Upgrade k8s.io/client-go to version 2

vendor/k8s.io/client-go/pkg/api/requestcontext.go

@@ -0,0 +1,117 @@
+/*
+Copyright 2014 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 api
+
+import (
+	"errors"
+	"net/http"
+	"sync"
+
+	"github.com/golang/glog"
+)
+
+// RequestContextMapper keeps track of the context associated with a particular request
+type RequestContextMapper interface {
+	// 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(req *http.Request) (Context, bool)
+	// Update maps the request to the given context. If no context was previously associated with the request, an error is returned.
+	// Update should only be called with a descendant context of the previously associated context.
+	// Updating to an unrelated context may return an error in the future.
+	// The context associated with a request should only be updated by a limited set of callers.
+	// Valid examples include the authentication layer, or an audit/tracing layer.
+	Update(req *http.Request, context Context) error
+}
+
+type requestContextMap struct {
+	contexts map[*http.Request]Context
+	lock     sync.Mutex
+}
+
+// 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),
+	}
+}
+
+// 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()
+	defer c.lock.Unlock()
+	context, ok := c.contexts[req]
+	return context, ok
+}
+
+// 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()
+	defer c.lock.Unlock()
+	if _, ok := c.contexts[req]; !ok {
+		return errors.New("No context associated")
+	}
+	// TODO: ensure the new context is a descendant of the existing one
+	c.contexts[req] = context
+	return nil
+}
+
+// init maps the request to the given context and returns true if there was no context associated with the request already.
+// if a context was already associated with the request, it ignores the given context and returns false.
+// init is intentionally unexported to ensure that all init calls are paired with a remove after a request is handled
+func (c *requestContextMap) init(req *http.Request, context Context) bool {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	if _, exists := c.contexts[req]; exists {
+		return false
+	}
+	c.contexts[req] = context
+	return true
+}
+
+// remove is intentionally unexported to ensure that the context is not removed until a request is handled
+func (c *requestContextMap) remove(req *http.Request) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	delete(c.contexts, req)
+}
+
+// WithRequestContext ensures there is a Context object associated with the request before calling the passed handler.
+// After the passed handler runs, the context is cleaned up.
+func WithRequestContext(handler http.Handler, mapper RequestContextMapper) http.Handler {
+	rcMap, ok := mapper.(*requestContextMap)
+	if !ok {
+		glog.Fatal("Unknown RequestContextMapper implementation.")
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		if rcMap.init(req, NewContext()) {
+			// If we were the ones to successfully initialize, pair with a remove
+			defer rcMap.remove(req)
+		}
+		handler.ServeHTTP(w, req)
+	})
+}
+
+// IsEmpty returns true if there are no contexts registered, or an error if it could not be determined. Intended for use by tests.
+func IsEmpty(requestsToContexts RequestContextMapper) (bool, error) {
+	if requestsToContexts, ok := requestsToContexts.(*requestContextMap); ok {
+		return len(requestsToContexts.contexts) == 0, nil
+	}
+	return true, errors.New("Unknown RequestContextMapper implementation")
+}