Merge pull request #21470 from deads2k/fix-limit-ranger

Godeps/Godeps.json

@@ -683,6 +683,10 @@
 			"Rev": "fa3f63826f7c23912c15263591e65d54d080b458"
 		},
 		{
+			"ImportPath": "github.com/hashicorp/golang-lru",
+			"Rev": "a0d98a5f288019575c6d1f4bb1573fef2d1fcdc4"
+		},
+		{
 			"ImportPath": "github.com/hashicorp/raft",
 			"Rev": "057b893fd996696719e98b6c44649ea14968c811"
 		},

Godeps/LICENSES.md

@@ -51,6 +51,7 @@ github.com/google/gofuzz | Apache-2
 github.com/gorilla/context | spdxBSD3
 github.com/gorilla/mux | spdxBSD3
 github.com/hashicorp/go-msgpack | spdxBSD3
+github.com/hashicorp/golang-lru | IntelPart08
 github.com/hashicorp/raft | IntelPart08
 github.com/hashicorp/raft-boltdb | IntelPart08
 github.com/imdario/mergo | spdxBSD3

Godeps/_workspace/src/github.com/hashicorp/golang-lru/.gitignore

+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test

Godeps/_workspace/src/github.com/hashicorp/golang-lru/2q.go

+package lru
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/hashicorp/golang-lru/simplelru"
+)
+
+const (
+	// Default2QRecentRatio is the ratio of the 2Q cache dedicated
+	// to recently added entries that have only been accessed once.
+	Default2QRecentRatio = 0.25
+
+	// Default2QGhostEntries is the default ratio of ghost
+	// entries kept to track entries recently evicted
+	Default2QGhostEntries = 0.50
+)
+
+// TwoQueueCache is a thread-safe fixed size 2Q cache.
+// 2Q is an enhancement over the standard LRU cache
+// in that it tracks both frequently and recently used
+// entries separately. This avoids a burst in access to new
+// entries from evicting frequently used entries. It adds some
+// additional tracking overhead to the standard LRU cache, and is
+// computationally about 2x the cost, and adds some metadata over
+// head. The ARCCache is similar, but does not require setting any
+// parameters.
+type TwoQueueCache struct {
+	size       int
+	recentSize int
+
+	recent      *simplelru.LRU
+	frequent    *simplelru.LRU
+	recentEvict *simplelru.LRU
+	lock        sync.RWMutex
+}
+
+// New2Q creates a new TwoQueueCache using the default
+// values for the parameters.
+func New2Q(size int) (*TwoQueueCache, error) {
+	return New2QParams(size, Default2QRecentRatio, Default2QGhostEntries)
+}
+
+// New2QParams creates a new TwoQueueCache using the provided
+// parameter values.
+func New2QParams(size int, recentRatio float64, ghostRatio float64) (*TwoQueueCache, error) {
+	if size <= 0 {
+		return nil, fmt.Errorf("invalid size")
+	}
+	if recentRatio < 0.0 || recentRatio > 1.0 {
+		return nil, fmt.Errorf("invalid recent ratio")
+	}
+	if ghostRatio < 0.0 || ghostRatio > 1.0 {
+		return nil, fmt.Errorf("invalid ghost ratio")
+	}
+
+	// Determine the sub-sizes
+	recentSize := int(float64(size) * recentRatio)
+	evictSize := int(float64(size) * ghostRatio)
+
+	// Allocate the LRUs
+	recent, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+	frequent, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+	recentEvict, err := simplelru.NewLRU(evictSize, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Initialize the cache
+	c := &TwoQueueCache{
+		size:        size,
+		recentSize:  recentSize,
+		recent:      recent,
+		frequent:    frequent,
+		recentEvict: recentEvict,
+	}
+	return c, nil
+}
+
+func (c *TwoQueueCache) Get(key interface{}) (interface{}, bool) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// Check if this is a frequent value
+	if val, ok := c.frequent.Get(key); ok {
+		return val, ok
+	}
+
+	// If the value is contained in recent, then we
+	// promote it to frequent
+	if val, ok := c.recent.Peek(key); ok {
+		c.recent.Remove(key)
+		c.frequent.Add(key, val)
+		return val, ok
+	}
+
+	// No hit
+	return nil, false
+}
+
+func (c *TwoQueueCache) Add(key, value interface{}) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// Check if the value is frequently used already,
+	// and just update the value
+	if c.frequent.Contains(key) {
+		c.frequent.Add(key, value)
+		return
+	}
+
+	// Check if the value is recently used, and promote
+	// the value into the frequent list
+	if c.recent.Contains(key) {
+		c.recent.Remove(key)
+		c.frequent.Add(key, value)
+		return
+	}
+
+	// If the value was recently evicted, add it to the
+	// frequently used list
+	if c.recentEvict.Contains(key) {
+		c.ensureSpace(true)
+		c.recentEvict.Remove(key)
+		c.frequent.Add(key, value)
+		return
+	}
+
+	// Add to the recently seen list
+	c.ensureSpace(false)
+	c.recent.Add(key, value)
+	return
+}
+
+// ensureSpace is used to ensure we have space in the cache
+func (c *TwoQueueCache) ensureSpace(recentEvict bool) {
+	// If we have space, nothing to do
+	recentLen := c.recent.Len()
+	freqLen := c.frequent.Len()
+	if recentLen+freqLen < c.size {
+		return
+	}
+
+	// If the recent buffer is larger than
+	// the target, evict from there
+	if recentLen > 0 && (recentLen > c.recentSize || (recentLen == c.recentSize && !recentEvict)) {
+		k, _, _ := c.recent.RemoveOldest()
+		c.recentEvict.Add(k, nil)
+		return
+	}
+
+	// Remove from the frequent list otherwise
+	c.frequent.RemoveOldest()
+}
+
+func (c *TwoQueueCache) Len() int {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.recent.Len() + c.frequent.Len()
+}
+
+func (c *TwoQueueCache) Keys() []interface{} {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	k1 := c.frequent.Keys()
+	k2 := c.recent.Keys()
+	return append(k1, k2...)
+}
+
+func (c *TwoQueueCache) Remove(key interface{}) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	if c.frequent.Remove(key) {
+		return
+	}
+	if c.recent.Remove(key) {
+		return
+	}
+	if c.recentEvict.Remove(key) {
+		return
+	}
+}
+
+func (c *TwoQueueCache) Purge() {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.recent.Purge()
+	c.frequent.Purge()
+	c.recentEvict.Purge()
+}
+
+func (c *TwoQueueCache) Contains(key interface{}) bool {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.frequent.Contains(key) || c.recent.Contains(key)
+}
+
+func (c *TwoQueueCache) Peek(key interface{}) (interface{}, bool) {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	if val, ok := c.frequent.Peek(key); ok {
+		return val, ok
+	}
+	return c.recent.Peek(key)
+}

Godeps/_workspace/src/github.com/hashicorp/golang-lru/README.md

+golang-lru
+==========
+
+This provides the `lru` package which implements a fixed-size
+thread safe LRU cache. It is based on the cache in Groupcache.
+
+Documentation
+=============
+
+Full docs are available on [Godoc](http://godoc.org/github.com/hashicorp/golang-lru)
+
+Example
+=======
+
+Using the LRU is very simple:
+
+```go
+l, _ := New(128)
+for i := 0; i < 256; i++ {
+    l.Add(i, nil)
+}
+if l.Len() != 128 {
+    panic(fmt.Sprintf("bad len: %v", l.Len()))
+}
+```

Godeps/_workspace/src/github.com/hashicorp/golang-lru/arc.go

+package lru
+
+import (
+	"sync"
+
+	"github.com/hashicorp/golang-lru/simplelru"
+)
+
+// ARCCache is a thread-safe fixed size Adaptive Replacement Cache (ARC).
+// ARC is an enhancement over the standard LRU cache in that tracks both
+// frequency and recency of use. This avoids a burst in access to new
+// entries from evicting the frequently used older entries. It adds some
+// additional tracking overhead to a standard LRU cache, computationally
+// it is roughly 2x the cost, and the extra memory overhead is linear
+// with the size of the cache. ARC has been patented by IBM, but is
+// similar to the TwoQueueCache (2Q) which requires setting parameters.
+type ARCCache struct {
+	size int // Size is the total capacity of the cache
+	p    int // P is the dynamic preference towards T1 or T2
+
+	t1 *simplelru.LRU // T1 is the LRU for recently accessed items
+	b1 *simplelru.LRU // B1 is the LRU for evictions from t1
+
+	t2 *simplelru.LRU // T2 is the LRU for frequently accessed items
+	b2 *simplelru.LRU // B2 is the LRU for evictions from t2
+
+	lock sync.RWMutex
+}
+
+// NewARC creates an ARC of the given size
+func NewARC(size int) (*ARCCache, error) {
+	// Create the sub LRUs
+	b1, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+	b2, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+	t1, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+	t2, err := simplelru.NewLRU(size, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Initialize the ARC
+	c := &ARCCache{
+		size: size,
+		p:    0,
+		t1:   t1,
+		b1:   b1,
+		t2:   t2,
+		b2:   b2,
+	}
+	return c, nil
+}
+
+// Get looks up a key's value from the cache.
+func (c *ARCCache) Get(key interface{}) (interface{}, bool) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// Ff the value is contained in T1 (recent), then
+	// promote it to T2 (frequent)
+	if val, ok := c.t1.Peek(key); ok {
+		c.t1.Remove(key)
+		c.t2.Add(key, val)
+		return val, ok
+	}
+
+	// Check if the value is contained in T2 (frequent)
+	if val, ok := c.t2.Get(key); ok {
+		return val, ok
+	}
+
+	// No hit
+	return nil, false
+}
+
+// Add adds a value to the cache.
+func (c *ARCCache) Add(key, value interface{}) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// Check if the value is contained in T1 (recent), and potentially
+	// promote it to frequent T2
+	if c.t1.Contains(key) {
+		c.t1.Remove(key)
+		c.t2.Add(key, value)
+		return
+	}
+
+	// Check if the value is already in T2 (frequent) and update it
+	if c.t2.Contains(key) {
+		c.t2.Add(key, value)
+		return
+	}
+
+	// Check if this value was recently evicted as part of the
+	// recently used list
+	if c.b1.Contains(key) {
+		// T1 set is too small, increase P appropriately
+		delta := 1
+		b1Len := c.b1.Len()
+		b2Len := c.b2.Len()
+		if b2Len > b1Len {
+			delta = b2Len / b1Len
+		}
+		if c.p+delta >= c.size {
+			c.p = c.size
+		} else {
+			c.p += delta
+		}
+
+		// Potentially need to make room in the cache
+		if c.t1.Len()+c.t2.Len() >= c.size {
+			c.replace(false)
+		}
+
+		// Remove from B1
+		c.b1.Remove(key)
+
+		// Add the key to the frequently used list
+		c.t2.Add(key, value)
+		return
+	}
+
+	// Check if this value was recently evicted as part of the
+	// frequently used list
+	if c.b2.Contains(key) {
+		// T2 set is too small, decrease P appropriately
+		delta := 1
+		b1Len := c.b1.Len()
+		b2Len := c.b2.Len()
+		if b1Len > b2Len {
+			delta = b1Len / b2Len
+		}
+		if delta >= c.p {
+			c.p = 0
+		} else {
+			c.p -= delta
+		}
+
+		// Potentially need to make room in the cache
+		if c.t1.Len()+c.t2.Len() >= c.size {
+			c.replace(true)
+		}
+
+		// Remove from B2
+		c.b2.Remove(key)
+
+		// Add the key to the frequntly used list
+		c.t2.Add(key, value)
+		return
+	}
+
+	// Potentially need to make room in the cache
+	if c.t1.Len()+c.t2.Len() >= c.size {
+		c.replace(false)
+	}
+
+	// Keep the size of the ghost buffers trim
+	if c.b1.Len() > c.size-c.p {
+		c.b1.RemoveOldest()
+	}
+	if c.b2.Len() > c.p {
+		c.b2.RemoveOldest()
+	}
+
+	// Add to the recently seen list
+	c.t1.Add(key, value)
+	return
+}
+
+// replace is used to adaptively evict from either T1 or T2
+// based on the current learned value of P
+func (c *ARCCache) replace(b2ContainsKey bool) {
+	t1Len := c.t1.Len()
+	if t1Len > 0 && (t1Len > c.p || (t1Len == c.p && b2ContainsKey)) {
+		k, _, ok := c.t1.RemoveOldest()
+		if ok {
+			c.b1.Add(k, nil)
+		}
+	} else {
+		k, _, ok := c.t2.RemoveOldest()
+		if ok {
+			c.b2.Add(k, nil)
+		}
+	}
+}
+
+// Len returns the number of cached entries
+func (c *ARCCache) Len() int {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.t1.Len() + c.t2.Len()
+}
+
+// Keys returns all the cached keys
+func (c *ARCCache) Keys() []interface{} {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	k1 := c.t1.Keys()
+	k2 := c.t2.Keys()
+	return append(k1, k2...)
+}
+
+// Remove is used to purge a key from the cache
+func (c *ARCCache) Remove(key interface{}) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	if c.t1.Remove(key) {
+		return
+	}
+	if c.t2.Remove(key) {
+		return
+	}
+	if c.b1.Remove(key) {
+		return
+	}
+	if c.b2.Remove(key) {
+		return
+	}
+}
+
+// Purge is used to clear the cache
+func (c *ARCCache) Purge() {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.t1.Purge()
+	c.t2.Purge()
+	c.b1.Purge()
+	c.b2.Purge()
+}
+
+// Contains is used to check if the cache contains a key
+// without updating recency or frequency.
+func (c *ARCCache) Contains(key interface{}) bool {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.t1.Contains(key) || c.t2.Contains(key)
+}
+
+// Peek is used to inspect the cache value of a key
+// without updating recency or frequency.
+func (c *ARCCache) Peek(key interface{}) (interface{}, bool) {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	if val, ok := c.t1.Peek(key); ok {
+		return val, ok
+	}
+	return c.t2.Peek(key)
+}

Godeps/_workspace/src/github.com/hashicorp/golang-lru/lru.go

+// This package provides a simple LRU cache. It is based on the
+// LRU implementation in groupcache:
+// https://github.com/golang/groupcache/tree/master/lru
+package lru
+
+import (
+	"sync"
+
+	"github.com/hashicorp/golang-lru/simplelru"
+)
+
+// Cache is a thread-safe fixed size LRU cache.
+type Cache struct {
+	lru  *simplelru.LRU
+	lock sync.RWMutex
+}
+
+// New creates an LRU of the given size
+func New(size int) (*Cache, error) {
+	return NewWithEvict(size, nil)
+}
+
+// NewWithEvict constructs a fixed size cache with the given eviction
+// callback.
+func NewWithEvict(size int, onEvicted func(key interface{}, value interface{})) (*Cache, error) {
+	lru, err := simplelru.NewLRU(size, simplelru.EvictCallback(onEvicted))
+	if err != nil {
+		return nil, err
+	}
+	c := &Cache{
+		lru: lru,
+	}
+	return c, nil
+}
+
+// Purge is used to completely clear the cache
+func (c *Cache) Purge() {
+	c.lock.Lock()
+	c.lru.Purge()
+	c.lock.Unlock()
+}
+
+// Add adds a value to the cache.  Returns true if an eviction occurred.
+func (c *Cache) Add(key, value interface{}) bool {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	return c.lru.Add(key, value)
+}
+
+// Get looks up a key's value from the cache.
+func (c *Cache) Get(key interface{}) (interface{}, bool) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	return c.lru.Get(key)
+}
+
+// Check if a key is in the cache, without updating the recent-ness
+// or deleting it for being stale.
+func (c *Cache) Contains(key interface{}) bool {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.lru.Contains(key)
+}
+
+// Returns the key value (or undefined if not found) without updating
+// the "recently used"-ness of the key.
+func (c *Cache) Peek(key interface{}) (interface{}, bool) {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.lru.Peek(key)
+}
+
+// ContainsOrAdd checks if a key is in the cache  without updating the
+// recent-ness or deleting it for being stale,  and if not, adds the value.
+// Returns whether found and whether an eviction occurred.
+func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evict bool) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	if c.lru.Contains(key) {
+		return true, false
+	} else {
+		evict := c.lru.Add(key, value)
+		return false, evict
+	}
+}
+
+// Remove removes the provided key from the cache.
+func (c *Cache) Remove(key interface{}) {
+	c.lock.Lock()
+	c.lru.Remove(key)
+	c.lock.Unlock()
+}
+
+// RemoveOldest removes the oldest item from the cache.
+func (c *Cache) RemoveOldest() {
+	c.lock.Lock()
+	c.lru.RemoveOldest()
+	c.lock.Unlock()
+}
+
+// Keys returns a slice of the keys in the cache, from oldest to newest.
+func (c *Cache) Keys() []interface{} {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.lru.Keys()
+}
+
+// Len returns the number of items in the cache.
+func (c *Cache) Len() int {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+	return c.lru.Len()
+}

Godeps/_workspace/src/github.com/hashicorp/golang-lru/simplelru/lru.go

+package simplelru
+
+import (
+	"container/list"
+	"errors"
+)
+
+// EvictCallback is used to get a callback when a cache entry is evicted
+type EvictCallback func(key interface{}, value interface{})
+
+// LRU implements a non-thread safe fixed size LRU cache
+type LRU struct {
+	size      int
+	evictList *list.List
+	items     map[interface{}]*list.Element
+	onEvict   EvictCallback
+}
+
+// entry is used to hold a value in the evictList
+type entry struct {
+	key   interface{}
+	value interface{}
+}
+
+// NewLRU constructs an LRU of the given size
+func NewLRU(size int, onEvict EvictCallback) (*LRU, error) {
+	if size <= 0 {
+		return nil, errors.New("Must provide a positive size")
+	}
+	c := &LRU{
+		size:      size,
+		evictList: list.New(),
+		items:     make(map[interface{}]*list.Element),
+		onEvict:   onEvict,
+	}
+	return c, nil
+}
+
+// Purge is used to completely clear the cache
+func (c *LRU) Purge() {
+	for k, v := range c.items {
+		if c.onEvict != nil {
+			c.onEvict(k, v.Value.(*entry).value)
+		}
+		delete(c.items, k)
+	}
+	c.evictList.Init()
+}
+
+// Add adds a value to the cache.  Returns true if an eviction occured.
+func (c *LRU) Add(key, value interface{}) bool {
+	// Check for existing item
+	if ent, ok := c.items[key]; ok {
+		c.evictList.MoveToFront(ent)
+		ent.Value.(*entry).value = value
+		return false
+	}
+
+	// Add new item
+	ent := &entry{key, value}
+	entry := c.evictList.PushFront(ent)
+	c.items[key] = entry
+
+	evict := c.evictList.Len() > c.size
+	// Verify size not exceeded
+	if evict {
+		c.removeOldest()
+	}
+	return evict
+}
+
+// Get looks up a key's value from the cache.
+func (c *LRU) Get(key interface{}) (value interface{}, ok bool) {
+	if ent, ok := c.items[key]; ok {
+		c.evictList.MoveToFront(ent)
+		return ent.Value.(*entry).value, true
+	}
+	return
+}
+
+// Check if a key is in the cache, without updating the recent-ness
+// or deleting it for being stale.
+func (c *LRU) Contains(key interface{}) (ok bool) {
+	_, ok = c.items[key]
+	return ok
+}
+
+// Returns the key value (or undefined if not found) without updating
+// the "recently used"-ness of the key.
+func (c *LRU) Peek(key interface{}) (value interface{}, ok bool) {
+	if ent, ok := c.items[key]; ok {
+		return ent.Value.(*entry).value, true
+	}
+	return nil, ok
+}
+
+// Remove removes the provided key from the cache, returning if the
+// key was contained.
+func (c *LRU) Remove(key interface{}) bool {
+	if ent, ok := c.items[key]; ok {
+		c.removeElement(ent)
+		return true
+	}
+	return false
+}
+
+// RemoveOldest removes the oldest item from the cache.
+func (c *LRU) RemoveOldest() (interface{}, interface{}, bool) {
+	ent := c.evictList.Back()
+	if ent != nil {
+		c.removeElement(ent)
+		kv := ent.Value.(*entry)
+		return kv.key, kv.value, true
+	}
+	return nil, nil, false
+}
+
+// GetOldest returns the oldest entry
+func (c *LRU) GetOldest() (interface{}, interface{}, bool) {
+	ent := c.evictList.Back()
+	if ent != nil {
+		kv := ent.Value.(*entry)
+		return kv.key, kv.value, true
+	}
+	return nil, nil, false
+}
+
+// Keys returns a slice of the keys in the cache, from oldest to newest.
+func (c *LRU) Keys() []interface{} {
+	keys := make([]interface{}, len(c.items))
+	i := 0
+	for ent := c.evictList.Back(); ent != nil; ent = ent.Prev() {
+		keys[i] = ent.Value.(*entry).key
+		i++
+	}
+	return keys
+}
+
+// Len returns the number of items in the cache.
+func (c *LRU) Len() int {
+	return c.evictList.Len()
+}
+
+// removeOldest removes the oldest item from the cache.
+func (c *LRU) removeOldest() {
+	ent := c.evictList.Back()
+	if ent != nil {
+		c.removeElement(ent)
+	}
+}
+
+// removeElement is used to remove a given list element from the cache
+func (c *LRU) removeElement(e *list.Element) {
+	c.evictList.Remove(e)
+	kv := e.Value.(*entry)
+	delete(c.items, kv.key)
+	if c.onEvict != nil {
+		c.onEvict(kv.key, kv.value)
+	}
+}

plugin/pkg/admission/limitranger/admission.go

@@ -21,6 +21,9 @@ import (
 	"io"
 	"sort"
 	"strings"
+	"time"
+
+	"github.com/hashicorp/golang-lru"
 
 	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
 
@@ -40,7 +43,7 @@ const (
 
 func init() {
 	admission.RegisterPlugin("LimitRanger", func(client clientset.Interface, config io.Reader) (admission.Interface, error) {
-		return NewLimitRanger(client, Limit), nil
+		return NewLimitRanger(client, Limit)
 	})
 }
 
@@ -50,6 +53,17 @@ type limitRanger struct {
 	client    clientset.Interface
 	limitFunc LimitFunc
 	indexer   cache.Indexer
+
+	// liveLookups holds the last few live lookups we've done to help ammortize cost on repeated lookup failures.
+	// This let's us handle the case of latent caches, by looking up actual results for a namespace on cache miss/no results.
+	// We track the lookup result here so that for repeated requests, we don't look it up very often.
+	liveLookupCache *lru.Cache
+	liveTTL         time.Duration
+}
+
+type liveLookupEntry struct {
+	expiry time.Time
+	items  []*api.LimitRange
 }
 
 // Admit admits resources into cluster that do not violate any defined LimitRange in the namespace
@@ -79,8 +93,28 @@ func (l *limitRanger) Admit(a admission.Attributes) (err error) {
 	if err != nil {
 		return admission.NewForbidden(a, fmt.Errorf("Unable to %s %v at this time because there was an error enforcing limit ranges", a.GetOperation(), a.GetResource()))
 	}
+
+	// if there are no items held in our indexer, check our live-lookup LRU, if that misses, do the live lookup to prime it.
 	if len(items) == 0 {
-		return nil
+		lruItemObj, ok := l.liveLookupCache.Get(a.GetNamespace())
+		if !ok || lruItemObj.(liveLookupEntry).expiry.Before(time.Now()) {
+			liveList, err := l.client.Core().LimitRanges(a.GetNamespace()).List(api.ListOptions{})
+			if err != nil {
+				return admission.NewForbidden(a, err)
+			}
+			newEntry := liveLookupEntry{expiry: time.Now().Add(l.liveTTL)}
+			for i := range liveList.Items {
+				newEntry.items = append(newEntry.items, &liveList.Items[i])
+			}
+			l.liveLookupCache.Add(a.GetNamespace(), newEntry)
+			lruItemObj = newEntry
+		}
+		lruEntry := lruItemObj.(liveLookupEntry)
+
+		for i := range lruEntry.items {
+			items = append(items, lruEntry.items[i])
+		}
+
 	}
 
 	// ensure it meets each prescribed min/max
@@ -95,7 +129,12 @@ func (l *limitRanger) Admit(a admission.Attributes) (err error) {
 }
 
 // NewLimitRanger returns an object that enforces limits based on the supplied limit function
-func NewLimitRanger(client clientset.Interface, limitFunc LimitFunc) admission.Interface {
+func NewLimitRanger(client clientset.Interface, limitFunc LimitFunc) (admission.Interface, error) {
+	liveLookupCache, err := lru.New(10000)
+	if err != nil {
+		return nil, err
+	}
+
 	lw := &cache.ListWatch{
 		ListFunc: func(options api.ListOptions) (runtime.Object, error) {
 			return client.Core().LimitRanges(api.NamespaceAll).List(options)
@@ -107,11 +146,13 @@ func NewLimitRanger(client clientset.Interface, limitFunc LimitFunc) admission.I
 	indexer, reflector := cache.NewNamespaceKeyedIndexerAndReflector(lw, &api.LimitRange{}, 0)
 	reflector.Run()
 	return &limitRanger{
-		Handler:   admission.NewHandler(admission.Create, admission.Update),
-		client:    client,
-		limitFunc: limitFunc,
-		indexer:   indexer,
-	}
+		Handler:         admission.NewHandler(admission.Create, admission.Update),
+		client:          client,
+		limitFunc:       limitFunc,
+		indexer:         indexer,
+		liveLookupCache: liveLookupCache,
+		liveTTL:         time.Duration(30 * time.Second),
+	}, nil
 }
 
 // Min returns the lesser of its 2 arguments

plugin/pkg/admission/limitranger/admission_test.go

@@ -19,6 +19,9 @@ package limitranger
 import (
 	"strconv"
 	"testing"
+	"time"
+
+	"github.com/hashicorp/golang-lru"
 
 	"k8s.io/kubernetes/pkg/admission"
 	"k8s.io/kubernetes/pkg/api"
@@ -453,3 +456,99 @@ func TestLimitRangerIgnoresSubresource(t *testing.T) {
 	}
 
 }
+
+func TestLimitRangerCacheMisses(t *testing.T) {
+	liveLookupCache, err := lru.New(10000)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	client := fake.NewSimpleClientset()
+	indexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{"namespace": cache.MetaNamespaceIndexFunc})
+	handler := &limitRanger{
+		Handler:         admission.NewHandler(admission.Create, admission.Update),
+		client:          client,
+		limitFunc:       Limit,
+		indexer:         indexer,
+		liveLookupCache: liveLookupCache,
+	}
+
+	limitRange := validLimitRangeNoDefaults()
+	testPod := validPod("testPod", 1, api.ResourceRequirements{})
+
+	// add to the lru cache
+	liveLookupCache.Add(limitRange.Namespace, liveLookupEntry{expiry: time.Now().Add(time.Duration(30 * time.Second)), items: []*api.LimitRange{&limitRange}})
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "", admission.Update, nil))
+	if err == nil {
+		t.Errorf("Expected an error since the pod did not specify resource limits in its update call")
+	}
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "status", admission.Update, nil))
+	if err != nil {
+		t.Errorf("Should have ignored calls to any subresource of pod %v", err)
+	}
+}
+
+func TestLimitRangerCacheAndLRUMisses(t *testing.T) {
+	liveLookupCache, err := lru.New(10000)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	limitRange := validLimitRangeNoDefaults()
+	client := fake.NewSimpleClientset(&limitRange)
+	indexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{"namespace": cache.MetaNamespaceIndexFunc})
+	handler := &limitRanger{
+		Handler:         admission.NewHandler(admission.Create, admission.Update),
+		client:          client,
+		limitFunc:       Limit,
+		indexer:         indexer,
+		liveLookupCache: liveLookupCache,
+	}
+
+	testPod := validPod("testPod", 1, api.ResourceRequirements{})
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "", admission.Update, nil))
+	if err == nil {
+		t.Errorf("Expected an error since the pod did not specify resource limits in its update call")
+	}
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "status", admission.Update, nil))
+	if err != nil {
+		t.Errorf("Should have ignored calls to any subresource of pod %v", err)
+	}
+}
+
+func TestLimitRangerCacheAndLRUExpiredMisses(t *testing.T) {
+	liveLookupCache, err := lru.New(10000)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	limitRange := validLimitRangeNoDefaults()
+	client := fake.NewSimpleClientset(&limitRange)
+	indexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{"namespace": cache.MetaNamespaceIndexFunc})
+	handler := &limitRanger{
+		Handler:         admission.NewHandler(admission.Create, admission.Update),
+		client:          client,
+		limitFunc:       Limit,
+		indexer:         indexer,
+		liveLookupCache: liveLookupCache,
+	}
+
+	testPod := validPod("testPod", 1, api.ResourceRequirements{})
+
+	// add to the lru cache
+	liveLookupCache.Add(limitRange.Namespace, liveLookupEntry{expiry: time.Now().Add(time.Duration(-30 * time.Second)), items: []*api.LimitRange{}})
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "", admission.Update, nil))
+	if err == nil {
+		t.Errorf("Expected an error since the pod did not specify resource limits in its update call")
+	}
+
+	err = handler.Admit(admission.NewAttributesRecord(&testPod, api.Kind("Pod"), limitRange.Namespace, "testPod", api.Resource("pods"), "status", admission.Update, nil))
+	if err != nil {
+		t.Errorf("Should have ignored calls to any subresource of pod %v", err)
+	}
+}