package main import ( "fmt" "math/rand" "sync" "time" "github.com/micro/go-micro/client" "github.com/micro/go-micro/cmd" "github.com/micro/go-micro/registry" "github.com/micro/go-micro/selector" "golang.org/x/net/context" example "github.com/micro/go-micro/examples/server/proto/example" ) // Built in random hashed node selector type dcSelector struct { opts selector.Options } var ( datacenter = "local" ) func init() { rand.Seed(time.Now().Unix()) } func (n *dcSelector) Select(service string, opts ...selector.SelectOption) (selector.Next, error) { services, err := n.opts.Registry.GetService(service) if err != nil { return nil, err } if len(services) == 0 { return nil, selector.ErrNotFound } var nodes []*registry.Node // Filter the nodes for datacenter for _, service := range services { for _, node := range service.Nodes { if node.Metadata["datacenter"] == datacenter { 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 (n *dcSelector) Mark(service string, node *registry.Node, err error) { return } func (n *dcSelector) Reset(service string) { return } func (n *dcSelector) Close() error { return nil } // Return a new first node selector func DCSelector(opts ...selector.Option) selector.Selector { var sopts selector.Options for _, opt := range opts { opt(&sopts) } if sopts.Registry == nil { sopts.Registry = registry.DefaultRegistry } return &dcSelector{sopts} } func call(i int) { // Create new request to service go.micro.srv.example, method Example.Call req := client.NewRequest("go.micro.srv.example", "Example.Call", &example.Request{ Name: "John", }) rsp := &example.Response{} // Call service if err := client.Call(context.Background(), req, rsp); err != nil { fmt.Println("call err: ", err, rsp) return } fmt.Println("Call:", i, "rsp:", rsp.Msg) } func main() { cmd.Init() client.DefaultClient = client.NewClient( client.Selector(DCSelector()), ) fmt.Println("\n--- Call example ---\n") for i := 0; i < 10; i++ { call(i) } }