Merge pull request #47353 from apelisse/http-cache

Godeps/Godeps.json

@@ -1708,6 +1708,14 @@
 			"Rev": "6eb6ad425a89d9da7a5549bc6da8f79ba5c17844"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/grpc-ecosystem/go-grpc-prometheus",
 			"Comment": "v1.1-4-g2500245",
 			"Rev": "2500245aa6110c562d17020fb31a2c133d737799"
@@ -2240,6 +2248,11 @@
 			"Rev": "0049ab3dc4c4c70a9eee23087437b69c0dde2130"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Comment": "v2.0.0-2-g5dfcb07",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pkg/errors",
 			"Comment": "v0.7.0-13-ga221380",
 			"Rev": "a22138067af1c4942683050411a841ade67fe1eb"

Godeps/LICENSES

@@ -59442,6 +59442,34 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 ================================================================================
+= vendor/github.com/gregjones/httpcache licensed under: =
+
+Copyright © 2012 Greg Jones (greg.jones@gmail.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+= vendor/github.com/gregjones/httpcache/LICENSE.txt 3cfef421226b2dacde78a4871380ac24  -
+================================================================================
+
+
+================================================================================
+= vendor/github.com/gregjones/httpcache/diskcache licensed under: =
+
+Copyright © 2012 Greg Jones (greg.jones@gmail.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+= vendor/github.com/gregjones/httpcache/LICENSE.txt 3cfef421226b2dacde78a4871380ac24  -
+================================================================================
+
+
+================================================================================
 = vendor/github.com/grpc-ecosystem/go-grpc-prometheus licensed under: =
 
                  Apache License
@@ -71575,6 +71603,33 @@ SOFTWARE.
 
 
 ================================================================================
+= vendor/github.com/peterbourgon/diskv licensed under: =
+
+Copyright (c) 2011-2012 Peter Bourgon
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+= vendor/github.com/peterbourgon/diskv/LICENSE f9f3e815fc84aa04c4f4db33c553eef9  -
+================================================================================
+
+
+================================================================================
 = vendor/github.com/pkg/errors licensed under: =
 
 Copyright (c) 2015, Dave Cheney <dave@cheney.net>

pkg/kubectl/cmd/get.go

@@ -138,7 +138,6 @@ func NewCmdGet(f cmdutil.Factory, out io.Writer, errOut io.Writer) *cobra.Comman
 	usage := "identifying the resource to get from a server."
 	cmdutil.AddFilenameOptionFlags(cmd, &options.FilenameOptions, usage)
 	cmdutil.AddInclude3rdPartyFlags(cmd)
-	cmdutil.AddOpenAPIFlags(cmd)
 	cmd.Flags().StringVar(&options.Raw, "raw", options.Raw, "Raw URI to request from the server.  Uses the transport specified by the kubeconfig file.")
 	return cmd
 }
@@ -457,7 +456,7 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 			// if cmd does not specify output format and useOpenAPIPrintColumnFlagLabel flag is true,
 			// then get the default output options for this mapping from OpenAPI schema.
 			if !cmdSpecifiesOutputFmt(cmd) && useOpenAPIPrintColumns {
-				outputOpts, _ = outputOptsForMappingFromOpenAPI(f, cmdutil.GetOpenAPICacheDir(cmd), mapping)
+				outputOpts, _ = outputOptsForMappingFromOpenAPI(f, mapping)
 			}
 
 			printer, err = f.PrinterForMapping(cmd, false, outputOpts, mapping, allNamespaces)
@@ -556,11 +555,11 @@ func cmdSpecifiesOutputFmt(cmd *cobra.Command) bool {
 
 // outputOptsForMappingFromOpenAPI looks for the output format metatadata in the
 // openapi schema and returns the output options for the mapping if found.
-func outputOptsForMappingFromOpenAPI(f cmdutil.Factory, openAPIcacheDir string, mapping *meta.RESTMapping) (*printers.OutputOptions, bool) {
+func outputOptsForMappingFromOpenAPI(f cmdutil.Factory, mapping *meta.RESTMapping) (*printers.OutputOptions, bool) {
 
 	// user has not specified any output format, check if OpenAPI has
 	// default specification to print this resource type
-	api, err := f.OpenAPISchema(openAPIcacheDir)
+	api, err := f.OpenAPISchema()
 	if err != nil {
 		// Error getting schema
 		return nil, false

pkg/kubectl/cmd/testing/fake.go

@@ -418,7 +418,7 @@ func (f *FakeFactory) SwaggerSchema(schema.GroupVersionKind) (*swagger.ApiDeclar
 	return nil, nil
 }
 
-func (f *FakeFactory) OpenAPISchema(cacheDir string) (openapi.Resources, error) {
+func (f *FakeFactory) OpenAPISchema() (openapi.Resources, error) {
 	return nil, nil
 }
 
@@ -756,7 +756,7 @@ func (f *fakeAPIFactory) SwaggerSchema(schema.GroupVersionKind) (*swagger.ApiDec
 	return nil, nil
 }
 
-func (f *fakeAPIFactory) OpenAPISchema(cacheDir string) (openapi.Resources, error) {
+func (f *fakeAPIFactory) OpenAPISchema() (openapi.Resources, error) {
 	if f.tf.OpenAPISchemaFunc != nil {
 		return f.tf.OpenAPISchemaFunc()
 	}

pkg/kubectl/cmd/util/factory.go

@@ -224,7 +224,7 @@ type ObjectMappingFactory interface {
 	// SwaggerSchema returns the schema declaration for the provided group version kind.
 	SwaggerSchema(schema.GroupVersionKind) (*swagger.ApiDeclaration, error)
 	// OpenAPISchema returns the schema openapi schema definiton
-	OpenAPISchema(cacheDir string) (openapi.Resources, error)
+	OpenAPISchema() (openapi.Resources, error)
 }
 
 // BuilderFactory holds the second level of factory methods.  These functions depend upon ObjectMappingFactory and ClientAccessFactory methods.

pkg/kubectl/cmd/util/factory_object_mapping.go

@@ -439,13 +439,7 @@ func (f *ring1Factory) SwaggerSchema(gvk schema.GroupVersionKind) (*swagger.ApiD
 }
 
 // OpenAPISchema returns metadata and structural information about Kubernetes object definitions.
-// Will try to cache the data to a local file.  Cache is written and read from a
-// file created with ioutil.TempFile and obeys the expiration semantics of that file.
-// The cache location is a function of the client and server versions so that the open API
-// schema will be cached separately for different client / server combinations.
-// Note, the cache will not be invalidated if the server changes its open API schema without
-// changing the server version.
-func (f *ring1Factory) OpenAPISchema(cacheDir string) (openapi.Resources, error) {
+func (f *ring1Factory) OpenAPISchema() (openapi.Resources, error) {
 	discovery, err := f.clientAccessFactory.DiscoveryClient()
 	if err != nil {
 		return nil, err
@@ -453,23 +447,8 @@ func (f *ring1Factory) OpenAPISchema(cacheDir string) (openapi.Resources, error)
 
 	// Lazily initialize the OpenAPIGetter once
 	f.openAPIGetter.once.Do(func() {
-		// Get the server version for caching the openapi spec
-		versionString := ""
-		version, err := discovery.ServerVersion()
-		if err != nil {
-			// Cache the result under the server version
-			versionString = version.String()
-		}
-
-		// Get the cache directory for caching the openapi spec
-		cacheDir, err = substituteUserHome(cacheDir)
-		if err != nil {
-			// Don't cache the result if we couldn't substitute the home directory
-			cacheDir = ""
-		}
-
 		// Create the caching OpenAPIGetter
-		f.openAPIGetter.getter = openapi.NewOpenAPIGetter(cacheDir, versionString, discovery)
+		f.openAPIGetter.getter = openapi.NewOpenAPIGetter(discovery)
 	})
 
 	// Delegate to the OpenAPIGetter

pkg/kubectl/cmd/util/helpers.go

@@ -404,19 +404,6 @@ func AddValidateOptionFlags(cmd *cobra.Command, options *ValidateOptions) {
 	cmd.MarkFlagFilename("schema-cache-dir")
 }
 
-func AddOpenAPIFlags(cmd *cobra.Command) {
-	cmd.Flags().String("schema-cache-dir",
-		fmt.Sprintf("~/%s/%s", clientcmd.RecommendedHomeDir, clientcmd.RecommendedSchemaName),
-		fmt.Sprintf("If non-empty, load/store cached API schemas in this directory, default is '$HOME/%s/%s'",
-			clientcmd.RecommendedHomeDir, clientcmd.RecommendedSchemaName),
-	)
-	cmd.MarkFlagFilename("schema-cache-dir")
-}
-
-func GetOpenAPICacheDir(cmd *cobra.Command) string {
-	return GetFlagString(cmd, "schema-cache-dir")
-}
-
 func AddFilenameOptionFlags(cmd *cobra.Command, options *resource.FilenameOptions, usage string) {
 	kubectl.AddJsonFilenameFlag(cmd, &options.Filenames, "Filename, directory, or URL to files "+usage)
 	cmd.Flags().BoolVarP(&options.Recursive, "recursive", "R", options.Recursive, "Process the directory used in -f, --filename recursively. Useful when you want to manage related manifests organized within the same directory.")

pkg/kubectl/cmd/util/openapi/BUILD

@@ -15,15 +15,11 @@ go_library(
         "document.go",
         "extensions.go",
         "openapi.go",
-        "openapi_cache.go",
         "openapi_getter.go",
     ],
     tags = ["automanaged"],
     deps = [
-        "//pkg/version:go_default_library",
         "//vendor/github.com/go-openapi/spec:go_default_library",
-        "//vendor/github.com/golang/glog:go_default_library",
-        "//vendor/github.com/golang/protobuf/proto:go_default_library",
         "//vendor/github.com/googleapis/gnostic/OpenAPIv2:go_default_library",
         "//vendor/gopkg.in/yaml.v2:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
@@ -35,7 +31,6 @@ go_test(
     name = "go_default_xtest",
     size = "small",
     srcs = [
-        "openapi_cache_test.go",
         "openapi_getter_test.go",
         "openapi_suite_test.go",
         "openapi_test.go",

pkg/kubectl/cmd/util/openapi/openapi_cache.go

-/*
-Copyright 2017 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 openapi
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-
-	"github.com/golang/glog"
-	"github.com/golang/protobuf/proto"
-	openapi_v2 "github.com/googleapis/gnostic/OpenAPIv2"
-
-	"k8s.io/client-go/discovery"
-	"k8s.io/kubernetes/pkg/version"
-)
-
-const openapiFileName = "openapi_cache"
-
-type CachingOpenAPIClient struct {
-	version      string
-	client       discovery.OpenAPISchemaInterface
-	cacheDirName string
-}
-
-// NewCachingOpenAPIClient returns a new discovery.OpenAPISchemaInterface
-// that will read the openapi spec from a local cache if it exists, and
-// if not will then fetch an openapi spec using a client.
-// client: used to fetch a new openapi spec if a local cache is not found
-// version: the server version and used as part of the cache file location
-// cacheDir: the directory under which the cache file will be written
-func NewCachingOpenAPIClient(client discovery.OpenAPISchemaInterface, version, cacheDir string) *CachingOpenAPIClient {
-	return &CachingOpenAPIClient{
-		client:       client,
-		version:      version,
-		cacheDirName: cacheDir,
-	}
-}
-
-// OpenAPIData returns an openapi spec.
-// It will first attempt to read the spec from a local cache
-// If it cannot read a local cache, it will read the file
-// using the client and then write the cache.
-func (c *CachingOpenAPIClient) OpenAPIData() (Resources, error) {
-	// Try to use the cached version
-	if c.useCache() {
-		doc, err := c.readOpenAPICache()
-		if err == nil {
-			return NewOpenAPIData(doc)
-		}
-	}
-
-	// No cached version found, download from server
-	s, err := c.client.OpenAPISchema()
-	if err != nil {
-		glog.V(2).Infof("Failed to download openapi data %v", err)
-		return nil, err
-	}
-
-	oa, err := NewOpenAPIData(s)
-	if err != nil {
-		glog.V(2).Infof("Failed to parse openapi data %v", err)
-		return nil, err
-	}
-
-	// Try to cache the openapi spec
-	if c.useCache() {
-		err = c.writeToCache(s)
-		if err != nil {
-			// Just log an message, no need to fail the command since we got the data we need
-			glog.V(2).Infof("Unable to cache openapi spec %v", err)
-		}
-	}
-
-	// Return the parsed data
-	return oa, nil
-}
-
-// useCache returns true if the client should try to use the cache file
-func (c *CachingOpenAPIClient) useCache() bool {
-	return len(c.version) > 0 && len(c.cacheDirName) > 0
-}
-
-// readOpenAPICache tries to read the openapi spec from the local file cache
-func (c *CachingOpenAPIClient) readOpenAPICache() (*openapi_v2.Document, error) {
-	// Get the filename to read
-	filename := c.openAPICacheFilename()
-
-	// Read the cached file
-	data, err := ioutil.ReadFile(filename)
-	if err != nil {
-		return nil, err
-	}
-
-	doc := &openapi_v2.Document{}
-	return doc, proto.Unmarshal(data, doc)
-}
-
-// writeToCache tries to write the openapi spec to the local file cache.
-// writes the data to a new tempfile, and then links the cache file and the tempfile
-func (c *CachingOpenAPIClient) writeToCache(doc *openapi_v2.Document) error {
-	// Get the constant filename used to read the cache.
-	cacheFile := c.openAPICacheFilename()
-
-	// Binary encode the spec.  This is 10x as fast as using json encoding.  (60ms vs 600ms)
-	b, err := proto.Marshal(doc)
-	if err != nil {
-		return fmt.Errorf("Could not binary encode openapi spec: %v", err)
-	}
-
-	// Create a new temp file for the cached openapi spec.
-	cacheDir := filepath.Dir(cacheFile)
-	if err := os.MkdirAll(cacheDir, 0755); err != nil {
-		return fmt.Errorf("Could not create directory: %v %v", cacheDir, err)
-	}
-	tmpFile, err := ioutil.TempFile(cacheDir, "openapi")
-	if err != nil {
-		return fmt.Errorf("Could not create temp cache file: %v %v", cacheFile, err)
-	}
-
-	// Write the binary encoded openapi spec to the temp file
-	if _, err := io.Copy(tmpFile, bytes.NewBuffer(b)); err != nil {
-		return fmt.Errorf("Could not write temp cache file: %v", err)
-	}
-
-	// Link the temp cache file to the constant cache filepath
-	return linkFiles(tmpFile.Name(), cacheFile)
-}
-
-// openAPICacheFilename returns the filename to read the cache from
-func (c *CachingOpenAPIClient) openAPICacheFilename() string {
-	// Cache using the client and server versions
-	return filepath.Join(c.cacheDirName, c.version, version.Get().GitVersion, openapiFileName)
-}
-
-// linkFiles links the old file to the new file
-func linkFiles(old, new string) error {
-	if err := os.Link(old, new); err != nil {
-		// If we can't write due to file existing, or permission problems, keep going.
-		if os.IsExist(err) || os.IsPermission(err) {
-			return nil
-		}
-		return err
-	}
-	return nil
-}

pkg/kubectl/cmd/util/openapi/openapi_cache_test.go

-/*
-Copyright 2017 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 openapi_test
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"sync"
-
-	"gopkg.in/yaml.v2"
-
-	"github.com/googleapis/gnostic/OpenAPIv2"
-	"github.com/googleapis/gnostic/compiler"
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
-
-	"k8s.io/kubernetes/pkg/kubectl/cmd/util/openapi"
-)
-
-var _ = Describe("When reading openAPIData", func() {
-	var tmpDir string
-	var err error
-	var client *fakeOpenAPIClient
-	var instance *openapi.CachingOpenAPIClient
-	var expectedData openapi.Resources
-
-	BeforeEach(func() {
-		tmpDir, err = ioutil.TempDir("", "openapi_cache_test")
-		Expect(err).To(BeNil())
-		client = &fakeOpenAPIClient{}
-		instance = openapi.NewCachingOpenAPIClient(client, "v1.6", tmpDir)
-
-		d, err := data.OpenAPISchema()
-		Expect(err).To(BeNil())
-
-		expectedData, err = openapi.NewOpenAPIData(d)
-		Expect(err).To(BeNil())
-	})
-
-	AfterEach(func() {
-		os.RemoveAll(tmpDir)
-	})
-
-	It("should write to the cache", func() {
-		By("getting the live openapi spec from the server")
-		result, err := instance.OpenAPIData()
-		Expect(err).To(BeNil())
-		Expect(result).To(Equal(expectedData))
-		Expect(client.calls).To(Equal(1))
-
-		By("writing the live openapi spec to a local cache file")
-		names, err := getFilenames(tmpDir)
-		Expect(err).To(BeNil())
-		Expect(names).To(ConsistOf("v1.6"))
-
-		names, err = getFilenames(filepath.Join(tmpDir, "v1.6"))
-		Expect(err).To(BeNil())
-		Expect(names).To(HaveLen(1))
-		clientVersion := names[0]
-
-		names, err = getFilenames(filepath.Join(tmpDir, "v1.6", clientVersion))
-		Expect(err).To(BeNil())
-		Expect(names).To(ContainElement("openapi_cache"))
-	})
-
-	It("should read from the cache", func() {
-		// First call should use the client
-		result, err := instance.OpenAPIData()
-		Expect(err).To(BeNil())
-		Expect(result).To(Equal(expectedData))
-		Expect(client.calls).To(Equal(1))
-
-		// Second call shouldn't use the client
-		result, err = instance.OpenAPIData()
-		Expect(err).To(BeNil())
-		Expect(result).To(Equal(expectedData))
-		Expect(client.calls).To(Equal(1))
-
-		names, err := getFilenames(tmpDir)
-		Expect(err).To(BeNil())
-		Expect(names).To(ConsistOf("v1.6"))
-	})
-
-	It("propagate errors that are encountered", func() {
-		// Expect an error
-		client.err = fmt.Errorf("expected error")
-		result, err := instance.OpenAPIData()
-		Expect(err.Error()).To(Equal(client.err.Error()))
-		Expect(result).To(BeNil())
-		Expect(client.calls).To(Equal(1))
-
-		// No cache file is written
-		files, err := ioutil.ReadDir(tmpDir)
-		Expect(err).To(BeNil())
-		Expect(files).To(HaveLen(0))
-
-		// Client error is not cached
-		result, err = instance.OpenAPIData()
-		Expect(err.Error()).To(Equal(client.err.Error()))
-		Expect(result).To(BeNil())
-		Expect(client.calls).To(Equal(2))
-	})
-})
-
-var _ = Describe("Reading openAPIData", func() {
-	var tmpDir string
-	var serverVersion string
-	var cacheDir string
-
-	BeforeEach(func() {
-		var err error
-		tmpDir, err = ioutil.TempDir("", "openapi_cache_test")
-		Expect(err).To(BeNil())
-	})
-
-	AfterEach(func() {
-		os.RemoveAll(tmpDir)
-	})
-
-	// Set the serverVersion to empty
-	Context("when the server version is empty", func() {
-		BeforeEach(func() {
-			serverVersion = ""
-			cacheDir = tmpDir
-		})
-		It("should not cache the result", func() {
-			client := &fakeOpenAPIClient{}
-
-			instance := openapi.NewCachingOpenAPIClient(client, serverVersion, cacheDir)
-
-			d, err := data.OpenAPISchema()
-			Expect(err).To(BeNil())
-
-			expectedData, err := openapi.NewOpenAPIData(d)
-			Expect(err).To(BeNil())
-
-			By("getting the live openapi schema")
-			result, err := instance.OpenAPIData()
-			Expect(err).To(BeNil())
-			Expect(result).To(Equal(expectedData))
-			Expect(client.calls).To(Equal(1))
-
-			files, err := ioutil.ReadDir(tmpDir)
-			Expect(err).To(BeNil())
-			Expect(files).To(HaveLen(0))
-		})
-	})
-
-	Context("when the cache directory is empty", func() {
-		BeforeEach(func() {
-			serverVersion = "v1.6"
-			cacheDir = ""
-		})
-		It("should not cache the result", func() {
-			client := &fakeOpenAPIClient{}
-
-			instance := openapi.NewCachingOpenAPIClient(client, serverVersion, cacheDir)
-
-			d, err := data.OpenAPISchema()
-			Expect(err).To(BeNil())
-
-			expectedData, err := openapi.NewOpenAPIData(d)
-			Expect(err).To(BeNil())
-
-			By("getting the live openapi schema")
-			result, err := instance.OpenAPIData()
-			Expect(err).To(BeNil())
-			Expect(result).To(Equal(expectedData))
-			Expect(client.calls).To(Equal(1))
-
-			files, err := ioutil.ReadDir(tmpDir)
-			Expect(err).To(BeNil())
-			Expect(files).To(HaveLen(0))
-		})
-	})
-})
-
-// Test Utils
-func getFilenames(path string) ([]string, error) {
-	files, err := ioutil.ReadDir(path)
-	if err != nil {
-		return nil, err
-	}
-	result := []string{}
-	for _, n := range files {
-		result = append(result, n.Name())
-	}
-	return result, nil
-}
-
-type fakeOpenAPIClient struct {
-	calls int
-	err   error
-}
-
-func (f *fakeOpenAPIClient) OpenAPISchema() (*openapi_v2.Document, error) {
-	f.calls = f.calls + 1
-
-	if f.err != nil {
-		return nil, f.err
-	}
-
-	return data.OpenAPISchema()
-}
-
-// Test utils
-var data apiData
-
-type apiData struct {
-	sync.Once
-	data *openapi_v2.Document
-	err  error
-}
-
-func (d *apiData) OpenAPISchema() (*openapi_v2.Document, error) {
-	d.Do(func() {
-		// Get the path to the swagger.json file
-		wd, err := os.Getwd()
-		if err != nil {
-			d.err = err
-			return
-		}
-
-		abs, err := filepath.Abs(wd)
-		if err != nil {
-			d.err = err
-			return
-		}
-
-		root := filepath.Dir(filepath.Dir(filepath.Dir(filepath.Dir(filepath.Dir(abs)))))
-		specpath := filepath.Join(root, "api", "openapi-spec", "swagger.json")
-		_, err = os.Stat(specpath)
-		if err != nil {
-			d.err = err
-			return
-		}
-		spec, err := ioutil.ReadFile(specpath)
-		if err != nil {
-			d.err = err
-			return
-		}
-		var info yaml.MapSlice
-		err = yaml.Unmarshal(spec, &info)
-		if err != nil {
-			d.err = err
-			return
-		}
-		d.data, d.err = openapi_v2.NewDocument(info, compiler.NewContext("$root", nil))
-	})
-
-	return d.data, d.err
-}

pkg/kubectl/cmd/util/openapi/openapi_getter.go

@@ -29,8 +29,6 @@ type synchronizedOpenAPIGetter struct {
 	openAPISchema Resources
 	err           error
 
-	serverVersion string
-	cacheDir      string
 	openAPIClient discovery.OpenAPISchemaInterface
 }
 
@@ -42,12 +40,10 @@ type Getter interface {
 	Get() (Resources, error)
 }
 
-// NewOpenAPIGetter returns an object to return OpenAPIDatas which either read from a
-// local file cache or read from a server, and then stored in memory for subsequent invocations
-func NewOpenAPIGetter(cacheDir, serverVersion string, openAPIClient discovery.OpenAPISchemaInterface) Getter {
+// NewOpenAPIGetter returns an object to return OpenAPIDatas which reads
+// from a server, and then stores in memory for subsequent invocations
+func NewOpenAPIGetter(openAPIClient discovery.OpenAPISchemaInterface) Getter {
 	return &synchronizedOpenAPIGetter{
-		serverVersion: serverVersion,
-		cacheDir:      cacheDir,
 		openAPIClient: openAPIClient,
 	}
 }
@@ -55,15 +51,13 @@ func NewOpenAPIGetter(cacheDir, serverVersion string, openAPIClient discovery.Op
 // Resources implements Getter
 func (g *synchronizedOpenAPIGetter) Get() (Resources, error) {
 	g.Do(func() {
-		client := NewCachingOpenAPIClient(g.openAPIClient, g.serverVersion, g.cacheDir)
-		result, err := client.OpenAPIData()
+		s, err := g.openAPIClient.OpenAPISchema()
 		if err != nil {
 			g.err = err
 			return
 		}
 
-		// Save the result
-		g.openAPISchema = result
+		g.openAPISchema, g.err = NewOpenAPIData(s)
 	})
 
 	// Return the save result

pkg/kubectl/cmd/util/openapi/openapi_getter_test.go

@@ -18,13 +18,83 @@ package openapi_test
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
 
+	"gopkg.in/yaml.v2"
+
+	"github.com/googleapis/gnostic/OpenAPIv2"
+	"github.com/googleapis/gnostic/compiler"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 
 	"k8s.io/kubernetes/pkg/kubectl/cmd/util/openapi"
 )
 
+// Test utils
+var data apiData
+
+type apiData struct {
+	sync.Once
+	data *openapi_v2.Document
+	err  error
+}
+
+func (d *apiData) OpenAPISchema() (*openapi_v2.Document, error) {
+	d.Do(func() {
+		// Get the path to the swagger.json file
+		wd, err := os.Getwd()
+		if err != nil {
+			d.err = err
+			return
+		}
+
+		abs, err := filepath.Abs(wd)
+		if err != nil {
+			d.err = err
+			return
+		}
+
+		root := filepath.Dir(filepath.Dir(filepath.Dir(filepath.Dir(filepath.Dir(abs)))))
+		specpath := filepath.Join(root, "api", "openapi-spec", "swagger.json")
+		_, err = os.Stat(specpath)
+		if err != nil {
+			d.err = err
+			return
+		}
+		spec, err := ioutil.ReadFile(specpath)
+		if err != nil {
+			d.err = err
+			return
+		}
+		var info yaml.MapSlice
+		err = yaml.Unmarshal(spec, &info)
+		if err != nil {
+			d.err = err
+			return
+		}
+		d.data, d.err = openapi_v2.NewDocument(info, compiler.NewContext("$root", nil))
+	})
+	return d.data, d.err
+}
+
+type fakeOpenAPIClient struct {
+	calls int
+	err   error
+}
+
+func (f *fakeOpenAPIClient) OpenAPISchema() (*openapi_v2.Document, error) {
+	f.calls = f.calls + 1
+
+	if f.err != nil {
+		return nil, f.err
+	}
+
+	return data.OpenAPISchema()
+}
+
 var _ = Describe("Getting the Resources", func() {
 	var client *fakeOpenAPIClient
 	var expectedData openapi.Resources
@@ -38,7 +108,7 @@ var _ = Describe("Getting the Resources", func() {
 		expectedData, err = openapi.NewOpenAPIData(d)
 		Expect(err).To(BeNil())
 
-		instance = openapi.NewOpenAPIGetter("", "", client)
+		instance = openapi.NewOpenAPIGetter(client)
 	})
 
 	Context("when the server returns a successful result", func() {

staging/src/k8s.io/apiextensions-apiserver/Godeps/Godeps.json

@@ -163,6 +163,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -179,6 +183,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/grpc-ecosystem/go-grpc-prometheus",
 			"Rev": "2500245aa6110c562d17020fb31a2c133d737799"
 		},
@@ -243,6 +255,10 @@
 			"Rev": "ca53cad383cad2479bbba7f7a1a05797ec1386e4"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pkg/errors",
 			"Rev": "a22138067af1c4942683050411a841ade67fe1eb"
 		},

staging/src/k8s.io/apiserver/Godeps/Godeps.json

@@ -431,6 +431,14 @@
 			"Rev": "ed590d9afe113c6107cd60717b196155e6579e78"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/grpc-ecosystem/go-grpc-prometheus",
 			"Rev": "2500245aa6110c562d17020fb31a2c133d737799"
 		},
@@ -499,6 +507,10 @@
 			"Rev": "ca53cad383cad2479bbba7f7a1a05797ec1386e4"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pkg/errors",
 			"Rev": "a22138067af1c4942683050411a841ade67fe1eb"
 		},

staging/src/k8s.io/client-go/Godeps/Godeps.json

@@ -155,6 +155,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -171,6 +175,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/hashicorp/golang-lru",
 			"Rev": "a0d98a5f288019575c6d1f4bb1573fef2d1fcdc4"
 		},
@@ -207,6 +219,10 @@
 			"Rev": "d5b7844b561a7bc640052f1b935f7b800330d7e0"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pmezard/go-difflib/difflib",
 			"Rev": "d8ed2627bdf02c080bf22230dbb337003b7aba2d"
 		},

staging/src/k8s.io/client-go/rest/config.go

@@ -71,6 +71,10 @@ type Config struct {
 	// TODO: demonstrate an OAuth2 compatible client.
 	BearerToken string
 
+	// CacheDir is the directory where we'll store HTTP cached responses.
+	// If set to empty string, no caching mechanism will be used.
+	CacheDir string
+
 	// Impersonate is the configuration that RESTClient will use for impersonation.
 	Impersonate ImpersonationConfig
 

staging/src/k8s.io/client-go/rest/config_test.go

@@ -249,6 +249,7 @@ func TestAnonymousConfig(t *testing.T) {
 		expected.BearerToken = ""
 		expected.Username = ""
 		expected.Password = ""
+		expected.CacheDir = ""
 		expected.AuthProvider = nil
 		expected.AuthConfigPersister = nil
 		expected.TLSClientConfig.CertData = nil

staging/src/k8s.io/client-go/rest/transport.go

@@ -89,6 +89,7 @@ func (c *Config) TransportConfig() (*transport.Config, error) {
 		},
 		Username:    c.Username,
 		Password:    c.Password,
+		CacheDir:    c.CacheDir,
 		BearerToken: c.BearerToken,
 		Impersonate: transport.ImpersonationConfig{
 			UserName: c.Impersonate.UserName,

staging/src/k8s.io/client-go/tools/clientcmd/client_config.go

@@ -22,6 +22,7 @@ import (
 	"io/ioutil"
 	"net/url"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/golang/glog"
@@ -31,16 +32,19 @@ import (
 	restclient "k8s.io/client-go/rest"
 	clientauth "k8s.io/client-go/tools/auth"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	"k8s.io/client-go/util/homedir"
 )
 
 var (
 	// ClusterDefaults has the same behavior as the old EnvVar and DefaultCluster fields
 	// DEPRECATED will be replaced
 	ClusterDefaults = clientcmdapi.Cluster{Server: getDefaultServer()}
+	cacheDirDefault = filepath.Join(homedir.HomeDir(), ".kube", "http-cache")
 	// DefaultClientConfig represents the legacy behavior of this package for defaulting
 	// DEPRECATED will be replace
 	DefaultClientConfig = DirectClientConfig{*clientcmdapi.NewConfig(), "", &ConfigOverrides{
 		ClusterDefaults: ClusterDefaults,
+		CacheDir:        cacheDirDefault,
 	}, nil, NewDefaultClientConfigLoadingRules(), promptedCredentials{}}
 )
 
@@ -131,6 +135,7 @@ func (config *DirectClientConfig) ClientConfig() (*restclient.Config, error) {
 
 	clientConfig := &restclient.Config{}
 	clientConfig.Host = configClusterInfo.Server
+	clientConfig.CacheDir = config.overrides.CacheDir
 
 	if len(config.overrides.Timeout) > 0 {
 		timeout, err := ParseTimeout(config.overrides.Timeout)

staging/src/k8s.io/client-go/tools/clientcmd/overrides.go

@@ -17,11 +17,13 @@ limitations under the License.
 package clientcmd
 
 import (
+	"path/filepath"
 	"strconv"
 
 	"github.com/spf13/pflag"
 
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	"k8s.io/client-go/util/homedir"
 )
 
 // ConfigOverrides holds values that should override whatever information is pulled from the actual Config object.  You can't
@@ -34,6 +36,7 @@ type ConfigOverrides struct {
 	Context         clientcmdapi.Context
 	CurrentContext  string
 	Timeout         string
+	CacheDir        string
 }
 
 // ConfigOverrideFlags holds the flag names to be used for binding command line flags.  Notice that this structure tightly
@@ -44,6 +47,7 @@ type ConfigOverrideFlags struct {
 	ContextOverrideFlags ContextOverrideFlags
 	CurrentContext       FlagInfo
 	Timeout              FlagInfo
+	CacheDir             FlagInfo
 }
 
 // AuthOverrideFlags holds the flag names to be used for binding command line flags for AuthInfo objects
@@ -146,10 +150,12 @@ const (
 	FlagUsername         = "username"
 	FlagPassword         = "password"
 	FlagTimeout          = "request-timeout"
+	FlagCacheDir         = "cachedir"
 )
 
 // RecommendedConfigOverrideFlags is a convenience method to return recommended flag names prefixed with a string of your choosing
 func RecommendedConfigOverrideFlags(prefix string) ConfigOverrideFlags {
+	defaultCacheDir := filepath.Join(homedir.HomeDir(), ".kube", "http-cache")
 	return ConfigOverrideFlags{
 		AuthOverrideFlags:    RecommendedAuthOverrideFlags(prefix),
 		ClusterOverrideFlags: RecommendedClusterOverrideFlags(prefix),
@@ -157,6 +163,7 @@ func RecommendedConfigOverrideFlags(prefix string) ConfigOverrideFlags {
 
 		CurrentContext: FlagInfo{prefix + FlagContext, "", "", "The name of the kubeconfig context to use"},
 		Timeout:        FlagInfo{prefix + FlagTimeout, "", "0", "The length of time to wait before giving up on a single server request. Non-zero values should contain a corresponding time unit (e.g. 1s, 2m, 3h). A value of zero means don't timeout requests."},
+		CacheDir:       FlagInfo{prefix + FlagCacheDir, "", defaultCacheDir, "Path to http-cache directory"},
 	}
 }
 
@@ -198,6 +205,7 @@ func BindOverrideFlags(overrides *ConfigOverrides, flags *pflag.FlagSet, flagNam
 	BindContextFlags(&overrides.Context, flags, flagNames.ContextOverrideFlags)
 	flagNames.CurrentContext.BindStringFlag(flags, &overrides.CurrentContext)
 	flagNames.Timeout.BindStringFlag(flags, &overrides.Timeout)
+	flagNames.CacheDir.BindStringFlag(flags, &overrides.CacheDir)
 }
 
 // BindAuthInfoFlags is a convenience method to bind the specified flags to their associated variables

staging/src/k8s.io/client-go/transport/BUILD

@@ -30,6 +30,9 @@ go_library(
     tags = ["automanaged"],
     deps = [
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/gregjones/httpcache:go_default_library",
+        "//vendor/github.com/gregjones/httpcache/diskcache:go_default_library",
+        "//vendor/github.com/peterbourgon/diskv:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/net:go_default_library",
     ],
 )

staging/src/k8s.io/client-go/transport/config.go

@@ -34,6 +34,10 @@ type Config struct {
 	// Bearer token for authentication
 	BearerToken string
 
+	// CacheDir is the directory where we'll store HTTP cached responses.
+	// If set to empty string, no caching mechanism will be used.
+	CacheDir string
+
 	// Impersonate is the config that this Config will impersonate using
 	Impersonate ImpersonationConfig
 

staging/src/k8s.io/client-go/transport/round_trippers.go

@@ -23,6 +23,9 @@ import (
 	"time"
 
 	"github.com/golang/glog"
+	"github.com/gregjones/httpcache"
+	"github.com/gregjones/httpcache/diskcache"
+	"github.com/peterbourgon/diskv"
 
 	utilnet "k8s.io/apimachinery/pkg/util/net"
 )
@@ -56,6 +59,9 @@ func HTTPWrappersForConfig(config *Config, rt http.RoundTripper) (http.RoundTrip
 		len(config.Impersonate.Extra) > 0 {
 		rt = NewImpersonatingRoundTripper(config.Impersonate, rt)
 	}
+	if len(config.CacheDir) > 0 {
+		rt = NewCacheRoundTripper(config.CacheDir, rt)
+	}
 	return rt, nil
 }
 
@@ -87,6 +93,17 @@ type authProxyRoundTripper struct {
 	rt http.RoundTripper
 }
 
+// NewCacheRoundTripper creates a roundtripper that reads the ETag on
+// response headers and send the If-None-Match header on subsequent
+// corresponding requests.
+func NewCacheRoundTripper(cacheDir string, rt http.RoundTripper) http.RoundTripper {
+	d := diskv.New(diskv.Options{BasePath: cacheDir})
+	t := httpcache.NewTransport(diskcache.NewWithDiskv(d))
+	t.Transport = rt
+
+	return t
+}
+
 // NewAuthProxyRoundTripper provides a roundtripper which will add auth proxy fields to requests for
 // authentication terminating proxy cases
 // assuming you pull the user from the context:

staging/src/k8s.io/client-go/transport/round_trippers_test.go

@@ -17,7 +17,11 @@ limitations under the License.
 package transport
 
 import (
+	"bytes"
+	"io/ioutil"
 	"net/http"
+	"net/url"
+	"os"
 	"reflect"
 	"strings"
 	"testing"
@@ -216,3 +220,60 @@ func TestAuthProxyRoundTripper(t *testing.T) {
 		}
 	}
 }
+
+func TestCacheRoundTripper(t *testing.T) {
+	rt := &testRoundTripper{}
+	cacheDir, err := ioutil.TempDir("", "cache-rt")
+	defer os.RemoveAll(cacheDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cache := NewCacheRoundTripper(cacheDir, rt)
+
+	// First call, caches the response
+	req := &http.Request{
+		Method: http.MethodGet,
+		URL:    &url.URL{Host: "localhost"},
+	}
+	rt.Response = &http.Response{
+		Header:     http.Header{"ETag": []string{`"123456"`}},
+		Body:       ioutil.NopCloser(bytes.NewReader([]byte("Content"))),
+		StatusCode: http.StatusOK,
+	}
+	resp, err := cache.RoundTrip(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	content, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(content) != "Content" {
+		t.Errorf(`Expected Body to be "Content", got %q`, string(content))
+	}
+
+	// Second call, returns cached response
+	req = &http.Request{
+		Method: http.MethodGet,
+		URL:    &url.URL{Host: "localhost"},
+	}
+	rt.Response = &http.Response{
+		StatusCode: http.StatusNotModified,
+		Body:       ioutil.NopCloser(bytes.NewReader([]byte("Other Content"))),
+	}
+
+	resp, err = cache.RoundTrip(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Read body and make sure we have the initial content
+	content, err = ioutil.ReadAll(resp.Body)
+	resp.Body.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(content) != "Content" {
+		t.Errorf("Invalid content read from cache %q", string(content))
+	}
+}

staging/src/k8s.io/kube-aggregator/Godeps/Godeps.json

@@ -171,6 +171,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -187,6 +191,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/grpc-ecosystem/go-grpc-prometheus",
 			"Rev": "2500245aa6110c562d17020fb31a2c133d737799"
 		},
@@ -251,6 +263,10 @@
 			"Rev": "ca53cad383cad2479bbba7f7a1a05797ec1386e4"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pkg/errors",
 			"Rev": "a22138067af1c4942683050411a841ade67fe1eb"
 		},

staging/src/k8s.io/kube-gen/Godeps/Godeps.json

@@ -175,6 +175,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -191,6 +195,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/hashicorp/golang-lru",
 			"Rev": "a0d98a5f288019575c6d1f4bb1573fef2d1fcdc4"
 		},
@@ -215,6 +227,10 @@
 			"Rev": "d5b7844b561a7bc640052f1b935f7b800330d7e0"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/spf13/pflag",
 			"Rev": "9ff6c6923cfffbcd502984b8e0c80539a94968b7"
 		},

staging/src/k8s.io/metrics/Godeps/Godeps.json

@@ -83,6 +83,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -99,6 +103,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/juju/ratelimit",
 			"Rev": "5b9ff866471762aa2ab2dced63c9fb6f53921342"
 		},
@@ -115,6 +127,10 @@
 			"Rev": "d5b7844b561a7bc640052f1b935f7b800330d7e0"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/spf13/pflag",
 			"Rev": "9ff6c6923cfffbcd502984b8e0c80539a94968b7"
 		},

staging/src/k8s.io/sample-apiserver/Godeps/Godeps.json

@@ -163,6 +163,10 @@
 			"Rev": "4bd1920723d7b7c925de087aa32e2187708897f7"
 		},
 		{
+			"ImportPath": "github.com/google/btree",
+			"Rev": "7d79101e329e5a3adf994758c578dab82b90c017"
+		},
+		{
 			"ImportPath": "github.com/google/gofuzz",
 			"Rev": "44d81051d367757e1c7c6a5a86423ece9afcf63c"
 		},
@@ -179,6 +183,14 @@
 			"Rev": "0c5108395e2debce0d731cf0287ddf7242066aba"
 		},
 		{
+			"ImportPath": "github.com/gregjones/httpcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
+			"ImportPath": "github.com/gregjones/httpcache/diskcache",
+			"Rev": "787624de3eb7bd915c329cba748687a3b22666a6"
+		},
+		{
 			"ImportPath": "github.com/grpc-ecosystem/go-grpc-prometheus",
 			"Rev": "2500245aa6110c562d17020fb31a2c133d737799"
 		},
@@ -243,6 +255,10 @@
 			"Rev": "ca53cad383cad2479bbba7f7a1a05797ec1386e4"
 		},
 		{
+			"ImportPath": "github.com/peterbourgon/diskv",
+			"Rev": "5dfcb07a075adbaaa4094cddfd160b1e1c77a043"
+		},
+		{
 			"ImportPath": "github.com/pkg/errors",
 			"Rev": "a22138067af1c4942683050411a841ade67fe1eb"
 		},

vendor/BUILD

@@ -230,6 +230,7 @@ filegroup(
         "//vendor/github.com/gorilla/context:all-srcs",
         "//vendor/github.com/gorilla/mux:all-srcs",
         "//vendor/github.com/gorilla/websocket:all-srcs",
+        "//vendor/github.com/gregjones/httpcache:all-srcs",
         "//vendor/github.com/grpc-ecosystem/go-grpc-prometheus:all-srcs",
         "//vendor/github.com/grpc-ecosystem/grpc-gateway/runtime:all-srcs",
         "//vendor/github.com/grpc-ecosystem/grpc-gateway/utilities:all-srcs",
@@ -276,6 +277,7 @@ filegroup(
         "//vendor/github.com/pborman/uuid:all-srcs",
         "//vendor/github.com/pelletier/go-buffruneio:all-srcs",
         "//vendor/github.com/pelletier/go-toml:all-srcs",
+        "//vendor/github.com/peterbourgon/diskv:all-srcs",
         "//vendor/github.com/pkg/errors:all-srcs",
         "//vendor/github.com/pkg/sftp:all-srcs",
         "//vendor/github.com/pmezard/go-difflib/difflib:all-srcs",

vendor/github.com/gregjones/httpcache/.travis.yml

+sudo: false
+language: go
+go:
+  - 1.6.x
+  - 1.7.x
+  - 1.8.x
+  - master
+matrix:
+  allow_failures:
+    - go: master
+  fast_finish: true
+install:
+  - # Do nothing. This is needed to prevent default install action "go get -t -v ./..." from happening here (we want it to happen inside script step).
+script:
+  - go get -t -v ./...
+  - diff -u <(echo -n) <(gofmt -d .)
+  - go tool vet .
+  - go test -v -race ./...

vendor/github.com/gregjones/httpcache/BUILD

+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["httpcache.go"],
+    tags = ["automanaged"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//vendor/github.com/gregjones/httpcache/diskcache:all-srcs",
+    ],
+    tags = ["automanaged"],
+)

vendor/github.com/gregjones/httpcache/LICENSE.txt

+Copyright © 2012 Greg Jones (greg.jones@gmail.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\ No newline at end of file

vendor/github.com/gregjones/httpcache/README.md

+httpcache
+=========
+
+[![Build Status](https://travis-ci.org/gregjones/httpcache.svg?branch=master)](https://travis-ci.org/gregjones/httpcache) [![GoDoc](https://godoc.org/github.com/gregjones/httpcache?status.svg)](https://godoc.org/github.com/gregjones/httpcache)
+
+Package httpcache provides a http.RoundTripper implementation that works as a mostly RFC-compliant cache for http responses.
+
+It is only suitable for use as a 'private' cache (i.e. for a web-browser or an API-client and not for a shared proxy).
+
+Cache Backends
+--------------
+
+- The built-in 'memory' cache stores responses in an in-memory map.
+- [`github.com/gregjones/httpcache/diskcache`](https://github.com/gregjones/httpcache/tree/master/diskcache) provides a filesystem-backed cache using the [diskv](https://github.com/peterbourgon/diskv) library.
+- [`github.com/gregjones/httpcache/memcache`](https://github.com/gregjones/httpcache/tree/master/memcache) provides memcache implementations, for both App Engine and 'normal' memcache servers.
+- [`sourcegraph.com/sourcegraph/s3cache`](https://sourcegraph.com/github.com/sourcegraph/s3cache) uses Amazon S3 for storage.
+- [`github.com/gregjones/httpcache/leveldbcache`](https://github.com/gregjones/httpcache/tree/master/leveldbcache) provides a filesystem-backed cache using [leveldb](https://github.com/syndtr/goleveldb/leveldb).
+- [`github.com/die-net/lrucache`](https://github.com/die-net/lrucache) provides an in-memory cache that will evict least-recently used entries.
+- [`github.com/die-net/lrucache/twotier`](https://github.com/die-net/lrucache/tree/master/twotier) allows caches to be combined, for example to use lrucache above with a persistent disk-cache.
+
+License
+-------
+
+-	[MIT License](LICENSE.txt)

vendor/github.com/gregjones/httpcache/diskcache/BUILD

+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["diskcache.go"],
+    tags = ["automanaged"],
+    deps = ["//vendor/github.com/peterbourgon/diskv:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

vendor/github.com/gregjones/httpcache/diskcache/diskcache.go

+// Package diskcache provides an implementation of httpcache.Cache that uses the diskv package
+// to supplement an in-memory map with persistent storage
+//
+package diskcache
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/hex"
+	"github.com/peterbourgon/diskv"
+	"io"
+)
+
+// Cache is an implementation of httpcache.Cache that supplements the in-memory map with persistent storage
+type Cache struct {
+	d *diskv.Diskv
+}
+
+// Get returns the response corresponding to key if present
+func (c *Cache) Get(key string) (resp []byte, ok bool) {
+	key = keyToFilename(key)
+	resp, err := c.d.Read(key)
+	if err != nil {
+		return []byte{}, false
+	}
+	return resp, true
+}
+
+// Set saves a response to the cache as key
+func (c *Cache) Set(key string, resp []byte) {
+	key = keyToFilename(key)
+	c.d.WriteStream(key, bytes.NewReader(resp), true)
+}
+
+// Delete removes the response with key from the cache
+func (c *Cache) Delete(key string) {
+	key = keyToFilename(key)
+	c.d.Erase(key)
+}
+
+func keyToFilename(key string) string {
+	h := md5.New()
+	io.WriteString(h, key)
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// New returns a new Cache that will store files in basePath
+func New(basePath string) *Cache {
+	return &Cache{
+		d: diskv.New(diskv.Options{
+			BasePath:     basePath,
+			CacheSizeMax: 100 * 1024 * 1024, // 100MB
+		}),
+	}
+}
+
+// NewWithDiskv returns a new Cache using the provided Diskv as underlying
+// storage.
+func NewWithDiskv(d *diskv.Diskv) *Cache {
+	return &Cache{d}
+}

vendor/github.com/peterbourgon/diskv/BUILD

+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "compression.go",
+        "diskv.go",
+        "index.go",
+    ],
+    tags = ["automanaged"],
+    deps = ["//vendor/github.com/google/btree:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

vendor/github.com/peterbourgon/diskv/LICENSE

+Copyright (c) 2011-2012 Peter Bourgon
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/github.com/peterbourgon/diskv/README.md

+# What is diskv?
+
+Diskv (disk-vee) is a simple, persistent key-value store written in the Go
+language. It starts with an incredibly simple API for storing arbitrary data on
+a filesystem by key, and builds several layers of performance-enhancing
+abstraction on top.  The end result is a conceptually simple, but highly
+performant, disk-backed storage system.
+
+[![Build Status][1]][2]
+
+[1]: https://drone.io/github.com/peterbourgon/diskv/status.png
+[2]: https://drone.io/github.com/peterbourgon/diskv/latest
+
+
+# Installing
+
+Install [Go 1][3], either [from source][4] or [with a prepackaged binary][5].
+Then,
+
+```bash
+$ go get github.com/peterbourgon/diskv
+```
+
+[3]: http://golang.org
+[4]: http://golang.org/doc/install/source
+[5]: http://golang.org/doc/install
+
+
+# Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/peterbourgon/diskv"
+)
+
+func main() {
+	// Simplest transform function: put all the data files into the base dir.
+	flatTransform := func(s string) []string { return []string{} }
+
+	// Initialize a new diskv store, rooted at "my-data-dir", with a 1MB cache.
+	d := diskv.New(diskv.Options{
+		BasePath:     "my-data-dir",
+		Transform:    flatTransform,
+		CacheSizeMax: 1024 * 1024,
+	})
+
+	// Write three bytes to the key "alpha".
+	key := "alpha"
+	d.Write(key, []byte{'1', '2', '3'})
+
+	// Read the value back out of the store.
+	value, _ := d.Read(key)
+	fmt.Printf("%v\n", value)
+
+	// Erase the key+value from the store (and the disk).
+	d.Erase(key)
+}
+```
+
+More complex examples can be found in the "examples" subdirectory.
+
+
+# Theory
+
+## Basic idea
+
+At its core, diskv is a map of a key (`string`) to arbitrary data (`[]byte`).
+The data is written to a single file on disk, with the same name as the key.
+The key determines where that file will be stored, via a user-provided
+`TransformFunc`, which takes a key and returns a slice (`[]string`)
+corresponding to a path list where the key file will be stored. The simplest
+TransformFunc,
+
+```go
+func SimpleTransform (key string) []string {
+    return []string{}
+}
+```
+
+will place all keys in the same, base directory. The design is inspired by
+[Redis diskstore][6]; a TransformFunc which emulates the default diskstore
+behavior is available in the content-addressable-storage example.
+
+[6]: http://groups.google.com/group/redis-db/browse_thread/thread/d444bc786689bde9?pli=1
+
+**Note** that your TransformFunc should ensure that one valid key doesn't
+transform to a subset of another valid key. That is, it shouldn't be possible
+to construct valid keys that resolve to directory names. As a concrete example,
+if your TransformFunc splits on every 3 characters, then
+
+```go
+d.Write("abcabc", val) // OK: written to <base>/abc/abc/abcabc
+d.Write("abc", val)    // Error: attempted write to <base>/abc/abc, but it's a directory
+```
+
+This will be addressed in an upcoming version of diskv.
+
+Probably the most important design principle behind diskv is that your data is
+always flatly available on the disk. diskv will never do anything that would
+prevent you from accessing, copying, backing up, or otherwise interacting with
+your data via common UNIX commandline tools.
+
+## Adding a cache
+
+An in-memory caching layer is provided by combining the BasicStore
+functionality with a simple map structure, and keeping it up-to-date as
+appropriate. Since the map structure in Go is not threadsafe, it's combined
+with a RWMutex to provide safe concurrent access.
+
+## Adding order
+
+diskv is a key-value store and therefore inherently unordered. An ordering
+system can be injected into the store by passing something which satisfies the
+diskv.Index interface. (A default implementation, using Google's
+[btree][7] package, is provided.) Basically, diskv keeps an ordered (by a
+user-provided Less function) index of the keys, which can be queried.
+
+[7]: https://github.com/google/btree
+
+## Adding compression
+
+Something which implements the diskv.Compression interface may be passed
+during store creation, so that all Writes and Reads are filtered through
+a compression/decompression pipeline. Several default implementations,
+using stdlib compression algorithms, are provided. Note that data is cached
+compressed; the cost of decompression is borne with each Read.
+
+## Streaming
+
+diskv also now provides ReadStream and WriteStream methods, to allow very large
+data to be handled efficiently.
+
+
+# Future plans
+
+ * Needs plenty of robust testing: huge datasets, etc...
+ * More thorough benchmarking
+ * Your suggestions for use-cases I haven't thought of

vendor/github.com/peterbourgon/diskv/compression.go

+package diskv
+
+import (
+	"compress/flate"
+	"compress/gzip"
+	"compress/zlib"
+	"io"
+)
+
+// Compression is an interface that Diskv uses to implement compression of
+// data. Writer takes a destination io.Writer and returns a WriteCloser that
+// compresses all data written through it. Reader takes a source io.Reader and
+// returns a ReadCloser that decompresses all data read through it. You may
+// define these methods on your own type, or use one of the NewCompression
+// helpers.
+type Compression interface {
+	Writer(dst io.Writer) (io.WriteCloser, error)
+	Reader(src io.Reader) (io.ReadCloser, error)
+}
+
+// NewGzipCompression returns a Gzip-based Compression.
+func NewGzipCompression() Compression {
+	return NewGzipCompressionLevel(flate.DefaultCompression)
+}
+
+// NewGzipCompressionLevel returns a Gzip-based Compression with the given level.
+func NewGzipCompressionLevel(level int) Compression {
+	return &genericCompression{
+		wf: func(w io.Writer) (io.WriteCloser, error) { return gzip.NewWriterLevel(w, level) },
+		rf: func(r io.Reader) (io.ReadCloser, error) { return gzip.NewReader(r) },
+	}
+}
+
+// NewZlibCompression returns a Zlib-based Compression.
+func NewZlibCompression() Compression {
+	return NewZlibCompressionLevel(flate.DefaultCompression)
+}
+
+// NewZlibCompressionLevel returns a Zlib-based Compression with the given level.
+func NewZlibCompressionLevel(level int) Compression {
+	return NewZlibCompressionLevelDict(level, nil)
+}
+
+// NewZlibCompressionLevelDict returns a Zlib-based Compression with the given
+// level, based on the given dictionary.
+func NewZlibCompressionLevelDict(level int, dict []byte) Compression {
+	return &genericCompression{
+		func(w io.Writer) (io.WriteCloser, error) { return zlib.NewWriterLevelDict(w, level, dict) },
+		func(r io.Reader) (io.ReadCloser, error) { return zlib.NewReaderDict(r, dict) },
+	}
+}
+
+type genericCompression struct {
+	wf func(w io.Writer) (io.WriteCloser, error)
+	rf func(r io.Reader) (io.ReadCloser, error)
+}
+
+func (g *genericCompression) Writer(dst io.Writer) (io.WriteCloser, error) {
+	return g.wf(dst)
+}
+
+func (g *genericCompression) Reader(src io.Reader) (io.ReadCloser, error) {
+	return g.rf(src)
+}

vendor/github.com/peterbourgon/diskv/index.go

+package diskv
+
+import (
+	"sync"
+
+	"github.com/google/btree"
+)
+
+// Index is a generic interface for things that can
+// provide an ordered list of keys.
+type Index interface {
+	Initialize(less LessFunction, keys <-chan string)
+	Insert(key string)
+	Delete(key string)
+	Keys(from string, n int) []string
+}
+
+// LessFunction is used to initialize an Index of keys in a specific order.
+type LessFunction func(string, string) bool
+
+// btreeString is a custom data type that satisfies the BTree Less interface,
+// making the strings it wraps sortable by the BTree package.
+type btreeString struct {
+	s string
+	l LessFunction
+}
+
+// Less satisfies the BTree.Less interface using the btreeString's LessFunction.
+func (s btreeString) Less(i btree.Item) bool {
+	return s.l(s.s, i.(btreeString).s)
+}
+
+// BTreeIndex is an implementation of the Index interface using google/btree.
+type BTreeIndex struct {
+	sync.RWMutex
+	LessFunction
+	*btree.BTree
+}
+
+// Initialize populates the BTree tree with data from the keys channel,
+// according to the passed less function. It's destructive to the BTreeIndex.
+func (i *BTreeIndex) Initialize(less LessFunction, keys <-chan string) {
+	i.Lock()
+	defer i.Unlock()
+	i.LessFunction = less
+	i.BTree = rebuild(less, keys)
+}
+
+// Insert inserts the given key (only) into the BTree tree.
+func (i *BTreeIndex) Insert(key string) {
+	i.Lock()
+	defer i.Unlock()
+	if i.BTree == nil || i.LessFunction == nil {
+		panic("uninitialized index")
+	}
+	i.BTree.ReplaceOrInsert(btreeString{s: key, l: i.LessFunction})
+}
+
+// Delete removes the given key (only) from the BTree tree.
+func (i *BTreeIndex) Delete(key string) {
+	i.Lock()
+	defer i.Unlock()
+	if i.BTree == nil || i.LessFunction == nil {
+		panic("uninitialized index")
+	}
+	i.BTree.Delete(btreeString{s: key, l: i.LessFunction})
+}
+
+// Keys yields a maximum of n keys in order. If the passed 'from' key is empty,
+// Keys will return the first n keys. If the passed 'from' key is non-empty, the
+// first key in the returned slice will be the key that immediately follows the
+// passed key, in key order.
+func (i *BTreeIndex) Keys(from string, n int) []string {
+	i.RLock()
+	defer i.RUnlock()
+
+	if i.BTree == nil || i.LessFunction == nil {
+		panic("uninitialized index")
+	}
+
+	if i.BTree.Len() <= 0 {
+		return []string{}
+	}
+
+	btreeFrom := btreeString{s: from, l: i.LessFunction}
+	skipFirst := true
+	if len(from) <= 0 || !i.BTree.Has(btreeFrom) {
+		// no such key, so fabricate an always-smallest item
+		btreeFrom = btreeString{s: "", l: func(string, string) bool { return true }}
+		skipFirst = false
+	}
+
+	keys := []string{}
+	iterator := func(i btree.Item) bool {
+		keys = append(keys, i.(btreeString).s)
+		return len(keys) < n
+	}
+	i.BTree.AscendGreaterOrEqual(btreeFrom, iterator)
+
+	if skipFirst && len(keys) > 0 {
+		keys = keys[1:]
+	}
+
+	return keys
+}
+
+// rebuildIndex does the work of regenerating the index
+// with the given keys.
+func rebuild(less LessFunction, keys <-chan string) *btree.BTree {
+	tree := btree.New(2)
+	for key := range keys {
+		tree.ReplaceOrInsert(btreeString{s: key, l: less})
+	}
+	return tree
+}