Merge pull request #60824 from hzxuzhonghu/requestContextMap-rwlock

Automatic merge from submit-queue (batch tested with PRs 62425, 62212, 60824, 62383, 62384). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

optimize requestcontext: use RWMutex to improve r/w performance

RequestContextMapper is one of the mostly used interface by every request, and the underlying struct is a map with Mutex protect. So here we should use RWMutex.

**Release note**:

```release-note
NONE
```

hack/.golint_failures

@@ -541,6 +541,7 @@ staging/src/k8s.io/apiserver/pkg/endpoints/handlers
 staging/src/k8s.io/apiserver/pkg/endpoints/handlers/negotiation
 staging/src/k8s.io/apiserver/pkg/endpoints/metrics
 staging/src/k8s.io/apiserver/pkg/endpoints/openapi/testing
+staging/src/k8s.io/apiserver/pkg/endpoints/request
 staging/src/k8s.io/apiserver/pkg/endpoints/testing
 staging/src/k8s.io/apiserver/pkg/features
 staging/src/k8s.io/apiserver/pkg/registry/generic

staging/src/k8s.io/apiserver/pkg/endpoints/request/BUILD

@@ -8,11 +8,17 @@ load(
 
 go_test(
     name = "go_default_test",
-    srcs = ["requestinfo_test.go"],
+    srcs = [
+        "context_test.go",
+        "requestcontext_test.go",
+        "requestinfo_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/authentication/user:go_default_library",
     ],
 )
 
@@ -35,17 +41,6 @@ go_library(
     ],
 )
 
-go_test(
-    name = "go_default_xtest",
-    srcs = ["context_test.go"],
-    deps = [
-        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
-        "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
-        "//vendor/k8s.io/apiserver/pkg/authentication/user:go_default_library",
-        "//vendor/k8s.io/apiserver/pkg/endpoints/request:go_default_library",
-    ],
-)
-
 filegroup(
     name = "package-srcs",
     srcs = glob(["**"]),

staging/src/k8s.io/apiserver/pkg/endpoints/request/context.go

@@ -18,7 +18,7 @@ package request
 
 import (
 	"context"
-	stderrs "errors"
+	"errors"
 	"time"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -83,7 +83,7 @@ func NewDefaultContext() Context {
 func WithValue(parent Context, key interface{}, val interface{}) Context {
 	internalCtx, ok := parent.(context.Context)
 	if !ok {
-		panic(stderrs.New("Invalid context type"))
+		panic(errors.New("Invalid context type"))
 	}
 	return context.WithValue(internalCtx, key, val)
 }

staging/src/k8s.io/apiserver/pkg/endpoints/request/context_test.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package request_test
+package request
 
 import (
 	"testing"
@@ -22,13 +22,12 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apiserver/pkg/authentication/user"
-	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 )
 
 // TestNamespaceContext validates that a namespace can be get/set on a context object
 func TestNamespaceContext(t *testing.T) {
-	ctx := genericapirequest.NewDefaultContext()
+	ctx := NewDefaultContext()
-	result, ok := genericapirequest.NamespaceFrom(ctx)
+	result, ok := NamespaceFrom(ctx)
 	if !ok {
 		t.Fatalf("Error getting namespace")
 	}
@@ -36,8 +35,8 @@ func TestNamespaceContext(t *testing.T) {
 		t.Fatalf("Expected: %s, Actual: %s", metav1.NamespaceDefault, result)
 	}
 
-	ctx = genericapirequest.NewContext()
+	ctx = NewContext()
-	result, ok = genericapirequest.NamespaceFrom(ctx)
+	result, ok = NamespaceFrom(ctx)
 	if ok {
 		t.Fatalf("Should not be ok because there is no namespace on the context")
 	}
@@ -45,12 +44,12 @@ func TestNamespaceContext(t *testing.T) {
 
 //TestUserContext validates that a userinfo can be get/set on a context object
 func TestUserContext(t *testing.T) {
-	ctx := genericapirequest.NewContext()
+	ctx := NewContext()
-	_, ok := genericapirequest.UserFrom(ctx)
+	_, ok := UserFrom(ctx)
 	if ok {
 		t.Fatalf("Should not be ok because there is no user.Info on the context")
 	}
-	ctx = genericapirequest.WithUser(
+	ctx = WithUser(
 		ctx,
 		&user.DefaultInfo{
 			Name:   "bob",
@@ -60,7 +59,7 @@ func TestUserContext(t *testing.T) {
 		},
 	)
 
-	result, ok := genericapirequest.UserFrom(ctx)
+	result, ok := UserFrom(ctx)
 	if !ok {
 		t.Fatalf("Error getting user info")
 	}
@@ -96,16 +95,16 @@ func TestUserContext(t *testing.T) {
 
 //TestUIDContext validates that a UID can be get/set on a context object
 func TestUIDContext(t *testing.T) {
-	ctx := genericapirequest.NewContext()
+	ctx := NewContext()
-	_, ok := genericapirequest.UIDFrom(ctx)
+	_, ok := UIDFrom(ctx)
 	if ok {
 		t.Fatalf("Should not be ok because there is no UID on the context")
 	}
-	ctx = genericapirequest.WithUID(
+	ctx = WithUID(
 		ctx,
 		types.UID("testUID"),
 	)
-	_, ok = genericapirequest.UIDFrom(ctx)
+	_, ok = UIDFrom(ctx)
 	if !ok {
 		t.Fatalf("Error getting UID")
 	}
@@ -113,17 +112,17 @@ func TestUIDContext(t *testing.T) {
 
 //TestUserAgentContext validates that a useragent can be get/set on a context object
 func TestUserAgentContext(t *testing.T) {
-	ctx := genericapirequest.NewContext()
+	ctx := NewContext()
-	_, ok := genericapirequest.UserAgentFrom(ctx)
+	_, ok := UserAgentFrom(ctx)
 	if ok {
 		t.Fatalf("Should not be ok because there is no UserAgent on the context")
 	}
 
-	ctx = genericapirequest.WithUserAgent(
+	ctx = WithUserAgent(
 		ctx,
 		"TestUserAgent",
 	)
-	result, ok := genericapirequest.UserAgentFrom(ctx)
+	result, ok := UserAgentFrom(ctx)
 	if !ok {
 		t.Fatalf("Error getting UserAgent")
 	}

staging/src/k8s.io/apiserver/pkg/endpoints/request/requestcontext.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"net/http"
 	"sync"
+	"sync/atomic"
 
 	"github.com/golang/glog"
 )
@@ -40,37 +41,62 @@ type RequestContextMapper interface {
 }
 
 type requestContextMap struct {
-	contexts map[*http.Request]Context
+	// contexts contains a request Context map
-	lock     sync.Mutex
+	// atomic.Value has a very good read performance compared to sync.RWMutex
+	// almost all requests have 3-4 context updates associated with them,
+	// and they can use only read lock to protect updating context, which is of higher performance with higher burst.
+	contexts map[*http.Request]*atomic.Value
+	lock     sync.RWMutex
 }
 
 // NewRequestContextMapper returns a new RequestContextMapper.
 // The returned mapper must be added as a request filter using NewRequestContextFilter.
 func NewRequestContextMapper() RequestContextMapper {
 	return &requestContextMap{
-		contexts: make(map[*http.Request]Context),
+		contexts: make(map[*http.Request]*atomic.Value),
 	}
 }
 
+func (c *requestContextMap) getValue(req *http.Request) (*atomic.Value, bool) {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	value, ok := c.contexts[req]
+	return value, ok
+}
+
+// contextWrap is a wrapper of Context to prevent atomic.Value to be copied
+type contextWrap struct {
+	Context
+}
+
 // Get returns the context associated with the given request (if any), and true if the request has an associated context, and false if it does not.
 // Get will only return a valid context when called from inside the filter chain set up by NewRequestContextFilter()
 func (c *requestContextMap) Get(req *http.Request) (Context, bool) {
-	c.lock.Lock()
+	value, ok := c.getValue(req)
-	defer c.lock.Unlock()
+	if !ok {
-	context, ok := c.contexts[req]
+		return nil, false
-	return context, ok
+	}
+
+	if context, ok := value.Load().(contextWrap); ok {
+		return context.Context, ok
+	}
+
+	return nil, false
 }
 
 // Update maps the request to the given context.
 // If no context was previously associated with the request, an error is returned and the context is ignored.
 func (c *requestContextMap) Update(req *http.Request, context Context) error {
-	c.lock.Lock()
+	value, ok := c.getValue(req)
-	defer c.lock.Unlock()
+	if !ok {
-	if _, ok := c.contexts[req]; !ok {
+		return errors.New("no context associated")
-		return errors.New("No context associated")
 	}
-	// TODO: ensure the new context is a descendant of the existing one
+	wrapper, ok := value.Load().(contextWrap)
-	c.contexts[req] = context
+	if !ok {
+		return errors.New("value type does not match")
+	}
+	wrapper.Context = context
+	value.Store(wrapper)
 	return nil
 }
 
@@ -83,7 +109,10 @@ func (c *requestContextMap) init(req *http.Request, context Context) bool {
 	if _, exists := c.contexts[req]; exists {
 		return false
 	}
-	c.contexts[req] = context
+
+	value := &atomic.Value{}
+	value.Store(contextWrap{context})
+	c.contexts[req] = value
 	return true
 }
 

staging/src/k8s.io/apiserver/pkg/endpoints/request/requestcontext_test.go

@@ -0,0 +1,154 @@
+/*
+Copyright 2018 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 request
+
+import (
+	"net/http"
+	"sync"
+	"testing"
+)
+
+func TestRequestContextMapperGet(t *testing.T) {
+	mapper := NewRequestContextMapper()
+	context := NewContext()
+	req, _ := http.NewRequest("GET", "/api/version/resource", nil)
+
+	// empty mapper
+	if _, ok := mapper.Get(req); ok {
+		t.Fatalf("got unexpected context")
+	}
+
+	// init mapper
+	mapper.(*requestContextMap).init(req, context)
+	if _, ok := mapper.Get(req); !ok {
+		t.Fatalf("got no context")
+	}
+
+	// remove request context
+	mapper.(*requestContextMap).remove(req)
+	if _, ok := mapper.Get(req); ok {
+		t.Fatalf("got unexpected context")
+	}
+
+}
+func TestRequestContextMapperUpdate(t *testing.T) {
+	mapper := NewRequestContextMapper()
+	context := NewContext()
+	req, _ := http.NewRequest("GET", "/api/version/resource", nil)
+
+	// empty mapper
+	if err := mapper.Update(req, context); err == nil {
+		t.Fatalf("got no error")
+	}
+
+	// init mapper
+	if !mapper.(*requestContextMap).init(req, context) {
+		t.Fatalf("unexpected error, should init mapper")
+	}
+
+	context = WithNamespace(context, "default")
+	if err := mapper.Update(req, context); err != nil {
+		t.Fatalf("unexpected error")
+	}
+
+	if context, ok := mapper.Get(req); !ok {
+		t.Fatalf("go no context")
+	} else {
+		if ns, _ := NamespaceFrom(context); ns != "default" {
+			t.Fatalf("unexpected namespace %s", ns)
+		}
+	}
+}
+
+func TestRequestContextMapperConcurrent(t *testing.T) {
+	mapper := NewRequestContextMapper()
+
+	testCases := []struct{ url, namespace string }{
+		{"/api/version/resource1", "ns1"},
+		{"/api/version/resource2", "ns2"},
+		{"/api/version/resource3", "ns3"},
+		{"/api/version/resource4", "ns4"},
+		{"/api/version/resource5", "ns5"},
+	}
+
+	wg := sync.WaitGroup{}
+	for _, testcase := range testCases {
+		wg.Add(1)
+		go func(testcase struct{ url, namespace string }) {
+			defer wg.Done()
+			context := NewContext()
+			req, _ := http.NewRequest("GET", testcase.url, nil)
+
+			if !mapper.(*requestContextMap).init(req, context) {
+				t.Errorf("unexpected init error")
+				return
+			}
+			if _, ok := mapper.Get(req); !ok {
+				t.Errorf("got no context")
+				return
+			}
+			context2 := WithNamespace(context, testcase.namespace)
+			if err := mapper.Update(req, context2); err != nil {
+				t.Errorf("unexpected update error")
+				return
+			}
+			if context, ok := mapper.Get(req); !ok {
+				t.Errorf("got no context")
+				return
+			} else {
+				if ns, _ := NamespaceFrom(context); ns != testcase.namespace {
+					t.Errorf("unexpected namespace %s", ns)
+					return
+				}
+			}
+		}(testcase)
+	}
+	wg.Wait()
+}
+
+func BenchmarkRequestContextMapper(b *testing.B) {
+	mapper := NewRequestContextMapper()
+
+	b.SetParallelism(500)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			context := NewContext()
+			req, _ := http.NewRequest("GET", "/api/version/resource", nil)
+
+			// 1 init
+			mapper.(*requestContextMap).init(req, context)
+
+			// 5 Get + 4 Update
+			mapper.Get(req)
+			context = WithNamespace(context, "default1")
+			mapper.Update(req, context)
+			mapper.Get(req)
+			context = WithNamespace(context, "default2")
+			mapper.Update(req, context)
+			mapper.Get(req)
+			context = WithNamespace(context, "default3")
+			mapper.Update(req, context)
+			mapper.Get(req)
+			context = WithNamespace(context, "default4")
+			mapper.Update(req, context)
+			mapper.Get(req)
+
+			// 1 remove
+			mapper.(*requestContextMap).remove(req)
+		}
+	})
+}