-ethereum/common/hexutil"
    21  	"github.com/ethereum/go-ethereum/swarm/storage"
    22  )
    23  
    24  //源表示特定用户对主题的更新流
    25  type Feed struct {
    26  	Topic Topic          `json:"topic"`
    27  	User  common.Address `json:"user"`
    28  }
    29  
    30  //饲料布局：
    31  //TopicLength字节
    32  //useraddr common.addresslength字节
    33  const feedLength = TopicLength + common.AddressLength
    34  
    35  //mapkey计算此源的唯一ID。由“handler”中的缓存映射使用
    36  func (f *Feed) mapKey() uint64 {
    37  	serializedData := make([]byte, feedLength)
    38  	f.binaryPut(serializedData)
    39  	hasher := hashPool.Get().(hash.Hash)
    40  	defer hashPool.Put(hasher)
    41  	hasher.Reset()
    42  	hasher.Write(serializedData)
    43  	hash := hasher.Sum(nil)
    44  	return *(*uint64)(unsafe.Pointer(&hash[0]))
    45  }
    46  
    47  //BinaryPut将此源实例序列化到提供的切片中
    48  func (f *Feed) binaryPut(serializedData []byte) error {
    49  	if len(serializedData) != feedLength {
    50  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to serialize feed. Expected %d, got %d", feedLength, len(serializedData))
    51  	}
    52  	var cursor int
    53  	copy(serializedData[cursor:cursor+TopicLength], f.Topic[:TopicLength])
    54  	cursor += TopicLength
    55  
    56  	copy(serializedData[cursor:cursor+common.AddressLength], f.User[:])
    57  	cursor += common.AddressLength
    58  
    59  	return nil
    60  }
    61  
    62  //BinaryLength返回序列化时此结构的预期大小
    63  func (f *Feed) binaryLength() int {
    64  	return feedLength
    65  }
    66  
    67  //binaryget从传递的切片中包含的信息还原当前实例
    68  func (f *Feed) binaryGet(serializedData []byte) error {
    69  	if len(serializedData) != feedLength {
    70  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to read feed. Expected %d, got %d", feedLength, len(serializedData))
    71  	}
    72  
    73  	var cursor int
    74  	copy(f.Topic[:], serializedData[cursor:cursor+TopicLength])
    75  	cursor += TopicLength
    76  
    77  	copy(f.User[:], serializedData[cursor:cursor+common.AddressLength])
    78  	cursor += common.AddressLength
    79  
    80  	return nil
    81  }
    82  
    83  //十六进制将提要序列化为十六进制字符串
    84  func (f *Feed) Hex() string {
    85  	serializedData := make([]byte, feedLength)
    86  	f.binaryPut(serializedData)
    87  	return hexutil.Encode(serializedData)
    88  }
    89  
    90  //FromValues从字符串键值存储中反序列化此实例
    91  //用于分析查询字符串
    92  func (f *Feed) FromValues(values Values) (err error) {
    93  	topic := values.Get("topic")
    94  	if topic != "" {
    95  		if err := f.Topic.FromHex(values.Get("topic")); err != nil {
    96  			return err
    97  		}
    98  } else { //查看用户集名称和相关内容
    99  		name := values.Get("name")
   100  		relatedContent, _ := hexutil.Decode(values.Get("relatedcontent"))
   101  		if len(relatedContent) > 0 {
   102  			if len(relatedContent) < storage.AddressLength {
   103  				return NewErrorf(ErrInvalidValue, "relatedcontent field must be a hex-encoded byte array exactly %d bytes long", storage.AddressLength)
   104  			}
   105  			relatedContent = relatedContent[:storage.AddressLength]
   106  		}
   107  		f.Topic, err = NewTopic(name, relatedContent)
   108  		if err != nil {
   109  			return err
   110  		}
   111  	}
   112  	f.User = common.HexToAddress(values.Get("user"))
   113  	return nil
   114  }
   115  
   116  //AppendValues将此结构序列化到提供的字符串键值存储区中
   117  //用于生成查询字符串
   118  func (f *Feed) AppendValues(values Values) {
   119  	values.Set("topic", f.Topic.Hex())
   120  	values.Set("user", f.User.Hex())
   121  }
   122