Expiring cache

api/models/error.go

@@ -20,10 +20,6 @@ var (
 		code:  http.StatusGatewayTimeout,
 		error: errors.New("Timed out"),
 	}
-	ErrRunnerRouteNotFound = err{
-		code:  http.StatusNotFound,
-		error: errors.New("Route not found on that application"),
-	}
 	ErrAppsValidationMissingName = err{
 		code:  http.StatusBadRequest,
 		error: errors.New("Missing app name"),

api/server/internal/routecache/lru.go

@@ -1,88 +0,0 @@
-// Package routecache is meant to assist in resolving the most used routes at
-// an application. Implemented as a LRU, it returns always its full context for
-// iteration at the router handler.
-package routecache
-
-// based on groupcache's LRU
-
-import (
-	"container/list"
-
-	"gitlab-odx.oracle.com/odx/functions/api/models"
-)
-
-// Cache holds an internal linkedlist for hotness management. It is not safe
-// for concurrent use, must be guarded externally.
-type Cache struct {
-	MaxEntries int
-
-	ll    *list.List
-	cache map[string]*list.Element
-}
-
-// New returns a route cache.
-func New(maxentries int) *Cache {
-	return &Cache{
-		MaxEntries: maxentries,
-		ll:         list.New(),
-		cache:      make(map[string]*list.Element),
-	}
-}
-
-// Refresh updates internal linkedlist either adding a new route to the front,
-// or moving it to the front when used. It will discard seldom used routes.
-func (c *Cache) Refresh(route *models.Route) {
-	if c.cache == nil {
-		return
-	}
-
-	if ee, ok := c.cache[route.AppName+route.Path]; ok {
-		c.ll.MoveToFront(ee)
-		ee.Value = route
-		return
-	}
-
-	ele := c.ll.PushFront(route)
-	c.cache[route.AppName+route.Path] = ele
-	if c.MaxEntries != 0 && c.ll.Len() > c.MaxEntries {
-		c.removeOldest()
-	}
-}
-
-// Get looks up a path's route from the cache.
-func (c *Cache) Get(appname, path string) (route *models.Route, ok bool) {
-	if c.cache == nil {
-		return
-	}
-	if ele, hit := c.cache[appname+path]; hit {
-		c.ll.MoveToFront(ele)
-		return ele.Value.(*models.Route), true
-	}
-	return
-}
-
-// Delete removes the element for the given appname and path from the cache.
-func (c *Cache) Delete(appname, path string) {
-	if ele, hit := c.cache[appname+path]; hit {
-		c.removeElement(ele)
-	}
-}
-
-func (c *Cache) removeOldest() {
-	if c.cache == nil {
-		return
-	}
-	if ele := c.ll.Back(); ele != nil {
-		c.removeElement(ele)
-	}
-}
-
-func (c *Cache) removeElement(e *list.Element) {
-	c.ll.Remove(e)
-	kv := e.Value.(*models.Route)
-	delete(c.cache, kv.AppName+kv.Path)
-}
-
-func (c *Cache) Len() int {
-	return len(c.cache)
-}

api/server/routes_create_update.go

@@ -47,7 +47,7 @@ func (s *Server) handleRouteCreateOrUpdate(c *gin.Context) {
 		return
 	}
 
-	s.cacheRefresh(resp.Route)
+	s.cachedelete(resp.Route.AppName, resp.Route.Path)
 
 	c.JSON(http.StatusOK, resp)
 }

api/server/runner.go

@@ -14,6 +14,7 @@ import (
 	"github.com/Sirupsen/logrus"
 	"github.com/gin-gonic/gin"
 	"github.com/go-openapi/strfmt"
+	cache "github.com/patrickmn/go-cache"
 	"gitlab-odx.oracle.com/odx/functions/api"
 	"gitlab-odx.oracle.com/odx/functions/api/id"
 	"gitlab-odx.oracle.com/odx/functions/api/models"
@@ -44,7 +45,7 @@ func (s *Server) handleSpecial(c *gin.Context) {
 	c.Request = r
 	c.Set(api.AppName, r.Context().Value(api.AppName).(string))
 	if c.MustGet(api.AppName).(string) == "" {
-		handleErrorResponse(c, models.ErrRunnerRouteNotFound)
+		handleErrorResponse(c, models.ErrRoutesNotFound)
 		return
 	}
 
@@ -111,40 +112,45 @@ func (s *Server) handleRequest(c *gin.Context, enqueue models.Enqueue) {
 	}
 
 	log.WithFields(logrus.Fields{"app": appName, "path": path}).Debug("Finding route on datastore")
-	routes, err := s.loadroutes(ctx, models.RouteFilter{AppName: appName, Path: path})
+	route, err := s.loadroute(ctx, appName, path)
 	if err != nil {
 		handleErrorResponse(c, err)
 		return
 	}
 
-	if len(routes) == 0 {
-		handleErrorResponse(c, models.ErrRunnerRouteNotFound)
+	if route == nil {
+		handleErrorResponse(c, models.ErrRoutesNotFound)
 		return
 	}
 
-	log.WithField("routes", len(routes)).Debug("Got routes from datastore")
-	route := routes[0]
 	log = log.WithFields(logrus.Fields{"app": appName, "path": route.Path, "image": route.Image})
+	log.Debug("Got route from datastore")
 
 	if s.serve(ctx, c, appName, route, app, path, reqID, payload, enqueue) {
 		s.FireAfterDispatch(ctx, reqRoute)
 		return
 	}
 
-	handleErrorResponse(c, models.ErrRunnerRouteNotFound)
+	handleErrorResponse(c, models.ErrRoutesNotFound)
 }
 
-func (s *Server) loadroutes(ctx context.Context, filter models.RouteFilter) ([]*models.Route, error) {
-	if route, ok := s.cacheget(filter.AppName, filter.Path); ok {
-		return []*models.Route{route}, nil
+func (s *Server) loadroute(ctx context.Context, appName, path string) (*models.Route, error) {
+	if route, ok := s.cacheget(appName, path); ok {
+		return route, nil
 	}
+	key := routeCacheKey(appName, path)
 	resp, err := s.singleflight.do(
-		filter,
+		key,
 		func() (interface{}, error) {
-			return s.Datastore.GetRoutesByApp(ctx, filter.AppName, &filter)
+			return s.Datastore.GetRoute(ctx, appName, path)
 		},
 	)
-	return resp.([]*models.Route), err
+	if err != nil {
+		return nil, err
+	}
+	route := resp.(*models.Route)
+	s.routeCache.Set(key, route, cache.DefaultExpiration)
+	return route, nil
 }
 
 // TODO: Should remove *gin.Context from these functions, should use only context.Context

api/server/runner_async_test.go

@@ -7,25 +7,26 @@ import (
 	"net/http"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/gin-gonic/gin"
+	cache "github.com/patrickmn/go-cache"
 	"gitlab-odx.oracle.com/odx/functions/api/datastore"
 	"gitlab-odx.oracle.com/odx/functions/api/models"
 	"gitlab-odx.oracle.com/odx/functions/api/mqs"
 	"gitlab-odx.oracle.com/odx/functions/api/runner"
-	"gitlab-odx.oracle.com/odx/functions/api/server/internal/routecache"
 )
 
 func testRouterAsync(ds models.Datastore, mq models.MessageQueue, rnr *runner.Runner, enqueue models.Enqueue) *gin.Engine {
 	ctx := context.Background()
 
 	s := &Server{
-		Runner:    rnr,
-		Router:    gin.New(),
-		Datastore: ds,
-		MQ:        mq,
-		Enqueue:   enqueue,
-		hotroutes: routecache.New(10),
+		Runner:     rnr,
+		Router:     gin.New(),
+		Datastore:  ds,
+		MQ:         mq,
+		Enqueue:    enqueue,
+		routeCache: cache.New(60*time.Second, 5*time.Minute),
 	}
 
 	r := s.Router

api/server/runner_test.go

@@ -45,7 +45,7 @@ func TestRouteRunnerGet(t *testing.T) {
 	}{
 		{"/route", "", http.StatusNotFound, nil},
 		{"/r/app/route", "", http.StatusNotFound, models.ErrAppsNotFound},
-		{"/r/myapp/route", "", http.StatusNotFound, models.ErrRunnerRouteNotFound},
+		{"/r/myapp/route", "", http.StatusNotFound, models.ErrRoutesNotFound},
 	} {
 		_, rec := routerRequest(t, srv.Router, "GET", test.path, nil)
 
@@ -60,8 +60,8 @@ func TestRouteRunnerGet(t *testing.T) {
 
 			if !strings.Contains(resp.Error.Message, test.expectedError.Error()) {
 				t.Log(buf.String())
-				t.Errorf("Test %d: Expected error message to have `%s`",
-					i, test.expectedError.Error())
+				t.Errorf("Test %d: Expected error message to have `%s`, but got `%s`",
+					i, test.expectedError.Error(), resp.Error.Message)
 			}
 		}
 	}
@@ -89,7 +89,7 @@ func TestRouteRunnerPost(t *testing.T) {
 	}{
 		{"/route", `{ "payload": "" }`, http.StatusNotFound, nil},
 		{"/r/app/route", `{ "payload": "" }`, http.StatusNotFound, models.ErrAppsNotFound},
-		{"/r/myapp/route", `{ "payload": "" }`, http.StatusNotFound, models.ErrRunnerRouteNotFound},
+		{"/r/myapp/route", `{ "payload": "" }`, http.StatusNotFound, models.ErrRoutesNotFound},
 	} {
 		body := bytes.NewBuffer([]byte(test.body))
 		_, rec := routerRequest(t, srv.Router, "POST", test.path, body)

api/server/server.go

@@ -10,11 +10,12 @@ import (
 	"net/http"
 	"os"
 	"path"
-	"sync"
+	"time"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/ccirello/supervisor"
 	"github.com/gin-gonic/gin"
+	"github.com/patrickmn/go-cache"
 	"github.com/spf13/viper"
 	"gitlab-odx.oracle.com/odx/functions/api"
 	"gitlab-odx.oracle.com/odx/functions/api/datastore"
@@ -24,7 +25,6 @@ import (
 	"gitlab-odx.oracle.com/odx/functions/api/mqs"
 	"gitlab-odx.oracle.com/odx/functions/api/runner"
 	"gitlab-odx.oracle.com/odx/functions/api/runner/common"
-	"gitlab-odx.oracle.com/odx/functions/api/server/internal/routecache"
 )
 
 const (
@@ -51,8 +51,7 @@ type Server struct {
 	middlewares     []Middleware
 	runnerListeners []RunnerListener
 
-	mu           sync.Mutex // protects hotroutes
-	hotroutes    *routecache.Cache
+	routeCache   *cache.Cache
 	singleflight singleflight // singleflight assists Datastore
 }
 
@@ -95,14 +94,14 @@ func New(ctx context.Context, ds models.Datastore, mq models.MessageQueue, logDB
 	}
 
 	s := &Server{
-		Runner:    rnr,
-		Router:    gin.New(),
-		Datastore: ds,
-		MQ:        mq,
-		hotroutes: routecache.New(cacheSize),
-		LogDB:     logDB,
-		Enqueue:   DefaultEnqueue,
-		apiURL:    apiURL,
+		Runner:     rnr,
+		Router:     gin.New(),
+		Datastore:  ds,
+		MQ:         mq,
+		routeCache: cache.New(5*time.Second, 5*time.Minute),
+		LogDB:      logDB,
+		Enqueue:    DefaultEnqueue,
+		apiURL:     apiURL,
 	}
 
 	setMachineId()
@@ -110,6 +109,9 @@ func New(ctx context.Context, ds models.Datastore, mq models.MessageQueue, logDB
 	s.bindHandlers(ctx)
 
 	for _, opt := range opts {
+		if opt == nil {
+			continue
+		}
 		opt(s)
 	}
 	return s
@@ -171,26 +173,19 @@ func DefaultEnqueue(ctx context.Context, mq models.MessageQueue, task *models.Ta
 	return mq.Push(ctx, task)
 }
 
+func routeCacheKey(appname, path string) string {
+	return fmt.Sprintf("%s_%s", appname, path)
+}
 func (s *Server) cacheget(appname, path string) (*models.Route, bool) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	route, ok := s.hotroutes.Get(appname, path)
+	route, ok := s.routeCache.Get(routeCacheKey(appname, path))
 	if !ok {
 		return nil, false
 	}
-	return route, ok
-}
-
-func (s *Server) cacheRefresh(route *models.Route) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.hotroutes.Refresh(route)
+	return route.(*models.Route), ok
 }
 
 func (s *Server) cachedelete(appname, path string) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.hotroutes.Delete(appname, path)
+	s.routeCache.Delete(routeCacheKey(appname, path))
 }
 
 func (s *Server) handleRunnerRequest(c *gin.Context) {

api/server/server_test.go

@@ -10,13 +10,14 @@ import (
 	"net/http/httptest"
 	"os"
 	"testing"
+	"time"
 
 	"github.com/gin-gonic/gin"
+	cache "github.com/patrickmn/go-cache"
 	"gitlab-odx.oracle.com/odx/functions/api/datastore"
 	"gitlab-odx.oracle.com/odx/functions/api/models"
 	"gitlab-odx.oracle.com/odx/functions/api/mqs"
 	"gitlab-odx.oracle.com/odx/functions/api/runner"
-	"gitlab-odx.oracle.com/odx/functions/api/server/internal/routecache"
 )
 
 var tmpDatastoreTests = "/tmp/func_test_datastore.db"
@@ -25,13 +26,13 @@ func testServer(ds models.Datastore, mq models.MessageQueue, logDB models.FnLog,
 	ctx := context.Background()
 
 	s := &Server{
-		Runner:    rnr,
-		Router:    gin.New(),
-		Datastore: ds,
-		LogDB:     nil,
-		MQ:        mq,
-		Enqueue:   DefaultEnqueue,
-		hotroutes: routecache.New(2),
+		Runner:     rnr,
+		Router:     gin.New(),
+		Datastore:  ds,
+		LogDB:      nil,
+		MQ:         mq,
+		Enqueue:    DefaultEnqueue,
+		routeCache: cache.New(60*time.Second, 5*time.Minute),
 	}
 
 	r := s.Router
@@ -102,7 +103,6 @@ func TestFullStack(t *testing.T) {
 	defer rnrcancel()
 
 	srv := testServer(ds, &mqs.Mock{}, logDB, rnr)
-	srv.hotroutes = routecache.New(2)
 
 	for _, test := range []struct {
 		name              string
@@ -115,13 +115,15 @@ func TestFullStack(t *testing.T) {
 		{"create my app", "POST", "/v1/apps", `{ "app": { "name": "myapp" } }`, http.StatusOK, 0},
 		{"list apps", "GET", "/v1/apps", ``, http.StatusOK, 0},
 		{"get app", "GET", "/v1/apps/myapp", ``, http.StatusOK, 0},
-		{"add myroute", "POST", "/v1/apps/myapp/routes", `{ "route": { "name": "myroute", "path": "/myroute", "image": "funcy/hello" } }`, http.StatusOK, 1},
-		{"add myroute2", "POST", "/v1/apps/myapp/routes", `{ "route": { "name": "myroute2", "path": "/myroute2", "image": "funcy/error" } }`, http.StatusOK, 2},
-		{"get myroute", "GET", "/v1/apps/myapp/routes/myroute", ``, http.StatusOK, 2},
-		{"get myroute2", "GET", "/v1/apps/myapp/routes/myroute2", ``, http.StatusOK, 2},
-		{"get all routes", "GET", "/v1/apps/myapp/routes", ``, http.StatusOK, 2},
-		{"execute myroute", "POST", "/r/myapp/myroute", `{ "name": "Teste" }`, http.StatusOK, 2},
+		// NOTE: cache is lazy, loads when a request comes in for the route, not when added
+		{"add myroute", "POST", "/v1/apps/myapp/routes", `{ "route": { "name": "myroute", "path": "/myroute", "image": "funcy/hello" } }`, http.StatusOK, 0},
+		{"add myroute2", "POST", "/v1/apps/myapp/routes", `{ "route": { "name": "myroute2", "path": "/myroute2", "image": "funcy/error" } }`, http.StatusOK, 0},
+		{"get myroute", "GET", "/v1/apps/myapp/routes/myroute", ``, http.StatusOK, 0},
+		{"get myroute2", "GET", "/v1/apps/myapp/routes/myroute2", ``, http.StatusOK, 0},
+		{"get all routes", "GET", "/v1/apps/myapp/routes", ``, http.StatusOK, 0},
+		{"execute myroute", "POST", "/r/myapp/myroute", `{ "name": "Teste" }`, http.StatusOK, 1},
 		{"execute myroute2", "POST", "/r/myapp/myroute2", `{ "name": "Teste" }`, http.StatusInternalServerError, 2},
+		{"get myroute2", "GET", "/v1/apps/myapp/routes/myroute2", ``, http.StatusOK, 2},
 		{"delete myroute", "DELETE", "/v1/apps/myapp/routes/myroute", ``, http.StatusOK, 1},
 		{"delete app (fail)", "DELETE", "/v1/apps/myapp", ``, http.StatusConflict, 1},
 		{"delete myroute2", "DELETE", "/v1/apps/myapp/routes/myroute2", ``, http.StatusOK, 0},
@@ -136,10 +138,10 @@ func TestFullStack(t *testing.T) {
 			t.Errorf("Test \"%s\": Expected status code to be %d but was %d",
 				test.name, test.expectedCode, rec.Code)
 		}
-		if srv.hotroutes.Len() != test.expectedCacheSize {
+		if srv.routeCache.ItemCount() != test.expectedCacheSize {
 			t.Log(buf.String())
 			t.Errorf("Test \"%s\": Expected cache size to be %d but was %d",
-				test.name, test.expectedCacheSize, srv.hotroutes.Len())
+				test.name, test.expectedCacheSize, srv.routeCache.ItemCount())
 		}
 	}
 }

api/server/singleflight.go

@@ -4,8 +4,6 @@ package server
 
 import (
 	"sync"
-
-	"gitlab-odx.oracle.com/odx/functions/api/models"
 )
 
 // call is an in-flight or completed do call
@@ -16,18 +14,18 @@ type call struct {
 }
 
 type singleflight struct {
-	mu sync.Mutex                   // protects m
-	m  map[models.RouteFilter]*call // lazily initialized
+	mu sync.Mutex            // protects m
+	m  map[interface{}]*call // lazily initialized
 }
 
 // do executes and returns the results of the given function, making
 // sure that only one execution is in-flight for a given key at a
 // time. If a duplicate comes in, the duplicate caller waits for the
 // original to complete and receives the same results.
-func (g *singleflight) do(key models.RouteFilter, fn func() (interface{}, error)) (interface{}, error) {
+func (g *singleflight) do(key interface{}, fn func() (interface{}, error)) (interface{}, error) {
 	g.mu.Lock()
 	if g.m == nil {
-		g.m = make(map[models.RouteFilter]*call)
+		g.m = make(map[interface{}]*call)
 	}
 	if c, ok := g.m[key]; ok {
 		g.mu.Unlock()

glide.lock

@@ -1,5 +1,5 @@
-hash: 91e44ada5fc186bf55c6e794c2ea7733ae1b915e850261e67f0e2ed1ba55eb8b
-updated: 2017-07-17T12:03:47.884564997-07:00
+hash: ed88f1a46f149bac3eea6052d409a2a619f762ee51f2655b3fc22e8b2fa806ad
+updated: 2017-07-19T22:11:29.697513445-07:00
 imports:
 - name: code.cloudfoundry.org/bytefmt
   version: f4415fafc5619dd75599a54a7c91fb3948ad58bd
@@ -201,6 +201,8 @@ imports:
   subpackages:
   - libcontainer/system
   - libcontainer/user
+- name: github.com/patrickmn/go-cache
+  version: 7ac151875ffb48b9f3ccce9ea20f020b0c1596c8
 - name: github.com/pelletier/go-buffruneio
   version: c37440a7cf42ac63b919c752ca73a85067e05992
 - name: github.com/pelletier/go-toml

glide.yaml

@@ -72,4 +72,6 @@ testImport:
 - package: github.com/vrischmann/envconfig
 - package: github.com/opencontainers/go-digest
   branch: master
+- package: github.com/patrickmn/go-cache
+  branch: master
   

vendor/github.com/patrickmn/go-cache/CONTRIBUTORS

@@ -0,0 +1,9 @@
+This is a list of people who have contributed code to go-cache. They, or their
+employers, are the copyright holders of the contributed code. Contributed code
+is subject to the license restrictions listed in LICENSE (as they were when the
+code was contributed.)
+
+Dustin Sallings <dustin@spy.net>
+Jason Mooberry <jasonmoo@me.com>
+Sergey Shepelev <temotor@gmail.com>
+Alex Edwards <ajmedwards@gmail.com>

vendor/github.com/patrickmn/go-cache/LICENSE

@@ -0,0 +1,19 @@
+Copyright (c) 2012-2017 Patrick Mylund Nielsen and the go-cache contributors
+
+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/patrickmn/go-cache/README.md

@@ -0,0 +1,83 @@
+# go-cache
+
+go-cache is an in-memory key:value store/cache similar to memcached that is
+suitable for applications running on a single machine. Its major advantage is
+that, being essentially a thread-safe `map[string]interface{}` with expiration
+times, it doesn't need to serialize or transmit its contents over the network.
+
+Any object can be stored, for a given duration or forever, and the cache can be
+safely used by multiple goroutines.
+
+Although go-cache isn't meant to be used as a persistent datastore, the entire
+cache can be saved to and loaded from a file (using `c.Items()` to retrieve the
+items map to serialize, and `NewFrom()` to create a cache from a deserialized
+one) to recover from downtime quickly. (See the docs for `NewFrom()` for caveats.)
+
+### Installation
+
+`go get github.com/patrickmn/go-cache`
+
+### Usage
+
+```go
+import (
+	"fmt"
+	"github.com/patrickmn/go-cache"
+	"time"
+)
+
+func main() {
+	// Create a cache with a default expiration time of 5 minutes, and which
+	// purges expired items every 10 minutes
+	c := cache.New(5*time.Minute, 10*time.Minute)
+
+	// Set the value of the key "foo" to "bar", with the default expiration time
+	c.Set("foo", "bar", cache.DefaultExpiration)
+
+	// Set the value of the key "baz" to 42, with no expiration time
+	// (the item won't be removed until it is re-set, or removed using
+	// c.Delete("baz")
+	c.Set("baz", 42, cache.NoExpiration)
+
+	// Get the string associated with the key "foo" from the cache
+	foo, found := c.Get("foo")
+	if found {
+		fmt.Println(foo)
+	}
+
+	// Since Go is statically typed, and cache values can be anything, type
+	// assertion is needed when values are being passed to functions that don't
+	// take arbitrary types, (i.e. interface{}). The simplest way to do this for
+	// values which will only be used once--e.g. for passing to another
+	// function--is:
+	foo, found := c.Get("foo")
+	if found {
+		MyFunction(foo.(string))
+	}
+
+	// This gets tedious if the value is used several times in the same function.
+	// You might do either of the following instead:
+	if x, found := c.Get("foo"); found {
+		foo := x.(string)
+		// ...
+	}
+	// or
+	var foo string
+	if x, found := c.Get("foo"); found {
+		foo = x.(string)
+	}
+	// ...
+	// foo can then be passed around freely as a string
+
+	// Want performance? Store pointers!
+	c.Set("foo", &MyStruct, cache.DefaultExpiration)
+	if x, found := c.Get("foo"); found {
+		foo := x.(*MyStruct)
+			// ...
+	}
+}
+```
+
+### Reference
+
+`godoc` or [http://godoc.org/github.com/patrickmn/go-cache](http://godoc.org/github.com/patrickmn/go-cache)

vendor/github.com/patrickmn/go-cache/sharded.go

@@ -0,0 +1,192 @@
+package cache
+
+import (
+	"crypto/rand"
+	"math"
+	"math/big"
+	insecurerand "math/rand"
+	"os"
+	"runtime"
+	"time"
+)
+
+// This is an experimental and unexported (for now) attempt at making a cache
+// with better algorithmic complexity than the standard one, namely by
+// preventing write locks of the entire cache when an item is added. As of the
+// time of writing, the overhead of selecting buckets results in cache
+// operations being about twice as slow as for the standard cache with small
+// total cache sizes, and faster for larger ones.
+//
+// See cache_test.go for a few benchmarks.
+
+type unexportedShardedCache struct {
+	*shardedCache
+}
+
+type shardedCache struct {
+	seed    uint32
+	m       uint32
+	cs      []*cache
+	janitor *shardedJanitor
+}
+
+// djb2 with better shuffling. 5x faster than FNV with the hash.Hash overhead.
+func djb33(seed uint32, k string) uint32 {
+	var (
+		l = uint32(len(k))
+		d = 5381 + seed + l
+		i = uint32(0)
+	)
+	// Why is all this 5x faster than a for loop?
+	if l >= 4 {
+		for i < l-4 {
+			d = (d * 33) ^ uint32(k[i])
+			d = (d * 33) ^ uint32(k[i+1])
+			d = (d * 33) ^ uint32(k[i+2])
+			d = (d * 33) ^ uint32(k[i+3])
+			i += 4
+		}
+	}
+	switch l - i {
+	case 1:
+	case 2:
+		d = (d * 33) ^ uint32(k[i])
+	case 3:
+		d = (d * 33) ^ uint32(k[i])
+		d = (d * 33) ^ uint32(k[i+1])
+	case 4:
+		d = (d * 33) ^ uint32(k[i])
+		d = (d * 33) ^ uint32(k[i+1])
+		d = (d * 33) ^ uint32(k[i+2])
+	}
+	return d ^ (d >> 16)
+}
+
+func (sc *shardedCache) bucket(k string) *cache {
+	return sc.cs[djb33(sc.seed, k)%sc.m]
+}
+
+func (sc *shardedCache) Set(k string, x interface{}, d time.Duration) {
+	sc.bucket(k).Set(k, x, d)
+}
+
+func (sc *shardedCache) Add(k string, x interface{}, d time.Duration) error {
+	return sc.bucket(k).Add(k, x, d)
+}
+
+func (sc *shardedCache) Replace(k string, x interface{}, d time.Duration) error {
+	return sc.bucket(k).Replace(k, x, d)
+}
+
+func (sc *shardedCache) Get(k string) (interface{}, bool) {
+	return sc.bucket(k).Get(k)
+}
+
+func (sc *shardedCache) Increment(k string, n int64) error {
+	return sc.bucket(k).Increment(k, n)
+}
+
+func (sc *shardedCache) IncrementFloat(k string, n float64) error {
+	return sc.bucket(k).IncrementFloat(k, n)
+}
+
+func (sc *shardedCache) Decrement(k string, n int64) error {
+	return sc.bucket(k).Decrement(k, n)
+}
+
+func (sc *shardedCache) Delete(k string) {
+	sc.bucket(k).Delete(k)
+}
+
+func (sc *shardedCache) DeleteExpired() {
+	for _, v := range sc.cs {
+		v.DeleteExpired()
+	}
+}
+
+// Returns the items in the cache. This may include items that have expired,
+// but have not yet been cleaned up. If this is significant, the Expiration
+// fields of the items should be checked. Note that explicit synchronization
+// is needed to use a cache and its corresponding Items() return values at
+// the same time, as the maps are shared.
+func (sc *shardedCache) Items() []map[string]Item {
+	res := make([]map[string]Item, len(sc.cs))
+	for i, v := range sc.cs {
+		res[i] = v.Items()
+	}
+	return res
+}
+
+func (sc *shardedCache) Flush() {
+	for _, v := range sc.cs {
+		v.Flush()
+	}
+}
+
+type shardedJanitor struct {
+	Interval time.Duration
+	stop     chan bool
+}
+
+func (j *shardedJanitor) Run(sc *shardedCache) {
+	j.stop = make(chan bool)
+	tick := time.Tick(j.Interval)
+	for {
+		select {
+		case <-tick:
+			sc.DeleteExpired()
+		case <-j.stop:
+			return
+		}
+	}
+}
+
+func stopShardedJanitor(sc *unexportedShardedCache) {
+	sc.janitor.stop <- true
+}
+
+func runShardedJanitor(sc *shardedCache, ci time.Duration) {
+	j := &shardedJanitor{
+		Interval: ci,
+	}
+	sc.janitor = j
+	go j.Run(sc)
+}
+
+func newShardedCache(n int, de time.Duration) *shardedCache {
+	max := big.NewInt(0).SetUint64(uint64(math.MaxUint32))
+	rnd, err := rand.Int(rand.Reader, max)
+	var seed uint32
+	if err != nil {
+		os.Stderr.Write([]byte("WARNING: go-cache's newShardedCache failed to read from the system CSPRNG (/dev/urandom or equivalent.) Your system's security may be compromised. Continuing with an insecure seed.\n"))
+		seed = insecurerand.Uint32()
+	} else {
+		seed = uint32(rnd.Uint64())
+	}
+	sc := &shardedCache{
+		seed: seed,
+		m:    uint32(n),
+		cs:   make([]*cache, n),
+	}
+	for i := 0; i < n; i++ {
+		c := &cache{
+			defaultExpiration: de,
+			items:             map[string]Item{},
+		}
+		sc.cs[i] = c
+	}
+	return sc
+}
+
+func unexportedNewSharded(defaultExpiration, cleanupInterval time.Duration, shards int) *unexportedShardedCache {
+	if defaultExpiration == 0 {
+		defaultExpiration = -1
+	}
+	sc := newShardedCache(shards, defaultExpiration)
+	SC := &unexportedShardedCache{sc}
+	if cleanupInterval > 0 {
+		runShardedJanitor(sc, cleanupInterval)
+		runtime.SetFinalizer(SC, stopShardedJanitor)
+	}
+	return SC
+}

vendor/github.com/patrickmn/go-cache/sharded_test.go

@@ -0,0 +1,85 @@
+package cache
+
+import (
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+)
+
+// func TestDjb33(t *testing.T) {
+// }
+
+var shardedKeys = []string{
+	"f",
+	"fo",
+	"foo",
+	"barf",
+	"barfo",
+	"foobar",
+	"bazbarf",
+	"bazbarfo",
+	"bazbarfoo",
+	"foobarbazq",
+	"foobarbazqu",
+	"foobarbazquu",
+	"foobarbazquux",
+}
+
+func TestShardedCache(t *testing.T) {
+	tc := unexportedNewSharded(DefaultExpiration, 0, 13)
+	for _, v := range shardedKeys {
+		tc.Set(v, "value", DefaultExpiration)
+	}
+}
+
+func BenchmarkShardedCacheGetExpiring(b *testing.B) {
+	benchmarkShardedCacheGet(b, 5*time.Minute)
+}
+
+func BenchmarkShardedCacheGetNotExpiring(b *testing.B) {
+	benchmarkShardedCacheGet(b, NoExpiration)
+}
+
+func benchmarkShardedCacheGet(b *testing.B, exp time.Duration) {
+	b.StopTimer()
+	tc := unexportedNewSharded(exp, 0, 10)
+	tc.Set("foobarba", "zquux", DefaultExpiration)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		tc.Get("foobarba")
+	}
+}
+
+func BenchmarkShardedCacheGetManyConcurrentExpiring(b *testing.B) {
+	benchmarkShardedCacheGetManyConcurrent(b, 5*time.Minute)
+}
+
+func BenchmarkShardedCacheGetManyConcurrentNotExpiring(b *testing.B) {
+	benchmarkShardedCacheGetManyConcurrent(b, NoExpiration)
+}
+
+func benchmarkShardedCacheGetManyConcurrent(b *testing.B, exp time.Duration) {
+	b.StopTimer()
+	n := 10000
+	tsc := unexportedNewSharded(exp, 0, 20)
+	keys := make([]string, n)
+	for i := 0; i < n; i++ {
+		k := "foo" + strconv.Itoa(n)
+		keys[i] = k
+		tsc.Set(k, "bar", DefaultExpiration)
+	}
+	each := b.N / n
+	wg := new(sync.WaitGroup)
+	wg.Add(n)
+	for _, v := range keys {
+		go func() {
+			for j := 0; j < each; j++ {
+				tsc.Get(v)
+			}
+			wg.Done()
+		}()
+	}
+	b.StartTimer()
+	wg.Wait()
+}