init

vendor/github.com/bluele/gcache/BUILD.bazel

@@ -0,0 +1,33 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "arc.go",
+        "cache.go",
+        "clock.go",
+        "lfu.go",
+        "lru.go",
+        "simple.go",
+        "singleflight.go",
+        "stats.go",
+        "utils.go",
+    ],
+    importmap = "go-common/vendor/github.com/bluele/gcache",
+    importpath = "github.com/bluele/gcache",
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

vendor/github.com/bluele/gcache/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 Jun Kimura
+
+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/bluele/gcache/README.md

@@ -0,0 +1,319 @@
+# GCache
+
+[![wercker status](https://app.wercker.com/status/1471b6c9cbc9ebbd15f8f9fe8f71ac67/m/master "wercker status")](https://app.wercker.com/project/bykey/1471b6c9cbc9ebbd15f8f9fe8f71ac67)[![GoDoc](https://godoc.org/github.com/bluele/gcache?status.png)](https://godoc.org/github.com/bluele/gcache)
+
+Cache library for golang. It supports expirable Cache, LFU, LRU and ARC.
+
+## Features
+
+* Supports expirable Cache, LFU, LRU and ARC.
+
+* Goroutine safe.
+
+* Supports event handlers which evict, purge, and add entry. (Optional)
+
+* Automatically load cache if it doesn't exists. (Optional)
+
+## Install
+
+```
+$ go get github.com/bluele/gcache
+```
+
+## Example
+
+### Manually set a key-value pair.
+
+```go
+package main
+
+import (
+  "github.com/bluele/gcache"
+  "fmt"
+)
+
+func main() {
+  gc := gcache.New(20).
+    LRU().
+    Build()
+  gc.Set("key", "ok")
+  value, err := gc.Get("key")
+  if err != nil {
+    panic(err)
+  }
+  fmt.Println("Get:", value)
+}
+```
+
+```
+Get: ok
+```
+
+### Manually set a key-value pair, with an expiration time.
+
+```go
+package main
+
+import (
+  "github.com/bluele/gcache"
+  "fmt"
+  "time"
+)
+
+func main() {
+  gc := gcache.New(20).
+    LRU().
+    Build()
+  gc.SetWithExpire("key", "ok", time.Second*10)
+  value, _ := gc.Get("key")
+  fmt.Println("Get:", value)
+
+  // Wait for value to expire
+  time.Sleep(time.Second*10)
+
+  value, err = gc.Get("key")
+  if err != nil {
+    panic(err)
+  }
+  fmt.Println("Get:", value)
+}
+```
+
+```
+Get: ok
+// 10 seconds later, new attempt:
+panic: ErrKeyNotFound
+```
+
+
+### Automatically load value
+
+```go
+package main
+
+import (
+  "github.com/bluele/gcache"
+  "fmt"
+)
+
+func main() {
+  gc := gcache.New(20).
+    LRU().
+    LoaderFunc(func(key interface{}) (interface{}, error) {
+      return "ok", nil
+    }).
+    Build()
+  value, err := gc.Get("key")
+  if err != nil {
+    panic(err)
+  }
+  fmt.Println("Get:", value)
+}
+```
+
+```
+Get: ok
+```
+
+### Automatically load value with expiration
+
+```go
+package main
+
+import (
+  "fmt"
+  "time"
+
+  "github.com/bluele/gcache"
+)
+
+func main() {
+  var evictCounter, loaderCounter, purgeCounter int
+  gc := gcache.New(20).
+    LRU().
+    LoaderExpireFunc(func(key interface{}) (interface{}, *time.Duration, error) {
+      loaderCounter++
+      expire := 1 * time.Second
+      return "ok", &expire, nil
+    }).
+    EvictedFunc(func(key, value interface{}) {
+      evictCounter++
+      fmt.Println("evicted key:", key)
+    }).
+    PurgeVisitorFunc(func(key, value interface{}) {
+      purgeCounter++
+      fmt.Println("purged key:", key)
+    }).
+    Build()
+  value, err := gc.Get("key")
+  if err != nil {
+    panic(err)
+  }
+  fmt.Println("Get:", value)
+  time.Sleep(1 * time.Second)
+  value, err = gc.Get("key")
+  if err != nil {
+    panic(err)
+  }
+  fmt.Println("Get:", value)
+  gc.Purge()
+  if loaderCounter != evictCounter+purgeCounter {
+    panic("bad")
+  }
+}
+```
+
+```
+Get: ok
+evicted key: key
+Get: ok
+purged key: key
+```
+
+
+## Cache Algorithm
+
+  * Least-Frequently Used (LFU)
+
+  Discards the least frequently used items first.
+
+  ```go
+  func main() {
+    // size: 10
+    gc := gcache.New(10).
+      LFU().
+      Build()
+    gc.Set("key", "value")
+  }
+  ```
+
+  * Least Recently Used (LRU)
+
+  Discards the least recently used items first.
+
+  ```go
+  func main() {
+    // size: 10
+    gc := gcache.New(10).
+      LRU().
+      Build()
+    gc.Set("key", "value")
+  }
+  ```
+
+  * Adaptive Replacement Cache (ARC)
+
+  Constantly balances between LRU and LFU, to improve the combined result.
+
+  detail: http://en.wikipedia.org/wiki/Adaptive_replacement_cache
+
+  ```go
+  func main() {
+    // size: 10
+    gc := gcache.New(10).
+      ARC().
+      Build()
+    gc.Set("key", "value")
+  }
+  ```
+
+  * SimpleCache (Default)
+
+  SimpleCache has no clear priority for evict cache. It depends on key-value map order.
+
+  ```go
+  func main() {
+    // size: 10
+    gc := gcache.New(10).Build()
+    gc.Set("key", "value")
+    v, err := gc.Get("key")
+    if err != nil {
+      panic(err)
+    }
+  }
+  ```
+
+## Loading Cache
+
+If specified `LoaderFunc`, values are automatically loaded by the cache, and are stored in the cache until either evicted or manually invalidated.
+
+```go
+func main() {
+  gc := gcache.New(10).
+    LRU().
+    LoaderFunc(func(key interface{}) (interface{}, error) {
+      return "value", nil
+    }).
+    Build()
+  v, _ := gc.Get("key")
+  // output: "value"
+  fmt.Println(v)
+}
+```
+
+GCache coordinates cache fills such that only one load in one process of an entire replicated set of processes populates the cache, then multiplexes the loaded value to all callers.
+
+## Expirable cache
+
+```go
+func main() {
+  // LRU cache, size: 10, expiration: after a hour
+  gc := gcache.New(10).
+    LRU().
+    Expiration(time.Hour).
+    Build()
+}
+```
+
+## Event handlers
+
+### Evicted handler
+
+Event handler for evict the entry.
+
+```go
+func main() {
+  gc := gcache.New(2).
+    EvictedFunc(func(key, value interface{}) {
+      fmt.Println("evicted key:", key)
+    }).
+    Build()
+  for i := 0; i < 3; i++ {
+    gc.Set(i, i*i)
+  }
+}
+```
+
+```
+evicted key: 0
+```
+
+### Added handler
+
+Event handler for add the entry.
+
+```go
+func main() {
+  gc := gcache.New(2).
+    AddedFunc(func(key, value interface{}) {
+      fmt.Println("added key:", key)
+    }).
+    Build()
+  for i := 0; i < 3; i++ {
+    gc.Set(i, i*i)
+  }
+}
+```
+
+```
+added key: 0
+added key: 1
+added key: 2
+```
+
+# Author
+
+**Jun Kimura**
+
+* <http://github.com/bluele>
+* <junkxdev@gmail.com>

vendor/github.com/bluele/gcache/arc.go

@@ -0,0 +1,418 @@
+package gcache
+
+import (
+	"container/list"
+	"time"
+)
+
+// Constantly balances between LRU and LFU, to improve the combined result.
+type ARC struct {
+	baseCache
+	items map[interface{}]*arcItem
+
+	part int
+	t1   *arcList
+	t2   *arcList
+	b1   *arcList
+	b2   *arcList
+}
+
+func newARC(cb *CacheBuilder) *ARC {
+	c := &ARC{}
+	buildCache(&c.baseCache, cb)
+
+	c.init()
+	c.loadGroup.cache = c
+	return c
+}
+
+func (c *ARC) init() {
+	c.items = make(map[interface{}]*arcItem)
+	c.t1 = newARCList()
+	c.t2 = newARCList()
+	c.b1 = newARCList()
+	c.b2 = newARCList()
+}
+
+func (c *ARC) replace(key interface{}) {
+	var old interface{}
+	if (c.t1.Len() > 0 && c.b2.Has(key) && c.t1.Len() == c.part) || (c.t1.Len() > c.part) {
+		old = c.t1.RemoveTail()
+		c.b1.PushFront(old)
+	} else if c.t2.l.Len() > 0 {
+		old = c.t2.RemoveTail()
+		c.b2.PushFront(old)
+	} else {
+		return
+	}
+	item, ok := c.items[old]
+	if ok {
+		delete(c.items, old)
+		if c.evictedFunc != nil {
+			c.evictedFunc(item.key, item.value)
+		}
+	}
+}
+
+func (c *ARC) Set(key, value interface{}) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, err := c.set(key, value)
+	return err
+}
+
+// Set a new key-value pair with an expiration time
+func (c *ARC) SetWithExpire(key, value interface{}, expiration time.Duration) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	item, err := c.set(key, value)
+	if err != nil {
+		return err
+	}
+
+	t := c.clock.Now().Add(expiration)
+	item.(*arcItem).expiration = &t
+	return nil
+}
+
+func (c *ARC) set(key, value interface{}) (interface{}, error) {
+	var err error
+	if c.serializeFunc != nil {
+		value, err = c.serializeFunc(key, value)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	item, ok := c.items[key]
+	if ok {
+		item.value = value
+	} else {
+		item = &arcItem{
+			clock: c.clock,
+			key:   key,
+			value: value,
+		}
+		c.items[key] = item
+	}
+
+	if c.expiration != nil {
+		t := c.clock.Now().Add(*c.expiration)
+		item.expiration = &t
+	}
+
+	defer func() {
+		if c.addedFunc != nil {
+			c.addedFunc(key, value)
+		}
+	}()
+
+	if c.t1.Has(key) || c.t2.Has(key) {
+		return item, nil
+	}
+
+	if elt := c.b1.Lookup(key); elt != nil {
+		c.part = minInt(c.size, c.part+maxInt(c.b2.Len()/c.b1.Len(), 1))
+		c.replace(key)
+		c.b1.Remove(key, elt)
+		c.t2.PushFront(key)
+		return item, nil
+	}
+
+	if elt := c.b2.Lookup(key); elt != nil {
+		c.part = maxInt(0, c.part-maxInt(c.b1.Len()/c.b2.Len(), 1))
+		c.replace(key)
+		c.b2.Remove(key, elt)
+		c.t2.PushFront(key)
+		return item, nil
+	}
+
+	if c.t1.Len()+c.b1.Len() == c.size {
+		if c.t1.Len() < c.size {
+			c.b1.RemoveTail()
+			c.replace(key)
+		} else {
+			pop := c.t1.RemoveTail()
+			item, ok := c.items[pop]
+			if ok {
+				delete(c.items, pop)
+				if c.evictedFunc != nil {
+					c.evictedFunc(item.key, item.value)
+				}
+			}
+		}
+	} else {
+		total := c.t1.Len() + c.b1.Len() + c.t2.Len() + c.b2.Len()
+		if total >= c.size {
+			if total == (2 * c.size) {
+				c.b2.RemoveTail()
+			}
+			c.replace(key)
+		}
+	}
+	c.t1.PushFront(key)
+	return item, nil
+}
+
+// Get a value from cache pool using key if it exists. If not exists and it has LoaderFunc, it will generate the value using you have specified LoaderFunc method returns value.
+func (c *ARC) Get(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, true)
+	}
+	return v, err
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key, returns KeyNotFoundError.
+// And send a request which refresh value for specified key if cache object has LoaderFunc.
+func (c *ARC) GetIFPresent(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, false)
+	}
+	return v, err
+}
+
+func (c *ARC) get(key interface{}, onLoad bool) (interface{}, error) {
+	v, err := c.getValue(key, onLoad)
+	if err != nil {
+		return nil, err
+	}
+	if c.deserializeFunc != nil {
+		return c.deserializeFunc(key, v)
+	}
+	return v, nil
+}
+
+func (c *ARC) getValue(key interface{}, onLoad bool) (interface{}, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if elt := c.t1.Lookup(key); elt != nil {
+		c.t1.Remove(key, elt)
+		item := c.items[key]
+		if !item.IsExpired(nil) {
+			c.t2.PushFront(key)
+			if !onLoad {
+				c.stats.IncrHitCount()
+			}
+			return item.value, nil
+		} else {
+			delete(c.items, key)
+			c.b1.PushFront(key)
+			if c.evictedFunc != nil {
+				c.evictedFunc(item.key, item.value)
+			}
+		}
+	}
+	if elt := c.t2.Lookup(key); elt != nil {
+		item := c.items[key]
+		if !item.IsExpired(nil) {
+			c.t2.MoveToFront(elt)
+			if !onLoad {
+				c.stats.IncrHitCount()
+			}
+			return item.value, nil
+		} else {
+			delete(c.items, key)
+			c.t2.Remove(key, elt)
+			c.b2.PushFront(key)
+			if c.evictedFunc != nil {
+				c.evictedFunc(item.key, item.value)
+			}
+		}
+	}
+
+	if !onLoad {
+		c.stats.IncrMissCount()
+	}
+	return nil, KeyNotFoundError
+}
+
+func (c *ARC) getWithLoader(key interface{}, isWait bool) (interface{}, error) {
+	if c.loaderExpireFunc == nil {
+		return nil, KeyNotFoundError
+	}
+	value, _, err := c.load(key, func(v interface{}, expiration *time.Duration, e error) (interface{}, error) {
+		if e != nil {
+			return nil, e
+		}
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		item, err := c.set(key, v)
+		if err != nil {
+			return nil, err
+		}
+		if expiration != nil {
+			t := c.clock.Now().Add(*expiration)
+			item.(*arcItem).expiration = &t
+		}
+		return v, nil
+	}, isWait)
+	if err != nil {
+		return nil, err
+	}
+	return value, nil
+}
+
+// Remove removes the provided key from the cache.
+func (c *ARC) Remove(key interface{}) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.remove(key)
+}
+
+func (c *ARC) remove(key interface{}) bool {
+	if elt := c.t1.Lookup(key); elt != nil {
+		c.t1.Remove(key, elt)
+		item := c.items[key]
+		delete(c.items, key)
+		c.b1.PushFront(key)
+		if c.evictedFunc != nil {
+			c.evictedFunc(key, item.value)
+		}
+		return true
+	}
+
+	if elt := c.t2.Lookup(key); elt != nil {
+		c.t2.Remove(key, elt)
+		item := c.items[key]
+		delete(c.items, key)
+		c.b2.PushFront(key)
+		if c.evictedFunc != nil {
+			c.evictedFunc(key, item.value)
+		}
+		return true
+	}
+
+	return false
+}
+
+func (c *ARC) keys() []interface{} {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	keys := make([]interface{}, len(c.items))
+	var i = 0
+	for k := range c.items {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
+// Keys returns a slice of the keys in the cache.
+func (c *ARC) Keys() []interface{} {
+	keys := []interface{}{}
+	for _, k := range c.keys() {
+		_, err := c.GetIFPresent(k)
+		if err == nil {
+			keys = append(keys, k)
+		}
+	}
+	return keys
+}
+
+// Returns all key-value pairs in the cache.
+func (c *ARC) GetALL() map[interface{}]interface{} {
+	m := make(map[interface{}]interface{})
+	for _, k := range c.keys() {
+		v, err := c.GetIFPresent(k)
+		if err == nil {
+			m[k] = v
+		}
+	}
+	return m
+}
+
+// Len returns the number of items in the cache.
+func (c *ARC) Len() int {
+	return len(c.GetALL())
+}
+
+// Purge is used to completely clear the cache
+func (c *ARC) Purge() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.purgeVisitorFunc != nil {
+		for _, item := range c.items {
+			c.purgeVisitorFunc(item.key, item.value)
+		}
+	}
+
+	c.init()
+}
+
+// returns boolean value whether this item is expired or not.
+func (it *arcItem) IsExpired(now *time.Time) bool {
+	if it.expiration == nil {
+		return false
+	}
+	if now == nil {
+		t := it.clock.Now()
+		now = &t
+	}
+	return it.expiration.Before(*now)
+}
+
+type arcList struct {
+	l    *list.List
+	keys map[interface{}]*list.Element
+}
+
+type arcItem struct {
+	clock      Clock
+	key        interface{}
+	value      interface{}
+	expiration *time.Time
+}
+
+func newARCList() *arcList {
+	return &arcList{
+		l:    list.New(),
+		keys: make(map[interface{}]*list.Element),
+	}
+}
+
+func (al *arcList) Has(key interface{}) bool {
+	_, ok := al.keys[key]
+	return ok
+}
+
+func (al *arcList) Lookup(key interface{}) *list.Element {
+	elt := al.keys[key]
+	return elt
+}
+
+func (al *arcList) MoveToFront(elt *list.Element) {
+	al.l.MoveToFront(elt)
+}
+
+func (al *arcList) PushFront(key interface{}) {
+	if elt, ok := al.keys[key]; ok {
+		al.l.MoveToFront(elt)
+		return
+	}
+	elt := al.l.PushFront(key)
+	al.keys[key] = elt
+}
+
+func (al *arcList) Remove(key interface{}, elt *list.Element) {
+	delete(al.keys, key)
+	al.l.Remove(elt)
+}
+
+func (al *arcList) RemoveTail() interface{} {
+	elt := al.l.Back()
+	al.l.Remove(elt)
+
+	key := elt.Value
+	delete(al.keys, key)
+
+	return key
+}
+
+func (al *arcList) Len() int {
+	return al.l.Len()
+}

vendor/github.com/bluele/gcache/cache.go

@@ -0,0 +1,204 @@
+package gcache
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+)
+
+const (
+	TYPE_SIMPLE = "simple"
+	TYPE_LRU    = "lru"
+	TYPE_LFU    = "lfu"
+	TYPE_ARC    = "arc"
+)
+
+var KeyNotFoundError = errors.New("Key not found.")
+
+type Cache interface {
+	Set(interface{}, interface{}) error
+	SetWithExpire(interface{}, interface{}, time.Duration) error
+	Get(interface{}) (interface{}, error)
+	GetIFPresent(interface{}) (interface{}, error)
+	GetALL() map[interface{}]interface{}
+	get(interface{}, bool) (interface{}, error)
+	Remove(interface{}) bool
+	Purge()
+	Keys() []interface{}
+	Len() int
+
+	statsAccessor
+}
+
+type baseCache struct {
+	clock            Clock
+	size             int
+	loaderExpireFunc LoaderExpireFunc
+	evictedFunc      EvictedFunc
+	purgeVisitorFunc PurgeVisitorFunc
+	addedFunc        AddedFunc
+	deserializeFunc  DeserializeFunc
+	serializeFunc    SerializeFunc
+	expiration       *time.Duration
+	mu               sync.RWMutex
+	loadGroup        Group
+	*stats
+}
+
+type (
+	LoaderFunc       func(interface{}) (interface{}, error)
+	LoaderExpireFunc func(interface{}) (interface{}, *time.Duration, error)
+	EvictedFunc      func(interface{}, interface{})
+	PurgeVisitorFunc func(interface{}, interface{})
+	AddedFunc        func(interface{}, interface{})
+	DeserializeFunc  func(interface{}, interface{}) (interface{}, error)
+	SerializeFunc    func(interface{}, interface{}) (interface{}, error)
+)
+
+type CacheBuilder struct {
+	clock            Clock
+	tp               string
+	size             int
+	loaderExpireFunc LoaderExpireFunc
+	evictedFunc      EvictedFunc
+	purgeVisitorFunc PurgeVisitorFunc
+	addedFunc        AddedFunc
+	expiration       *time.Duration
+	deserializeFunc  DeserializeFunc
+	serializeFunc    SerializeFunc
+}
+
+func New(size int) *CacheBuilder {
+	return &CacheBuilder{
+		clock: NewRealClock(),
+		tp:    TYPE_SIMPLE,
+		size:  size,
+	}
+}
+
+func (cb *CacheBuilder) Clock(clock Clock) *CacheBuilder {
+	cb.clock = clock
+	return cb
+}
+
+// Set a loader function.
+// loaderFunc: create a new value with this function if cached value is expired.
+func (cb *CacheBuilder) LoaderFunc(loaderFunc LoaderFunc) *CacheBuilder {
+	cb.loaderExpireFunc = func(k interface{}) (interface{}, *time.Duration, error) {
+		v, err := loaderFunc(k)
+		return v, nil, err
+	}
+	return cb
+}
+
+// Set a loader function with expiration.
+// loaderExpireFunc: create a new value with this function if cached value is expired.
+// If nil returned instead of time.Duration from loaderExpireFunc than value will never expire.
+func (cb *CacheBuilder) LoaderExpireFunc(loaderExpireFunc LoaderExpireFunc) *CacheBuilder {
+	cb.loaderExpireFunc = loaderExpireFunc
+	return cb
+}
+
+func (cb *CacheBuilder) EvictType(tp string) *CacheBuilder {
+	cb.tp = tp
+	return cb
+}
+
+func (cb *CacheBuilder) Simple() *CacheBuilder {
+	return cb.EvictType(TYPE_SIMPLE)
+}
+
+func (cb *CacheBuilder) LRU() *CacheBuilder {
+	return cb.EvictType(TYPE_LRU)
+}
+
+func (cb *CacheBuilder) LFU() *CacheBuilder {
+	return cb.EvictType(TYPE_LFU)
+}
+
+func (cb *CacheBuilder) ARC() *CacheBuilder {
+	return cb.EvictType(TYPE_ARC)
+}
+
+func (cb *CacheBuilder) EvictedFunc(evictedFunc EvictedFunc) *CacheBuilder {
+	cb.evictedFunc = evictedFunc
+	return cb
+}
+
+func (cb *CacheBuilder) PurgeVisitorFunc(purgeVisitorFunc PurgeVisitorFunc) *CacheBuilder {
+	cb.purgeVisitorFunc = purgeVisitorFunc
+	return cb
+}
+
+func (cb *CacheBuilder) AddedFunc(addedFunc AddedFunc) *CacheBuilder {
+	cb.addedFunc = addedFunc
+	return cb
+}
+
+func (cb *CacheBuilder) DeserializeFunc(deserializeFunc DeserializeFunc) *CacheBuilder {
+	cb.deserializeFunc = deserializeFunc
+	return cb
+}
+
+func (cb *CacheBuilder) SerializeFunc(serializeFunc SerializeFunc) *CacheBuilder {
+	cb.serializeFunc = serializeFunc
+	return cb
+}
+
+func (cb *CacheBuilder) Expiration(expiration time.Duration) *CacheBuilder {
+	cb.expiration = &expiration
+	return cb
+}
+
+func (cb *CacheBuilder) Build() Cache {
+	if cb.size <= 0 && cb.tp != TYPE_SIMPLE {
+		panic("gcache: Cache size <= 0")
+	}
+
+	return cb.build()
+}
+
+func (cb *CacheBuilder) build() Cache {
+	switch cb.tp {
+	case TYPE_SIMPLE:
+		return newSimpleCache(cb)
+	case TYPE_LRU:
+		return newLRUCache(cb)
+	case TYPE_LFU:
+		return newLFUCache(cb)
+	case TYPE_ARC:
+		return newARC(cb)
+	default:
+		panic("gcache: Unknown type " + cb.tp)
+	}
+}
+
+func buildCache(c *baseCache, cb *CacheBuilder) {
+	c.clock = cb.clock
+	c.size = cb.size
+	c.loaderExpireFunc = cb.loaderExpireFunc
+	c.expiration = cb.expiration
+	c.addedFunc = cb.addedFunc
+	c.deserializeFunc = cb.deserializeFunc
+	c.serializeFunc = cb.serializeFunc
+	c.evictedFunc = cb.evictedFunc
+	c.purgeVisitorFunc = cb.purgeVisitorFunc
+	c.stats = &stats{}
+}
+
+// load a new value using by specified key.
+func (c *baseCache) load(key interface{}, cb func(interface{}, *time.Duration, error) (interface{}, error), isWait bool) (interface{}, bool, error) {
+	v, called, err := c.loadGroup.Do(key, func() (v interface{}, e error) {
+		defer func() {
+			if r := recover(); r != nil {
+				e = fmt.Errorf("Loader panics: %v", r)
+			}
+		}()
+		return cb(c.loaderExpireFunc(key))
+	}, isWait)
+	if err != nil {
+		return nil, called, err
+	}
+	return v, called, nil
+}

vendor/github.com/bluele/gcache/clock.go

@@ -0,0 +1,53 @@
+package gcache
+
+import (
+	"sync"
+	"time"
+)
+
+type Clock interface {
+	Now() time.Time
+}
+
+type RealClock struct{}
+
+func NewRealClock() Clock {
+	return RealClock{}
+}
+
+func (rc RealClock) Now() time.Time {
+	t := time.Now()
+	return t
+}
+
+type FakeClock interface {
+	Clock
+
+	Advance(d time.Duration)
+}
+
+func NewFakeClock() FakeClock {
+	return &fakeclock{
+		// Taken from github.com/jonboulle/clockwork: use a fixture that does not fulfill Time.IsZero()
+		now: time.Date(1984, time.April, 4, 0, 0, 0, 0, time.UTC),
+	}
+}
+
+type fakeclock struct {
+	now time.Time
+
+	mutex sync.RWMutex
+}
+
+func (fc *fakeclock) Now() time.Time {
+	fc.mutex.RLock()
+	defer fc.mutex.RUnlock()
+	t := fc.now
+	return t
+}
+
+func (fc *fakeclock) Advance(d time.Duration) {
+	fc.mutex.Lock()
+	defer fc.mutex.Unlock()
+	fc.now = fc.now.Add(d)
+}

vendor/github.com/bluele/gcache/lfu.go

@@ -0,0 +1,319 @@
+package gcache
+
+import (
+	"container/list"
+	"time"
+)
+
+// Discards the least frequently used items first.
+type LFUCache struct {
+	baseCache
+	items    map[interface{}]*lfuItem
+	freqList *list.List // list for freqEntry
+}
+
+func newLFUCache(cb *CacheBuilder) *LFUCache {
+	c := &LFUCache{}
+	buildCache(&c.baseCache, cb)
+
+	c.init()
+	c.loadGroup.cache = c
+	return c
+}
+
+func (c *LFUCache) init() {
+	c.freqList = list.New()
+	c.items = make(map[interface{}]*lfuItem, c.size+1)
+	c.freqList.PushFront(&freqEntry{
+		freq:  0,
+		items: make(map[*lfuItem]struct{}),
+	})
+}
+
+// Set a new key-value pair
+func (c *LFUCache) Set(key, value interface{}) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, err := c.set(key, value)
+	return err
+}
+
+// Set a new key-value pair with an expiration time
+func (c *LFUCache) SetWithExpire(key, value interface{}, expiration time.Duration) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	item, err := c.set(key, value)
+	if err != nil {
+		return err
+	}
+
+	t := c.clock.Now().Add(expiration)
+	item.(*lfuItem).expiration = &t
+	return nil
+}
+
+func (c *LFUCache) set(key, value interface{}) (interface{}, error) {
+	var err error
+	if c.serializeFunc != nil {
+		value, err = c.serializeFunc(key, value)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Check for existing item
+	item, ok := c.items[key]
+	if ok {
+		item.value = value
+	} else {
+		// Verify size not exceeded
+		if len(c.items) >= c.size {
+			c.evict(1)
+		}
+		item = &lfuItem{
+			clock:       c.clock,
+			key:         key,
+			value:       value,
+			freqElement: nil,
+		}
+		el := c.freqList.Front()
+		fe := el.Value.(*freqEntry)
+		fe.items[item] = struct{}{}
+
+		item.freqElement = el
+		c.items[key] = item
+	}
+
+	if c.expiration != nil {
+		t := c.clock.Now().Add(*c.expiration)
+		item.expiration = &t
+	}
+
+	if c.addedFunc != nil {
+		c.addedFunc(key, value)
+	}
+
+	return item, nil
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key and has LoaderFunc,
+// generate a value using `LoaderFunc` method returns value.
+func (c *LFUCache) Get(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, true)
+	}
+	return v, err
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key, returns KeyNotFoundError.
+// And send a request which refresh value for specified key if cache object has LoaderFunc.
+func (c *LFUCache) GetIFPresent(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, false)
+	}
+	return v, err
+}
+
+func (c *LFUCache) get(key interface{}, onLoad bool) (interface{}, error) {
+	v, err := c.getValue(key, onLoad)
+	if err != nil {
+		return nil, err
+	}
+	if c.deserializeFunc != nil {
+		return c.deserializeFunc(key, v)
+	}
+	return v, nil
+}
+
+func (c *LFUCache) getValue(key interface{}, onLoad bool) (interface{}, error) {
+	c.mu.Lock()
+	item, ok := c.items[key]
+	if ok {
+		if !item.IsExpired(nil) {
+			c.increment(item)
+			v := item.value
+			c.mu.Unlock()
+			if !onLoad {
+				c.stats.IncrHitCount()
+			}
+			return v, nil
+		}
+		c.removeItem(item)
+	}
+	c.mu.Unlock()
+	if !onLoad {
+		c.stats.IncrMissCount()
+	}
+	return nil, KeyNotFoundError
+}
+
+func (c *LFUCache) getWithLoader(key interface{}, isWait bool) (interface{}, error) {
+	if c.loaderExpireFunc == nil {
+		return nil, KeyNotFoundError
+	}
+	value, _, err := c.load(key, func(v interface{}, expiration *time.Duration, e error) (interface{}, error) {
+		if e != nil {
+			return nil, e
+		}
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		item, err := c.set(key, v)
+		if err != nil {
+			return nil, err
+		}
+		if expiration != nil {
+			t := c.clock.Now().Add(*expiration)
+			item.(*lfuItem).expiration = &t
+		}
+		return v, nil
+	}, isWait)
+	if err != nil {
+		return nil, err
+	}
+	return value, nil
+}
+
+func (c *LFUCache) increment(item *lfuItem) {
+	currentFreqElement := item.freqElement
+	currentFreqEntry := currentFreqElement.Value.(*freqEntry)
+	nextFreq := currentFreqEntry.freq + 1
+	delete(currentFreqEntry.items, item)
+
+	nextFreqElement := currentFreqElement.Next()
+	if nextFreqElement == nil {
+		nextFreqElement = c.freqList.InsertAfter(&freqEntry{
+			freq:  nextFreq,
+			items: make(map[*lfuItem]struct{}),
+		}, currentFreqElement)
+	}
+	nextFreqElement.Value.(*freqEntry).items[item] = struct{}{}
+	item.freqElement = nextFreqElement
+}
+
+// evict removes the least frequence item from the cache.
+func (c *LFUCache) evict(count int) {
+	entry := c.freqList.Front()
+	for i := 0; i < count; {
+		if entry == nil {
+			return
+		} else {
+			for item, _ := range entry.Value.(*freqEntry).items {
+				if i >= count {
+					return
+				}
+				c.removeItem(item)
+				i++
+			}
+			entry = entry.Next()
+		}
+	}
+}
+
+// Removes the provided key from the cache.
+func (c *LFUCache) Remove(key interface{}) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.remove(key)
+}
+
+func (c *LFUCache) remove(key interface{}) bool {
+	if item, ok := c.items[key]; ok {
+		c.removeItem(item)
+		return true
+	}
+	return false
+}
+
+// removeElement is used to remove a given list element from the cache
+func (c *LFUCache) removeItem(item *lfuItem) {
+	delete(c.items, item.key)
+	delete(item.freqElement.Value.(*freqEntry).items, item)
+	if c.evictedFunc != nil {
+		c.evictedFunc(item.key, item.value)
+	}
+}
+
+func (c *LFUCache) keys() []interface{} {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	keys := make([]interface{}, len(c.items))
+	var i = 0
+	for k := range c.items {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
+// Returns a slice of the keys in the cache.
+func (c *LFUCache) Keys() []interface{} {
+	keys := []interface{}{}
+	for _, k := range c.keys() {
+		_, err := c.GetIFPresent(k)
+		if err == nil {
+			keys = append(keys, k)
+		}
+	}
+	return keys
+}
+
+// Returns all key-value pairs in the cache.
+func (c *LFUCache) GetALL() map[interface{}]interface{} {
+	m := make(map[interface{}]interface{})
+	for _, k := range c.keys() {
+		v, err := c.GetIFPresent(k)
+		if err == nil {
+			m[k] = v
+		}
+	}
+	return m
+}
+
+// Returns the number of items in the cache.
+func (c *LFUCache) Len() int {
+	return len(c.GetALL())
+}
+
+// Completely clear the cache
+func (c *LFUCache) Purge() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.purgeVisitorFunc != nil {
+		for key, item := range c.items {
+			c.purgeVisitorFunc(key, item.value)
+		}
+	}
+
+	c.init()
+}
+
+type freqEntry struct {
+	freq  uint
+	items map[*lfuItem]struct{}
+}
+
+type lfuItem struct {
+	clock       Clock
+	key         interface{}
+	value       interface{}
+	freqElement *list.Element
+	expiration  *time.Time
+}
+
+// returns boolean value whether this item is expired or not.
+func (it *lfuItem) IsExpired(now *time.Time) bool {
+	if it.expiration == nil {
+		return false
+	}
+	if now == nil {
+		t := it.clock.Now()
+		now = &t
+	}
+	return it.expiration.Before(*now)
+}

vendor/github.com/bluele/gcache/lru.go

@@ -0,0 +1,285 @@
+package gcache
+
+import (
+	"container/list"
+	"time"
+)
+
+// Discards the least recently used items first.
+type LRUCache struct {
+	baseCache
+	items     map[interface{}]*list.Element
+	evictList *list.List
+}
+
+func newLRUCache(cb *CacheBuilder) *LRUCache {
+	c := &LRUCache{}
+	buildCache(&c.baseCache, cb)
+
+	c.init()
+	c.loadGroup.cache = c
+	return c
+}
+
+func (c *LRUCache) init() {
+	c.evictList = list.New()
+	c.items = make(map[interface{}]*list.Element, c.size+1)
+}
+
+func (c *LRUCache) set(key, value interface{}) (interface{}, error) {
+	var err error
+	if c.serializeFunc != nil {
+		value, err = c.serializeFunc(key, value)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Check for existing item
+	var item *lruItem
+	if it, ok := c.items[key]; ok {
+		c.evictList.MoveToFront(it)
+		item = it.Value.(*lruItem)
+		item.value = value
+	} else {
+		// Verify size not exceeded
+		if c.evictList.Len() >= c.size {
+			c.evict(1)
+		}
+		item = &lruItem{
+			clock: c.clock,
+			key:   key,
+			value: value,
+		}
+		c.items[key] = c.evictList.PushFront(item)
+	}
+
+	if c.expiration != nil {
+		t := c.clock.Now().Add(*c.expiration)
+		item.expiration = &t
+	}
+
+	if c.addedFunc != nil {
+		c.addedFunc(key, value)
+	}
+
+	return item, nil
+}
+
+// set a new key-value pair
+func (c *LRUCache) Set(key, value interface{}) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, err := c.set(key, value)
+	return err
+}
+
+// Set a new key-value pair with an expiration time
+func (c *LRUCache) SetWithExpire(key, value interface{}, expiration time.Duration) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	item, err := c.set(key, value)
+	if err != nil {
+		return err
+	}
+
+	t := c.clock.Now().Add(expiration)
+	item.(*lruItem).expiration = &t
+	return nil
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key and has LoaderFunc,
+// generate a value using `LoaderFunc` method returns value.
+func (c *LRUCache) Get(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, true)
+	}
+	return v, err
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key, returns KeyNotFoundError.
+// And send a request which refresh value for specified key if cache object has LoaderFunc.
+func (c *LRUCache) GetIFPresent(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, false)
+	}
+	return v, err
+}
+
+func (c *LRUCache) get(key interface{}, onLoad bool) (interface{}, error) {
+	v, err := c.getValue(key, onLoad)
+	if err != nil {
+		return nil, err
+	}
+	if c.deserializeFunc != nil {
+		return c.deserializeFunc(key, v)
+	}
+	return v, nil
+}
+
+func (c *LRUCache) getValue(key interface{}, onLoad bool) (interface{}, error) {
+	c.mu.Lock()
+	item, ok := c.items[key]
+	if ok {
+		it := item.Value.(*lruItem)
+		if !it.IsExpired(nil) {
+			c.evictList.MoveToFront(item)
+			v := it.value
+			c.mu.Unlock()
+			if !onLoad {
+				c.stats.IncrHitCount()
+			}
+			return v, nil
+		}
+		c.removeElement(item)
+	}
+	c.mu.Unlock()
+	if !onLoad {
+		c.stats.IncrMissCount()
+	}
+	return nil, KeyNotFoundError
+}
+
+func (c *LRUCache) getWithLoader(key interface{}, isWait bool) (interface{}, error) {
+	if c.loaderExpireFunc == nil {
+		return nil, KeyNotFoundError
+	}
+	value, _, err := c.load(key, func(v interface{}, expiration *time.Duration, e error) (interface{}, error) {
+		if e != nil {
+			return nil, e
+		}
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		item, err := c.set(key, v)
+		if err != nil {
+			return nil, err
+		}
+		if expiration != nil {
+			t := c.clock.Now().Add(*expiration)
+			item.(*lruItem).expiration = &t
+		}
+		return v, nil
+	}, isWait)
+	if err != nil {
+		return nil, err
+	}
+	return value, nil
+}
+
+// evict removes the oldest item from the cache.
+func (c *LRUCache) evict(count int) {
+	for i := 0; i < count; i++ {
+		ent := c.evictList.Back()
+		if ent == nil {
+			return
+		} else {
+			c.removeElement(ent)
+		}
+	}
+}
+
+// Removes the provided key from the cache.
+func (c *LRUCache) Remove(key interface{}) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.remove(key)
+}
+
+func (c *LRUCache) remove(key interface{}) bool {
+	if ent, ok := c.items[key]; ok {
+		c.removeElement(ent)
+		return true
+	}
+	return false
+}
+
+func (c *LRUCache) removeElement(e *list.Element) {
+	c.evictList.Remove(e)
+	entry := e.Value.(*lruItem)
+	delete(c.items, entry.key)
+	if c.evictedFunc != nil {
+		entry := e.Value.(*lruItem)
+		c.evictedFunc(entry.key, entry.value)
+	}
+}
+
+func (c *LRUCache) keys() []interface{} {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	keys := make([]interface{}, len(c.items))
+	var i = 0
+	for k := range c.items {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
+// Returns a slice of the keys in the cache.
+func (c *LRUCache) Keys() []interface{} {
+	keys := []interface{}{}
+	for _, k := range c.keys() {
+		_, err := c.GetIFPresent(k)
+		if err == nil {
+			keys = append(keys, k)
+		}
+	}
+	return keys
+}
+
+// Returns all key-value pairs in the cache.
+func (c *LRUCache) GetALL() map[interface{}]interface{} {
+	m := make(map[interface{}]interface{})
+	for _, k := range c.keys() {
+		v, err := c.GetIFPresent(k)
+		if err == nil {
+			m[k] = v
+		}
+	}
+	return m
+}
+
+// Returns the number of items in the cache.
+func (c *LRUCache) Len() int {
+	return len(c.GetALL())
+}
+
+// Completely clear the cache
+func (c *LRUCache) Purge() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.purgeVisitorFunc != nil {
+		for key, item := range c.items {
+			it := item.Value.(*lruItem)
+			v := it.value
+			c.purgeVisitorFunc(key, v)
+		}
+	}
+
+	c.init()
+}
+
+type lruItem struct {
+	clock      Clock
+	key        interface{}
+	value      interface{}
+	expiration *time.Time
+}
+
+// returns boolean value whether this item is expired or not.
+func (it *lruItem) IsExpired(now *time.Time) bool {
+	if it.expiration == nil {
+		return false
+	}
+	if now == nil {
+		t := it.clock.Now()
+		now = &t
+	}
+	return it.expiration.Before(*now)
+}

vendor/github.com/bluele/gcache/simple.go

@@ -0,0 +1,273 @@
+package gcache
+
+import "time"
+
+// SimpleCache has no clear priority for evict cache. It depends on key-value map order.
+type SimpleCache struct {
+	baseCache
+	items map[interface{}]*simpleItem
+}
+
+func newSimpleCache(cb *CacheBuilder) *SimpleCache {
+	c := &SimpleCache{}
+	buildCache(&c.baseCache, cb)
+
+	c.init()
+	c.loadGroup.cache = c
+	return c
+}
+
+func (c *SimpleCache) init() {
+	if c.size <= 0 {
+		c.items = make(map[interface{}]*simpleItem)
+	} else {
+		c.items = make(map[interface{}]*simpleItem, c.size)
+	}
+}
+
+// Set a new key-value pair
+func (c *SimpleCache) Set(key, value interface{}) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, err := c.set(key, value)
+	return err
+}
+
+// Set a new key-value pair with an expiration time
+func (c *SimpleCache) SetWithExpire(key, value interface{}, expiration time.Duration) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	item, err := c.set(key, value)
+	if err != nil {
+		return err
+	}
+
+	t := c.clock.Now().Add(expiration)
+	item.(*simpleItem).expiration = &t
+	return nil
+}
+
+func (c *SimpleCache) set(key, value interface{}) (interface{}, error) {
+	var err error
+	if c.serializeFunc != nil {
+		value, err = c.serializeFunc(key, value)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Check for existing item
+	item, ok := c.items[key]
+	if ok {
+		item.value = value
+	} else {
+		// Verify size not exceeded
+		if (len(c.items) >= c.size) && c.size > 0 {
+			c.evict(1)
+		}
+		item = &simpleItem{
+			clock: c.clock,
+			value: value,
+		}
+		c.items[key] = item
+	}
+
+	if c.expiration != nil {
+		t := c.clock.Now().Add(*c.expiration)
+		item.expiration = &t
+	}
+
+	if c.addedFunc != nil {
+		c.addedFunc(key, value)
+	}
+
+	return item, nil
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key and has LoaderFunc,
+// generate a value using `LoaderFunc` method returns value.
+func (c *SimpleCache) Get(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, true)
+	}
+	return v, err
+}
+
+// Get a value from cache pool using key if it exists.
+// If it dose not exists key, returns KeyNotFoundError.
+// And send a request which refresh value for specified key if cache object has LoaderFunc.
+func (c *SimpleCache) GetIFPresent(key interface{}) (interface{}, error) {
+	v, err := c.get(key, false)
+	if err == KeyNotFoundError {
+		return c.getWithLoader(key, false)
+	}
+	return v, nil
+}
+
+func (c *SimpleCache) get(key interface{}, onLoad bool) (interface{}, error) {
+	v, err := c.getValue(key, onLoad)
+	if err != nil {
+		return nil, err
+	}
+	if c.deserializeFunc != nil {
+		return c.deserializeFunc(key, v)
+	}
+	return v, nil
+}
+
+func (c *SimpleCache) getValue(key interface{}, onLoad bool) (interface{}, error) {
+	c.mu.Lock()
+	item, ok := c.items[key]
+	if ok {
+		if !item.IsExpired(nil) {
+			v := item.value
+			c.mu.Unlock()
+			if !onLoad {
+				c.stats.IncrHitCount()
+			}
+			return v, nil
+		}
+		c.remove(key)
+	}
+	c.mu.Unlock()
+	if !onLoad {
+		c.stats.IncrMissCount()
+	}
+	return nil, KeyNotFoundError
+}
+
+func (c *SimpleCache) getWithLoader(key interface{}, isWait bool) (interface{}, error) {
+	if c.loaderExpireFunc == nil {
+		return nil, KeyNotFoundError
+	}
+	value, _, err := c.load(key, func(v interface{}, expiration *time.Duration, e error) (interface{}, error) {
+		if e != nil {
+			return nil, e
+		}
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		item, err := c.set(key, v)
+		if err != nil {
+			return nil, err
+		}
+		if expiration != nil {
+			t := c.clock.Now().Add(*expiration)
+			item.(*simpleItem).expiration = &t
+		}
+		return v, nil
+	}, isWait)
+	if err != nil {
+		return nil, err
+	}
+	return value, nil
+}
+
+func (c *SimpleCache) evict(count int) {
+	now := c.clock.Now()
+	current := 0
+	for key, item := range c.items {
+		if current >= count {
+			return
+		}
+		if item.expiration == nil || now.After(*item.expiration) {
+			defer c.remove(key)
+			current++
+		}
+	}
+}
+
+// Removes the provided key from the cache.
+func (c *SimpleCache) Remove(key interface{}) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.remove(key)
+}
+
+func (c *SimpleCache) remove(key interface{}) bool {
+	item, ok := c.items[key]
+	if ok {
+		delete(c.items, key)
+		if c.evictedFunc != nil {
+			c.evictedFunc(key, item.value)
+		}
+		return true
+	}
+	return false
+}
+
+// Returns a slice of the keys in the cache.
+func (c *SimpleCache) keys() []interface{} {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	keys := make([]interface{}, len(c.items))
+	var i = 0
+	for k := range c.items {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
+// Returns a slice of the keys in the cache.
+func (c *SimpleCache) Keys() []interface{} {
+	keys := []interface{}{}
+	for _, k := range c.keys() {
+		_, err := c.GetIFPresent(k)
+		if err == nil {
+			keys = append(keys, k)
+		}
+	}
+	return keys
+}
+
+// Returns all key-value pairs in the cache.
+func (c *SimpleCache) GetALL() map[interface{}]interface{} {
+	m := make(map[interface{}]interface{})
+	for _, k := range c.keys() {
+		v, err := c.GetIFPresent(k)
+		if err == nil {
+			m[k] = v
+		}
+	}
+	return m
+}
+
+// Returns the number of items in the cache.
+func (c *SimpleCache) Len() int {
+	return len(c.GetALL())
+}
+
+// Completely clear the cache
+func (c *SimpleCache) Purge() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.purgeVisitorFunc != nil {
+		for key, item := range c.items {
+			c.purgeVisitorFunc(key, item.value)
+		}
+	}
+
+	c.init()
+}
+
+type simpleItem struct {
+	clock      Clock
+	value      interface{}
+	expiration *time.Time
+}
+
+// returns boolean value whether this item is expired or not.
+func (si *simpleItem) IsExpired(now *time.Time) bool {
+	if si.expiration == nil {
+		return false
+	}
+	if now == nil {
+		t := si.clock.Now()
+		now = &t
+	}
+	return si.expiration.Before(*now)
+}

vendor/github.com/bluele/gcache/singleflight.go

@@ -0,0 +1,82 @@
+package gcache
+
+/*
+Copyright 2012 Google Inc.
+
+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.
+*/
+
+// This module provides a duplicate function call suppression
+// mechanism.
+
+import "sync"
+
+// call is an in-flight or completed Do call
+type call struct {
+	wg  sync.WaitGroup
+	val interface{}
+	err error
+}
+
+// Group represents a class of work and forms a namespace in which
+// units of work can be executed with duplicate suppression.
+type Group struct {
+	cache Cache
+	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 *Group) Do(key interface{}, fn func() (interface{}, error), isWait bool) (interface{}, bool, error) {
+	g.mu.Lock()
+	v, err := g.cache.get(key, true)
+	if err == nil {
+		g.mu.Unlock()
+		return v, false, nil
+	}
+	if g.m == nil {
+		g.m = make(map[interface{}]*call)
+	}
+	if c, ok := g.m[key]; ok {
+		g.mu.Unlock()
+		if !isWait {
+			return nil, false, KeyNotFoundError
+		}
+		c.wg.Wait()
+		return c.val, false, c.err
+	}
+	c := new(call)
+	c.wg.Add(1)
+	g.m[key] = c
+	g.mu.Unlock()
+	if !isWait {
+		go g.call(c, key, fn)
+		return nil, false, KeyNotFoundError
+	}
+	v, err = g.call(c, key, fn)
+	return v, true, err
+}
+
+func (g *Group) call(c *call, key interface{}, fn func() (interface{}, error)) (interface{}, error) {
+	c.val, c.err = fn()
+	c.wg.Done()
+
+	g.mu.Lock()
+	delete(g.m, key)
+	g.mu.Unlock()
+
+	return c.val, c.err
+}

vendor/github.com/bluele/gcache/stats.go

@@ -0,0 +1,53 @@
+package gcache
+
+import (
+	"sync/atomic"
+)
+
+type statsAccessor interface {
+	HitCount() uint64
+	MissCount() uint64
+	LookupCount() uint64
+	HitRate() float64
+}
+
+// statistics
+type stats struct {
+	hitCount  uint64
+	missCount uint64
+}
+
+// increment hit count
+func (st *stats) IncrHitCount() uint64 {
+	return atomic.AddUint64(&st.hitCount, 1)
+}
+
+// increment miss count
+func (st *stats) IncrMissCount() uint64 {
+	return atomic.AddUint64(&st.missCount, 1)
+}
+
+// HitCount returns hit count
+func (st *stats) HitCount() uint64 {
+	return atomic.LoadUint64(&st.hitCount)
+}
+
+// MissCount returns miss count
+func (st *stats) MissCount() uint64 {
+	return atomic.LoadUint64(&st.missCount)
+}
+
+// LookupCount returns lookup count
+func (st *stats) LookupCount() uint64 {
+	return st.HitCount() + st.MissCount()
+}
+
+// HitRate returns rate for cache hitting
+func (st *stats) HitRate() float64 {
+	hc, mc := st.HitCount(), st.MissCount()
+	total := hc + mc
+	if total == 0 {
+		return 0.0
+	}
+	return float64(hc) / float64(total)
+}

vendor/github.com/bluele/gcache/utils.go

@@ -0,0 +1,15 @@
+package gcache
+
+func minInt(x, y int) int {
+	if x < y {
+		return x
+	}
+	return y
+}
+
+func maxInt(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}

vendor/github.com/bluele/gcache/wercker.yml

@@ -0,0 +1,51 @@
+# This references the default golang container from
+# the Docker Hub: https://registry.hub.docker.com/u/library/golang/
+# If you want Google's container you would reference google/golang
+# Read more about containers on our dev center
+# http://devcenter.wercker.com/docs/containers/index.html
+box: golang
+# This is the build pipeline. Pipelines are the core of wercker
+# Read more about pipelines on our dev center
+# http://devcenter.wercker.com/docs/pipelines/index.html
+
+# You can also use services such as databases. Read more on our dev center:
+# http://devcenter.wercker.com/docs/services/index.html
+# services:
+    # - postgres
+    # http://devcenter.wercker.com/docs/services/postgresql.html
+
+    # - mongo
+    # http://devcenter.wercker.com/docs/services/mongodb.html
+build:
+  # The steps that will be executed on build
+  # Steps make up the actions in your pipeline
+  # Read more about steps on our dev center:
+  # http://devcenter.wercker.com/docs/steps/index.html
+  steps:
+    # Sets the go workspace and places you package
+    # at the right place in the workspace tree
+    - setup-go-workspace
+
+    # Prints go version
+    - script:
+        name: go version
+        code: |
+          go version
+
+    # Gets the dependencies
+    - script:
+        name: go get
+        code: |
+          go get
+
+    # Build the project
+    - script:
+        name: go build
+        code: |
+          go build
+
+    # Test the project
+    - script:
+        name: go test
+        code: |
+          go test -v