Cooldown-based eager marshaling

pkg/handler/handler.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"encoding/json"
+	"math"
 	"mime"
 	"net/http"
 	"sync"
@@ -54,6 +55,10 @@ type OpenAPIService struct {
 	// rwMutex protects All members of this service.
 	rwMutex sync.RWMutex
 
+	// eagerMarshalingTimer fires if no updates to the spec are made
+	// for the defined duration.
+	eagerMarshalingTimer *time.Timer
+
 	lastModified time.Time
 
 	jsonCache  handler.HandlerCache
@@ -69,7 +74,9 @@ func init() {
 // NewOpenAPIService builds an OpenAPIService starting with the given spec.
 func NewOpenAPIService(spec *spec.Swagger) (*OpenAPIService, error) {
 	o := &OpenAPIService{}
+	o.eagerMarshalingTimer = buildEagerMarshalingTimer(o)
 	if err := o.UpdateSpec(spec); err != nil {
+		_ = o.eagerMarshalingTimer.Stop()
 		return nil, err
 	}
 	return o, nil
@@ -110,6 +117,8 @@ func (o *OpenAPIService) UpdateSpec(openapiSpec *spec.Swagger) (err error) {
 	})
 	o.lastModified = time.Now()
 
+	_ = o.eagerMarshalingTimer.Reset(handler.EagerMarshalingCoolDown)
+
 	return nil
 }
 
@@ -256,3 +265,12 @@ func BuildAndRegisterOpenAPIVersionedServiceFromRoutes(servePath string, routeCo
 	}
 	return o, o.RegisterOpenAPIVersionedService(servePath, handler)
 }
+
+func buildEagerMarshalingTimer(o *OpenAPIService) *time.Timer {
+	return time.AfterFunc(
+		time.Duration(math.MaxInt64), // placeholder duration, will be reset later
+		func() {
+			_, _, _ = o.jsonCache.Get()
+			_, _, _ = o.protoCache.Get()
+		})
+}

pkg/handler/handler_test.go

@@ -9,9 +9,11 @@ import (
 	"reflect"
 	"sort"
 	"testing"
+	"time"
 
 	"github.com/davecgh/go-spew/spew"
 	yaml "gopkg.in/yaml.v2"
+	"k8s.io/kube-openapi/pkg/internal/handler"
 	"k8s.io/kube-openapi/pkg/validation/spec"
 )
 
@@ -177,3 +179,36 @@ func TestToProtoBinary(t *testing.T) {
 	}
 	// TODO: add some kind of roundtrip test here
 }
+
+func TestEagerMarshaling(t *testing.T) {
+	jsonCacheLoaded := false
+	protoCacheLoaded := false
+	o := &OpenAPIService{}
+	o.eagerMarshalingTimer = buildEagerMarshalingTimer(o)
+	o.jsonCache = handler.HandlerCache{BuildCache: func() ([]byte, error) {
+		jsonCacheLoaded = true
+		return nil, nil
+	}}
+	o.protoCache = handler.HandlerCache{
+		BuildCache: func() ([]byte, error) {
+			protoCacheLoaded = true
+			return nil, nil
+		},
+	}
+	// kick off the eager marshalling timer
+	_ = o.eagerMarshalingTimer.Reset(time.Microsecond)
+	timeout := time.After(100 * time.Millisecond)
+	for {
+		if jsonCacheLoaded && protoCacheLoaded {
+			// test passed: both cache eager-loaded
+			return
+		}
+		select {
+		case <-timeout:
+			t.Errorf("timeout waiting for cache to eager load")
+			break
+		default:
+			time.Sleep(time.Millisecond)
+		}
+	}
+}

pkg/handler3/handler.go

@@ -21,6 +21,7 @@ import (
 	"crypto/sha512"
 	"encoding/json"
 	"fmt"
+	"math"
 	"mime"
 	"net/http"
 	"sort"
@@ -51,7 +52,6 @@ const (
 
 // OpenAPIService is the service responsible for serving OpenAPI spec. It has
 // the ability to safely change the spec while serving it.
-// OpenAPI V3 currently does not use the lazy marshaling strategy that OpenAPI V2 is using
 type OpenAPIService struct {
 	// rwMutex protects All members of this service.
 	rwMutex      sync.RWMutex
@@ -62,6 +62,10 @@ type OpenAPIService struct {
 type OpenAPIV3Group struct {
 	rwMutex sync.RWMutex
 
+	// eagerMarshalingTimer fires if no updates to the spec are made
+	// for the defined duration.
+	eagerMarshalingTimer *time.Timer
+
 	lastModified time.Time
 
 	pbCache   handler.HandlerCache
@@ -85,6 +89,18 @@ func NewOpenAPIService(spec *spec.Swagger) (*OpenAPIService, error) {
 	return o, nil
 }
 
+// NewOpenAPIGroup builds an empty OpenAPIGroup
+func NewOpenAPIGroup() *OpenAPIV3Group {
+	g := &OpenAPIV3Group{}
+	g.eagerMarshalingTimer = time.AfterFunc(
+		time.Duration(math.MaxInt64), // placeholder duration, will be reset later
+		func() {
+			_, _, _ = g.jsonCache.Get()
+			_, _, _ = g.pbCache.Get()
+		})
+	return g
+}
+
 func (o *OpenAPIService) getGroupBytes() ([]byte, error) {
 	o.rwMutex.RLock()
 	defer o.rwMutex.RUnlock()
@@ -133,7 +149,7 @@ func (o *OpenAPIService) UpdateGroupVersion(group string, openapi *spec3.OpenAPI
 	}
 
 	if _, ok := o.v3Schema[group]; !ok {
-		o.v3Schema[group] = &OpenAPIV3Group{}
+		o.v3Schema[group] = NewOpenAPIGroup()
 	}
 	return o.v3Schema[group].UpdateSpec(specBytes)
 }
@@ -211,6 +227,8 @@ func (o *OpenAPIV3Group) UpdateSpec(specBytes []byte) (err error) {
 	o.rwMutex.Lock()
 	defer o.rwMutex.Unlock()
 
+	_ = o.eagerMarshalingTimer.Reset(handler.EagerMarshalingCoolDown)
+
 	o.pbCache = o.pbCache.New(func() ([]byte, error) {
 		return ToV3ProtoBinary(specBytes)
 	})

pkg/internal/handler/eager.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package handler
+
+import "time"
+
+// EagerMarshalingCoolDown is the duration after the last update to the spec
+// before an eager marshalling of the spec happens.
+var EagerMarshalingCoolDown = 20 * time.Second