feat: add observer

Author: thinkgos

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/spf13/cast v1.7.1
 	github.com/stretchr/testify v1.10.0
 	github.com/things-go/limiter v0.1.5
+	github.com/things-go/proc v0.0.0-20250308140217-2fbab6367193
 	github.com/xuri/excelize/v2 v2.9.0
 	go.opentelemetry.io/otel/sdk v1.35.0
 	go.opentelemetry.io/otel/trace v1.35.0

go.sum

@@ -77,6 +77,8 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/things-go/limiter v0.1.5 h1:vCVzm0897TSWFhy2G52rU27hdhJl/lgvfiRQrek53JQ=
 github.com/things-go/limiter v0.1.5/go.mod h1:C7SPsXIfiPPC44k/mb0TCwZa5DzqxXcL7Zg6g5hPL5I=
+github.com/things-go/proc v0.0.0-20250308140217-2fbab6367193 h1:3+vbs76RM7I1SsaOrxeSp/gvQzlu7+B8zodgPHxO4NU=
+github.com/things-go/proc v0.0.0-20250308140217-2fbab6367193/go.mod h1:aQJ7LTcxq+1R1Air5QGcYd9GsS5WPw45Ix/pHfQSPO4=
 github.com/xuri/efp v0.0.0-20250227110027-3491fafc2b79 h1:78nKszZqigiBRBVcoe/AuPzyLTWW5B+ltBaUX1rlIXA=
 github.com/xuri/efp v0.0.0-20250227110027-3491fafc2b79/go.mod h1:ybY/Jr0T0GTCnYjKqmdwxyxn2BQf2RcQIIvex5QldPI=
 github.com/xuri/excelize/v2 v2.9.0 h1:1tgOaEq92IOEumR1/JfYS/eR0KHOCsRv/rYXXh6YJQE=

observer/observer.go

@@ -0,0 +1,109 @@
+package observer
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/things-go/proc-extra/gpool"
+	"github.com/things-go/proc/topic"
+)
+
+type Message interface {
+	IntoPayload() ([]byte, error)
+}
+
+type Observer interface {
+	Name() string
+	Dispose(context.Context, Message) error
+}
+
+type AllowOptions struct {
+	spawn bool
+}
+
+type AllowOption func(*AllowOptions)
+
+func newAllowOption(opts ...AllowOption) AllowOptions {
+	ao := AllowOptions{
+		spawn: false,
+	}
+	for _, f := range opts {
+		f(&ao)
+	}
+	return ao
+}
+
+func AllowSpawn() AllowOption {
+	return func(a *AllowOptions) {
+		a.spawn = true
+	}
+}
+
+type ConcreteObserver struct {
+	subs       *topic.Tree
+	wg         sync.WaitGroup
+	errHandler func(ctx context.Context, name string, err error)
+}
+
+func NewConcreteObserver() *ConcreteObserver {
+	return &ConcreteObserver{
+		subs:       topic.NewStandardTree(),
+		errHandler: func(ctx context.Context, name string, err error) {},
+	}
+}
+func (cc *ConcreteObserver) SetErrHandler(f func(ctx context.Context, name string, err error)) *ConcreteObserver {
+	if f != nil {
+		cc.errHandler = f
+	}
+	return cc
+}
+
+func (cc *ConcreteObserver) GetObserverNames(topic string) []string {
+	values := cc.subs.Match(topic)
+	names := make([]string, 0, len(values))
+	for _, v := range values {
+		names = append(names, v.(Observer).Name())
+	}
+	return names
+}
+
+func (cc *ConcreteObserver) Notify(ctx context.Context, topic string, m Message, opts ...AllowOption) error {
+	ao := newAllowOption(opts...)
+	values := cc.subs.Match(topic)
+	for _, v := range values {
+		ob := v.(Observer)
+		if ao.spawn {
+			cc.wg.Add(1)
+			gpool.Go(func() {
+				defer cc.wg.Done()
+				err := ob.Dispose(ctx, m)
+				if err != nil {
+					cc.errHandler(ctx, ob.Name(), err)
+				}
+			})
+		} else {
+			err := ob.Dispose(ctx, m)
+			if err != nil {
+				return fmt.Errorf("observer: '%v' dispose failure, %w", ob.Name(), err)
+			}
+		}
+	}
+	return nil
+}
+
+func (cc *ConcreteObserver) AddObserver(topic string, ob Observer) error {
+	cc.subs.Add(topic, ob)
+	return nil
+}
+
+func (cc *ConcreteObserver) DeleteObserver(topic string, ob Observer) error {
+	cc.subs.Remove(topic, ob)
+	return nil
+}
+
+func (cc *ConcreteObserver) Close() error {
+	cc.subs.Reset()
+	cc.wg.Wait()
+	return nil
+}

observer/observer_test.go

@@ -0,0 +1,128 @@
+package observer
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"log"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var _ Observer = (*c1)(nil)
+var _ Observer = (*c2)(nil)
+var _ Observer = (*c3)(nil)
+
+type c1 struct{}
+
+func (c *c1) Name() string { return "c1" }
+func (c *c1) Dispose(ctx context.Context, m Message) error {
+	log.Printf("dispose c1! notifier: %v\n", m.(*CallMessage).Name)
+	return nil
+}
+
+type c2 struct{}
+
+func (c *c2) Name() string { return "c2" }
+func (c *c2) Dispose(ctx context.Context, m Message) error {
+	cm := m.(*CallMessage)
+	if cm.Name == "c2nodo" {
+		return errors.New("no do for this notifier!")
+	}
+	log.Printf("dispose c2! notifier: %v\n", cm.Name)
+	return nil
+}
+
+type c3 struct{}
+
+func (c *c3) Name() string { return "c3" }
+func (c *c3) Dispose(ctx context.Context, m Message) error {
+	log.Printf("dispose c3! notifier: %v\n", m.(*CallMessage).Name)
+	return nil
+}
+
+type CallMessage struct {
+	Name string `json:"name"`
+}
+
+func (c *CallMessage) IntoPayload() ([]byte, error) {
+	return json.Marshal(c)
+}
+
+func Test_ObserverCallChain(t *testing.T) {
+	var err error
+
+	topic := "/observer/call-chain"
+	cc := NewConcreteObserver()
+	defer cc.Close()
+	cc1 := &c1{}
+	cc2 := &c2{}
+	cc3 := &c3{}
+	err = cc.AddObserver(topic, cc1)
+	require.NoError(t, err)
+	err = cc.AddObserver(topic, cc2)
+	require.NoError(t, err)
+	err = cc.AddObserver(topic, cc3)
+	require.NoError(t, err)
+
+	t.Run("match names", func(t *testing.T) {
+		names := cc.GetObserverNames(topic)
+		t.Logf("Observers for topic '%s': %v", topic, names)
+	})
+
+	t.Run("normal", func(t *testing.T) {
+		err := cc.Notify(context.Background(), topic, &CallMessage{
+			Name: "aaa",
+		})
+		require.NoError(t, err)
+	})
+
+	t.Run("error stop", func(t *testing.T) {
+		err := cc.Notify(context.Background(), topic, &CallMessage{
+			Name: "c2nodo",
+		})
+		require.Error(t, err)
+		t.Log(err)
+	})
+
+	t.Run("drop c2(which can't do) then notify", func(t *testing.T) {
+		err := cc.DeleteObserver(topic, cc2)
+		require.NoError(t, err)
+		err = cc.Notify(context.Background(), topic, &CallMessage{
+			Name: "c2nodo",
+		})
+		require.NoError(t, err)
+	})
+}
+
+func Test_ObserverSpawn(t *testing.T) {
+	var err error
+
+	topic := "/observer/spawn"
+	cc := NewConcreteObserver()
+	defer cc.Close()
+	cc1 := &c1{}
+	cc2 := &c2{}
+	cc3 := &c3{}
+	err = cc.AddObserver(topic, cc1)
+	require.NoError(t, err)
+	err = cc.AddObserver(topic, cc2)
+	require.NoError(t, err)
+	err = cc.AddObserver(topic, cc3)
+	require.NoError(t, err)
+
+	t.Run("normal", func(t *testing.T) {
+		err := cc.Notify(context.Background(), topic, &CallMessage{
+			Name: "aaa",
+		}, AllowSpawn())
+		require.NoError(t, err)
+	})
+
+	t.Run("error stop", func(t *testing.T) {
+		err := cc.Notify(context.Background(), topic, &CallMessage{
+			Name: "c2nodo",
+		}, AllowSpawn())
+		require.NoError(t, err)
+	})
+}