*: add put prevkv

clientv3/kv.go

@@ -156,7 +156,7 @@ func (kv *kv) do(ctx context.Context, op Op) (OpResponse, error) {
 		}
 	case tPut:
 		var resp *pb.PutResponse
-		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID)}
+		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID), PrevKv: op.prevKV}
 		resp, err = kv.remote.Put(ctx, r)
 		if err == nil {
 			return OpResponse{put: (*PutResponse)(resp)}, nil

clientv3/op.go

@@ -74,7 +74,7 @@ func (op Op) toRequestOp() *pb.RequestOp {
 		}
 		return &pb.RequestOp{Request: &pb.RequestOp_RequestRange{RequestRange: r}}
 	case tPut:
-		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID)}
+		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID), PrevKv: op.prevKV}
 		return &pb.RequestOp{Request: &pb.RequestOp_RequestPut{RequestPut: r}}
 	case tDeleteRange:
 		r := &pb.DeleteRangeRequest{Key: op.key, RangeEnd: op.end, PrevKv: op.prevKV}

etcdctl/ctlv3/command/printer.go

@@ -119,7 +119,12 @@ func (s *simplePrinter) Get(resp v3.GetResponse) {
 	}
 }
 
-func (s *simplePrinter) Put(r v3.PutResponse) { fmt.Println("OK") }
+func (s *simplePrinter) Put(r v3.PutResponse) {
+	fmt.Println("OK")
+	if r.PrevKv != nil {
+		printKV(s.isHex, r.PrevKv)
+	}
+}
 
 func (s *simplePrinter) Txn(resp v3.TxnResponse) {
 	if resp.Succeeded {

etcdctl/ctlv3/command/put_command.go

@@ -24,7 +24,8 @@ import (
 )
 
 var (
-	leaseStr string
+	leaseStr  string
+	putPrevKV bool
 )
 
 // NewPutCommand returns the cobra command for "put".
@@ -49,6 +50,7 @@ will store the content of the file to <key>.
 		Run: putCommandFunc,
 	}
 	cmd.Flags().StringVar(&leaseStr, "lease", "0", "lease ID (in hexadecimal) to attach to the key")
+	cmd.Flags().BoolVar(&putPrevKV, "prev-kv", false, "return changed key-value pairs")
 	return cmd
 }
 
@@ -85,6 +87,9 @@ func getPutOp(cmd *cobra.Command, args []string) (string, string, []clientv3.OpO
 	if id != 0 {
 		opts = append(opts, clientv3.WithLease(clientv3.LeaseID(id)))
 	}
+	if putPrevKV {
+		opts = append(opts, clientv3.WithPrevKV())
+	}
 
 	return key, value, opts
 }

etcdserver/apply.go

@@ -159,6 +159,22 @@ func (a *applierV3backend) Put(txnID int64, p *pb.PutRequest) (*pb.PutResponse,
 		rev int64
 		err error
 	)
+
+	var rr *mvcc.RangeResult
+	if p.PrevKv {
+		if txnID != noTxn {
+			rr, err = a.s.KV().TxnRange(txnID, p.Key, nil, mvcc.RangeOptions{})
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			rr, err = a.s.KV().Range(p.Key, nil, mvcc.RangeOptions{})
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
 	if txnID != noTxn {
 		rev, err = a.s.KV().TxnPut(txnID, p.Key, p.Value, lease.LeaseID(p.Lease))
 		if err != nil {
@@ -174,6 +190,9 @@ func (a *applierV3backend) Put(txnID int64, p *pb.PutRequest) (*pb.PutResponse,
 		rev = a.s.KV().Put(p.Key, p.Value, leaseID)
 	}
 	resp.Header.Revision = rev
+	if rr != nil && len(rr.KVs) != 0 {
+		resp.PrevKv = &rr.KVs[0]
+	}
 	return resp, nil
 }
 

etcdserver/apply_auth.go

@@ -56,6 +56,9 @@ func (aa *authApplierV3) Put(txnID int64, r *pb.PutRequest) (*pb.PutResponse, er
 	if !aa.as.IsPutPermitted(aa.user, r.Key) {
 		return nil, auth.ErrPermissionDenied
 	}
+	if r.PrevKv && !aa.as.IsRangePermitted(aa.user, r.Key, nil) {
+		return nil, auth.ErrPermissionDenied
+	}
 	return aa.applierV3.Put(txnID, r)
 }