satellite/overlay: implement an exclude filter for placement configuration

https://github.com/storj/storj/issues/6126

Change-Id: I05215b5d46bec958001cc020edf1fa97b00d3299

satellite/nodeselection/filter.go

@@ -196,3 +196,22 @@ func (t TagFilter) MatchInclude(node *SelectedNode) bool {
 }
 
 var _ NodeFilter = TagFilter{}
+
+// ExcludeFilter excludes only the matched nodes.
+type ExcludeFilter struct {
+	matchToExclude NodeFilter
+}
+
+// MatchInclude implements NodeFilter interface.
+func (e ExcludeFilter) MatchInclude(node *SelectedNode) bool {
+	return !e.matchToExclude.MatchInclude(node)
+}
+
+// NewExcludeFilter creates filter, nodes matching the given filter will be excluded.
+func NewExcludeFilter(filter NodeFilter) ExcludeFilter {
+	return ExcludeFilter{
+		matchToExclude: filter,
+	}
+}
+
+var _ NodeFilter = ExcludeFilter{}

satellite/overlay/placement.go

@@ -126,6 +126,9 @@ func (d *ConfigurablePlacementRule) AddPlacementFromString(definitions string) e
 				key: value,
 			}, nil
 		},
+		"exclude": func(filter nodeselection.NodeFilter) (nodeselection.NodeFilter, error) {
+			return nodeselection.NewExcludeFilter(filter), nil
+		},
 	}
 	for _, definition := range strings.Split(definitions, ";") {
 		definition = strings.TrimSpace(definition)

satellite/overlay/placement_test.go

@@ -124,6 +124,18 @@ func TestPlacementFromString(t *testing.T) {
 		require.Equal(t, nodeselection.GetAnnotation(filters, "autoExcludeSubnet"), "off")
 
 	})
+	t.Run("exclude", func(t *testing.T) {
+		p := NewPlacementRules()
+		err := p.AddPlacementFromString(`11:exclude(country("GB"))`)
+		require.NoError(t, err)
+		filters := p.placements[storj.PlacementConstraint(11)]
+		require.False(t, filters.MatchInclude(&nodeselection.SelectedNode{
+			CountryCode: location.UnitedKingdom,
+		}))
+		require.True(t, filters.MatchInclude(&nodeselection.SelectedNode{
+			CountryCode: location.Germany,
+		}))
+	})
 
 	t.Run("legacy geofencing rules", func(t *testing.T) {
 		p := NewPlacementRules()