Replace snowball/snowflake interface with single shared snow interface (#2717)

Signed-off-by: aaronbuchwald <aaron.buchwald56@gmail.com>
Signed-off-by: Stephen Buttolph <stephen@avalabs.org>
Co-authored-by: Stephen Buttolph <stephen@avalabs.org>

Author: aaronbuchwald

snow/consensus/snowball/binary_slush.go

@@ -5,8 +5,6 @@ package snowball
 
 import "fmt"
 
-var _ BinarySlush = (*binarySlush)(nil)
-
 func newBinarySlush(choice int) binarySlush {
 	return binarySlush{
 		preference: choice,

snow/consensus/snowball/binary_snowball.go

@@ -5,7 +5,7 @@ package snowball
 
 import "fmt"
 
-var _ BinarySnowball = (*binarySnowball)(nil)
+var _ Binary = (*binarySnowball)(nil)
 
 func newBinarySnowball(beta, choice int) binarySnowball {
 	return binarySnowball{

snow/consensus/snowball/binary_snowflake.go

@@ -5,7 +5,7 @@ package snowball
 
 import "fmt"
 
-var _ BinarySnowflake = (*binarySnowflake)(nil)
+var _ Binary = (*binarySnowflake)(nil)
 
 func newBinarySnowflake(beta, choice int) binarySnowflake {
 	return binarySnowflake{

snow/consensus/snowball/consensus.go

@@ -40,15 +40,18 @@ type Consensus interface {
 	Finalized() bool
 }
 
-// NnarySnowball augments NnarySnowflake with a counter that tracks the total
-// number of positive responses from a network sample.
-type NnarySnowball interface{ NnarySnowflake }
-
-// NnarySnowflake is a snowflake instance deciding between an unbounded number
-// of values. After performing a network sample of k nodes, if you have alpha
-// votes for one of the choices, you should vote for that choice. Otherwise, you
-// should reset.
-type NnarySnowflake interface {
+// Factory produces Nnary and Unary decision instances
+type Factory interface {
+	NewNnary(params Parameters, choice ids.ID) Nnary
+	NewUnary(params Parameters) Unary
+}
+
+// Nnary is a snow instance deciding between an unbounded number of values.
+// The caller samples k nodes and then calls
+// 1. RecordSuccessfulPoll if choice collects >= alphaConfidence votes
+// 2. RecordPollPreference if choice collects >= alphaPreference votes
+// 3. RecordUnsuccessfulPoll otherwise
+type Nnary interface {
 	fmt.Stringer
 
 	// Adds a new possible choice
@@ -73,29 +76,12 @@ type NnarySnowflake interface {
 	Finalized() bool
 }
 
-// NnarySlush is a slush instance deciding between an unbounded number of
-// values. After performing a network sample of k nodes, if you have alpha
-// votes for one of the choices, you should vote for that choice.
-type NnarySlush interface {
-	fmt.Stringer
-
-	// Returns the currently preferred choice to be finalized
-	Preference() ids.ID
-
-	// RecordSuccessfulPoll records a successful poll towards finalizing the
-	// specified choice. Assumes the choice was previously added.
-	RecordSuccessfulPoll(choice ids.ID)
-}
-
-// BinarySnowball augments BinarySnowflake with a counter that tracks the total
-// number of positive responses from a network sample.
-type BinarySnowball interface{ BinarySnowflake }
-
-// BinarySnowflake is a snowball instance deciding between two values
-// After performing a network sample of k nodes, if you have alpha votes for
-// one of the choices, you should vote for that choice. Otherwise, you should
-// reset.
-type BinarySnowflake interface {
+// Binary is a snow instance deciding between two values.
+// The caller samples k nodes and then calls
+// 1. RecordSuccessfulPoll if choice collects >= alphaConfidence votes
+// 2. RecordPollPreference if choice collects >= alphaPreference votes
+// 3. RecordUnsuccessfulPoll otherwise
+type Binary interface {
 	fmt.Stringer
 
 	// Returns the currently preferred choice to be finalized
@@ -116,31 +102,20 @@ type BinarySnowflake interface {
 	Finalized() bool
 }
 
-// BinarySlush is a slush instance deciding between two values. After performing
-// a network sample of k nodes, if you have alpha votes for one of the choices,
-// you should vote for that choice.
-type BinarySlush interface {
-	fmt.Stringer
-
-	// Returns the currently preferred choice to be finalized
-	Preference() int
-
-	// RecordSuccessfulPoll records a successful poll towards finalizing the
-	// specified choice
-	RecordSuccessfulPoll(choice int)
-}
-
-// UnarySnowball is a snowball instance deciding on one value. After performing
-// a network sample of k nodes, if you have alpha votes for the choice, you
-// should vote. Otherwise, you should reset.
-type UnarySnowball interface {
+// Unary is a snow instance deciding on one value.
+// The caller samples k nodes and then calls
+// 1. RecordSuccessfulPoll if choice collects >= alphaConfidence votes
+// 2. RecordPollPreference if choice collects >= alphaPreference votes
+// 3. RecordUnsuccessfulPoll otherwise
+type Unary interface {
 	fmt.Stringer
 
-	// RecordSuccessfulPoll records a successful poll towards finalizing
+	// RecordSuccessfulPoll records a successful poll that reaches an alpha
+	// confidence threshold.
 	RecordSuccessfulPoll()
 
-	// RecordPollPreference records a poll that strengthens the preference but
-	// did not contribute towards finalizing
+	// RecordPollPreference records a poll that receives an alpha preference
+	// threshold, but not an alpha confidence threshold.
 	RecordPollPreference()
 
 	// RecordUnsuccessfulPoll resets the snowflake counter of this instance
@@ -151,31 +126,8 @@ type UnarySnowball interface {
 
 	// Returns a new binary snowball instance with the agreement parameters
 	// transferred. Takes in the new beta value and the original choice
-	Extend(beta, originalPreference int) BinarySnowball
-
-	// Returns a new unary snowball instance with the same state
-	Clone() UnarySnowball
-}
-
-// UnarySnowflake is a snowflake instance deciding on one value. After
-// performing a network sample of k nodes, if you have alpha votes for the
-// choice, you should vote. Otherwise, you should reset.
-type UnarySnowflake interface {
-	fmt.Stringer
-
-	// RecordSuccessfulPoll records a successful poll towards finalizing
-	RecordSuccessfulPoll()
-
-	// RecordUnsuccessfulPoll resets the snowflake counter of this instance
-	RecordUnsuccessfulPoll()
-
-	// Return whether a choice has been finalized
-	Finalized() bool
-
-	// Returns a new binary snowball instance with the agreement parameters
-	// transferred. Takes in the new beta value and the original choice
-	Extend(beta, originalPreference int) BinarySnowflake
+	Extend(beta, originalPreference int) Binary
 
 	// Returns a new unary snowflake instance with the same state
-	Clone() UnarySnowflake
+	Clone() Unary
 }

snow/consensus/snowball/consensus_performance_test.go

@@ -29,10 +29,10 @@ func TestDualAlphaOptimization(t *testing.T) {
 		source        = prng.NewMT19937()
 	)
 
-	singleAlphaNetwork := NewNetwork(params, numColors, source)
+	singleAlphaNetwork := NewNetwork(SnowballFactory, params, numColors, source)
 
 	params.AlphaPreference = params.K/2 + 1
-	dualAlphaNetwork := NewNetwork(params, numColors, source)
+	dualAlphaNetwork := NewNetwork(SnowballFactory, params, numColors, source)
 
 	source.Seed(seed)
 	for i := 0; i < numNodes; i++ {
@@ -62,8 +62,8 @@ func TestTreeConvergenceOptimization(t *testing.T) {
 		source           = prng.NewMT19937()
 	)
 
-	treeNetwork := NewNetwork(params, numColors, source)
-	flatNetwork := NewNetwork(params, numColors, source)
+	treeNetwork := NewNetwork(SnowballFactory, params, numColors, source)
+	flatNetwork := NewNetwork(SnowballFactory, params, numColors, source)
 
 	source.Seed(seed)
 	for i := 0; i < numNodes; i++ {

snow/consensus/snowball/consensus_reversibility_test.go

@@ -23,7 +23,7 @@ func TestSnowballGovernance(t *testing.T) {
 		source              = prng.NewMT19937()
 	)
 
-	nBitwise := NewNetwork(params, numColors, source)
+	nBitwise := NewNetwork(SnowballFactory, params, numColors, source)
 
 	source.Seed(seed)
 	for i := 0; i < numRed; i++ {

snow/consensus/snowball/consensus_test.go

@@ -16,7 +16,7 @@ var (
 	_ Consensus = (*Byzantine)(nil)
 )
 
-func NewByzantine(_ Parameters, choice ids.ID) Consensus {
+func NewByzantine(_ Factory, _ Parameters, choice ids.ID) Consensus {
 	return &Byzantine{
 		preference: choice,
 	}

snow/consensus/snowball/factory.go

@@ -0,0 +1,35 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package snowball
+
+import "github.com/ava-labs/avalanchego/ids"
+
+var (
+	SnowballFactory  Factory = snowballFactory{}
+	SnowflakeFactory Factory = snowflakeFactory{}
+)
+
+type snowballFactory struct{}
+
+func (snowballFactory) NewNnary(params Parameters, choice ids.ID) Nnary {
+	sb := newNnarySnowball(params.BetaVirtuous, params.BetaRogue, choice)
+	return &sb
+}
+
+func (snowballFactory) NewUnary(params Parameters) Unary {
+	sb := newUnarySnowball(params.BetaVirtuous)
+	return &sb
+}
+
+type snowflakeFactory struct{}
+
+func (snowflakeFactory) NewNnary(params Parameters, choice ids.ID) Nnary {
+	sf := newNnarySnowflake(params.BetaVirtuous, params.BetaRogue, choice)
+	return &sf
+}
+
+func (snowflakeFactory) NewUnary(params Parameters) Unary {
+	sf := newUnarySnowflake(params.BetaVirtuous)
+	return &sf
+}

snow/consensus/snowball/flat.go

@@ -10,19 +10,19 @@ import (
 
 var _ Consensus = (*Flat)(nil)
 
-func NewFlat(params Parameters, choice ids.ID) Consensus {
+func NewFlat(factory Factory, params Parameters, choice ids.ID) Consensus {
 	return &Flat{
-		nnarySnowball: newNnarySnowball(params.BetaVirtuous, params.BetaRogue, choice),
-		params:        params,
+		Nnary:  factory.NewNnary(params, choice),
+		params: params,
 	}
 }
 
-// Flat is a naive implementation of a multi-choice snowball instance
+// Flat is a naive implementation of a multi-choice snow instance
 type Flat struct {
-	// wraps the n-nary snowball logic
-	nnarySnowball
+	// wraps the n-nary snow logic
+	Nnary
 
-	// params contains all the configurations of a snowball instance
+	// params contains all the configurations of a snow instance
 	params Parameters
 }
 

snow/consensus/snowball/flat_test.go

@@ -21,7 +21,7 @@ func TestFlat(t *testing.T) {
 		BetaVirtuous:    1,
 		BetaRogue:       2,
 	}
-	f := NewFlat(params, Red)
+	f := NewFlat(SnowballFactory, params, Red)
 	f.Add(Green)
 	f.Add(Blue)