selector: add filters to replace depricated client/selector filters (#1785)

selector/options.go

@@ -0,0 +1,41 @@
+package selector
+
+import "github.com/micro/go-micro/v2/router"
+
+// Options used to configure a selector
+type Options struct{}
+
+// Option updates the options
+type Option func(*Options)
+
+// Filter the routes
+type Filter func([]router.Route) []router.Route
+
+// SelectOptions used to configure selection
+type SelectOptions struct {
+	Filters []Filter
+}
+
+// SelectOption updates the select options
+type SelectOption func(*SelectOptions)
+
+// WithFilter adds a filter to the options
+func WithFilter(f Filter) SelectOption {
+	return func(o *SelectOptions) {
+		o.Filters = append(o.Filters, f)
+	}
+}
+
+// NewSelectOptions parses select options
+func NewSelectOptions(opts ...SelectOption) SelectOptions {
+	var options SelectOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	if options.Filters == nil {
+		options.Filters = make([]Filter, 0)
+	}
+
+	return options
+}

selector/random.go

@@ -16,7 +16,15 @@ func (r *random) Options() Options {
 	return Options{}
 }
 
-func (r *random) Select(routes []router.Route) (*router.Route, error) {
+func (r *random) Select(routes []router.Route, opts ...SelectOption) (*router.Route, error) {
+	// parse the options
+	options := NewSelectOptions(opts...)
+
+	// apply the filters
+	for _, f := range options.Filters {
+		routes = f(routes)
+	}
+
 	// we can't select from an empty pool of routes
 	if len(routes) == 0 {
 		return nil, ErrNoneAvailable

selector/roundrobin/roundrobin.go

@@ -38,7 +38,15 @@ func (r *roundrobin) Options() selector.Options {
 	return selector.Options{}
 }
 
-func (r *roundrobin) Select(routes []router.Route) (*router.Route, error) {
+func (r *roundrobin) Select(routes []router.Route, opts ...selector.SelectOption) (*router.Route, error) {
+	// parse the options
+	options := selector.NewSelectOptions(opts...)
+
+	// apply the filters
+	for _, f := range options.Filters {
+		routes = f(routes)
+	}
+
 	if len(routes) == 0 {
 		return nil, selector.ErrNoneAvailable
 	}

selector/selector.go

@@ -21,7 +21,7 @@ type Selector interface {
 	// Options the selector is using
 	Options() Options
 	// Select a route from the pool using the strategy
-	Select([]router.Route) (*router.Route, error)
+	Select([]router.Route, ...SelectOption) (*router.Route, error)
 	// Record the error returned from a route to inform future selection
 	Record(router.Route, error) error
 	// Close the selector
@@ -30,12 +30,6 @@ type Selector interface {
 	String() string
 }
 
-// Options used to configure a selector
-type Options struct{}
-
-// Option updates the options
-type Option func(*Options)
-
 // NewSelector creates new selector and returns it
 func NewSelector(opts ...Option) Selector {
 	return newSelector(opts...)

selector/tests.go

@@ -32,6 +32,18 @@ func Tests(t *testing.T, s Selector) {
 				t.Errorf("Expected the route to be one of the inputs")
 			}
 		})
+
+		t.Run("Filters", func(t *testing.T) {
+			var filterApplied bool
+			filter := func(rts []router.Route) []router.Route {
+				filterApplied = true
+				return rts
+			}
+
+			_, err := s.Select([]router.Route{r1, r2}, WithFilter(filter))
+			assert.Nil(t, err, "Error should be nil")
+			assert.True(t, filterApplied, "Filters should be applied")
+		})
 	})
 
 	t.Run("Record", func(t *testing.T) {