From b6a08a97e23737613b61998f690af7d979e9747b Mon Sep 17 00:00:00 2001
From: Anthony Romano <anthony.romano@coreos.com>
Date: Wed, 3 Feb 2016 14:49:33 -0800
Subject: [PATCH] clientv3: don't retry txns that may modify the store

---
 clientv3/kv.go  | 2 +-
 clientv3/op.go  | 4 ++++
 clientv3/txn.go | 8 ++++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/clientv3/kv.go b/clientv3/kv.go
index 2c6a3ff84..d71e7da8a 100644
--- a/clientv3/kv.go
+++ b/clientv3/kv.go
@@ -185,7 +185,7 @@ func (kv *kv) do(op Op) (*pb.ResponseUnion, error) {
 		}
 
 		// do not retry on modifications
-		if op.t != tRange {
+		if op.isWrite() {
 			go kv.switchRemote(err)
 			return nil, err
 		}
diff --git a/clientv3/op.go b/clientv3/op.go
index fdc333469..07c80c0d6 100644
--- a/clientv3/op.go
+++ b/clientv3/op.go
@@ -64,6 +64,10 @@ func (op Op) toRequestUnion() *pb.RequestUnion {
 	}
 }
 
+func (op Op) isWrite() bool {
+	return op.t != tRange
+}
+
 func OpRange(key, end string, limit, rev int64, sort *SortOption) Op {
 	return Op{
 		t:   tRange,
diff --git a/clientv3/txn.go b/clientv3/txn.go
index 84f224834..0e0804457 100644
--- a/clientv3/txn.go
+++ b/clientv3/txn.go
@@ -58,6 +58,8 @@ type txn struct {
 	cthen bool
 	celse bool
 
+	isWrite bool
+
 	cmps []*pb.Compare
 
 	sus []*pb.RequestUnion
@@ -101,6 +103,7 @@ func (txn *txn) Then(ops ...Op) Txn {
 	txn.cthen = true
 
 	for _, op := range ops {
+		txn.isWrite = txn.isWrite || op.isWrite()
 		txn.sus = append(txn.sus, op.toRequestUnion())
 	}
 
@@ -118,6 +121,7 @@ func (txn *txn) Else(ops ...Op) Txn {
 	txn.celse = true
 
 	for _, op := range ops {
+		txn.isWrite = txn.isWrite || op.isWrite()
 		txn.fas = append(txn.fas, op.toRequestUnion())
 	}
 
@@ -137,6 +141,10 @@ func (txn *txn) Commit() (*TxnResponse, error) {
 			return (*TxnResponse)(resp), nil
 		}
 
+		if txn.isWrite {
+			return nil, err
+		}
+
 		if isRPCError(err) {
 			return nil, err
 		}