gcache

package module
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 Go to latest Published: Apr 10, 2023 License: MIT Imports: 6 Imported by: 0

README

GCache

Test GoDoc

Cache library for golang. It supports expirable Cache, LFU, LRU and ARC.

Features

  • Supports expirable Cache, LFU, LRU and ARC.

  • Goroutine safe.

  • Supports event handlers which evict, purge, and add entry. (Optional)

  • Automatically load cache if it doesn't exists. (Optional)

Install

$ go get github.com/bluele/gcache

Example

Manually set a key-value pair.
package main

import (
  "github.com/bluele/gcache"
  "fmt"
)

func main() {
  gc := gcache.New(20).
    LRU().
    Build()
  gc.Set("key", "ok")
  value, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
}

Get: ok
Manually set a key-value pair, with an expiration time.
package main

import (
  "github.com/bluele/gcache"
  "fmt"
  "time"
)

func main() {
  gc := gcache.New(20).
    LRU().
    Build()
  gc.SetWithExpire("key", "ok", time.Second*10)
  value, _ := gc.Get("key")
  fmt.Println("Get:", value)

  // Wait for value to expire
  time.Sleep(time.Second*10)

  value, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
}

Get: ok
// 10 seconds later, new attempt:
panic: ErrKeyNotFound
Automatically load value
package main

import (
  "github.com/bluele/gcache"
  "fmt"
)

func main() {
  gc := gcache.New(20).
    LRU().
    LoaderFunc(func(key interface{}) (interface{}, error) {
      return "ok", nil
    }).
    Build()
  value, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
}

Get: ok
Automatically load value with expiration
package main

import (
  "fmt"
  "time"

  "github.com/bluele/gcache"
)

func main() {
  var evictCounter, loaderCounter, purgeCounter int
  gc := gcache.New(20).
    LRU().
    LoaderExpireFunc(func(key interface{}) (interface{}, *time.Duration, error) {
      loaderCounter++
      expire := 1 * time.Second
      return "ok", &expire, nil
    }).
    EvictedFunc(func(key, value interface{}) {
      evictCounter++
      fmt.Println("evicted key:", key)
    }).
    PurgeVisitorFunc(func(key, value interface{}) {
      purgeCounter++
      fmt.Println("purged key:", key)
    }).
    Build()
  value, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
  time.Sleep(1 * time.Second)
  value, err = gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
  gc.Purge()
  if loaderCounter != evictCounter+purgeCounter {
    panic("bad")
  }
}

Get: ok
evicted key: key
Get: ok
purged key: key

Cache Algorithm

  • Least-Frequently Used (LFU)

Discards the least frequently used items first.

func main() {
  // size: 10
  gc := gcache.New(10).
    LFU().
    Build()
  gc.Set("key", "value")
}
  • Least Recently Used (LRU)

Discards the least recently used items first.

func main() {
  // size: 10
  gc := gcache.New(10).
    LRU().
    Build()
  gc.Set("key", "value")
}
  • Adaptive Replacement Cache (ARC)

Constantly balances between LRU and LFU, to improve the combined result.

detail: http://en.wikipedia.org/wiki/Adaptive_replacement_cache

func main() {
  // size: 10
  gc := gcache.New(10).
    ARC().
    Build()
  gc.Set("key", "value")
}
  • SimpleCache (Default)

SimpleCache has no clear priority for evict cache. It depends on key-value map order.

func main() {
  // size: 10
  gc := gcache.New(10).Build()
  gc.Set("key", "value")
  v, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
}

Loading Cache

If specified LoaderFunc, values are automatically loaded by the cache, and are stored in the cache until either evicted or manually invalidated.

func main() {
  gc := gcache.New(10).
    LRU().
    LoaderFunc(func(key interface{}) (interface{}, error) {
      return "value", nil
    }).
    Build()
  v, _ := gc.Get("key")
  // output: "value"
  fmt.Println(v)
}

GCache coordinates cache fills such that only one load in one process of an entire replicated set of processes populates the cache, then multiplexes the loaded value to all callers.

Expirable cache

func main() {
  // LRU cache, size: 10, expiration: after a hour
  gc := gcache.New(10).
    LRU().
    Expiration(time.Hour).
    Build()
}

Event handlers

Evicted handler

Event handler for evict the entry.

func main() {
  gc := gcache.New(2).
    EvictedFunc(func(key, value interface{}) {
      fmt.Println("evicted key:", key)
    }).
    Build()
  for i := 0; i < 3; i++ {
    gc.Set(i, i*i)
  }
}

evicted key: 0
Added handler

Event handler for add the entry.

func main() {
  gc := gcache.New(2).
    AddedFunc(func(key, value interface{}) {
      fmt.Println("added key:", key)
    }).
    Build()
  for i := 0; i < 3; i++ {
    gc.Set(i, i*i)
  }
}

added key: 0
added key: 1
added key: 2

Author

Jun Kimura

Documentation

Index

Constants

View Source 
const (
	TYPE_SIMPLE = "simple"
	TYPE_LRU    = "lru"
	TYPE_LFU    = "lfu"
	TYPE_ARC    = "arc"
)

Variables

View Source 
var KeyNotFoundError = errors.New("Key not found.")

Functions

This section is empty.

Types

type ARC 

type ARC[K comparable, V any] struct {
	// contains filtered or unexported fields
}

Constantly balances between LRU and LFU, to improve the combined result.

func (*ARC[K, V]) Get 

func (c *ARC[K, V]) Get(key K) (V, error)

Get a value from cache pool using key if it exists. If not exists and it has LoaderFunc, it will generate the value using you have specified LoaderFunc method returns value.

func (*ARC[K, V]) GetALL 

func (c *ARC[K, V]) GetALL(checkExpired bool) map[K]V

GetALL returns all key-value pairs in the cache.

func (*ARC[K, V]) GetIFPresent 

func (c *ARC[K, V]) GetIFPresent(key K) (V, error)

GetIFPresent gets a value from cache pool using key if it exists. If it does not exists key, returns KeyNotFoundError. And send a request which refresh value for specified key if cache object has LoaderFunc.

func (*ARC[K, V]) Has 

func (c *ARC[K, V]) Has(key K) bool

Has checks if key exists in cache

func (*ARC[K, V]) Keys 

func (c *ARC[K, V]) Keys(checkExpired bool) []K

Keys returns a slice of the keys in the cache.

func (*ARC[K, V]) Len 

func (c *ARC[K, V]) Len(checkExpired bool) int

Len returns the number of items in the cache.

func (*ARC[K, V]) Purge 

func (c *ARC[K, V]) Purge()

Purge is used to completely clear the cache

func (*ARC[K, V]) Remove 

func (c *ARC[K, V]) Remove(key K) bool

Remove removes the provided key from the cache.

func (*ARC[K, V]) Set 

func (c *ARC[K, V]) Set(key K, value V) error

func (*ARC[K, V]) SetWithExpire 

func (c *ARC[K, V]) SetWithExpire(key K, value V, expiration time.Duration) error

Set a new key-value pair with an expiration time

type Cache 

type Cache[K comparable, V any] interface {
	// Set inserts or updates the specified key-value pair.
	Set(key K, value V) error
	// SetWithExpire inserts or updates the specified key-value pair with an expiration time.
	SetWithExpire(key K, value V, expiration time.Duration) error
	// Get returns the value for the specified key if it is present in the cache.
	// If the key is not present in the cache and the cache has LoaderFunc,
	// invoke the `LoaderFunc` function and inserts the key-value pair in the cache.
	// If the key is not present in the cache and the cache does not have a LoaderFunc,
	// return KeyNotFoundError.
	Get(key K) (V, error)
	// GetIFPresent returns the value for the specified key if it is present in the cache.
	// Return KeyNotFoundError if the key is not present.
	GetIFPresent(key K) (V, error)
	// GetAll returns a map containing all key-value pairs in the cache.
	GetALL(checkExpired bool) map[K]V

	// Remove removes the specified key from the cache if the key is present.
	// Returns true if the key was present and the key has been deleted.
	Remove(key K) bool
	// Purge removes all key-value pairs from the cache.
	Purge()
	// Keys returns a slice containing all keys in the cache.
	Keys(checkExpired bool) []K
	// Len returns the number of items in the cache.
	Len(checkExpired bool) int
	// Has returns true if the key exists in the cache.
	Has(key K) bool
	// contains filtered or unexported methods
}

type CacheBuilder 

type CacheBuilder[K comparable, V any] struct {
	// contains filtered or unexported fields
}

func New 

func New[K comparable, V any](size int) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) ARC 

func (cb *CacheBuilder[K, V]) ARC() *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) AddedFunc 

func (cb *CacheBuilder[K, V]) AddedFunc(addedFunc func(k K, v V)) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) Build 

func (cb *CacheBuilder[K, V]) Build() Cache[K, V]

func (*CacheBuilder[K, V]) Clock 

func (cb *CacheBuilder[K, V]) Clock(clock Clock) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) DeserializeFunc 

func (cb *CacheBuilder[K, V]) DeserializeFunc(deserializeFunc func(k K, v V) (V, error)) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) EvictType 

func (cb *CacheBuilder[K, V]) EvictType(tp string) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) EvictedFunc 

func (cb *CacheBuilder[K, V]) EvictedFunc(evictedFunc func(k K, v V)) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) Expiration 

func (cb *CacheBuilder[K, V]) Expiration(expiration time.Duration) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) LFU 

func (cb *CacheBuilder[K, V]) LFU() *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) LRU 

func (cb *CacheBuilder[K, V]) LRU() *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) Lease 

func (cb *CacheBuilder[K, V]) Lease(lease time.Duration) *CacheBuilder[K, V]

Lease: 当 Item 具备 Expiration 时，每次被访问成功则自动续租一次

func (*CacheBuilder[K, V]) LoaderExpireFunc 

func (cb *CacheBuilder[K, V]) LoaderExpireFunc(loaderExpireFunc func(k K) (V, *time.Duration, error)) *CacheBuilder[K, V]

Set a loader function with expiration. loaderExpireFunc: create a new value with this function if cached value is expired. If nil returned instead of time.Duration from loaderExpireFunc than value will never expire.

func (*CacheBuilder[K, V]) LoaderFunc 

func (cb *CacheBuilder[K, V]) LoaderFunc(loaderFunc func(k K) (V, error)) *CacheBuilder[K, V]

Set a loader function. loaderFunc: create a new value with this function if cached value is expired.

func (*CacheBuilder[K, V]) PurgeVisitorFunc 

func (cb *CacheBuilder[K, V]) PurgeVisitorFunc(purgeVisitorFunc func(k K, v V)) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) SerializeFunc 

func (cb *CacheBuilder[K, V]) SerializeFunc(serializeFunc func(k K, v V) (V, error)) *CacheBuilder[K, V]

func (*CacheBuilder[K, V]) Simple 

func (cb *CacheBuilder[K, V]) Simple() *CacheBuilder[K, V]

type Clock 

type Clock interface {
	Now() time.Time
}

func NewRealClock 

func NewRealClock() Clock

type FakeClock 

type FakeClock interface {
	Clock

	Advance(d time.Duration)
}

func NewFakeClock 

func NewFakeClock() FakeClock

type Group 

type Group[K comparable, V any] struct {
	// contains filtered or unexported fields
}

Group represents a class of work and forms a namespace in which units of work can be executed with duplicate suppression.

func (*Group[K, V]) Do 

func (g *Group[K, V]) Do(key K, fn func() (V, error), isWait bool) (V, bool, error)

Do executes and returns the results of the given function, making sure that only one execution is in-flight for a given key at a time. If a duplicate comes in, the duplicate caller waits for the original to complete and receives the same results.

type LFUCache 

type LFUCache[K comparable, V any] struct {
	// contains filtered or unexported fields
}

Discards the least frequently used items first.

func (*LFUCache[K, V]) Get 

func (c *LFUCache[K, V]) Get(key K) (V, error)

Get a value from cache pool using key if it exists. If it does not exists key and has LoaderFunc, generate a value using `LoaderFunc` method returns value.

func (*LFUCache[K, V]) GetALL 

func (c *LFUCache[K, V]) GetALL(checkExpired bool) map[K]V

GetALL returns all key-value pairs in the cache.

func (*LFUCache[K, V]) GetIFPresent 

func (c *LFUCache[K, V]) GetIFPresent(key K) (V, error)

GetIFPresent gets a value from cache pool using key if it exists. If it does not exists key, returns KeyNotFoundError. And send a request which refresh value for specified key if cache object has LoaderFunc.

func (*LFUCache[K, V]) Has 

func (c *LFUCache[K, V]) Has(key K) bool

Has checks if key exists in cache

func (*LFUCache[K, V]) Keys 

func (c *LFUCache[K, V]) Keys(checkExpired bool) []K

Keys returns a slice of the keys in the cache.

func (*LFUCache[K, V]) Len 

func (c *LFUCache[K, V]) Len(checkExpired bool) int

Len returns the number of items in the cache.

func (*LFUCache[K, V]) Purge 

func (c *LFUCache[K, V]) Purge()

Completely clear the cache

func (*LFUCache[K, V]) Remove 

func (c *LFUCache[K, V]) Remove(key K) bool

Remove removes the provided key from the cache.

func (*LFUCache[K, V]) Set 

func (c *LFUCache[K, V]) Set(key K, value V) error

Set a new key-value pair

func (*LFUCache[K, V]) SetWithExpire 

func (c *LFUCache[K, V]) SetWithExpire(key K, value V, expiration time.Duration) error

Set a new key-value pair with an expiration time

type LRUCache 

type LRUCache[K comparable, V any] struct {
	// contains filtered or unexported fields
}

Discards the least recently used items first.

func (*LRUCache[K, V]) Get 

func (c *LRUCache[K, V]) Get(key K) (V, error)

Get a value from cache pool using key if it exists. If it does not exists key and has LoaderFunc, generate a value using `LoaderFunc` method returns value.

func (*LRUCache[K, V]) GetALL 

func (c *LRUCache[K, V]) GetALL(checkExpired bool) map[K]V

GetALL returns all key-value pairs in the cache.

func (*LRUCache[K, V]) GetIFPresent 

func (c *LRUCache[K, V]) GetIFPresent(key K) (V, error)

GetIFPresent gets a value from cache pool using key if it exists. If it does not exists key, returns KeyNotFoundError. And send a request which refresh value for specified key if cache object has LoaderFunc.

func (*LRUCache[K, V]) Has 

func (c *LRUCache[K, V]) Has(key K) bool

Has checks if key exists in cache

func (*LRUCache[K, V]) Keys 

func (c *LRUCache[K, V]) Keys(checkExpired bool) []K

Keys returns a slice of the keys in the cache.

func (*LRUCache[K, V]) Len 

func (c *LRUCache[K, V]) Len(checkExpired bool) int

Len returns the number of items in the cache.

func (*LRUCache[K, V]) Purge 

func (c *LRUCache[K, V]) Purge()

Completely clear the cache

func (*LRUCache[K, V]) Remove 

func (c *LRUCache[K, V]) Remove(key K) bool

Remove removes the provided key from the cache.

func (*LRUCache[K, V]) Set 

func (c *LRUCache[K, V]) Set(key K, value V) error

set a new key-value pair

func (*LRUCache[K, V]) SetWithExpire 

func (c *LRUCache[K, V]) SetWithExpire(key K, value V, expiration time.Duration) error

Set a new key-value pair with an expiration time

type RealClock 

type RealClock struct{}

func (RealClock) Now 

func (rc RealClock) Now() time.Time

type SimpleCache 

type SimpleCache[K comparable, V any] struct {
	// contains filtered or unexported fields
}

SimpleCache has no clear priority for evict cache. It depends on key-value map order.

func (*SimpleCache[K, V]) Get 

func (c *SimpleCache[K, V]) Get(key K) (V, error)

Get a value from cache pool using key if it exists. If it does not exists key and has LoaderFunc, generate a value using `LoaderFunc` method returns value.

func (*SimpleCache[K, V]) GetALL 

func (c *SimpleCache[K, V]) GetALL(checkExpired bool) map[K]V

GetALL returns all key-value pairs in the cache.

func (*SimpleCache[K, V]) GetIFPresent 

func (c *SimpleCache[K, V]) GetIFPresent(key K) (V, error)

GetIFPresent gets a value from cache pool using key if it exists. If it does not exists key, returns KeyNotFoundError. And send a request which refresh value for specified key if cache object has LoaderFunc.

func (*SimpleCache[K, V]) Has 

func (c *SimpleCache[K, V]) Has(key K) bool

Has checks if key exists in cache

func (*SimpleCache[K, V]) Keys 

func (c *SimpleCache[K, V]) Keys(checkExpired bool) []K

Keys returns a slice of the keys in the cache.

func (*SimpleCache[K, V]) Len 

func (c *SimpleCache[K, V]) Len(checkExpired bool) int

Len returns the number of items in the cache.

func (*SimpleCache[K, V]) Purge 

func (c *SimpleCache[K, V]) Purge()

Completely clear the cache

func (*SimpleCache[K, V]) Remove 

func (c *SimpleCache[K, V]) Remove(key K) bool

Remove removes the provided key from the cache.

func (*SimpleCache[K, V]) Set 

func (c *SimpleCache[K, V]) Set(key K, value V) error

Set a new key-value pair

func (*SimpleCache[K, V]) SetWithExpire 

func (c *SimpleCache[K, V]) SetWithExpire(key K, value V, expiration time.Duration) error

Set a new key-value pair with an expiration time

Source Files

View all Source files

Directories

Path Synopsis
examples
autoloading
internal
list
Package list implements a doubly linked list.
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