time: make median time library type private (#6853)

This is a very minor change, but I was looking through the code, and
this seems like it shouldn't be exported or used more broadly, so I've
moved it out.

libs/time/time.go

@@ -1,7 +1,6 @@
 package time
 
 import (
-	"sort"
 	"time"
 )
 
@@ -16,43 +15,3 @@ func Now() time.Time {
 func Canonical(t time.Time) time.Time {
 	return t.Round(0).UTC()
 }
-
-// WeightedTime for computing a median.
-type WeightedTime struct {
-	Time   time.Time
-	Weight int64
-}
-
-// NewWeightedTime with time and weight.
-func NewWeightedTime(time time.Time, weight int64) *WeightedTime {
-	return &WeightedTime{
-		Time:   time,
-		Weight: weight,
-	}
-}
-
-// WeightedMedian computes weighted median time for a given array of WeightedTime and the total voting power.
-func WeightedMedian(weightedTimes []*WeightedTime, totalVotingPower int64) (res time.Time) {
-	median := totalVotingPower / 2
-
-	sort.Slice(weightedTimes, func(i, j int) bool {
-		if weightedTimes[i] == nil {
-			return false
-		}
-		if weightedTimes[j] == nil {
-			return true
-		}
-		return weightedTimes[i].Time.UnixNano() < weightedTimes[j].Time.UnixNano()
-	})
-
-	for _, weightedTime := range weightedTimes {
-		if weightedTime != nil {
-			if median <= weightedTime.Weight {
-				res = weightedTime.Time
-				break
-			}
-			median -= weightedTime.Weight
-		}
-	}
-	return
-}

state/state.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 
-	tmtime "github.com/tendermint/tendermint/libs/time"
 	tmstate "github.com/tendermint/tendermint/proto/tendermint/state"
 	tmversion "github.com/tendermint/tendermint/proto/tendermint/version"
 	"github.com/tendermint/tendermint/types"
@@ -287,7 +286,7 @@ func (state State) MakeBlock(
 // the votes sent by honest processes, i.e., a faulty processes can not arbitrarily increase or decrease the
 // computed value.
 func MedianTime(commit *types.Commit, validators *types.ValidatorSet) time.Time {
-	weightedTimes := make([]*tmtime.WeightedTime, len(commit.Signatures))
+	weightedTimes := make([]*weightedTime, len(commit.Signatures))
 	totalVotingPower := int64(0)
 
 	for i, commitSig := range commit.Signatures {
@@ -298,11 +297,11 @@ func MedianTime(commit *types.Commit, validators *types.ValidatorSet) time.Time
 		// If there's no condition, TestValidateBlockCommit panics; not needed normally.
 		if validator != nil {
 			totalVotingPower += validator.VotingPower
-			weightedTimes[i] = tmtime.NewWeightedTime(commitSig.Timestamp, validator.VotingPower)
+			weightedTimes[i] = newWeightedTime(commitSig.Timestamp, validator.VotingPower)
 		}
 	}
 
-	return tmtime.WeightedMedian(weightedTimes, totalVotingPower)
+	return weightedMedian(weightedTimes, totalVotingPower)
 }
 
 //------------------------------------------------------------------------

state/time.go

@@ -0,0 +1,46 @@
+package state
+
+import (
+	"sort"
+	"time"
+)
+
+// weightedTime for computing a median.
+type weightedTime struct {
+	Time   time.Time
+	Weight int64
+}
+
+// newWeightedTime with time and weight.
+func newWeightedTime(time time.Time, weight int64) *weightedTime {
+	return &weightedTime{
+		Time:   time,
+		Weight: weight,
+	}
+}
+
+// weightedMedian computes weighted median time for a given array of WeightedTime and the total voting power.
+func weightedMedian(weightedTimes []*weightedTime, totalVotingPower int64) (res time.Time) {
+	median := totalVotingPower / 2
+
+	sort.Slice(weightedTimes, func(i, j int) bool {
+		if weightedTimes[i] == nil {
+			return false
+		}
+		if weightedTimes[j] == nil {
+			return true
+		}
+		return weightedTimes[i].Time.UnixNano() < weightedTimes[j].Time.UnixNano()
+	})
+
+	for _, weightedTime := range weightedTimes {
+		if weightedTime != nil {
+			if median <= weightedTime.Weight {
+				res = weightedTime.Time
+				break
+			}
+			median -= weightedTime.Weight
+		}
+	}
+	return
+}

state/time_test.go

@@ -1,54 +1,55 @@
-package time
+package state
 
 import (
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	tmtime "github.com/tendermint/tendermint/libs/time"
 )
 
 func TestWeightedMedian(t *testing.T) {
-	m := make([]*WeightedTime, 3)
+	m := make([]*weightedTime, 3)
 
-	t1 := Now()
+	t1 := tmtime.Now()
 	t2 := t1.Add(5 * time.Second)
 	t3 := t1.Add(10 * time.Second)
 
-	m[2] = NewWeightedTime(t1, 33) // faulty processes
-	m[0] = NewWeightedTime(t2, 40) // correct processes
-	m[1] = NewWeightedTime(t3, 27) // correct processes
+	m[2] = newWeightedTime(t1, 33) // faulty processes
+	m[0] = newWeightedTime(t2, 40) // correct processes
+	m[1] = newWeightedTime(t3, 27) // correct processes
 	totalVotingPower := int64(100)
 
-	median := WeightedMedian(m, totalVotingPower)
+	median := weightedMedian(m, totalVotingPower)
 	assert.Equal(t, t2, median)
 	// median always returns value between values of correct processes
 	assert.Equal(t, true, (median.After(t1) || median.Equal(t1)) &&
 		(median.Before(t3) || median.Equal(t3)))
 
-	m[1] = NewWeightedTime(t1, 40) // correct processes
-	m[2] = NewWeightedTime(t2, 27) // correct processes
-	m[0] = NewWeightedTime(t3, 33) // faulty processes
+	m[1] = newWeightedTime(t1, 40) // correct processes
+	m[2] = newWeightedTime(t2, 27) // correct processes
+	m[0] = newWeightedTime(t3, 33) // faulty processes
 	totalVotingPower = int64(100)
 
-	median = WeightedMedian(m, totalVotingPower)
+	median = weightedMedian(m, totalVotingPower)
 	assert.Equal(t, t2, median)
 	// median always returns value between values of correct processes
 	assert.Equal(t, true, (median.After(t1) || median.Equal(t1)) &&
 		(median.Before(t2) || median.Equal(t2)))
 
-	m = make([]*WeightedTime, 8)
+	m = make([]*weightedTime, 8)
 	t4 := t1.Add(15 * time.Second)
 	t5 := t1.Add(60 * time.Second)
 
-	m[3] = NewWeightedTime(t1, 10) // correct processes
-	m[1] = NewWeightedTime(t2, 10) // correct processes
-	m[5] = NewWeightedTime(t2, 10) // correct processes
-	m[4] = NewWeightedTime(t3, 23) // faulty processes
-	m[0] = NewWeightedTime(t4, 20) // correct processes
-	m[7] = NewWeightedTime(t5, 10) // faulty processes
+	m[3] = newWeightedTime(t1, 10) // correct processes
+	m[1] = newWeightedTime(t2, 10) // correct processes
+	m[5] = newWeightedTime(t2, 10) // correct processes
+	m[4] = newWeightedTime(t3, 23) // faulty processes
+	m[0] = newWeightedTime(t4, 20) // correct processes
+	m[7] = newWeightedTime(t5, 10) // faulty processes
 	totalVotingPower = int64(83)
 
-	median = WeightedMedian(m, totalVotingPower)
+	median = weightedMedian(m, totalVotingPower)
 	assert.Equal(t, t3, median)
 	// median always returns value between values of correct processes
 	assert.Equal(t, true, (median.After(t1) || median.Equal(t1)) &&