github.com/leonlxy/hyperledger@v1.0.0-alpha.0.20170427033203-34922035d248/gossip/state/metastate.go (about) 1 /* 2 Copyright IBM Corp. 2016 All Rights Reserved. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package state 18 19 import ( 20 "bytes" 21 "encoding/binary" 22 ) 23 24 // NodeMetastate information to store the information about current 25 // height of the ledger (last accepted block sequence number). 26 type NodeMetastate struct { 27 28 // Actual ledger height 29 LedgerHeight uint64 30 } 31 32 // NewNodeMetastate creates new meta data with given ledger height148.69 33 func NewNodeMetastate(height uint64) *NodeMetastate { 34 return &NodeMetastate{height} 35 } 36 37 // Bytes decodes meta state into byte array for serialization 38 func (n *NodeMetastate) Bytes() ([]byte, error) { 39 buffer := new(bytes.Buffer) 40 // Explicitly specify byte order for write into the buffer 41 // to provide cross platform support, note the it consistent 42 // with FromBytes function 43 err := binary.Write(buffer, binary.BigEndian, *n) 44 if err != nil { 45 return nil, err 46 } 47 return buffer.Bytes(), nil 48 } 49 50 // Height returns ledger height from the state 51 func (n *NodeMetastate) Height() uint64 { 52 return n.LedgerHeight 53 } 54 55 // Update state with new ledger height 56 func (n *NodeMetastate) Update(height uint64) { 57 n.LedgerHeight = height 58 } 59 60 // FromBytes - encode from byte array into meta data structure 61 func FromBytes(buf []byte) (*NodeMetastate, error) { 62 state := NodeMetastate{} 63 reader := bytes.NewReader(buf) 64 // As bytes are written in the big endian to keep supporting 65 // cross platforming and for consistency reasons read also 66 // done using same order 67 err := binary.Read(reader, binary.BigEndian, &state) 68 if err != nil { 69 return nil, err 70 } 71 return &state, nil 72 }