vendor
This commit is contained in:
Alex Dadgar
parent
35ab48bc3d
commit
25eba68015
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@ -0,0 +1,23 @@
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# Compiled Object files, Static and Dynamic libs (Shared Objects)
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*.o
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*.a
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*.so
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# Folders
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_obj
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_test
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# Architecture specific extensions/prefixes
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*.[568vq]
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[568vq].out
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*.cgo1.go
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*.cgo2.c
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_cgo_defun.c
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_cgo_gotypes.go
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_cgo_export.*
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_testmain.go
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*.exe
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*.test
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@ -0,0 +1,212 @@
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package lru
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import (
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"fmt"
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"sync"
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"github.com/hashicorp/golang-lru/simplelru"
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)
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const (
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// Default2QRecentRatio is the ratio of the 2Q cache dedicated
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// to recently added entries that have only been accessed once.
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Default2QRecentRatio = 0.25
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// Default2QGhostEntries is the default ratio of ghost
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// entries kept to track entries recently evicted
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Default2QGhostEntries = 0.50
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)
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// TwoQueueCache is a thread-safe fixed size 2Q cache.
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// 2Q is an enhancement over the standard LRU cache
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// in that it tracks both frequently and recently used
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// entries separately. This avoids a burst in access to new
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// entries from evicting frequently used entries. It adds some
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// additional tracking overhead to the standard LRU cache, and is
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// computationally about 2x the cost, and adds some metadata over
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// head. The ARCCache is similar, but does not require setting any
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// parameters.
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type TwoQueueCache struct {
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size int
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recentSize int
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recent *simplelru.LRU
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frequent *simplelru.LRU
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recentEvict *simplelru.LRU
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lock sync.RWMutex
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}
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// New2Q creates a new TwoQueueCache using the default
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// values for the parameters.
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func New2Q(size int) (*TwoQueueCache, error) {
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return New2QParams(size, Default2QRecentRatio, Default2QGhostEntries)
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}
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// New2QParams creates a new TwoQueueCache using the provided
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// parameter values.
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func New2QParams(size int, recentRatio float64, ghostRatio float64) (*TwoQueueCache, error) {
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if size <= 0 {
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return nil, fmt.Errorf("invalid size")
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}
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if recentRatio < 0.0 || recentRatio > 1.0 {
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return nil, fmt.Errorf("invalid recent ratio")
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}
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if ghostRatio < 0.0 || ghostRatio > 1.0 {
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return nil, fmt.Errorf("invalid ghost ratio")
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}
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// Determine the sub-sizes
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recentSize := int(float64(size) * recentRatio)
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evictSize := int(float64(size) * ghostRatio)
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// Allocate the LRUs
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recent, err := simplelru.NewLRU(size, nil)
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if err != nil {
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return nil, err
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}
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frequent, err := simplelru.NewLRU(size, nil)
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if err != nil {
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return nil, err
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}
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recentEvict, err := simplelru.NewLRU(evictSize, nil)
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if err != nil {
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return nil, err
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}
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// Initialize the cache
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c := &TwoQueueCache{
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size: size,
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recentSize: recentSize,
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recent: recent,
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frequent: frequent,
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recentEvict: recentEvict,
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}
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return c, nil
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}
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func (c *TwoQueueCache) Get(key interface{}) (interface{}, bool) {
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c.lock.Lock()
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defer c.lock.Unlock()
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// Check if this is a frequent value
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if val, ok := c.frequent.Get(key); ok {
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return val, ok
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}
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// If the value is contained in recent, then we
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// promote it to frequent
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if val, ok := c.recent.Peek(key); ok {
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c.recent.Remove(key)
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c.frequent.Add(key, val)
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return val, ok
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}
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// No hit
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return nil, false
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}
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func (c *TwoQueueCache) Add(key, value interface{}) {
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c.lock.Lock()
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defer c.lock.Unlock()
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// Check if the value is frequently used already,
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// and just update the value
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if c.frequent.Contains(key) {
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c.frequent.Add(key, value)
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return
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}
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// Check if the value is recently used, and promote
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// the value into the frequent list
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if c.recent.Contains(key) {
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c.recent.Remove(key)
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c.frequent.Add(key, value)
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return
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}
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// If the value was recently evicted, add it to the
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// frequently used list
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if c.recentEvict.Contains(key) {
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c.ensureSpace(true)
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c.recentEvict.Remove(key)
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c.frequent.Add(key, value)
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return
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}
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// Add to the recently seen list
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c.ensureSpace(false)
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c.recent.Add(key, value)
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return
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}
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// ensureSpace is used to ensure we have space in the cache
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func (c *TwoQueueCache) ensureSpace(recentEvict bool) {
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// If we have space, nothing to do
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recentLen := c.recent.Len()
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freqLen := c.frequent.Len()
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if recentLen+freqLen < c.size {
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return
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}
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// If the recent buffer is larger than
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// the target, evict from there
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if recentLen > 0 && (recentLen > c.recentSize || (recentLen == c.recentSize && !recentEvict)) {
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k, _, _ := c.recent.RemoveOldest()
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c.recentEvict.Add(k, nil)
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return
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}
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// Remove from the frequent list otherwise
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c.frequent.RemoveOldest()
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}
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func (c *TwoQueueCache) Len() int {
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c.lock.RLock()
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defer c.lock.RUnlock()
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return c.recent.Len() + c.frequent.Len()
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}
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func (c *TwoQueueCache) Keys() []interface{} {
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c.lock.RLock()
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defer c.lock.RUnlock()
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k1 := c.frequent.Keys()
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k2 := c.recent.Keys()
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return append(k1, k2...)
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}
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func (c *TwoQueueCache) Remove(key interface{}) {
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c.lock.Lock()
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defer c.lock.Unlock()
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if c.frequent.Remove(key) {
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return
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}
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if c.recent.Remove(key) {
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return
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}
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if c.recentEvict.Remove(key) {
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return
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}
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}
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func (c *TwoQueueCache) Purge() {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.recent.Purge()
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c.frequent.Purge()
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c.recentEvict.Purge()
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}
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func (c *TwoQueueCache) Contains(key interface{}) bool {
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c.lock.RLock()
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defer c.lock.RUnlock()
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return c.frequent.Contains(key) || c.recent.Contains(key)
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}
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func (c *TwoQueueCache) Peek(key interface{}) (interface{}, bool) {
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c.lock.RLock()
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defer c.lock.RUnlock()
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if val, ok := c.frequent.Peek(key); ok {
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return val, ok
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}
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return c.recent.Peek(key)
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}
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@ -0,0 +1,362 @@
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Mozilla Public License, version 2.0
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1. Definitions
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1.1. "Contributor"
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means each individual or legal entity that creates, contributes to the
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creation of, or owns Covered Software.
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1.2. "Contributor Version"
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means the combination of the Contributions of others (if any) used by a
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Contributor and that particular Contributor's Contribution.
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1.3. "Contribution"
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means Covered Software of a particular Contributor.
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1.4. "Covered Software"
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means Source Code Form to which the initial Contributor has attached the
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notice in Exhibit A, the Executable Form of such Source Code Form, and
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Modifications of such Source Code Form, in each case including portions
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thereof.
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1.5. "Incompatible With Secondary Licenses"
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means
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a. that the initial Contributor has attached the notice described in
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Exhibit B to the Covered Software; or
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b. that the Covered Software was made available under the terms of
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version 1.1 or earlier of the License, but not also under the terms of
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a Secondary License.
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1.6. "Executable Form"
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means any form of the work other than Source Code Form.
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1.7. "Larger Work"
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means a work that combines Covered Software with other material, in a
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separate file or files, that is not Covered Software.
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1.8. "License"
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means this document.
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1.9. "Licensable"
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means having the right to grant, to the maximum extent possible, whether
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at the time of the initial grant or subsequently, any and all of the
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rights conveyed by this License.
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1.10. "Modifications"
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means any of the following:
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a. any file in Source Code Form that results from an addition to,
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deletion from, or modification of the contents of Covered Software; or
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b. any new file in Source Code Form that contains any Covered Software.
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1.11. "Patent Claims" of a Contributor
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means any patent claim(s), including without limitation, method,
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process, and apparatus claims, in any patent Licensable by such
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Contributor that would be infringed, but for the grant of the License,
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by the making, using, selling, offering for sale, having made, import,
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or transfer of either its Contributions or its Contributor Version.
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1.12. "Secondary License"
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means either the GNU General Public License, Version 2.0, the GNU Lesser
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General Public License, Version 2.1, the GNU Affero General Public
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License, Version 3.0, or any later versions of those licenses.
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1.13. "Source Code Form"
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means the form of the work preferred for making modifications.
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1.14. "You" (or "Your")
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means an individual or a legal entity exercising rights under this
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License. For legal entities, "You" includes any entity that controls, is
|
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controlled by, or is under common control with You. For purposes of this
|
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definition, "control" means (a) the power, direct or indirect, to cause
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the direction or management of such entity, whether by contract or
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otherwise, or (b) ownership of more than fifty percent (50%) of the
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outstanding shares or beneficial ownership of such entity.
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2. License Grants and Conditions
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2.1. Grants
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|
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Each Contributor hereby grants You a world-wide, royalty-free,
|
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non-exclusive license:
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|
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a. under intellectual property rights (other than patent or trademark)
|
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Licensable by such Contributor to use, reproduce, make available,
|
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modify, display, perform, distribute, and otherwise exploit its
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Contributions, either on an unmodified basis, with Modifications, or
|
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as part of a Larger Work; and
|
||||
|
||||
b. under Patent Claims of such Contributor to make, use, sell, offer for
|
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sale, have made, import, and otherwise transfer either its
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||||
Contributions or its Contributor Version.
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2.2. Effective Date
|
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|
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The licenses granted in Section 2.1 with respect to any Contribution
|
||||
become effective for each Contribution on the date the Contributor first
|
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distributes such Contribution.
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|
||||
2.3. Limitations on Grant Scope
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|
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The licenses granted in this Section 2 are the only rights granted under
|
||||
this License. No additional rights or licenses will be implied from the
|
||||
distribution or licensing of Covered Software under this License.
|
||||
Notwithstanding Section 2.1(b) above, no patent license is granted by a
|
||||
Contributor:
|
||||
|
||||
a. for any code that a Contributor has removed from Covered Software; or
|
||||
|
||||
b. for infringements caused by: (i) Your and any other third party's
|
||||
modifications of Covered Software, or (ii) the combination of its
|
||||
Contributions with other software (except as part of its Contributor
|
||||
Version); or
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||||
|
||||
c. under Patent Claims infringed by Covered Software in the absence of
|
||||
its Contributions.
|
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|
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This License does not grant any rights in the trademarks, service marks,
|
||||
or logos of any Contributor (except as may be necessary to comply with
|
||||
the notice requirements in Section 3.4).
|
||||
|
||||
2.4. Subsequent Licenses
|
||||
|
||||
No Contributor makes additional grants as a result of Your choice to
|
||||
distribute the Covered Software under a subsequent version of this
|
||||
License (see Section 10.2) or under the terms of a Secondary License (if
|
||||
permitted under the terms of Section 3.3).
|
||||
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||||
2.5. Representation
|
||||
|
||||
Each Contributor represents that the Contributor believes its
|
||||
Contributions are its original creation(s) or it has sufficient rights to
|
||||
grant the rights to its Contributions conveyed by this License.
|
||||
|
||||
2.6. Fair Use
|
||||
|
||||
This License is not intended to limit any rights You have under
|
||||
applicable copyright doctrines of fair use, fair dealing, or other
|
||||
equivalents.
|
||||
|
||||
2.7. Conditions
|
||||
|
||||
Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in
|
||||
Section 2.1.
|
||||
|
||||
|
||||
3. Responsibilities
|
||||
|
||||
3.1. Distribution of Source Form
|
||||
|
||||
All distribution of Covered Software in Source Code Form, including any
|
||||
Modifications that You create or to which You contribute, must be under
|
||||
the terms of this License. You must inform recipients that the Source
|
||||
Code Form of the Covered Software is governed by the terms of this
|
||||
License, and how they can obtain a copy of this License. You may not
|
||||
attempt to alter or restrict the recipients' rights in the Source Code
|
||||
Form.
|
||||
|
||||
3.2. Distribution of Executable Form
|
||||
|
||||
If You distribute Covered Software in Executable Form then:
|
||||
|
||||
a. such Covered Software must also be made available in Source Code Form,
|
||||
as described in Section 3.1, and You must inform recipients of the
|
||||
Executable Form how they can obtain a copy of such Source Code Form by
|
||||
reasonable means in a timely manner, at a charge no more than the cost
|
||||
of distribution to the recipient; and
|
||||
|
||||
b. You may distribute such Executable Form under the terms of this
|
||||
License, or sublicense it under different terms, provided that the
|
||||
license for the Executable Form does not attempt to limit or alter the
|
||||
recipients' rights in the Source Code Form under this License.
|
||||
|
||||
3.3. Distribution of a Larger Work
|
||||
|
||||
You may create and distribute a Larger Work under terms of Your choice,
|
||||
provided that You also comply with the requirements of this License for
|
||||
the Covered Software. If the Larger Work is a combination of Covered
|
||||
Software with a work governed by one or more Secondary Licenses, and the
|
||||
Covered Software is not Incompatible With Secondary Licenses, this
|
||||
License permits You to additionally distribute such Covered Software
|
||||
under the terms of such Secondary License(s), so that the recipient of
|
||||
the Larger Work may, at their option, further distribute the Covered
|
||||
Software under the terms of either this License or such Secondary
|
||||
License(s).
|
||||
|
||||
3.4. Notices
|
||||
|
||||
You may not remove or alter the substance of any license notices
|
||||
(including copyright notices, patent notices, disclaimers of warranty, or
|
||||
limitations of liability) contained within the Source Code Form of the
|
||||
Covered Software, except that You may alter any license notices to the
|
||||
extent required to remedy known factual inaccuracies.
|
||||
|
||||
3.5. Application of Additional Terms
|
||||
|
||||
You may choose to offer, and to charge a fee for, warranty, support,
|
||||
indemnity or liability obligations to one or more recipients of Covered
|
||||
Software. However, You may do so only on Your own behalf, and not on
|
||||
behalf of any Contributor. You must make it absolutely clear that any
|
||||
such warranty, support, indemnity, or liability obligation is offered by
|
||||
You alone, and You hereby agree to indemnify every Contributor for any
|
||||
liability incurred by such Contributor as a result of warranty, support,
|
||||
indemnity or liability terms You offer. You may include additional
|
||||
disclaimers of warranty and limitations of liability specific to any
|
||||
jurisdiction.
|
||||
|
||||
4. Inability to Comply Due to Statute or Regulation
|
||||
|
||||
If it is impossible for You to comply with any of the terms of this License
|
||||
with respect to some or all of the Covered Software due to statute,
|
||||
judicial order, or regulation then You must: (a) comply with the terms of
|
||||
this License to the maximum extent possible; and (b) describe the
|
||||
limitations and the code they affect. Such description must be placed in a
|
||||
text file included with all distributions of the Covered Software under
|
||||
this License. Except to the extent prohibited by statute or regulation,
|
||||
such description must be sufficiently detailed for a recipient of ordinary
|
||||
skill to be able to understand it.
|
||||
|
||||
5. Termination
|
||||
|
||||
5.1. The rights granted under this License will terminate automatically if You
|
||||
fail to comply with any of its terms. However, if You become compliant,
|
||||
then the rights granted under this License from a particular Contributor
|
||||
are reinstated (a) provisionally, unless and until such Contributor
|
||||
explicitly and finally terminates Your grants, and (b) on an ongoing
|
||||
basis, if such Contributor fails to notify You of the non-compliance by
|
||||
some reasonable means prior to 60 days after You have come back into
|
||||
compliance. Moreover, Your grants from a particular Contributor are
|
||||
reinstated on an ongoing basis if such Contributor notifies You of the
|
||||
non-compliance by some reasonable means, this is the first time You have
|
||||
received notice of non-compliance with this License from such
|
||||
Contributor, and You become compliant prior to 30 days after Your receipt
|
||||
of the notice.
|
||||
|
||||
5.2. If You initiate litigation against any entity by asserting a patent
|
||||
infringement claim (excluding declaratory judgment actions,
|
||||
counter-claims, and cross-claims) alleging that a Contributor Version
|
||||
directly or indirectly infringes any patent, then the rights granted to
|
||||
You by any and all Contributors for the Covered Software under Section
|
||||
2.1 of this License shall terminate.
|
||||
|
||||
5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user
|
||||
license agreements (excluding distributors and resellers) which have been
|
||||
validly granted by You or Your distributors under this License prior to
|
||||
termination shall survive termination.
|
||||
|
||||
6. Disclaimer of Warranty
|
||||
|
||||
Covered Software is provided under this License on an "as is" basis,
|
||||
without warranty of any kind, either expressed, implied, or statutory,
|
||||
including, without limitation, warranties that the Covered Software is free
|
||||
of defects, merchantable, fit for a particular purpose or non-infringing.
|
||||
The entire risk as to the quality and performance of the Covered Software
|
||||
is with You. Should any Covered Software prove defective in any respect,
|
||||
You (not any Contributor) assume the cost of any necessary servicing,
|
||||
repair, or correction. This disclaimer of warranty constitutes an essential
|
||||
part of this License. No use of any Covered Software is authorized under
|
||||
this License except under this disclaimer.
|
||||
|
||||
7. Limitation of Liability
|
||||
|
||||
Under no circumstances and under no legal theory, whether tort (including
|
||||
negligence), contract, or otherwise, shall any Contributor, or anyone who
|
||||
distributes Covered Software as permitted above, be liable to You for any
|
||||
direct, indirect, special, incidental, or consequential damages of any
|
||||
character including, without limitation, damages for lost profits, loss of
|
||||
goodwill, work stoppage, computer failure or malfunction, or any and all
|
||||
other commercial damages or losses, even if such party shall have been
|
||||
informed of the possibility of such damages. This limitation of liability
|
||||
shall not apply to liability for death or personal injury resulting from
|
||||
such party's negligence to the extent applicable law prohibits such
|
||||
limitation. Some jurisdictions do not allow the exclusion or limitation of
|
||||
incidental or consequential damages, so this exclusion and limitation may
|
||||
not apply to You.
|
||||
|
||||
8. Litigation
|
||||
|
||||
Any litigation relating to this License may be brought only in the courts
|
||||
of a jurisdiction where the defendant maintains its principal place of
|
||||
business and such litigation shall be governed by laws of that
|
||||
jurisdiction, without reference to its conflict-of-law provisions. Nothing
|
||||
in this Section shall prevent a party's ability to bring cross-claims or
|
||||
counter-claims.
|
||||
|
||||
9. Miscellaneous
|
||||
|
||||
This License represents the complete agreement concerning the subject
|
||||
matter hereof. If any provision of this License is held to be
|
||||
unenforceable, such provision shall be reformed only to the extent
|
||||
necessary to make it enforceable. Any law or regulation which provides that
|
||||
the language of a contract shall be construed against the drafter shall not
|
||||
be used to construe this License against a Contributor.
|
||||
|
||||
|
||||
10. Versions of the License
|
||||
|
||||
10.1. New Versions
|
||||
|
||||
Mozilla Foundation is the license steward. Except as provided in Section
|
||||
10.3, no one other than the license steward has the right to modify or
|
||||
publish new versions of this License. Each version will be given a
|
||||
distinguishing version number.
|
||||
|
||||
10.2. Effect of New Versions
|
||||
|
||||
You may distribute the Covered Software under the terms of the version
|
||||
of the License under which You originally received the Covered Software,
|
||||
or under the terms of any subsequent version published by the license
|
||||
steward.
|
||||
|
||||
10.3. Modified Versions
|
||||
|
||||
If you create software not governed by this License, and you want to
|
||||
create a new license for such software, you may create and use a
|
||||
modified version of this License if you rename the license and remove
|
||||
any references to the name of the license steward (except to note that
|
||||
such modified license differs from this License).
|
||||
|
||||
10.4. Distributing Source Code Form that is Incompatible With Secondary
|
||||
Licenses If You choose to distribute Source Code Form that is
|
||||
Incompatible With Secondary Licenses under the terms of this version of
|
||||
the License, the notice described in Exhibit B of this License must be
|
||||
attached.
|
||||
|
||||
Exhibit A - Source Code Form License Notice
|
||||
|
||||
This Source Code Form is subject to the
|
||||
terms of the Mozilla Public License, v.
|
||||
2.0. If a copy of the MPL was not
|
||||
distributed with this file, You can
|
||||
obtain one at
|
||||
http://mozilla.org/MPL/2.0/.
|
||||
|
||||
If it is not possible or desirable to put the notice in a particular file,
|
||||
then You may include the notice in a location (such as a LICENSE file in a
|
||||
relevant directory) where a recipient would be likely to look for such a
|
||||
notice.
|
||||
|
||||
You may add additional accurate notices of copyright ownership.
|
||||
|
||||
Exhibit B - "Incompatible With Secondary Licenses" Notice
|
||||
|
||||
This Source Code Form is "Incompatible
|
||||
With Secondary Licenses", as defined by
|
||||
the Mozilla Public License, v. 2.0.
|
||||
|
|
@ -0,0 +1,25 @@
|
|||
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()))
|
||||
}
|
||||
```
|
||||
|
|
@ -0,0 +1,257 @@
|
|||
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)
|
||||
}
|
||||
|
|
@ -0,0 +1,114 @@
|
|||
// 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()
|
||||
}
|
||||
|
|
@ -0,0 +1,160 @@
|
|||
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)
|
||||
}
|
||||
}
|
||||
|
|
@ -0,0 +1,10 @@
|
|||
# Proprietary License
|
||||
|
||||
This license is temporary while a more official one is drafted. However,
|
||||
this should make it clear:
|
||||
|
||||
* The text contents of this website are MPL 2.0 licensed.
|
||||
|
||||
* The design contents of this website are proprietary and may not be reproduced
|
||||
or reused in any way other than to run the Serf website locally. The license
|
||||
for the design is owned solely by HashiCorp, Inc.
|
||||
Loading…
Reference in New Issue