Use proto messages for Read-write set

https://jira.hyperledger.org/browse/FAB-2810

This CR:
- Introduces proto messages
- Removes custom types for read-write set in package kvledger/txmgmt/rwset
- Renames the package kvledger/txmgmt/rwset to kvledger/txmgmt/rwsetutil
  and rwset.go to rwset_builder_test.go in order to reflect the purpose
  of the remaining code better
- Modifies the other packages to use rwset from protos
  and utilities from rwsetutil package

Change-Id: Id01be87903ad30f0eea34ef4033195b17bec3e71
Signed-off-by: manish <manish.sethi@gmail.com>

core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb.go

@@ -21,7 +21,7 @@ import (
 	"github.com/hyperledger/fabric/common/ledger/util/leveldbhelper"
 	"github.com/hyperledger/fabric/core/ledger"
 	"github.com/hyperledger/fabric/core/ledger/kvledger/history/historydb"
-	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/rwset"
+	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/rwsetutil"
 	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/version"
 	"github.com/hyperledger/fabric/core/ledger/ledgerconfig"
 	"github.com/hyperledger/fabric/core/ledger/util"
@@ -137,19 +137,19 @@ func (historyDB *historyDB) Commit(block *common.Block) error {
 			}
 
 			//preparation for extracting RWSet from transaction
-			txRWSet := &rwset.TxReadWriteSet{}
+			txRWSet := &rwsetutil.TxRwSet{}
 
 			// Get the Result from the Action and then Unmarshal
 			// it into a TxReadWriteSet using custom unmarshalling
-			if err = txRWSet.Unmarshal(respPayload.Results); err != nil {
+			if err = txRWSet.FromProtoBytes(respPayload.Results); err != nil {
 				return err
 			}
 			// for each transaction, loop through the namespaces and writesets
 			// and add a history record for each write
-			for _, nsRWSet := range txRWSet.NsRWs {
+			for _, nsRWSet := range txRWSet.NsRwSets {
 				ns := nsRWSet.NameSpace
 
-				for _, kvWrite := range nsRWSet.Writes {
+				for _, kvWrite := range nsRWSet.KvRwSet.Writes {
 					writeKey := kvWrite.Key
 
 					//composite key for history records is in the form ns~key~blockNo~tranNo

core/ledger/kvledger/history/historydb/historyleveldb/historyleveldb_query_executer.go

@@ -24,7 +24,7 @@ import (
 	"github.com/hyperledger/fabric/common/ledger/util"
 	"github.com/hyperledger/fabric/core/ledger"
 	"github.com/hyperledger/fabric/core/ledger/kvledger/history/historydb"
-	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/rwset"
+	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/rwsetutil"
 	"github.com/hyperledger/fabric/core/ledger/ledgerconfig"
 	"github.com/hyperledger/fabric/protos/common"
 	putils "github.com/hyperledger/fabric/protos/utils"
@@ -129,19 +129,19 @@ func getTxIDandKeyWriteValueFromTran(
 
 	txID := chdr.TxId
 
-	txRWSet := &rwset.TxReadWriteSet{}
+	txRWSet := &rwsetutil.TxRwSet{}
 
 	// Get the Result from the Action and then Unmarshal
 	// it into a TxReadWriteSet using custom unmarshalling
-	if err = txRWSet.Unmarshal(respPayload.Results); err != nil {
+	if err = txRWSet.FromProtoBytes(respPayload.Results); err != nil {
 		return txID, nil, err
 	}
 
 	// look for the namespace and key by looping through the transaction's ReadWriteSets
-	for _, nsRWSet := range txRWSet.NsRWs {
+	for _, nsRWSet := range txRWSet.NsRwSets {
 		if nsRWSet.NameSpace == namespace {
 			// got the correct namespace, now find the key write
-			for _, kvWrite := range nsRWSet.Writes {
+			for _, kvWrite := range nsRWSet.KvRwSet.Writes {
 				if kvWrite.Key == key {
 					return txID, kvWrite.Value, nil
 				}