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package kvstore
import (
"bytes"
"encoding/binary"
"encoding/json"
"fmt"
"github.com/tendermint/tendermint/abci/example/code"
"github.com/tendermint/tendermint/abci/types"
cmn "github.com/tendermint/tendermint/libs/common"
dbm "github.com/tendermint/tendermint/libs/db"
"github.com/tendermint/tendermint/version"
)
var (
stateKey = []byte("stateKey")
kvPairPrefixKey = []byte("kvPairKey:")
ProtocolVersion version.Protocol = 0x1
)
type State struct {
db dbm.DB
Size int64 `json:"size"`
Height int64 `json:"height"`
AppHash []byte `json:"app_hash"`
}
func loadState(db dbm.DB) State {
stateBytes := db.Get(stateKey)
var state State
if len(stateBytes) != 0 {
err := json.Unmarshal(stateBytes, &state)
if err != nil {
panic(err)
}
}
state.db = db
return state
}
func saveState(state State) {
stateBytes, err := json.Marshal(state)
if err != nil {
panic(err)
}
state.db.Set(stateKey, stateBytes)
}
func prefixKey(key []byte) []byte {
return append(kvPairPrefixKey, key...)
}
//---------------------------------------------------
var _ types.Application = (*KVStoreApplication)(nil)
type KVStoreApplication struct {
types.BaseApplication
state State
}
func NewKVStoreApplication() *KVStoreApplication {
state := loadState(dbm.NewMemDB())
return &KVStoreApplication{state: state}
}
func (app *KVStoreApplication) Info(req types.RequestInfo) (resInfo types.ResponseInfo) {
return types.ResponseInfo{
Data: fmt.Sprintf("{\"size\":%v}", app.state.Size),
Version: version.ABCIVersion,
AppVersion: ProtocolVersion.Uint64(),
}
}
// tx is either "key=value" or just arbitrary bytes
func (app *KVStoreApplication) DeliverTx(tx []byte) types.ResponseDeliverTx {
var key, value []byte
parts := bytes.Split(tx, []byte("="))
if len(parts) == 2 {
key, value = parts[0], parts[1]
} else {
key, value = tx, tx
}
app.state.db.Set(prefixKey(key), value)
app.state.Size += 1
tags := []cmn.KVPair{
{Key: []byte("app.creator"), Value: []byte("Cosmoshi Netowoko")},
{Key: []byte("app.key"), Value: key},
}
return types.ResponseDeliverTx{Code: code.CodeTypeOK, Tags: tags}
}
func (app *KVStoreApplication) CheckTx(tx []byte) types.ResponseCheckTx {
return types.ResponseCheckTx{Code: code.CodeTypeOK, GasWanted: 1}
}
func (app *KVStoreApplication) Commit() types.ResponseCommit {
// Using a memdb - just return the big endian size of the db
appHash := make([]byte, 8)
binary.PutVarint(appHash, app.state.Size)
app.state.AppHash = appHash
app.state.Height += 1
saveState(app.state)
return types.ResponseCommit{Data: appHash}
}
func (app *KVStoreApplication) Query(reqQuery types.RequestQuery) (resQuery types.ResponseQuery) {
if reqQuery.Prove {
value := app.state.db.Get(prefixKey(reqQuery.Data))
resQuery.Index = -1 // TODO make Proof return index
resQuery.Key = reqQuery.Data
resQuery.Value = value
if value != nil {
resQuery.Log = "exists"
} else {
resQuery.Log = "does not exist"
}
return
} else {
resQuery.Key = reqQuery.Data
value := app.state.db.Get(prefixKey(reqQuery.Data))
resQuery.Value = value
if value != nil {
resQuery.Log = "exists"
} else {
resQuery.Log = "does not exist"
}
return
}
}
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