feat: scheduler (2/): add ClusterScore related structs, etc.

pkg/scheduler/framework/score.go

@@ -0,0 +1,57 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package framework
+
+import (
+	fleetv1 "go.goms.io/fleet/apis/v1"
+)
+
+// ClusterScore is the scores the scheduler assigns to a cluster.
+type ClusterScore struct {
+	// TopologySpreadScore determines how much a binding would satisfy the topology spread
+	// constraints specified by the user.
+	TopologySpreadScore int
+	// AffinityScore determines how much a binding would satisfy the affinity terms
+	// specified by the user.
+	AffinityScore int
+}
+
+// Add adds a ClusterScore to another ClusterScore.
+func (s1 *ClusterScore) Add(s2 ClusterScore) {
+	s1.TopologySpreadScore += s2.TopologySpreadScore
+	s1.AffinityScore += s2.AffinityScore
+}
+
+// Less returns true if a ClusterScore is less than another.
+func (s1 *ClusterScore) Less(s2 *ClusterScore) bool {
+	if s1.TopologySpreadScore != s2.TopologySpreadScore {
+		return s1.TopologySpreadScore < s2.TopologySpreadScore
+	}
+
+	return s1.AffinityScore < s2.AffinityScore
+}
+
+// ScoredCluster is a cluster with a score.
+type ScoredCluster struct {
+	Cluster *fleetv1.MemberCluster
+	Score   *ClusterScore
+}
+
+// ScoredClusters is a list of ScoredClusters; this type implements the sort.Interface.
+type ScoredClusters []*ScoredCluster
+
+// Len returns the length of a ScoredClusters; it implemented sort.Interface.Len().
+func (sc ScoredClusters) Len() int { return len(sc) }
+
+// Less returns true if a ScoredCluster is of a lower score than another; it implemented sort.Interface.Less().
+func (sc ScoredClusters) Less(i, j int) bool {
+	return sc[i].Score.Less(sc[j].Score)
+}
+
+// Swap swaps two ScoredClusters in the list; it implemented sort.Interface.Swap().
+func (sc ScoredClusters) Swap(i, j int) {
+	sc[i], sc[j] = sc[j], sc[i]
+}

pkg/scheduler/framework/score_test.go

@@ -0,0 +1,310 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package framework
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+
+	fleetv1 "go.goms.io/fleet/apis/v1"
+)
+
+func TestClusterScoreAdd(t *testing.T) {
+	s1 := &ClusterScore{
+		TopologySpreadScore: 0,
+		AffinityScore:       0,
+	}
+
+	s2 := &ClusterScore{
+		TopologySpreadScore: 1,
+		AffinityScore:       5,
+	}
+
+	s1.Add(*s2)
+	want := &ClusterScore{
+		TopologySpreadScore: 1,
+		AffinityScore:       5,
+	}
+	if !cmp.Equal(s1, want) {
+		t.Fatalf("Add() = %v, want %v", s1, want)
+	}
+}
+
+func TestClusterScoreLess(t *testing.T) {
+	testCases := []struct {
+		name string
+		s1   *ClusterScore
+		s2   *ClusterScore
+		want bool
+	}{
+		{
+			name: "s1 is less than s2 in topology spread score",
+			s1: &ClusterScore{
+				TopologySpreadScore: 0,
+				AffinityScore:       10,
+			},
+			s2: &ClusterScore{
+				TopologySpreadScore: 1,
+				AffinityScore:       20,
+			},
+			want: true,
+		},
+		{
+			name: "s1 is less than s2 in affinity score",
+			s1: &ClusterScore{
+				TopologySpreadScore: 1,
+				AffinityScore:       10,
+			},
+			s2: &ClusterScore{
+				TopologySpreadScore: 1,
+				AffinityScore:       20,
+			},
+			want: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			if tc.s1.Less(tc.s2) != tc.want {
+				t.Fatalf("Less(%v, %v) = %t, want %t", tc.s1, tc.s2, !tc.want, tc.want)
+			}
+
+			if tc.s2.Less(tc.s1) != !tc.want {
+				t.Fatalf("Less(%v, %v) = %t, want %t", tc.s2, tc.s1, tc.want, !tc.want)
+			}
+		})
+	}
+}
+
+func TestClusterScoreEqual(t *testing.T) {
+	s1 := &ClusterScore{
+		TopologySpreadScore: 0,
+		AffinityScore:       0,
+	}
+
+	s2 := &ClusterScore{
+		TopologySpreadScore: 0,
+		AffinityScore:       0,
+	}
+
+	if s1.Less(s2) || s2.Less(s1) {
+		t.Fatalf("Less(%v, %v) = %v, Less(%v, %v) = %v, want both to be false", s1, s2, s1.Less(s2), s2, s1, s2.Less(s1))
+	}
+}
+
+func TestScoredClustersSort(t *testing.T) {
+	clusterA := &fleetv1.MemberCluster{}
+	clusterB := &fleetv1.MemberCluster{}
+	clusterC := &fleetv1.MemberCluster{}
+	clusterD := &fleetv1.MemberCluster{}
+
+	testCases := []struct {
+		name string
+		scs  ScoredClusters
+		want ScoredClusters
+	}{
+		{
+			name: "sort asc values",
+			scs: ScoredClusters{
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+			},
+			want: ScoredClusters{
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+			},
+		},
+		{
+			name: "sort desc values",
+			scs: ScoredClusters{
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+			},
+			want: ScoredClusters{
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+			},
+		},
+		{
+			name: "sort values in random",
+			scs: ScoredClusters{
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+			},
+			want: ScoredClusters{
+				{
+					Cluster: clusterD,
+					Score: &ClusterScore{
+						TopologySpreadScore: 2,
+						AffinityScore:       30,
+					},
+				},
+				{
+					Cluster: clusterC,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       20,
+					},
+				},
+				{
+					Cluster: clusterB,
+					Score: &ClusterScore{
+						TopologySpreadScore: 1,
+						AffinityScore:       10,
+					},
+				},
+				{
+					Cluster: clusterA,
+					Score: &ClusterScore{
+						TopologySpreadScore: 0,
+						AffinityScore:       10,
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			sort.Sort(sort.Reverse(tc.scs))
+			if !cmp.Equal(tc.scs, tc.want) {
+				t.Fatalf("Sort() = %v, want %v", tc.scs, tc.want)
+			}
+		})
+	}
+}