fix: FindVoteResult logic

Author: soonkuk

base/vote.go

@@ -1,9 +1,5 @@
 package base
 
-import (
-	"sort"
-)
-
 type VoteResult string
 
 const (
@@ -47,86 +43,74 @@ func (v *VoteResult) UnmarshalText(b []byte) error {
 	return nil
 }
 
-// FindMajority finds the majority(over threshold) set between the given sets.
-// The returned value means,
-// 0-N: index number of set
-// -1: not yet majority
-// -2: draw
-func FindMajority(quorum, threshold uint, set ...uint) int {
+func FindVoteResult(quorum, threshold uint, s []string) (result VoteResult, key string) {
 	th := threshold
 	if th > quorum {
 		th = quorum
 	}
-
-	if len(set) < 1 {
-		return -1
+	if len(s) == 0 {
+		return VoteResultNotYet, ""
 	}
 
-	var sum uint
-
-	for i := range set {
-		n := set[i]
-
-		if n >= quorum {
-			return i
-		}
+	count := make(map[string]uint, len(s))
+	for _, v := range s {
+		count[v]++
+	}
 
-		if n >= th {
-			return i
+	var (
+		maxCount       uint
+		secondMaxCount uint
+		topTies        uint
+		mhs            string
+	)
+
+	for hs, cn := range count {
+		switch {
+		case cn > maxCount:
+			secondMaxCount = maxCount
+			maxCount = cn
+			mhs = hs
+			topTies = 1
+		case cn == maxCount:
+			topTies++
+			if hs < mhs {
+				mhs = hs
+			}
+		case cn > secondMaxCount:
+			secondMaxCount = cn
 		}
-
-		sum += n
 	}
 
-	sort.Slice(set, func(i, j int) bool {
-		return set[i] > set[j]
-	})
-
-	if quorum-sum+set[0] < th {
-		return -2
+	total := uint(len(s))
+	var remain uint
+	if total >= quorum {
+		remain = 0
+	} else {
+		remain = quorum - total
 	}
 
-	return -1
-}
-
-func FindVoteResult(quorum, threshold uint, s []string) (result VoteResult, key string) {
-	th := threshold
-	if th > quorum {
-		th = quorum
+	if maxCount >= th {
+		return VoteResultMajority, mhs
 	}
 
-	if len(s) < 1 {
-		return VoteResultNotYet, ""
+	if remain == 0 {
+		return VoteResultDraw, ""
 	}
 
-	keys := map[uint]string{}
-	defer clear(keys)
-
-	count := map[string]uint{}
-	defer clear(count)
-
-	for i := range s {
-		count[s[i]]++
+	if topTies > 1 {
+		if maxCount+remain < th {
+			return VoteResultDraw, ""
+		}
+		return VoteResultNotYet, ""
 	}
 
-	set := make([]uint, len(count))
-	var i int
-
-	for j := range count {
-		c := count[j]
-		keys[c] = j
-		set[i] = c
-		i++
+	maxPossible := maxCount + remain
+	if maxPossible < th {
+		return VoteResultDraw, ""
 	}
-
-	sort.Slice(set, func(i, j int) bool { return set[i] > set[j] })
-
-	switch index := FindMajority(quorum, th, set...); index {
-	case -1:
-		return VoteResultNotYet, ""
-	case -2:
+	if secondMaxCount+remain <= maxCount && maxPossible <= th {
 		return VoteResultDraw, ""
-	default:
-		return VoteResultMajority, keys[set[index]]
 	}
+
+	return VoteResultNotYet, ""
 }