1// Copyright 2017 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package ordering
16
17import (
18	"errors"
19	"sync"
20	"time"
21
22	"github.com/coreos/etcd/clientv3"
23)
24
25type OrderViolationFunc func(op clientv3.Op, resp clientv3.OpResponse, prevRev int64) error
26
27var ErrNoGreaterRev = errors.New("etcdclient: no cluster members have a revision higher than the previously received revision")
28
29func NewOrderViolationSwitchEndpointClosure(c clientv3.Client) OrderViolationFunc {
30	var mu sync.Mutex
31	violationCount := 0
32	return func(op clientv3.Op, resp clientv3.OpResponse, prevRev int64) error {
33		if violationCount > len(c.Endpoints()) {
34			return ErrNoGreaterRev
35		}
36		mu.Lock()
37		defer mu.Unlock()
38		eps := c.Endpoints()
39		// force client to connect to given endpoint by limiting to a single endpoint
40		c.SetEndpoints(eps[violationCount%len(eps)])
41		// give enough time for operation
42		time.Sleep(1 * time.Second)
43		// set available endpoints back to all endpoints in to ensure
44		// the client has access to all the endpoints.
45		c.SetEndpoints(eps...)
46		violationCount++
47		return nil
48	}
49}
50