From 8782bbae65eda5582d52a3cb4e67f2b35e56b62e Mon Sep 17 00:00:00 2001
From: "Sahdev P. Zala" <spzala@us.ibm.com>
Date: Tue, 26 Feb 2019 16:45:47 -0500
Subject: [PATCH] clientV3: fix behavior of WithPrefix and WithFromKey
 functions

The use of WithPrefix() and WithFromKey() together is not supported. The
client doesn't respect this behavior currently.

Fixes #10431
---
 clientv3/op.go    | 14 ++++++++++++++
 clientv3/utils.go | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/clientv3/op.go b/clientv3/op.go
index 13507c99a..085dd28ab 100644
--- a/clientv3/op.go
+++ b/clientv3/op.go
@@ -218,6 +218,10 @@ func (op Op) isWrite() bool {
 
 // OpGet returns "get" operation based on given key and operation options.
 func OpGet(key string, opts ...OpOption) Op {
+	// WithPrefix and WithFromKey are not supported together
+	if isWithPrefix(opts) && isWithFromKey(opts) {
+		panic("`WithPrefix` and `WithFromKey` cannot be set at the same time, choose one")
+	}
 	ret := Op{t: tRange, key: []byte(key)}
 	ret.applyOpts(opts)
 	return ret
@@ -225,6 +229,10 @@ func OpGet(key string, opts ...OpOption) Op {
 
 // OpDelete returns "delete" operation based on given key and operation options.
 func OpDelete(key string, opts ...OpOption) Op {
+	// WithPrefix and WithFromKey are not supported together
+	if isWithPrefix(opts) && isWithFromKey(opts) {
+		panic("`WithPrefix` and `WithFromKey` cannot be set at the same time, choose one")
+	}
 	ret := Op{t: tDeleteRange, key: []byte(key)}
 	ret.applyOpts(opts)
 	switch {
@@ -544,3 +552,9 @@ func toLeaseTimeToLiveRequest(id LeaseID, opts ...LeaseOption) *pb.LeaseTimeToLi
 	ret.applyOpts(opts)
 	return &pb.LeaseTimeToLiveRequest{ID: int64(id), Keys: ret.attachedKeys}
 }
+
+// isWithPrefix returns true if WithPrefix is being called in the op
+func isWithPrefix(opts []OpOption) bool { return isOpFuncCalled("WithPrefix", opts) }
+
+// isWithFromKey returns true if WithFromKey is being called in the op
+func isWithFromKey(opts []OpOption) bool { return isOpFuncCalled("WithFromKey", opts) }
diff --git a/clientv3/utils.go b/clientv3/utils.go
index 850275877..b998c41b9 100644
--- a/clientv3/utils.go
+++ b/clientv3/utils.go
@@ -16,6 +16,9 @@ package clientv3
 
 import (
 	"math/rand"
+	"reflect"
+	"runtime"
+	"strings"
 	"time"
 )
 
@@ -29,3 +32,18 @@ func jitterUp(duration time.Duration, jitter float64) time.Duration {
 	multiplier := jitter * (rand.Float64()*2 - 1)
 	return time.Duration(float64(duration) * (1 + multiplier))
 }
+
+// Check if the provided function is being called in the op options.
+func isOpFuncCalled(op string, opts []OpOption) bool {
+	for _, opt := range opts {
+		v := reflect.ValueOf(opt)
+		if v.Kind() == reflect.Func {
+			if opFunc := runtime.FuncForPC(v.Pointer()); opFunc != nil {
+				if strings.Contains(opFunc.Name(), op) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}