[FAB-2980] Replace gob with proto for QueryResult

QueryResults (i.e., KV and KeyModification structs) are serialized
using gob in the peer and deserialized in golang chaincode shim.
As gob encoding is not supported in java, this CR replaces gob
with proto (provided that QueryResults are defined as protobuf
message -- https://gerrit.hyperledger.org/r/#/c/7687/).

Change-Id: Ice9133fdc30a59397aa0670050401502150f60f5
Signed-off-by: senthil <[email protected]>
Signed-off-by: Luis Sanchez <[email protected]>

Author: cendhu

core/chaincode/handler.go

@@ -18,7 +18,6 @@ package chaincode
 
 import (
 	"bytes"
-	"encoding/gob"
 	"fmt"
 	"io"
 	"sync"
@@ -761,16 +760,6 @@ func (handler *Handler) handleGetStateByRange(msg *pb.ChaincodeMessage) {
 	}()
 }
 
-func getBytes(qresult interface{}) ([]byte, error) {
-	var buf bytes.Buffer
-	enc := gob.NewEncoder(&buf)
-	err := enc.Encode(qresult)
-	if err != nil {
-		return nil, err
-	}
-	return buf.Bytes(), nil
-}
-
 //getQueryResponse takes an iterator and fetch state to construct QueryResponse
 func getQueryResponse(handler *Handler, txContext *transactionContext, iter commonledger.ResultsIterator,
 	iterID string) (*pb.QueryResponse, error) {
@@ -790,7 +779,7 @@ func getQueryResponse(handler *Handler, txContext *transactionContext, iter comm
 			break
 		}
 		var resultBytes []byte
-		resultBytes, err = getBytes(queryResult)
+		resultBytes, err = proto.Marshal(queryResult.(proto.Message))
 		if err != nil {
 			return nil, err
 		}

core/chaincode/shim/chaincode.go

@@ -19,8 +19,6 @@ limitations under the License.
 package shim
 
 import (
-	"bytes"
-	"encoding/gob"
 	"errors"
 	"flag"
 	"fmt"
@@ -491,11 +489,17 @@ func getStateByPartialCompositeKey(stub ChaincodeStubInterface, objectType strin
 
 func (iter *StateQueryIterator) Next() (*queryresult.KV, error) {
 	result, err := next(iter.CommonIterator, STATE_QUERY_RESULT)
+	if err != nil {
+		return nil, err
+	}
 	return result.(*queryresult.KV), err
 }
 
 func (iter *HistoryQueryIterator) Next() (*queryresult.KeyModification, error) {
 	result, err := next(iter.CommonIterator, HISTORY_QUERY_RESULT)
+	if err != nil {
+		return nil, err
+	}
 	return result.(*queryresult.KeyModification), err
 }
 
@@ -515,23 +519,21 @@ func (iter *CommonIterator) HasNext() bool {
 func getResultFromBytes(queryResultBytes *pb.QueryResultBytes, iter *CommonIterator,
 	rType resultType) (commonledger.QueryResult, error) {
 
-	decoder := gob.NewDecoder(bytes.NewBuffer(queryResultBytes.ResultBytes))
-
 	if rType == STATE_QUERY_RESULT {
-		var stateQueryResult queryresult.KV
-		if err := decoder.Decode(&stateQueryResult); err != nil {
+		stateQueryResult := &queryresult.KV{}
+		if err := proto.Unmarshal(queryResultBytes.ResultBytes, stateQueryResult); err != nil {
 			return nil, err
 		}
 		iter.currentLoc++
-		return &stateQueryResult, nil
+		return stateQueryResult, nil
 
 	} else if rType == HISTORY_QUERY_RESULT {
-		var historyQueryResult queryresult.KeyModification
-		if err := decoder.Decode(&historyQueryResult); err != nil {
+		historyQueryResult := &queryresult.KeyModification{}
+		if err := proto.Unmarshal(queryResultBytes.ResultBytes, historyQueryResult); err != nil {
 			return nil, err
 		}
 		iter.currentLoc++
-		return &historyQueryResult, nil
+		return historyQueryResult, nil
 
 	}
 	return nil, errors.New("Wrong result type")