add data-driven tests for PreVote and CheckQuorum

Signed-off-by: Erik Grinaker <[email protected]>

interaction_test.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/cockroachdb/datadriven"
 
+	"go.etcd.io/raft/v3"
 	"go.etcd.io/raft/v3/rafttest"
 )
 
@@ -27,7 +28,9 @@ func TestInteraction(t *testing.T) {
 	// diff. Only commit the changes if you understand what caused them and if
 	// they are desired.
 	datadriven.Walk(t, "testdata", func(t *testing.T, path string) {
-		env := rafttest.NewInteractionEnv(nil)
+		env := rafttest.NewInteractionEnv(&rafttest.InteractionOpts{
+			SetRandomizedElectionTimeout: raft.SetRandomizedElectionTimeout,
+		})
 		datadriven.RunTest(t, path, func(t *testing.T, d *datadriven.TestData) string {
 			return env.Handle(t, *d)
 		})

raft_test.go

@@ -4978,6 +4978,12 @@ func setRandomizedElectionTimeout(r *raft, v int) {
 	r.randomizedElectionTimeout = v
 }
 
+// SetRandomizedElectionTimeout is like setRandomizedElectionTimeout, but
+// exported for use by tests that are not in the raft package, using RawNode.
+func SetRandomizedElectionTimeout(r *RawNode, v int) {
+	setRandomizedElectionTimeout(r.raft, v)
+}
+
 func newTestConfig(id uint64, election, heartbeat int, storage Storage) *Config {
 	return &Config{
 		ID:              id,

rafttest/interaction_env.go

@@ -27,6 +27,10 @@ import (
 // InteractionOpts groups the options for an InteractionEnv.
 type InteractionOpts struct {
 	OnConfig func(*raft.Config)
+
+	// SetRandomizedElectionTimeout is used to plumb this function down from the
+	// raft test package.
+	SetRandomizedElectionTimeout func(node *raft.RawNode, timeout int)
 }
 
 // Node is a member of a raft group tested via an InteractionEnv.

rafttest/interaction_env_handler.go

@@ -97,6 +97,14 @@ func (env *InteractionEnv) Handle(t *testing.T, d datadriven.TestData) string {
 		// following, etc.). The information for node n is based on
 		// n's view.
 		err = env.handleRaftState()
+	case "set-randomized-election-timeout":
+		// Set the randomized election timeout for the given node. Will be reset
+		// again when the node changes state.
+		//
+		// Example:
+		//
+		// set-randomized-election-timeout 1 timeout=5
+		err = env.handleSetRandomizedElectionTimeout(t, d)
 	case "stabilize":
 		// Deliver messages to and run process-ready on the set of IDs until
 		// no more work is to be done. If no ids are given, all nodes are used.
@@ -112,6 +120,14 @@ func (env *InteractionEnv) Handle(t *testing.T, d datadriven.TestData) string {
 		//
 		// status 5
 		err = env.handleStatus(t, d)
+	case "tick-election":
+		// Tick an election timeout interval for the given node (but beware the
+		// randomized timeout).
+		//
+		// Example:
+		//
+		// tick-election 3
+		err = env.handleTickElection(t, d)
 	case "tick-heartbeat":
 		// Tick a heartbeat interval.
 		//

rafttest/interaction_env_handler_add_nodes.go

@@ -50,6 +50,10 @@ func (env *InteractionEnv) handleAddNodes(t *testing.T, d datadriven.TestData) e
 				arg.Scan(t, i, &snap.Data)
 			case "async-storage-writes":
 				arg.Scan(t, i, &cfg.AsyncStorageWrites)
+			case "prevote":
+				arg.Scan(t, i, &cfg.PreVote)
+			case "checkquorum":
+				arg.Scan(t, i, &cfg.CheckQuorum)
 			}
 		}
 	}

rafttest/interaction_env_handler_set_randomized_election_timeout.go

@@ -0,0 +1,34 @@
+// Copyright 2023 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 (
+	"testing"
+
+	"github.com/cockroachdb/datadriven"
+	"github.com/stretchr/testify/require"
+)
+
+func (env *InteractionEnv) handleSetRandomizedElectionTimeout(
+	t *testing.T, d datadriven.TestData,
+) error {
+	idx := firstAsNodeIdx(t, d)
+	var timeout int
+	d.ScanArgs(t, "timeout", &timeout)
+	require.NotZero(t, timeout)
+
+	env.Options.SetRandomizedElectionTimeout(env.Nodes[idx].RawNode, timeout)
+	return nil
+}

rafttest/interaction_env_handler_tick_heartbeat.go → rafttest/interaction_env_handler_tick.go

@@ -20,6 +20,11 @@ import (
 	"github.com/cockroachdb/datadriven"
 )
 
+func (env *InteractionEnv) handleTickElection(t *testing.T, d datadriven.TestData) error {
+	idx := firstAsNodeIdx(t, d)
+	return env.Tick(idx, env.Nodes[idx].Config.ElectionTick)
+}
+
 func (env *InteractionEnv) handleTickHeartbeat(t *testing.T, d datadriven.TestData) error {
 	idx := firstAsNodeIdx(t, d)
 	return env.Tick(idx, env.Nodes[idx].Config.HeartbeatTick)

testdata/checkquorum.txt

@@ -0,0 +1,236 @@
+# Tests that CheckQuorum causes a leader to step down if it hasn't heard from a
+# quorum of followers in the past election timeout interval.
+#
+# Also tests that votes are rejected when there is a current leader. In the Raft
+# thesis this is part of PreVote, but etcd/raft enables this via CheckQuorum.
+
+log-level none
+----
+ok
+
+add-nodes 3 voters=(1,2,3) index=10 checkquorum=true
+----
+ok
+
+campaign 1
+----
+ok
+
+stabilize
+----
+ok (quiet)
+
+log-level debug
+----
+ok
+
+# Campaigning will fail when there is an active leader.
+campaign 2
+----
+INFO 2 is starting a new election at term 1
+INFO 2 became candidate at term 2
+INFO 2 [logterm: 1, index: 11] sent MsgVote request to 1 at term 2
+INFO 2 [logterm: 1, index: 11] sent MsgVote request to 3 at term 2
+
+stabilize
+----
+> 2 handling Ready
+  Ready MustSync=true:
+  Lead:0 State:StateCandidate
+  HardState Term:2 Vote:2 Commit:11
+  Messages:
+  2->1 MsgVote Term:2 Log:1/11
+  2->3 MsgVote Term:2 Log:1/11
+  INFO 2 received MsgVoteResp from 2 at term 2
+  INFO 2 has received 1 MsgVoteResp votes and 0 vote rejections
+> 1 receiving messages
+  2->1 MsgVote Term:2 Log:1/11
+  INFO 1 [logterm: 1, index: 11, vote: 1] ignored MsgVote from 2 [logterm: 1, index: 11] at term 1: lease is not expired (remaining ticks: 3)
+> 3 receiving messages
+  2->3 MsgVote Term:2 Log:1/11
+  INFO 3 [logterm: 1, index: 11, vote: 1] ignored MsgVote from 2 [logterm: 1, index: 11] at term 1: lease is not expired (remaining ticks: 3)
+
+# Tick the leader without processing any messages from followers. We have to
+# tick 2 election timeouts, since the followers were active in the current
+# interval (see messages above).
+tick-election 1
+----
+ok
+
+tick-election 1
+----
+WARN 1 stepped down to follower since quorum is not active
+INFO 1 became follower at term 1
+
+# We'll now send all of the heartbeats that were buffered during the ticks
+# above. Conceptually, "the network was slow".
+stabilize
+----
+> 1 handling Ready
+  Ready MustSync=false:
+  Lead:0 State:StateFollower
+  Messages:
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+> 2 receiving messages
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->2 MsgHeartbeat Term:1 Log:0/0 Commit:11
+> 3 receiving messages
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+  1->3 MsgHeartbeat Term:1 Log:0/0 Commit:11
+> 2 handling Ready
+  Ready MustSync=false:
+  Messages:
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+> 3 handling Ready
+  Ready MustSync=false:
+  Messages:
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+> 1 receiving messages
+  2->1 MsgAppResp Term:2 Log:0/0
+  INFO 1 [term: 1] received a MsgAppResp message with higher term from 2 [term: 2]
+  INFO 1 became follower at term 2
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  2->1 MsgAppResp Term:2 Log:0/0
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  INFO 1 [term: 2] ignored a MsgHeartbeatResp message with lower term from 3 [term: 1]
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  INFO 1 [term: 2] ignored a MsgHeartbeatResp message with lower term from 3 [term: 1]
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  INFO 1 [term: 2] ignored a MsgHeartbeatResp message with lower term from 3 [term: 1]
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  INFO 1 [term: 2] ignored a MsgHeartbeatResp message with lower term from 3 [term: 1]
+  3->1 MsgHeartbeatResp Term:1 Log:0/0
+  INFO 1 [term: 2] ignored a MsgHeartbeatResp message with lower term from 3 [term: 1]
+> 1 handling Ready
+  Ready MustSync=true:
+  HardState Term:2 Commit:11
+
+# Other nodes can now successfully campaign. Note that we haven't ticked 3, so
+# it won't grant votes.
+campaign 2
+----
+INFO 2 is starting a new election at term 2
+INFO 2 became candidate at term 3
+INFO 2 [logterm: 1, index: 11] sent MsgVote request to 1 at term 3
+INFO 2 [logterm: 1, index: 11] sent MsgVote request to 3 at term 3
+
+process-ready 2
+----
+Ready MustSync=true:
+HardState Term:3 Vote:2 Commit:11
+Messages:
+2->1 MsgVote Term:3 Log:1/11
+2->3 MsgVote Term:3 Log:1/11
+INFO 2 received MsgVoteResp from 2 at term 3
+INFO 2 has received 1 MsgVoteResp votes and 0 vote rejections
+
+deliver-msgs 1
+----
+2->1 MsgVote Term:3 Log:1/11
+INFO 1 [term: 2] received a MsgVote message with higher term from 2 [term: 3]
+INFO 1 became follower at term 3
+INFO 1 [logterm: 1, index: 11, vote: 0] cast MsgVote for 2 [logterm: 1, index: 11] at term 3
+
+deliver-msgs 3
+----
+2->3 MsgVote Term:3 Log:1/11
+INFO 3 [logterm: 1, index: 11, vote: 1] ignored MsgVote from 2 [logterm: 1, index: 11] at term 1: lease is not expired (remaining ticks: 3)
+
+stabilize
+----
+> 1 handling Ready
+  Ready MustSync=true:
+  HardState Term:3 Vote:2 Commit:11
+  Messages:
+  1->2 MsgVoteResp Term:3 Log:0/0
+> 2 receiving messages
+  1->2 MsgVoteResp Term:3 Log:0/0
+  INFO 2 received MsgVoteResp from 1 at term 3
+  INFO 2 has received 2 MsgVoteResp votes and 0 vote rejections
+  INFO 2 became leader at term 3
+> 2 handling Ready
+  Ready MustSync=true:
+  Lead:2 State:StateLeader
+  Entries:
+  3/12 EntryNormal ""
+  Messages:
+  2->1 MsgApp Term:3 Log:1/11 Commit:11 Entries:[3/12 EntryNormal ""]
+  2->3 MsgApp Term:3 Log:1/11 Commit:11 Entries:[3/12 EntryNormal ""]
+> 1 receiving messages
+  2->1 MsgApp Term:3 Log:1/11 Commit:11 Entries:[3/12 EntryNormal ""]
+> 3 receiving messages
+  2->3 MsgApp Term:3 Log:1/11 Commit:11 Entries:[3/12 EntryNormal ""]
+  INFO 3 [term: 1] received a MsgApp message with higher term from 2 [term: 3]
+  INFO 3 became follower at term 3
+> 1 handling Ready
+  Ready MustSync=true:
+  Lead:2 State:StateFollower
+  Entries:
+  3/12 EntryNormal ""
+  Messages:
+  1->2 MsgAppResp Term:3 Log:0/12
+> 3 handling Ready
+  Ready MustSync=true:
+  Lead:2 State:StateFollower
+  HardState Term:3 Commit:11
+  Entries:
+  3/12 EntryNormal ""
+  Messages:
+  3->2 MsgAppResp Term:3 Log:0/12
+> 2 receiving messages
+  1->2 MsgAppResp Term:3 Log:0/12
+  3->2 MsgAppResp Term:3 Log:0/12
+> 2 handling Ready
+  Ready MustSync=false:
+  HardState Term:3 Vote:2 Commit:12
+  CommittedEntries:
+  3/12 EntryNormal ""
+  Messages:
+  2->1 MsgApp Term:3 Log:3/12 Commit:12
+  2->3 MsgApp Term:3 Log:3/12 Commit:12
+> 1 receiving messages
+  2->1 MsgApp Term:3 Log:3/12 Commit:12
+> 3 receiving messages
+  2->3 MsgApp Term:3 Log:3/12 Commit:12
+> 1 handling Ready
+  Ready MustSync=false:
+  HardState Term:3 Vote:2 Commit:12
+  CommittedEntries:
+  3/12 EntryNormal ""
+  Messages:
+  1->2 MsgAppResp Term:3 Log:0/12
+> 3 handling Ready
+  Ready MustSync=false:
+  HardState Term:3 Commit:12
+  CommittedEntries:
+  3/12 EntryNormal ""
+  Messages:
+  3->2 MsgAppResp Term:3 Log:0/12
+> 2 receiving messages
+  1->2 MsgAppResp Term:3 Log:0/12
+  3->2 MsgAppResp Term:3 Log:0/12