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Nathan VanBenschoten b757e1bc87 raft: create new probe_and_replicate.txt interactive test
This commit creates a new probe_and_replicate.txt interactive test. The
test creates a complete Raft log configuration and demonstrates how a
leader probes and replicates to each of its followers. The log
configuration constructed is identical to the one present in Figure 7 of
the raft paper (https://raft.github.io/raft.pdf), which looks like:

```
     1  2  3  4  5  6  7  8  9  10 11 12
n1: [1][1][1][4][4][5][5][6][6][6]
n2: [1][1][1][4][4][5][5][6][6]
n3: [1][1][1][4]
n4: [1][1][1][4][4][5][5][6][6][6][6]
n5: [1][1][1][4][4][5][5][6][7][7][7][7]
n6: [1][1][1][4][4][4][4]
n7: [1][1][1][2][2][2][3][3][3][3][3]
```

Once in this state, we then elect node 1 as the leader and stabilize the
entire raft group. This demonstrates how a newly elected leader probes
for matching indexes, overwrites conflicting entries, and catches up all
followers.

This will be useful to demonstrate the impact of more efficient probing
behavior.
2021-02-10 15:02:36 -05:00

104 lines
2.6 KiB
Go

// Copyright 2019 The etcd Authors
//
// 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 rafttest
import (
"bufio"
"fmt"
"math"
"strings"
"go.etcd.io/etcd/raft/v3"
pb "go.etcd.io/etcd/raft/v3/raftpb"
)
// InteractionOpts groups the options for an InteractionEnv.
type InteractionOpts struct {
OnConfig func(*raft.Config)
}
// Node is a member of a raft group tested via an InteractionEnv.
type Node struct {
*raft.RawNode
Storage
Config *raft.Config
History []pb.Snapshot
}
// InteractionEnv facilitates testing of complex interactions between the
// members of a raft group.
type InteractionEnv struct {
Options *InteractionOpts
Nodes []Node
Messages []pb.Message // in-flight messages
Output *RedirectLogger
}
// NewInteractionEnv initializes an InteractionEnv. opts may be nil.
func NewInteractionEnv(opts *InteractionOpts) *InteractionEnv {
if opts == nil {
opts = &InteractionOpts{}
}
return &InteractionEnv{
Options: opts,
Output: &RedirectLogger{
Builder: &strings.Builder{},
},
}
}
func (env *InteractionEnv) withIndent(f func()) {
orig := env.Output.Builder
env.Output.Builder = &strings.Builder{}
f()
scanner := bufio.NewScanner(strings.NewReader(env.Output.Builder.String()))
for scanner.Scan() {
orig.WriteString(" " + scanner.Text() + "\n")
}
env.Output.Builder = orig
}
// Storage is the interface used by InteractionEnv. It is comprised of raft's
// Storage interface plus access to operations that maintain the log and drive
// the Ready handling loop.
type Storage interface {
raft.Storage
SetHardState(state pb.HardState) error
ApplySnapshot(pb.Snapshot) error
Compact(newFirstIndex uint64) error
Append([]pb.Entry) error
}
// defaultRaftConfig sets up a *raft.Config with reasonable testing defaults.
// In particular, no limits are set.
func defaultRaftConfig(id uint64, applied uint64, s raft.Storage) *raft.Config {
return &raft.Config{
ID: id,
Applied: applied,
ElectionTick: 3,
HeartbeatTick: 1,
Storage: s,
MaxSizePerMsg: math.MaxUint64,
MaxInflightMsgs: math.MaxInt32,
}
}
func defaultEntryFormatter(b []byte) string {
return fmt.Sprintf("%q", b)
}