adds server lock package

pkg/infra/serverlock/serverlock_integration_test.go

@@ -0,0 +1,75 @@
+// +build integration
+
+package serverlock
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestServerLok(t *testing.T) {
+	sl := createTestableServerLock(t)
+
+	Convey("Server lock integration test", t, func() {
+
+		Convey("Check that we can call OncePerServerGroup multiple times without executing callback", func() {
+			counter := 0
+			var err error
+
+			//this time `fn` should be executed
+			err = sl.OncePerServerGroup(context.Background(), "test-operation", time.Second*5, func() { counter++ })
+			So(err, ShouldBeNil)
+
+			//this should not execute `fn`
+			err = sl.OncePerServerGroup(context.Background(), "test-operation", time.Second*5, func() { counter++ })
+			So(err, ShouldBeNil)
+
+			//this should not execute `fn`
+			err = sl.OncePerServerGroup(context.Background(), "test-operation", time.Second*5, func() { counter++ })
+			So(err, ShouldBeNil)
+
+			// wg := sync.WaitGroup{}
+			// for i := 0; i < 3; i++ {
+			// 	wg.Add(1)
+			// 	go func(index int) {
+			// 		defer wg.Done()
+			// 		//sl := createTestableServerLock(t)
+			// 		//<-time.After(time.Second)
+
+			// 		j := 0
+			// 		for {
+			// 			select {
+			// 			case <-time.Tick(time.Second):
+			// 				fmt.Printf("running worker %d loop %d\n", index, j)
+			// 				err := sl.OncePerServerGroup(context.Background(), "test-operation", time.Second*2, func() {
+			// 					counter++
+			// 				})
+
+			// 				if err != nil {
+			// 					t.Errorf("expected. err: %v", err)
+			// 				}
+
+			// 				j++
+			// 				if j > 3 {
+			// 					return
+			// 				}
+			// 			}
+			// 		}
+			// 	}(i)
+			// }
+
+			// wg.Wait()
+
+			// wait 5 second.
+			<-time.After(time.Second * 10)
+
+			// now `fn` should be executed again
+			err = sl.OncePerServerGroup(context.Background(), "test-operation", time.Second*5, func() { counter++ })
+			So(err, ShouldBeNil)
+			So(counter, ShouldEqual, 2)
+		})
+	})
+}