github.com/yinchengtsinghua/golang-Eos-dpos-Ethereum@v0.0.0-20190121132951-92cc4225ed8e/swarm/storage/mru/lookup.go (about)

     1  
     2  //此源码被清华学神尹成大魔王专业翻译分析并修改
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     9  //
    10  //
    11  //
    12  //
    13  //
    14  //
    15  //
    16  //
    17  //
    18  //
    19  //
    20  //
    21  //
    22  //
    23  //
    24  
    25  package mru
    26  
    27  import (
    28  	"encoding/binary"
    29  	"hash"
    30  
    31  	"github.com/ethereum/go-ethereum/swarm/storage"
    32  )
    33  
    34  //
    35  //
    36  //
    37  type LookupParams struct {
    38  	UpdateLookup
    39  	Limit uint32
    40  }
    41  
    42  //
    43  func (r *LookupParams) RootAddr() storage.Address {
    44  	return r.rootAddr
    45  }
    46  
    47  func NewLookupParams(rootAddr storage.Address, period, version uint32, limit uint32) *LookupParams {
    48  	return &LookupParams{
    49  		UpdateLookup: UpdateLookup{
    50  			period:   period,
    51  			version:  version,
    52  			rootAddr: rootAddr,
    53  		},
    54  		Limit: limit,
    55  	}
    56  }
    57  
    58  //
    59  func LookupLatest(rootAddr storage.Address) *LookupParams {
    60  	return NewLookupParams(rootAddr, 0, 0, 0)
    61  }
    62  
    63  //
    64  func LookupLatestVersionInPeriod(rootAddr storage.Address, period uint32) *LookupParams {
    65  	return NewLookupParams(rootAddr, period, 0, 0)
    66  }
    67  
    68  //
    69  func LookupVersion(rootAddr storage.Address, period, version uint32) *LookupParams {
    70  	return NewLookupParams(rootAddr, period, version, 0)
    71  }
    72  
    73  //
    74  type UpdateLookup struct {
    75  	period   uint32
    76  	version  uint32
    77  	rootAddr storage.Address
    78  }
    79  
    80  //
    81  //
    82  //
    83  const updateLookupLength = 4 + 4 + storage.KeyLength
    84  
    85  //
    86  func (u *UpdateLookup) UpdateAddr() (updateAddr storage.Address) {
    87  	serializedData := make([]byte, updateLookupLength)
    88  	u.binaryPut(serializedData)
    89  	hasher := hashPool.Get().(hash.Hash)
    90  	defer hashPool.Put(hasher)
    91  	hasher.Reset()
    92  	hasher.Write(serializedData)
    93  	return hasher.Sum(nil)
    94  }
    95  
    96  //
    97  func (u *UpdateLookup) binaryPut(serializedData []byte) error {
    98  	if len(serializedData) != updateLookupLength {
    99  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to serialize UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
   100  	}
   101  	if len(u.rootAddr) != storage.KeyLength {
   102  		return NewError(ErrInvalidValue, "UpdateLookup.binaryPut called without rootAddr set")
   103  	}
   104  	binary.LittleEndian.PutUint32(serializedData[:4], u.period)
   105  	binary.LittleEndian.PutUint32(serializedData[4:8], u.version)
   106  	copy(serializedData[8:], u.rootAddr[:])
   107  	return nil
   108  }
   109  
   110  //
   111  func (u *UpdateLookup) binaryLength() int {
   112  	return updateLookupLength
   113  }
   114  
   115  //
   116  func (u *UpdateLookup) binaryGet(serializedData []byte) error {
   117  	if len(serializedData) != updateLookupLength {
   118  		return NewErrorf(ErrInvalidValue, "Incorrect slice size to read UpdateLookup. Expected %d, got %d", updateLookupLength, len(serializedData))
   119  	}
   120  	u.period = binary.LittleEndian.Uint32(serializedData[:4])
   121  	u.version = binary.LittleEndian.Uint32(serializedData[4:8])
   122  	u.rootAddr = storage.Address(make([]byte, storage.KeyLength))
   123  	copy(u.rootAddr[:], serializedData[8:])
   124  	return nil
   125  }