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Make snowman use snowflake directly instead of snowball
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Snowball was introduced in order to improve the stability of snowflake,
by taking into account the history when returning the preference.

However, if deployed with a configuration where the preference is small enough, and a network partition
causes a 50-50 split of the stake, it can actually backfire, as described in 6e1a905.

Additionally, latest research [1] points out that snowflake suffices for snowman.

This commit removes snowball from snowman and adds a test that simulates a mixed network
which runs snowman with and without snowball, and ensures that a mixed network still converges.

[1] https://arxiv.org/abs/2404.14250

Signed-off-by: Yacov Manevich <[email protected]>
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@yacovm
yacovm committed Sep 19, 2024
1 parent c18d475 commit e3597d8
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Showing 17 changed files with 400 additions and 501 deletions.
5 changes: 3 additions & 2 deletions chains/manager.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ import (
"github.com/ava-labs/avalanchego/network"
"github.com/ava-labs/avalanchego/network/p2p"
"github.com/ava-labs/avalanchego/snow"
"github.com/ava-labs/avalanchego/snow/consensus/snowball"
"github.com/ava-labs/avalanchego/snow/engine/avalanche/bootstrap/queue"
"github.com/ava-labs/avalanchego/snow/engine/avalanche/state"
"github.com/ava-labs/avalanchego/snow/engine/avalanche/vertex"
Expand Down Expand Up @@ -922,7 +923,7 @@ func (m *manager) createAvalancheChain(
return nil, fmt.Errorf("couldn't initialize snow base message handler: %w", err)
}

var snowmanConsensus smcon.Consensus = &smcon.Topological{}
var snowmanConsensus smcon.Consensus = &smcon.Topological{Factory: snowball.SnowflakeFactory}
if m.TracingEnabled {
snowmanConsensus = smcon.Trace(snowmanConsensus, m.Tracer)
}
Expand Down Expand Up @@ -1321,7 +1322,7 @@ func (m *manager) createSnowmanChain(
return nil, fmt.Errorf("couldn't initialize snow base message handler: %w", err)
}

var consensus smcon.Consensus = &smcon.Topological{}
var consensus smcon.Consensus = &smcon.Topological{Factory: snowball.SnowflakeFactory}
if m.TracingEnabled {
consensus = smcon.Trace(consensus, m.Tracer)
}
Expand Down
139 changes: 70 additions & 69 deletions snow/consensus/snowball/binary_snowball_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,25 +19,26 @@ func TestBinarySnowball(t *testing.T) {
beta := 2
terminationConditions := newSingleTerminationCondition(alphaConfidence, beta)

sb := newBinarySnowball(alphaPreference, terminationConditions, red)
require.Equal(red, sb.Preference())
require.False(sb.Finalized())
sf := newBinarySnowflake(alphaPreference, terminationConditions, red)

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.True(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.True(sf.Finalized())
}

func TestBinarySnowballRecordPollPreference(t *testing.T) {
Expand All @@ -50,32 +51,32 @@ func TestBinarySnowballRecordPollPreference(t *testing.T) {
beta := 2
terminationConditions := newSingleTerminationCondition(alphaConfidence, beta)

sb := newBinarySnowball(alphaPreference, terminationConditions, red)
require.Equal(red, sb.Preference())
require.False(sb.Finalized())
sf := newBinarySnowflake(alphaPreference, terminationConditions, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaPreference, red)
require.Equal(red, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaPreference, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
require.Equal(red, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
require.Equal(red, sb.Preference())
require.True(sb.Finalized())
sf.RecordPoll(alphaConfidence, red)
require.Equal(red, sf.Preference())
require.True(sf.Finalized())

expected := "SB(Preference = 0, PreferenceStrength[0] = 4, PreferenceStrength[1] = 1, SF(Confidence = [2], Finalized = true, SL(Preference = 0)))"
require.Equal(expected, sb.String())
expected := "SF(Confidence = [2], Finalized = true, SL(Preference = 0))"
require.Equal(expected, sf.String())
}

func TestBinarySnowballRecordUnsuccessfulPoll(t *testing.T) {
Expand All @@ -88,26 +89,26 @@ func TestBinarySnowballRecordUnsuccessfulPoll(t *testing.T) {
beta := 2
terminationConditions := newSingleTerminationCondition(alphaConfidence, beta)

sb := newBinarySnowball(alphaPreference, terminationConditions, red)
require.Equal(red, sb.Preference())
require.False(sb.Finalized())
sf := newBinarySnowflake(alphaPreference, terminationConditions, red)
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sb.RecordUnsuccessfulPoll()
sf.RecordUnsuccessfulPoll()

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.False(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sb.Preference())
require.True(sb.Finalized())
sf.RecordPoll(alphaConfidence, blue)
require.Equal(blue, sf.Preference())
require.True(sf.Finalized())

expected := "SB(Preference = 1, PreferenceStrength[0] = 0, PreferenceStrength[1] = 3, SF(Confidence = [2], Finalized = true, SL(Preference = 1)))"
require.Equal(expected, sb.String())
expected := "SF(Confidence = [2], Finalized = true, SL(Preference = 1))"
require.Equal(expected, sf.String())
}

func TestBinarySnowballAcceptWeirdColor(t *testing.T) {
Expand All @@ -120,36 +121,36 @@ func TestBinarySnowballAcceptWeirdColor(t *testing.T) {
beta := 2
terminationConditions := newSingleTerminationCondition(alphaConfidence, beta)

sb := newBinarySnowball(alphaPreference, terminationConditions, red)
sf := newBinarySnowflake(alphaPreference, terminationConditions, red)

require.Equal(red, sb.Preference())
require.False(sb.Finalized())
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
sb.RecordUnsuccessfulPoll()
sf.RecordPoll(alphaConfidence, red)
sf.RecordUnsuccessfulPoll()

require.Equal(red, sb.Preference())
require.False(sb.Finalized())
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, red)
sf.RecordPoll(alphaConfidence, red)

sb.RecordUnsuccessfulPoll()
sf.RecordUnsuccessfulPoll()

require.Equal(red, sb.Preference())
require.False(sb.Finalized())
require.Equal(red, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
sf.RecordPoll(alphaConfidence, blue)

require.Equal(red, sb.Preference())
require.False(sb.Finalized())
require.Equal(blue, sf.Preference())
require.False(sf.Finalized())

sb.RecordPoll(alphaConfidence, blue)
sf.RecordPoll(alphaConfidence, blue)

require.Equal(blue, sb.Preference())
require.True(sb.Finalized())
require.Equal(blue, sf.Preference())
require.True(sf.Finalized())

expected := "SB(Preference = 1, PreferenceStrength[0] = 2, PreferenceStrength[1] = 2, SF(Confidence = [2], Finalized = true, SL(Preference = 0)))"
require.Equal(expected, sb.String())
expected := "SF(Confidence = [2], Finalized = true, SL(Preference = 0))"
require.Equal(expected, sf.String())
}

func TestBinarySnowballLockColor(t *testing.T) {
Expand Down
8 changes: 4 additions & 4 deletions snow/consensus/snowball/consensus_performance_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,10 +28,10 @@ func TestDualAlphaOptimization(t *testing.T) {
source = prng.NewMT19937()
)

singleAlphaNetwork := NewNetwork(SnowballFactory, params, numColors, source)
singleAlphaNetwork := NewNetwork(SnowflakeFactory, params, numColors, source)

params.AlphaPreference = params.K/2 + 1
dualAlphaNetwork := NewNetwork(SnowballFactory, params, numColors, source)
dualAlphaNetwork := NewNetwork(SnowflakeFactory, params, numColors, source)

source.Seed(seed)
for i := 0; i < numNodes; i++ {
Expand Down Expand Up @@ -61,8 +61,8 @@ func TestTreeConvergenceOptimization(t *testing.T) {
source = prng.NewMT19937()
)

treeNetwork := NewNetwork(SnowballFactory, params, numColors, source)
flatNetwork := NewNetwork(SnowballFactory, params, numColors, source)
treeNetwork := NewNetwork(SnowflakeFactory, params, numColors, source)
flatNetwork := NewNetwork(SnowflakeFactory, params, numColors, source)

source.Seed(seed)
for i := 0; i < numNodes; i++ {
Expand Down
2 changes: 1 addition & 1 deletion snow/consensus/snowball/consensus_reversibility_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ func TestSnowballGovernance(t *testing.T) {
source = prng.NewMT19937()
)

nBitwise := NewNetwork(SnowballFactory, params, numColors, source)
nBitwise := NewNetwork(SnowflakeFactory, params, numColors, source)

source.Seed(seed)
for i := 0; i < numRed; i++ {
Expand Down
6 changes: 3 additions & 3 deletions snow/consensus/snowball/flat_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ func TestFlat(t *testing.T) {
AlphaConfidence: 3,
Beta: 2,
}
f := NewFlat(SnowballFactory, params, Red)
f := NewFlat(SnowflakeFactory, params, Red)
f.Add(Green)
f.Add(Blue)

Expand All @@ -34,7 +34,7 @@ func TestFlat(t *testing.T) {

twoGreen := bag.Of(Green, Green)
require.True(f.RecordPoll(twoGreen))
require.Equal(Blue, f.Preference())
require.Equal(Green, f.Preference())
require.False(f.Finalized())

threeGreen := bag.Of(Green, Green, Green)
Expand All @@ -56,6 +56,6 @@ func TestFlat(t *testing.T) {
require.Equal(Green, f.Preference())
require.True(f.Finalized())

expected := "SB(Preference = 2mcwQKiD8VEspmMJpL1dc7okQQ5dDVAWeCBZ7FWBFAbxpv3t7w, PreferenceStrength = 4, SF(Confidence = [2], Finalized = true, SL(Preference = 2mcwQKiD8VEspmMJpL1dc7okQQ5dDVAWeCBZ7FWBFAbxpv3t7w)))"
expected := "SF(Confidence = [2], Finalized = true, SL(Preference = 2mcwQKiD8VEspmMJpL1dc7okQQ5dDVAWeCBZ7FWBFAbxpv3t7w))"
require.Equal(expected, f.String())
}
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