First commit in strategy rework

selector/cache/cache.go

@@ -2,7 +2,6 @@ package cache
 
 import (
 	"log"
-	"math/rand"
 	"sync"
 	"time"
 
@@ -33,10 +32,6 @@ var (
 	DefaultTTL = time.Minute
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
 func (c *cacheSelector) quit() bool {
 	select {
 	case <-c.exit:
@@ -329,7 +324,10 @@ func (c *cacheSelector) Options() selector.Options {
 }
 
 func (c *cacheSelector) Select(service string, opts ...selector.SelectOption) (selector.Next, error) {
-	var sopts selector.SelectOptions
+	sopts := selector.SelectOptions{
+		Strategy: c.so.Strategy,
+	}
+
 	for _, opt := range opts {
 		opt(&sopts)
 	}
@@ -352,29 +350,7 @@ func (c *cacheSelector) Select(service string, opts ...selector.SelectOption) (s
 		return nil, selector.ErrNotFound
 	}
 
-	var nodes []*registry.Node
+	return sopts.Strategy(services), nil
-
-	for _, service := range services {
-		for _, node := range service.Nodes {
-			nodes = append(nodes, node)
-		}
-	}
-
-	if len(nodes) == 0 {
-		return nil, selector.ErrNotFound
-	}
-
-	return func() (*registry.Node, error) {
-		i := rand.Int()
-		j := i % len(services)
-
-		if len(services[j].Nodes) == 0 {
-			return nil, selector.ErrNotFound
-		}
-
-		k := i % len(services[j].Nodes)
-		return services[j].Nodes[k], nil
-	}, nil
 }
 
 func (c *cacheSelector) Mark(service string, node *registry.Node, err error) {
@@ -407,7 +383,9 @@ func (c *cacheSelector) String() string {
 }
 
 func NewSelector(opts ...selector.Option) selector.Selector {
-	var sopts selector.Options
+	sopts := selector.Options{
+		Strategy: selector.Random,
+	}
 
 	for _, opt := range opts {
 		opt(&sopts)

selector/default.go

@@ -0,0 +1,87 @@
+package selector
+
+import (
+	"math/rand"
+	"time"
+
+	"github.com/micro/go-micro/registry"
+)
+
+type defaultSelector struct {
+	so Options
+}
+
+func init() {
+	rand.Seed(time.Now().Unix())
+}
+
+func (r *defaultSelector) Init(opts ...Option) error {
+	for _, o := range opts {
+		o(&r.so)
+	}
+	return nil
+}
+
+func (r *defaultSelector) Options() Options {
+	return r.so
+}
+
+func (r *defaultSelector) Select(service string, opts ...SelectOption) (Next, error) {
+	sopts := SelectOptions{
+		Strategy: r.so.Strategy,
+	}
+
+	for _, opt := range opts {
+		opt(&sopts)
+	}
+
+	// get the service
+	services, err := r.so.Registry.GetService(service)
+	if err != nil {
+		return nil, err
+	}
+
+	// apply the filters
+	for _, filter := range sopts.Filters {
+		services = filter(services)
+	}
+
+	// if there's nothing left, return
+	if len(services) == 0 {
+		return nil, ErrNotFound
+	}
+
+	return sopts.Strategy(services), nil
+}
+
+func (r *defaultSelector) Mark(service string, node *registry.Node, err error) {
+	return
+}
+
+func (r *defaultSelector) Reset(service string) {
+	return
+}
+
+func (r *defaultSelector) Close() error {
+	return nil
+}
+
+func (r *defaultSelector) String() string {
+	return "default"
+}
+
+func newDefaultSelector(opts ...Option) Selector {
+	sopts := Options{
+		Strategy: Random,
+	}
+
+	for _, opt := range opts {
+		opt(&sopts)
+	}
+
+	if sopts.Registry == nil {
+		sopts.Registry = registry.DefaultRegistry
+	}
+
+	return &defaultSelector{sopts}
+}

selector/default_test.go

@@ -9,15 +9,11 @@ import (
 func TestRandomSelector(t *testing.T) {
 	counts := map[string]int{}
 
-	rs := &randomSelector{
+	rs := newDefaultSelector(Registry(mock.NewRegistry()))
-		so: Options{
-			Registry: mock.NewRegistry(),
-		},
-	}
 
 	next, err := rs.Select("foo")
 	if err != nil {
-		t.Errorf("Unexpected error calling random select: %v", err)
+		t.Errorf("Unexpected error calling default select: %v", err)
 	}
 
 	for i := 0; i < 100; i++ {

selector/options.go

@@ -8,6 +8,7 @@ import (
 
 type Options struct {
 	Registry registry.Registry
+	Strategy Strategy
 
 	// Other options for implementations of the interface
 	// can be stored in a context
@@ -15,7 +16,8 @@ type Options struct {
 }
 
 type SelectOptions struct {
-	Filters []Filter
+	Filters  []Filter
+	Strategy Strategy
 
 	// Other options for implementations of the interface
 	// can be stored in a context
@@ -35,6 +37,13 @@ func Registry(r registry.Registry) Option {
 	}
 }
 
+// SetStrategy sets the default strategy for the selector
+func SetStrategy(fn Strategy) Option {
+	return func(o *Options) {
+		o.Strategy = fn
+	}
+}
+
 // WithFilter adds a filter function to the list of filters
 // used during the Select call.
 func WithFilter(fn ...Filter) SelectOption {
@@ -42,3 +51,10 @@ func WithFilter(fn ...Filter) SelectOption {
 		o.Filters = append(o.Filters, fn...)
 	}
 }
+
+// Strategy sets the selector strategy
+func WithStrategy(fn Strategy) SelectOption {
+	return func(o *SelectOptions) {
+		o.Strategy = fn
+	}
+}

selector/random/random.go

@@ -1,9 +0,0 @@
-package random
-
-import (
-	"github.com/micro/go-micro/selector"
-)
-
-func NewSelector(opts ...selector.Option) selector.Selector {
-	return selector.NewSelector(opts...)
-}

selector/random_selector.go

@@ -1,104 +0,0 @@
-package selector
-
-import (
-	"math/rand"
-	"time"
-
-	"github.com/micro/go-micro/registry"
-)
-
-type randomSelector struct {
-	so Options
-}
-
-func init() {
-	rand.Seed(time.Now().Unix())
-}
-
-func (r *randomSelector) Init(opts ...Option) error {
-	for _, o := range opts {
-		o(&r.so)
-	}
-	return nil
-}
-
-func (r *randomSelector) Options() Options {
-	return r.so
-}
-
-func (r *randomSelector) Select(service string, opts ...SelectOption) (Next, error) {
-	var sopts SelectOptions
-	for _, opt := range opts {
-		opt(&sopts)
-	}
-
-	// get the service
-	services, err := r.so.Registry.GetService(service)
-	if err != nil {
-		return nil, err
-	}
-
-	// apply the filters
-	for _, filter := range sopts.Filters {
-		services = filter(services)
-	}
-
-	// if there's nothing left, return
-	if len(services) == 0 {
-		return nil, ErrNotFound
-	}
-
-	var nodes []*registry.Node
-
-	for _, service := range services {
-		for _, node := range service.Nodes {
-			nodes = append(nodes, node)
-		}
-	}
-
-	if len(nodes) == 0 {
-		return nil, ErrNotFound
-	}
-
-	return func() (*registry.Node, error) {
-		i := rand.Int()
-		j := i % len(services)
-
-		if len(services[j].Nodes) == 0 {
-			return nil, ErrNotFound
-		}
-
-		k := i % len(services[j].Nodes)
-		return services[j].Nodes[k], nil
-	}, nil
-}
-
-func (r *randomSelector) Mark(service string, node *registry.Node, err error) {
-	return
-}
-
-func (r *randomSelector) Reset(service string) {
-	return
-}
-
-func (r *randomSelector) Close() error {
-	return nil
-}
-
-func (r *randomSelector) String() string {
-	return "random"
-}
-
-func newRandomSelector(opts ...Option) Selector {
-	var sopts Options
-
-	for _, opt := range opts {
-		opt(&sopts)
-	}
-
-	if sopts.Registry == nil {
-		sopts.Registry = registry.DefaultRegistry
-	}
-
-	return &randomSelector{sopts}
-}

selector/roundrobin/round_robin_selector.go

@@ -1,98 +0,0 @@
-package roundrobin
-
-import (
-	"sync"
-
-	"github.com/micro/go-micro/registry"
-	"github.com/micro/go-micro/selector"
-)
-
-type roundRobinSelector struct {
-	so selector.Options
-}
-
-func (r *roundRobinSelector) Init(opts ...selector.Option) error {
-	for _, o := range opts {
-		o(&r.so)
-	}
-	return nil
-}
-
-func (r *roundRobinSelector) Options() selector.Options {
-	return r.so
-}
-
-func (r *roundRobinSelector) Select(service string, opts ...selector.SelectOption) (selector.Next, error) {
-	var sopts selector.SelectOptions
-	for _, opt := range opts {
-		opt(&sopts)
-	}
-
-	// get the service
-	services, err := r.so.Registry.GetService(service)
-	if err != nil {
-		return nil, err
-	}
-
-	// apply the filters
-	for _, filter := range sopts.Filters {
-		services = filter(services)
-	}
-
-	// if there's nothing left, return
-	if len(services) == 0 {
-		return nil, selector.ErrNotFound
-	}
-
-	var nodes []*registry.Node
-
-	for _, service := range services {
-		for _, node := range service.Nodes {
-			nodes = append(nodes, node)
-		}
-	}
-
-	if len(nodes) == 0 {
-		return nil, selector.ErrNotFound
-	}
-
-	var i int
-	var mtx sync.Mutex
-
-	return func() (*registry.Node, error) {
-		mtx.Lock()
-		defer mtx.Unlock()
-		i++
-		return nodes[i%len(nodes)], nil
-	}, nil
-}
-
-func (r *roundRobinSelector) Mark(service string, node *registry.Node, err error) {
-	return
-}
-
-func (r *roundRobinSelector) Reset(service string) {
-	return
-}
-
-func (r *roundRobinSelector) Close() error {
-	return nil
-}
-
-func (r *roundRobinSelector) String() string {
-	return "roundrobin"
-}
-
-func NewSelector(opts ...selector.Option) selector.Selector {
-	var sopts selector.Options
-
-	for _, opt := range opts {
-		opt(&sopts)
-	}
-
-	if sopts.Registry == nil {
-		sopts.Registry = registry.DefaultRegistry
-	}
-
-	return &roundRobinSelector{sopts}
-}

selector/roundrobin/round_robin_selector_test.go

@@ -1,33 +0,0 @@
-package roundrobin
-
-import (
-	"testing"
-
-	"github.com/micro/go-micro/registry/mock"
-	"github.com/micro/go-micro/selector"
-)
-
-func TestRoundRobinSelector(t *testing.T) {
-	counts := map[string]int{}
-
-	rr := &roundRobinSelector{
-		so: selector.Options{
-			Registry: mock.NewRegistry(),
-		},
-	}
-
-	next, err := rr.Select("foo")
-	if err != nil {
-		t.Errorf("Unexpected error calling rr select: %v", err)
-	}
-
-	for i := 0; i < 100; i++ {
-		node, err := next()
-		if err != nil {
-			t.Errorf("Expected node err, got err: %v", err)
-		}
-		counts[node.Id]++
-	}
-
-	t.Logf("Round Robin Counts %v", counts)
-}

selector/selector.go

@@ -79,19 +79,22 @@ type Selector interface {
 }
 
 // Next is a function that returns the next node
-// based on the selector's algorithm
+// based on the selector's strategy
 type Next func() (*registry.Node, error)
 
 // Filter is used to filter a service during the selection process
 type Filter func([]*registry.Service) []*registry.Service
 
+// Strategy is a selection strategy e.g random, round robin
+type Strategy func([]*registry.Service) Next
+
 var (
-	DefaultSelector = newRandomSelector()
+	DefaultSelector = newDefaultSelector()
 
 	ErrNotFound      = errors.New("not found")
 	ErrNoneAvailable = errors.New("none available")
 )
 
 func NewSelector(opts ...Option) Selector {
-	return newRandomSelector(opts...)
+	return newDefaultSelector(opts...)
 }

selector/strategy.go

@@ -0,0 +1,56 @@
+package selector
+
+import (
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/micro/go-micro/registry"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+// Random is a random strategy algorithm for node selection
+func Random(services []*registry.Service) Next {
+	var nodes []*registry.Node
+
+	for _, service := range services {
+		nodes = append(nodes, service.Nodes...)
+	}
+
+	return func() (*registry.Node, error) {
+		if len(nodes) == 0 {
+			return nil, ErrNotFound
+		}
+
+		i := rand.Int() % len(nodes)
+		return nodes[i], nil
+	}
+}
+
+// RoundRobin is a roundrobin strategy algorithm for node selection
+func RoundRobin(services []*registry.Service) Next {
+	var nodes []*registry.Node
+
+	for _, service := range services {
+		nodes = append(nodes, service.Nodes...)
+	}
+
+	var i int
+	var mtx sync.Mutex
+
+	return func() (*registry.Node, error) {
+		if len(nodes) == 0 {
+			return nil, ErrNotFound
+		}
+
+		mtx.Lock()
+		node := nodes[i%len(nodes)]
+		i++
+		mtx.Unlock()
+
+		return node, nil
+	}
+}

selector/strategy_test.go

@@ -0,0 +1,59 @@
+package selector
+
+import (
+	"testing"
+
+	"github.com/micro/go-micro/registry"
+)
+
+func TestStrategies(t *testing.T) {
+	testData := []*registry.Service{
+		&registry.Service{
+			Name:    "test1",
+			Version: "latest",
+			Nodes: []*registry.Node{
+				&registry.Node{
+					Id:      "test1-1",
+					Address: "10.0.0.1",
+					Port:    1001,
+				},
+				&registry.Node{
+					Id:      "test1-2",
+					Address: "10.0.0.2",
+					Port:    1002,
+				},
+			},
+		},
+		&registry.Service{
+			Name:    "test1",
+			Version: "default",
+			Nodes: []*registry.Node{
+				&registry.Node{
+					Id:      "test1-3",
+					Address: "10.0.0.3",
+					Port:    1003,
+				},
+				&registry.Node{
+					Id:      "test1-4",
+					Address: "10.0.0.4",
+					Port:    1004,
+				},
+			},
+		},
+	}
+
+	for name, strategy := range map[string]Strategy{"random": Random, "roundrobin": RoundRobin} {
+		next := strategy(testData)
+		counts := make(map[string]int)
+
+		for i := 0; i < 100; i++ {
+			node, err := next()
+			if err != nil {
+				t.Fatal(err)
+			}
+			counts[node.Id]++
+		}
+
+		t.Logf("%s: %+v\n", name, counts)
+	}
+}