first commit

provider/watcher/provider.go

@@ -0,0 +1,71 @@
+package watcher
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"gitoa.ru/go-4devs/config"
+)
+
+var (
+	_ config.Provider      = (*Provider)(nil)
+	_ config.WatchProvider = (*Provider)(nil)
+)
+
+func New(duration time.Duration, provider config.Provider, opts ...Option) *Provider {
+	p := &Provider{
+		Provider: provider,
+		ticker:   time.NewTicker(duration),
+		logger: func(_ context.Context, msg string) {
+			log.Print(msg)
+		},
+	}
+
+	for _, opt := range opts {
+		opt(p)
+	}
+
+	return p
+}
+
+func WithLogger(l func(context.Context, string)) Option {
+	return func(p *Provider) {
+		p.logger = l
+	}
+}
+
+type Option func(*Provider)
+
+type Provider struct {
+	config.Provider
+	ticker *time.Ticker
+	logger func(context.Context, string)
+}
+
+func (p *Provider) Watch(ctx context.Context, key config.Key, callback config.WatchCallback) error {
+	oldVar, err := p.Provider.Read(ctx, key)
+	if err != nil {
+		return fmt.Errorf("%s: failed watch variable: %w", p.Provider.Name(), err)
+	}
+
+	go func() {
+		for {
+			select {
+			case <-p.ticker.C:
+				newVar, err := p.Provider.Read(ctx, key)
+				if err != nil {
+					p.logger(ctx, err.Error())
+				} else if !newVar.IsEquals(oldVar) {
+					callback(ctx, oldVar, newVar)
+					oldVar = newVar
+				}
+			case <-ctx.Done():
+				return
+			}
+		}
+	}()
+
+	return nil
+}

provider/watcher/provider_test.go

@@ -0,0 +1,58 @@
+package watcher_test
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"gitoa.ru/go-4devs/config"
+	"gitoa.ru/go-4devs/config/provider/watcher"
+	"gitoa.ru/go-4devs/config/value"
+)
+
+type provider struct {
+	cnt int32
+}
+
+func (p *provider) Name() string {
+	return "test"
+}
+
+func (p *provider) Read(ctx context.Context, k config.Key) (config.Variable, error) {
+	p.cnt++
+
+	return config.Variable{
+		Name:  "tmpname",
+		Value: value.JString(fmt.Sprint(p.cnt)),
+	}, nil
+}
+
+func TestWatcher(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	prov := &provider{}
+
+	w := watcher.New(time.Second, prov)
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	var cnt int32
+
+	err := w.Watch(
+		ctx,
+		config.Key{Name: "tmpname"},
+		func(ctx context.Context, oldVar, newVar config.Variable) {
+			atomic.AddInt32(&cnt, 1)
+			wg.Done()
+		},
+	)
+	require.NoError(t, err)
+	wg.Wait()
+
+	require.Equal(t, int32(2), cnt)
+}