can break tie score

4 files changed, 125 insertions, 4 deletions

diff --git a/internal/config.go b/internal/config.go
index 17ec25b..21df3b9 100644
--- a/internal/config.go
+++ b/internal/config.go
@@ -2,6 +2,7 @@ package internal
 
 import (
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"log"
 	"net"
@@ -37,6 +38,16 @@ func newConfig(configFile string) (config, error) {
 	return config, nil
 }
 
+func (c config) participantNumber(participant string) (int, error) {
+	for i, participant_ := range c.Participants {
+		if participant == stripPort(participant_) {
+			return i, nil
+		}
+	}
+
+	return 0, fmt.Errorf("participant %s not found", participant)
+}
+
 func (c config) isParticipant(remoteAddr string) bool {
 	remoteAddr = stripPort(remoteAddr)
 
diff --git a/internal/config_test.go b/internal/config_test.go
index 67a9fff..d1974b5 100644
--- a/internal/config_test.go
+++ b/internal/config_test.go
@@ -12,6 +12,31 @@ func TestStripPort(t *testing.T) {
 	}
 }
 
+func TestParticipantNumber(t *testing.T) {
+	config := config{Participants: []string{"localhost:1234", "hamburger:4321"}}
+
+	num, err := config.participantNumber("localhost")
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	if num != 0 {
+		t.Errorf("localhost should be participant number 0 but is %d", num)
+	}
+
+	num, err = config.participantNumber("hamburger")
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	if num != 1 {
+		t.Errorf("hamburger should be participant number 1 but is %d", num)
+	}
+
+	_, err = config.participantNumber("doener")
+	if err == nil {
+		t.Errorf("doener is not a participant")
+	}
+}
+
 func TestIsParticipant(t *testing.T) {
 	config := config{Participants: []string{"localhost:1234", "hamburger:4321"}}
 
diff --git a/internal/quorum.go b/internal/quorum.go
index 964d465..032ebc8 100644
--- a/internal/quorum.go
+++ b/internal/quorum.go
@@ -17,7 +17,7 @@ func (q quorumMap) vote(v vote) {
 	q[v.from] = v
 }
 
-func (q quorumMap) score() (scores []score) {
+func (q quorumMap) score(config config) (scores []score) {
 	q.cleanExpired()
 	scoreMap := make(map[string]int)
 
@@ -33,7 +33,14 @@ func (q quorumMap) score() (scores []score) {
 	}
 
 	sort.Slice(scores, func(i, j int) bool {
-		return scores[i].score < scores[j].score
+		if scores[i].score != scores[j].score {
+			return scores[i].score > scores[j].score
+		}
+
+		// Score tie, use participant number.
+		i_, _ := config.participantNumber(scores[i].id)
+		j_, _ := config.participantNumber(scores[j].id)
+		return i_ < j_
 	})
 
 	return
diff --git a/internal/quorum_test.go b/internal/quorum_test.go
index 80c4598..da2abdd 100644
--- a/internal/quorum_test.go
+++ b/internal/quorum_test.go
@@ -5,15 +5,93 @@ import (
 	"time"
 )
 
+func TestScore(t *testing.T) {
+	quorum := make(quorumMap)
+	config := config{Participants: []string{"foo:1234", "bar:4321", "baz:3444"}}
+
+	vote1 := newVote(config, "foo:334234", "foo bar\n")
+	vote1.expiresAt = time.Now().Add(1 * time.Hour)
+	quorum.vote(vote1)
+
+	vote2 := newVote(config, "bar:334234", "bar baz\n")
+	vote2.expiresAt = time.Now().Add(1 * time.Hour)
+	quorum.vote(vote2)
+
+	vote3_dup := newVote(config, "bar:33234", "bar baz\n")
+	vote3_dup.expiresAt = time.Now().Add(1 * time.Hour)
+	quorum.vote(vote3_dup)
+
+	vote4 := newVote(config, "baz:334234", "foo bar baz\n")
+	vote4.expiresAt = time.Now().Add(1 * time.Hour)
+	quorum.vote(vote4)
+
+	scores := quorum.score(config)
+	if len(scores) != 3 {
+		t.Errorf("Expected scores to be of length 3: %v", scores)
+	}
+
+	if scores[0].id != "bar" || scores[0].score != 3 {
+		t.Errorf("Expected score[0] to be {bar,3}: %v", scores[0])
+	}
+}
+
+func TestTieScore(t *testing.T) {
+	addVotes := func(config config, quorum quorumMap) {
+		vote1 := newVote(config, "foo:334234", "foo bar baz\n")
+		vote1.expiresAt = time.Now().Add(1 * time.Hour)
+		quorum.vote(vote1)
+
+		vote2 := newVote(config, "bar:334234", "foo bar baz\n")
+		vote2.expiresAt = time.Now().Add(1 * time.Hour)
+		quorum.vote(vote2)
+
+		vote3 := newVote(config, "baz:334234", "foo bar baz\n")
+		vote3.expiresAt = time.Now().Add(1 * time.Hour)
+		quorum.vote(vote3)
+	}
+
+	t.Run("First tie score test", func(t *testing.T) {
+		quorum := make(quorumMap)
+		// If it is a tie, the first particpant (here: "foo") will win.
+		config := config{Participants: []string{"foo:1234", "bar:4321", "baz:3444"}}
+
+		addVotes(config, quorum)
+		scores := quorum.score(config)
+
+		if len(scores) != 3 {
+			t.Errorf("Expected scores to be of length 3: %v", scores)
+		}
+		if scores[0].id != "foo" || scores[0].score != 3 {
+			t.Errorf("Expected score[0] to be {foo,3}: %v", scores[0])
+		}
+	})
+
+	t.Run("Second tie score test", func(t *testing.T) {
+		quorum := make(quorumMap)
+		// If it is a tie, the first particpant (here: "bar") will win.
+		config := config{Participants: []string{"bar:1234", "foo:4321", "baz:3444"}}
+
+		addVotes(config, quorum)
+		scores := quorum.score(config)
+
+		if len(scores) != 3 {
+			t.Errorf("Expected scores to be of length 3: %v", scores)
+		}
+		if scores[0].id != "bar" || scores[0].score != 3 {
+			t.Errorf("Expected score[0] to be {bar,3}: %v", scores[0])
+		}
+	})
+}
+
 func TestCleanExpired(t *testing.T) {
 	quorum := make(quorumMap)
 	config := config{Participants: []string{"foo:1234", "bay:4321"}}
 
-	vote1 := newVote(config, "earth:334234", " foo bar baz bay\n")
+	vote1 := newVote(config, "foo:334234", " foo bar baz bay\n")
 	vote1.expiresAt = time.Now().Add(1 * time.Hour)
 	quorum.vote(vote1)
 
-	vote2 := newVote(config, "bay:334234", " foo bar baz bay\n")
+	vote2 := newVote(config, "bar:334234", " foo bar baz bay\n")
 	vote2.expiresAt = time.Now()
 	quorum.vote(vote2)