Add IsNarrowerThan() function to socketmask abstraction

pkg/kubelet/cm/topologymanager/socketmask/socketmask.go

@@ -31,6 +31,7 @@ type SocketMask interface {
 	IsEqual(mask SocketMask) bool
 	IsEmpty() bool
 	IsSet(socket int) bool
+	IsNarrowerThan(mask SocketMask) bool
 	String() string
 	Count() int
 	GetSockets() []int
@@ -116,6 +117,20 @@ func (s *socketMask) IsEqual(mask SocketMask) bool {
 	return *s == *mask.(*socketMask)
 }
 
+// IsNarrowerThan checks if one mask is narrower than another.
+//
+// A mask is said to be "narrower" than another if it has lets bits set. If the
+// same number of bits are set in both masks, then the mask with more
+// lower-numbered bits set wins out.
+func (s *socketMask) IsNarrowerThan(mask SocketMask) bool {
+	if s.Count() == mask.Count() {
+		if *s < *mask.(*socketMask) {
+			return true
+		}
+	}
+	return s.Count() < mask.Count()
+}
+
 //String converts mask to string
 func (s *socketMask) String() string {
 	str := ""

pkg/kubelet/cm/topologymanager/socketmask/socketmask_test.go

@@ -288,3 +288,45 @@ func TestGetSockets(t *testing.T) {
 		}
 	}
 }
+
+func TestIsNarrowerThan(t *testing.T) {
+	tcases := []struct {
+		name                  string
+		firstMask             []int
+		secondMask            []int
+		expectedFirstNarrower bool
+	}{
+		{
+			name:                  "Check narrowness of masks with unequal bits set 1/2",
+			firstMask:             []int{0},
+			secondMask:            []int{0, 1},
+			expectedFirstNarrower: true,
+		},
+		{
+			name:                  "Check narrowness of masks with unequal bits set 2/2",
+			firstMask:             []int{0, 1},
+			secondMask:            []int{0},
+			expectedFirstNarrower: false,
+		},
+		{
+			name:                  "Check narrowness of masks with equal bits set 1/2",
+			firstMask:             []int{0},
+			secondMask:            []int{1},
+			expectedFirstNarrower: true,
+		},
+		{
+			name:                  "Check narrowness of masks with equal bits set 2/2",
+			firstMask:             []int{1},
+			secondMask:            []int{0},
+			expectedFirstNarrower: false,
+		},
+	}
+	for _, tc := range tcases {
+		firstMask, _ := NewSocketMask(tc.firstMask...)
+		secondMask, _ := NewSocketMask(tc.secondMask...)
+		expectedFirstNarrower := firstMask.IsNarrowerThan(secondMask)
+		if expectedFirstNarrower != tc.expectedFirstNarrower {
+			t.Errorf("Expected value to be %v, got %v", tc.expectedFirstNarrower, expectedFirstNarrower)
+		}
+	}
+}