First commit in strategy rework

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
+	}
+}