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gcache

> 编程语言
Open source

An in-memory cache library for golang. It supports multiple eviction policies: LRU, LFU, ARC

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An in-memory cache library for golang. It supports multiple eviction policies: LRU, LFU, ARC

GCache

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

Features

  • Supports expirable Cache, LFU, LRU and ARC.

  • Goroutine safe.

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

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

Install

$ go get github.com/bluele/gcache

Example

Manually set a key-value pair.

go
package main

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

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

Manually set a key-value pair, with an expiration time.

go
package main

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

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

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

  value, err := gc.Get("key")
  if err != nil {
    panic(err)
  }
  fmt.Println("Get:", value)
}
Get: ok
// 10 seconds later, new attempt:
panic: ErrKeyNotFound

Automatically load value

go
package main

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

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

Automatically load value with expiration

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

Cache Algorithm

  • Least-Frequently Used (LFU)

Discards the least frequently used items first.

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

Discards the least recently used items first.

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

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

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

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

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

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

Loading Cache

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

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

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

Expirable cache

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

Event handlers

Evicted handler

Event handler for evict the entry.

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

Added handler

Event handler for add the entry.

go
func main() {
  gc := gcache.New(2).
    AddedFunc(func(key, value interface{}) {
      fmt.Println("added key:", key)
    }).
    Build()
  for i := 0; i < 3; i++ {
    gc.Set(i, i*i)
  }
}
added key: 0
added key: 1
added key: 2

Author

Jun Kimura

  • http://github.com/bluele
  • [email protected]

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> Tags

Goarccachegogolang

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> Details

PublishedAug 1, 2026
UpdatedSep 17, 2026
Category编程语言
PricingOpen source

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