1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
// Copyright 2017 Canonical Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package raftmembership
import (
"fmt"
"time"
"github.com/hashicorp/raft"
)
// HandleChangeRequests processes ChangeRequest's received through the
// given channel, using the given raft.Raft instance to add or remove
// peers to the cluster according to the received requests.
func HandleChangeRequests(r *raft.Raft, requests <-chan *ChangeRequest) {
for request := range requests {
// If we currently think we're the leader, let's try
// to handle the request, otherwise let's bail out
// directly.
var err error
if r.State() == raft.Leader {
err = changeMembership(r, request).Error()
} else {
err = raft.ErrNotLeader
}
// Wrap not-leader errors.
if err == raft.ErrNotLeader {
if r.Leader() != "" {
err = &ErrDifferentLeader{leader: string(r.Leader())}
} else {
err = &ErrUnknownLeader{}
}
}
request.Done(err)
}
}
// Execute the appropriate Raft to handle the given request.
func changeMembership(raft *raft.Raft, request *ChangeRequest) raft.Future {
kind := request.Kind()
timeout := 10 * time.Second // FIXME: should be configurable
switch kind {
case JoinRequest:
return raft.AddVoter(request.ID(), request.Address(), 0, timeout)
case LeaveRequest:
return raft.RemoveServer(request.ID(), 0, timeout)
default:
panic(fmt.Sprintf("invalid change request kind: %d", int(kind)))
}
}
|
