store.go

/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"fmt"

	"github.com/golang/protobuf/proto"
	"github.com/TarantulaTechnology/fabric/core/chaincode/shim"
	"github.com/TarantulaTechnology/fabric/examples/chaincode/go/utxo/util"
)

// Store struct uses a chaincode stub for state access
type Store struct {
	stub *shim.ChaincodeStub
}

// MakeChaincodeStore returns a store for storing keys in the state
func MakeChaincodeStore(stub *shim.ChaincodeStub) util.Store {
	store := &Store{}
	store.stub = stub
	return store
}

func keyToString(key *util.Key) string {
	return key.TxHashAsHex + ":" + string(key.TxIndex)
}

// GetState returns the transaction for a given key
func (s *Store) GetState(key util.Key) (*util.TX_TXOUT, bool, error) {
	keyToFetch := keyToString(&key)
	data, err := s.stub.GetState(keyToFetch)
	if err != nil {
		return nil, false, fmt.Errorf("Error getting state from stub:  %s", err)
	}
	if data == nil {
		return nil, false, nil
	}
	// Value found, unmarshal
	var value = &util.TX_TXOUT{}
	err = proto.Unmarshal(data, value)
	if err != nil {
		return nil, false, fmt.Errorf("Error unmarshalling value:  %s", err)
	}
	return value, true, nil
}

// DelState deletes the transaction for the given key
func (s *Store) DelState(key util.Key) error {
	return s.stub.DelState(keyToString(&key))
}

// PutState stores the given transaction and key
func (s *Store) PutState(key util.Key, value *util.TX_TXOUT) error {
	data, err := proto.Marshal(value)
	if err != nil {
		return fmt.Errorf("Error marshalling value to bytes:  %s", err)
	}
	return s.stub.PutState(keyToString(&key), data)
}

// GetTran returns a transaction for the given hash
func (s *Store) GetTran(key string) ([]byte, bool, error) {
	data, err := s.stub.GetState(key)
	if err != nil {
		return nil, false, fmt.Errorf("Error getting state from stub:  %s", err)
	}
	if data == nil {
		return nil, false, nil
	}
	return data, true, nil
}

// PutTran adds a transaction to the state with the hash as a key
func (s *Store) PutTran(key string, value []byte) error {
	return s.stub.PutState(key, value)
}