Cache plugin: replace ARC cache with SIEVE

This commit is contained in:
Frank Denis 2024-01-19 00:05:33 +01:00
parent 63f8d9b30d
commit f2484f5bd5
19 changed files with 434 additions and 845 deletions

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@ -1,23 +0,0 @@
# 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

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@ -1,30 +0,0 @@
linters:
enable:
- megacheck
- revive
- govet
- unconvert
- megacheck
- gas
- gocyclo
- dupl
- misspell
- unparam
- unused
- typecheck
- ineffassign
- stylecheck
- exportloopref
- gocritic
- nakedret
- gosimple
- prealloc
fast: false
disable-all: true
issues:
exclude-rules:
- path: _test\.go
linters:
- dupl
exclude-use-default: false

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@ -1,222 +0,0 @@
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.LRUCache
frequent simplelru.LRUCache
recentEvict simplelru.LRUCache
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, 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
}
// Get looks up a key's value from the cache.
func (c *TwoQueueCache) Get(key interface{}) (value interface{}, ok 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
}
// Add adds a value to the cache.
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)
}
// 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()
}
// Len returns the number of items in the cache.
func (c *TwoQueueCache) Len() int {
c.lock.RLock()
defer c.lock.RUnlock()
return c.recent.Len() + c.frequent.Len()
}
// Keys returns a slice of the keys in the cache.
// The frequently used keys are first in the returned slice.
func (c *TwoQueueCache) Keys() []interface{} {
c.lock.RLock()
defer c.lock.RUnlock()
k1 := c.frequent.Keys()
k2 := c.recent.Keys()
return append(k1, k2...)
}
// Remove removes the provided key from the cache.
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
}
}
// Purge is used to completely clear the cache.
func (c *TwoQueueCache) Purge() {
c.lock.Lock()
defer c.lock.Unlock()
c.recent.Purge()
c.frequent.Purge()
c.recentEvict.Purge()
}
// Contains is used to check if the cache contains a key
// without updating recency or frequency.
func (c *TwoQueueCache) Contains(key interface{}) bool {
c.lock.RLock()
defer c.lock.RUnlock()
return c.frequent.Contains(key) || c.recent.Contains(key)
}
// Peek is used to inspect the cache value of a key
// without updating recency or frequency.
func (c *TwoQueueCache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
defer c.lock.RUnlock()
if val, ok := c.frequent.Peek(key); ok {
return val, ok
}
return c.recent.Peek(key)
}

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@ -1,5 +1,3 @@
Copyright (c) 2014 HashiCorp, Inc.
Mozilla Public License, version 2.0
1. Definitions

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@ -1,7 +0,0 @@
golang-lru
==========
Please upgrade to github.com/hashicorp/golang-lru/v2 for all new code as v1 will
not be updated anymore. The v2 version supports generics and is faster; old code
can specify a specific tag, e.g. github.com/hashicorp/golang-lru/v1.0.2 for
backwards compatibility.

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@ -1,256 +0,0 @@
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.LRUCache // T1 is the LRU for recently accessed items
b1 simplelru.LRUCache // B1 is the LRU for evictions from t1
t2 simplelru.LRUCache // T2 is the LRU for frequently accessed items
b2 simplelru.LRUCache // 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{}) (value interface{}, ok bool) {
c.lock.Lock()
defer c.lock.Unlock()
// If 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 frequently 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)
}
// 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{}) (value interface{}, ok bool) {
c.lock.RLock()
defer c.lock.RUnlock()
if val, ok := c.t1.Peek(key); ok {
return val, ok
}
return c.t2.Peek(key)
}

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@ -1,21 +0,0 @@
// Package lru provides three different LRU caches of varying sophistication.
//
// Cache is a simple LRU cache. It is based on the
// LRU implementation in groupcache:
// https://github.com/golang/groupcache/tree/master/lru
//
// TwoQueueCache tracks frequently used and recently used entries separately.
// This avoids a burst of accesses from taking out frequently used entries,
// at the cost of about 2x computational overhead and some extra bookkeeping.
//
// ARCCache is an adaptive replacement cache. It tracks recent evictions as
// well as recent usage in both the frequent and recent caches. Its
// computational overhead is comparable to TwoQueueCache, but the memory
// overhead is linear with the size of the cache.
//
// ARC has been patented by IBM, so do not use it if that is problematic for
// your program.
//
// All caches in this package take locks while operating, and are therefore
// thread-safe for consumers.
package lru

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@ -1,231 +0,0 @@
package lru
import (
"sync"
"github.com/hashicorp/golang-lru/simplelru"
)
const (
// DefaultEvictedBufferSize defines the default buffer size to store evicted key/val
DefaultEvictedBufferSize = 16
)
// Cache is a thread-safe fixed size LRU cache.
type Cache struct {
lru *simplelru.LRU
evictedKeys, evictedVals []interface{}
onEvictedCB func(k, v interface{})
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, value interface{})) (c *Cache, err error) {
// create a cache with default settings
c = &Cache{
onEvictedCB: onEvicted,
}
if onEvicted != nil {
c.initEvictBuffers()
onEvicted = c.onEvicted
}
c.lru, err = simplelru.NewLRU(size, onEvicted)
return
}
func (c *Cache) initEvictBuffers() {
c.evictedKeys = make([]interface{}, 0, DefaultEvictedBufferSize)
c.evictedVals = make([]interface{}, 0, DefaultEvictedBufferSize)
}
// onEvicted save evicted key/val and sent in externally registered callback
// outside of critical section
func (c *Cache) onEvicted(k, v interface{}) {
c.evictedKeys = append(c.evictedKeys, k)
c.evictedVals = append(c.evictedVals, v)
}
// Purge is used to completely clear the cache.
func (c *Cache) Purge() {
var ks, vs []interface{}
c.lock.Lock()
c.lru.Purge()
if c.onEvictedCB != nil && len(c.evictedKeys) > 0 {
ks, vs = c.evictedKeys, c.evictedVals
c.initEvictBuffers()
}
c.lock.Unlock()
// invoke callback outside of critical section
if c.onEvictedCB != nil {
for i := 0; i < len(ks); i++ {
c.onEvictedCB(ks[i], vs[i])
}
}
}
// Add adds a value to the cache. Returns true if an eviction occurred.
func (c *Cache) Add(key, value interface{}) (evicted bool) {
var k, v interface{}
c.lock.Lock()
evicted = c.lru.Add(key, value)
if c.onEvictedCB != nil && evicted {
k, v = c.evictedKeys[0], c.evictedVals[0]
c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0]
}
c.lock.Unlock()
if c.onEvictedCB != nil && evicted {
c.onEvictedCB(k, v)
}
return
}
// Get looks up a key's value from the cache.
func (c *Cache) Get(key interface{}) (value interface{}, ok bool) {
c.lock.Lock()
value, ok = c.lru.Get(key)
c.lock.Unlock()
return value, ok
}
// Contains checks 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()
containKey := c.lru.Contains(key)
c.lock.RUnlock()
return containKey
}
// Peek returns the key value (or undefined if not found) without updating
// the "recently used"-ness of the key.
func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) {
c.lock.RLock()
value, ok = c.lru.Peek(key)
c.lock.RUnlock()
return value, ok
}
// 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, evicted bool) {
var k, v interface{}
c.lock.Lock()
if c.lru.Contains(key) {
c.lock.Unlock()
return true, false
}
evicted = c.lru.Add(key, value)
if c.onEvictedCB != nil && evicted {
k, v = c.evictedKeys[0], c.evictedVals[0]
c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0]
}
c.lock.Unlock()
if c.onEvictedCB != nil && evicted {
c.onEvictedCB(k, v)
}
return false, evicted
}
// PeekOrAdd 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) PeekOrAdd(key, value interface{}) (previous interface{}, ok, evicted bool) {
var k, v interface{}
c.lock.Lock()
previous, ok = c.lru.Peek(key)
if ok {
c.lock.Unlock()
return previous, true, false
}
evicted = c.lru.Add(key, value)
if c.onEvictedCB != nil && evicted {
k, v = c.evictedKeys[0], c.evictedVals[0]
c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0]
}
c.lock.Unlock()
if c.onEvictedCB != nil && evicted {
c.onEvictedCB(k, v)
}
return nil, false, evicted
}
// Remove removes the provided key from the cache.
func (c *Cache) Remove(key interface{}) (present bool) {
var k, v interface{}
c.lock.Lock()
present = c.lru.Remove(key)
if c.onEvictedCB != nil && present {
k, v = c.evictedKeys[0], c.evictedVals[0]
c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0]
}
c.lock.Unlock()
if c.onEvictedCB != nil && present {
c.onEvictedCB(k, v)
}
return
}
// Resize changes the cache size.
func (c *Cache) Resize(size int) (evicted int) {
var ks, vs []interface{}
c.lock.Lock()
evicted = c.lru.Resize(size)
if c.onEvictedCB != nil && evicted > 0 {
ks, vs = c.evictedKeys, c.evictedVals
c.initEvictBuffers()
}
c.lock.Unlock()
if c.onEvictedCB != nil && evicted > 0 {
for i := 0; i < len(ks); i++ {
c.onEvictedCB(ks[i], vs[i])
}
}
return evicted
}
// RemoveOldest removes the oldest item from the cache.
func (c *Cache) RemoveOldest() (key, value interface{}, ok bool) {
var k, v interface{}
c.lock.Lock()
key, value, ok = c.lru.RemoveOldest()
if c.onEvictedCB != nil && ok {
k, v = c.evictedKeys[0], c.evictedVals[0]
c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0]
}
c.lock.Unlock()
if c.onEvictedCB != nil && ok {
c.onEvictedCB(k, v)
}
return
}
// GetOldest returns the oldest entry
func (c *Cache) GetOldest() (key, value interface{}, ok bool) {
c.lock.RLock()
key, value, ok = c.lru.GetOldest()
c.lock.RUnlock()
return
}
// Keys returns a slice of the keys in the cache, from oldest to newest.
func (c *Cache) Keys() []interface{} {
c.lock.RLock()
keys := c.lru.Keys()
c.lock.RUnlock()
return keys
}
// Len returns the number of items in the cache.
func (c *Cache) Len() int {
c.lock.RLock()
length := c.lru.Len()
c.lock.RUnlock()
return length
}

View file

@ -25,7 +25,7 @@ type entry struct {
// 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")
return nil, errors.New("Must provide a positive size")
}
c := &LRU{
size: size,
@ -73,9 +73,6 @@ func (c *LRU) Add(key, value interface{}) (evicted bool) {
func (c *LRU) Get(key interface{}) (value interface{}, ok bool) {
if ent, ok := c.items[key]; ok {
c.evictList.MoveToFront(ent)
if ent.Value.(*entry) == nil {
return nil, false
}
return ent.Value.(*entry).value, true
}
return
@ -109,7 +106,7 @@ func (c *LRU) Remove(key interface{}) (present bool) {
}
// RemoveOldest removes the oldest item from the cache.
func (c *LRU) RemoveOldest() (key, value interface{}, ok bool) {
func (c *LRU) RemoveOldest() (key interface{}, value interface{}, ok bool) {
ent := c.evictList.Back()
if ent != nil {
c.removeElement(ent)
@ -120,7 +117,7 @@ func (c *LRU) RemoveOldest() (key, value interface{}, ok bool) {
}
// GetOldest returns the oldest entry
func (c *LRU) GetOldest() (key, value interface{}, ok bool) {
func (c *LRU) GetOldest() (key interface{}, value interface{}, ok bool) {
ent := c.evictList.Back()
if ent != nil {
kv := ent.Value.(*entry)
@ -145,19 +142,6 @@ func (c *LRU) Len() int {
return c.evictList.Len()
}
// Resize changes the cache size.
func (c *LRU) Resize(size int) (evicted int) {
diff := c.Len() - size
if diff < 0 {
diff = 0
}
for i := 0; i < diff; i++ {
c.removeOldest()
}
c.size = size
return diff
}
// removeOldest removes the oldest item from the cache.
func (c *LRU) removeOldest() {
ent := c.evictList.Back()

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@ -1,4 +1,3 @@
// Package simplelru provides simple LRU implementation based on build-in container/list.
package simplelru
// LRUCache is the interface for simple LRU cache.
@ -11,7 +10,7 @@ type LRUCache interface {
// updates the "recently used"-ness of the key. #value, isFound
Get(key interface{}) (value interface{}, ok bool)
// Checks if a key exists in cache without updating the recent-ness.
// Check if a key exsists in cache without updating the recent-ness.
Contains(key interface{}) (ok bool)
// Returns key's value without updating the "recently used"-ness of the key.
@ -32,9 +31,6 @@ type LRUCache interface {
// Returns the number of items in the cache.
Len() int
// Clears all cache entries.
// Clear all cache entries
Purge()
// Resizes cache, returning number evicted
Resize(int) int
}

View file

@ -1,16 +0,0 @@
package lru
import (
"crypto/rand"
"math"
"math/big"
"testing"
)
func getRand(tb testing.TB) int64 {
out, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
tb.Fatal(err)
}
return out.Int64()
}