From e27f3847951e7a2e9e0615cdc0c122debf4fe2c7 Mon Sep 17 00:00:00 2001
From: Darren Shepherd <darren@rancher.com>
Date: Mon, 20 Jul 2020 09:21:03 -0700
Subject: [PATCH] Only send counts every second if there is a change

---
 pkg/resources/counts/buffer.go | 40 ++++++++++++++++++++++++++++++++++
 pkg/resources/counts/counts.go | 18 +++++++--------
 2 files changed, 49 insertions(+), 9 deletions(-)
 create mode 100644 pkg/resources/counts/buffer.go

diff --git a/pkg/resources/counts/buffer.go b/pkg/resources/counts/buffer.go
new file mode 100644
index 0000000..2552c5d
--- /dev/null
+++ b/pkg/resources/counts/buffer.go
@@ -0,0 +1,40 @@
+package counts
+
+import (
+	"time"
+
+	"github.com/rancher/apiserver/pkg/types"
+)
+
+func buffer(c chan types.APIEvent) chan types.APIEvent {
+	result := make(chan types.APIEvent)
+	go func() {
+		defer close(result)
+		debounce(result, c)
+	}()
+	return result
+}
+
+func debounce(result, input chan types.APIEvent) {
+	t := time.NewTicker(time.Second)
+	defer t.Stop()
+
+	var (
+		lastEvent *types.APIEvent
+	)
+	for {
+		select {
+		case event, ok := <-input:
+			if ok {
+				lastEvent = &event
+			} else {
+				return
+			}
+		case <-t.C:
+			if lastEvent != nil {
+				result <- *lastEvent
+				lastEvent = nil
+			}
+		}
+	}
+}
diff --git a/pkg/resources/counts/counts.go b/pkg/resources/counts/counts.go
index c57eb48..ce4dd87 100644
--- a/pkg/resources/counts/counts.go
+++ b/pkg/resources/counts/counts.go
@@ -118,6 +118,14 @@ func (s *Store) Watch(apiOp *types.APIRequest, schema *types.APISchema, w types.
 		countLock   sync.Mutex
 	)
 
+	go func() {
+		<-apiOp.Context().Done()
+		countLock.Lock()
+		close(result)
+		result = nil
+		countLock.Unlock()
+	}()
+
 	counts = s.getCount(apiOp).Counts
 	for id := range counts {
 		schema := apiOp.Schemas.LookupSchema(id)
@@ -128,14 +136,6 @@ func (s *Store) Watch(apiOp *types.APIRequest, schema *types.APISchema, w types.
 		gvrToSchema[attributes.GVR(schema)] = schema
 	}
 
-	go func() {
-		<-apiOp.Context().Done()
-		countLock.Lock()
-		close(result)
-		result = nil
-		countLock.Unlock()
-	}()
-
 	onChange := func(add bool, gvr schema2.GroupVersionResource, _ string, obj, oldObj runtime.Object) error {
 		countLock.Lock()
 		defer countLock.Unlock()
@@ -205,7 +205,7 @@ func (s *Store) Watch(apiOp *types.APIRequest, schema *types.APISchema, w types.
 		return onChange(false, gvr, key, obj, nil)
 	})
 
-	return result, nil
+	return buffer(result), nil
 }
 
 func (s *Store) schemasToWatch(apiOp *types.APIRequest) (result []*types.APISchema) {