fix global selector bug (#1564)

selector/balancer.go

@@ -10,6 +10,11 @@ type Balancer interface {
 	Pick(ctx context.Context, nodes []WeightedNode) (selected WeightedNode, done DoneFunc, err error)
 }
 
+// BalancerBuilder build balancer
+type BalancerBuilder interface {
+	Build() Balancer
+}
+
 // WeightedNode calculates scheduling weight in real time
 type WeightedNode interface {
 	Node

selector/default.go

@@ -52,3 +52,19 @@ func (d *Default) Apply(nodes []Node) {
 	d.weightedNodes = weightedNodes
 	d.lk.Unlock()
 }
+
+// DefaultBuilder is de
+type DefaultBuilder struct {
+	Node     WeightedNodeBuilder
+	Balancer BalancerBuilder
+	Filters  []Filter
+}
+
+// Build create builder
+func (db *DefaultBuilder) Build() Selector {
+	return &Default{
+		NodeBuilder: db.Node,
+		Balancer:    db.Balancer.Build(),
+		Filters:     db.Filters,
+	}
+}

selector/p2c/p2c.go

@@ -35,17 +35,7 @@ type options struct {
 
 // New creates a p2c selector.
 func New(opts ...Option) selector.Selector {
-	var option options
-	for _, opt := range opts {
-		opt(&option)
-	}
-	return &selector.Default{
-		NodeBuilder: &ewma.Builder{},
-		Balancer: &Balancer{
-			r: rand.New(rand.NewSource(time.Now().UnixNano())),
-		},
-		Filters: option.filters,
-	}
+	return NewBuilder(opts...).Build()
 }
 
 // Balancer is p2c selector.
@@ -92,3 +82,24 @@ func (s *Balancer) Pick(ctx context.Context, nodes []selector.WeightedNode) (sel
 	done := pc.Pick()
 	return pc, done, nil
 }
+
+// NewBuilder returns a selector builder with p2c balancer
+func NewBuilder(opts ...Option) selector.Builder {
+	var option options
+	for _, opt := range opts {
+		opt(&option)
+	}
+	return &selector.DefaultBuilder{
+		Filters:  option.filters,
+		Balancer: &Builder{},
+		Node:     &ewma.Builder{},
+	}
+}
+
+// Builder is p2c builder
+type Builder struct{}
+
+// Build creates Balancer
+func (b *Builder) Build() selector.Balancer {
+	return &Balancer{r: rand.New(rand.NewSource(time.Now().UnixNano()))}
+}

selector/random/random.go

@@ -33,18 +33,9 @@ type options struct {
 // Balancer is a random balancer.
 type Balancer struct{}
 
-// New random a selector.
+// New an random selector.
 func New(opts ...Option) selector.Selector {
-	var option options
-	for _, opt := range opts {
-		opt(&option)
-	}
-
-	return &selector.Default{
-		Balancer:    &Balancer{},
-		NodeBuilder: &direct.Builder{},
-		Filters:     option.filters,
-	}
+	return NewBuilder(opts...).Build()
 }
 
 // Pick pick a weighted node.
@@ -57,3 +48,24 @@ func (p *Balancer) Pick(_ context.Context, nodes []selector.WeightedNode) (selec
 	d := selected.Pick()
 	return selected, d, nil
 }
+
+// NewBuilder returns a selector builder with random balancer
+func NewBuilder(opts ...Option) selector.Builder {
+	var option options
+	for _, opt := range opts {
+		opt(&option)
+	}
+	return &selector.DefaultBuilder{
+		Filters:  option.filters,
+		Balancer: &Builder{},
+		Node:     &direct.Builder{},
+	}
+}
+
+// Builder is random builder
+type Builder struct{}
+
+// Build creates Balancer
+func (b *Builder) Build() selector.Balancer {
+	return &Balancer{}
+}

selector/selector.go

@@ -24,6 +24,11 @@ type Rebalancer interface {
 	Apply(nodes []Node)
 }
 
+// Builder build selector
+type Builder interface {
+	Build() Selector
+}
+
 // Node is node interface.
 type Node interface {
 	// Address is the unique address under the same service

selector/wrr/wrr.go

@@ -38,18 +38,7 @@ type Balancer struct {
 
 // New random a selector.
 func New(opts ...Option) selector.Selector {
-	var option options
-	for _, opt := range opts {
-		opt(&option)
-	}
-
-	return &selector.Default{
-		Balancer: &Balancer{
-			currentWeight: make(map[string]float64),
-		},
-		NodeBuilder: &direct.Builder{},
-		Filters:     option.filters,
-	}
+	return NewBuilder(opts...).Build()
 }
 
 // Pick pick a weighted node.
@@ -80,3 +69,24 @@ func (p *Balancer) Pick(_ context.Context, nodes []selector.WeightedNode) (selec
 	d := selected.Pick()
 	return selected, d, nil
 }
+
+// NewBuilder returns a selector builder with wrr balancer
+func NewBuilder(opts ...Option) selector.Builder {
+	var option options
+	for _, opt := range opts {
+		opt(&option)
+	}
+	return &selector.DefaultBuilder{
+		Filters:  option.filters,
+		Balancer: &Builder{},
+		Node:     &direct.Builder{},
+	}
+}
+
+// Builder is wrr builder
+type Builder struct{}
+
+// Build creates Balancer
+func (b *Builder) Build() selector.Balancer {
+	return &Balancer{currentWeight: make(map[string]float64)}
+}

transport/grpc/balancer.go

@@ -25,19 +25,19 @@ var (
 
 func init() {
 	// inject global grpc balancer
-	SetGlobalBalancer(random.Name, random.New())
-	SetGlobalBalancer(wrr.Name, wrr.New())
-	SetGlobalBalancer(p2c.Name, p2c.New())
+	SetGlobalBalancer(random.Name, random.NewBuilder())
+	SetGlobalBalancer(wrr.Name, wrr.NewBuilder())
+	SetGlobalBalancer(p2c.Name, p2c.NewBuilder())
 }
 
 // SetGlobalBalancer set grpc balancer with scheme.
-func SetGlobalBalancer(scheme string, selector selector.Selector) {
+func SetGlobalBalancer(scheme string, builder selector.Builder) {
 	mu.Lock()
 	defer mu.Unlock()
 
 	b := base.NewBalancerBuilder(
 		scheme,
-		&Builder{selector},
+		&Builder{builder: builder},
 		base.Config{HealthCheck: true},
 	)
 	gBalancer.Register(b)
@@ -45,7 +45,7 @@ func SetGlobalBalancer(scheme string, selector selector.Selector) {
 
 // Builder is grpc balancer builder.
 type Builder struct {
-	selector selector.Selector
+	builder selector.Builder
 }
 
 // Build creates a grpc Picker.
@@ -62,7 +62,7 @@ func (b *Builder) Build(info base.PickerBuildInfo) gBalancer.Picker {
 		nodes = append(nodes, node.New(info.Address.Addr, ins))
 	}
 	p := &Picker{
-		selector: b.selector,
+		selector: b.builder.Build(),
 		subConns: subConns,
 	}
 	p.selector.Apply(nodes)