Libcache

A Lightweight in-memory key:value cache library for Go.

Introduction

Caches are tremendously useful in a wide variety of use cases.
you should consider using caches when a value is expensive to compute or retrieve,
and you will need its value on a certain input more than once.
libcache is here to help with that.

Libcache are local to a single run of your application.
They do not store data in files, or on outside servers.

Libcache previously an go-guardian package and designed to be a companion with it.
While both can operate completely independently.

Features

• Rich caching API
• Maximum cache size enforcement
• Default cache TTL (time-to-live) as well as custom TTLs per cache entry
• Thread safe as well as non-thread safe
• Event-Driven callbacks (OnExpired,OnEvicted)
• Dynamic cache creation
• Multiple cache replacement policies:
  • FIFO (First In, First Out)
  • LIFO (Last In, First Out)
  • LRU (Least Recently Used)
  • MRU (Most Recently Used)
  • LFU (Least Frequently Used)
  • ARC (Adaptive Replacement Cache)

Quickstart

Installing

Using libcache is easy. First, use go get to install the latest version of the library.

go get github.com/shaj13/libcache

Next, include libcache in your application:

import (
    _ "github.com/shaj13/libcache/<desired-replacement-policy>"
    "github.com/shaj13/libcache"
)

Examples

Note: All examples use the LRU cache replacement policy for simplicity, any other cache replacement policy can be applied to them.

Basic

package main 
import (
    "fmt" 

    "github.com/shaj13/libcache"
    _ "github.com/shaj13/libcache/lru"
)

func main() {
    size := 10
    cache := libcache.LRU.NewUnsafe(size)
    for i:= 0 ; i < 10 ; i++ {
        cache.Store(i, i)
    }
    fmt.Println(cache.Load(0)) // nil, false  
    fmt.Println(cache.Load(1)) // 1, true
}

Thread Safe

package main

import (
	"fmt"

	"github.com/shaj13/libcache"
	_ "github.com/shaj13/libcache/lru"
)

func main() {
	done := make(chan struct{})

	f := func(c libcache.Cache) {
		for !c.Contains(5) {
		}
		fmt.Println(c.Load(5)) // 5, true
		done <- struct{}{}
	}

	size := 10
	cache := libcache.LRU.New(size)
	go f(cache)

	for i := 0; i < 10; i++ {
		cache.Store(i, i)
	}

	<-done
}

Unlimited Size

zero capacity means cache has no limit and replacement policy turned off.

package main 
import (
    "fmt" 

    "github.com/shaj13/libcache"
    _ "github.com/shaj13/libcache/lru"
)

func main() {
	cache := libcache.LRU.New(0)
    for i:= 0 ; i < 100000 ; i++ {
        cache.Store(i, i)
    }
	fmt.Println(cache.Load(55555))
}

TTL

package main 
import (
	"fmt"
	"time"

	"github.com/shaj13/libcache"
	_ "github.com/shaj13/libcache/lru"
)

func main() {
	cache := libcache.LRU.New(10)
	cache.SetTTL(time.Second) // default TTL 
	
	for i:= 0 ; i < 10 ; i++ {
        cache.Store(i, i)
	}
	fmt.Println(cache.Expiry(1))

	cache.StoreWithTTL("mykey", "value", time.Hour) // TTL per cache entry 
	fmt.Println(cache.Expiry("mykey"))

}

Events

Timed expiration by default is performed with lazy maintenance during reads operations,
Evict an expired entry immediately can be done using on expired callback.
You may also specify a eviction listener for your cache to perform some operation when an entry is evicted.
Note: Expiration events relying on golang runtime timers heap to call on expired callback when an entry TTL elapsed.

package main 
import (
	"fmt"
	"time"

	"github.com/shaj13/libcache"
	_ "github.com/shaj13/libcache/lru"
)

func main() {
	cache := libcache.LRU.New(10)
	cache.RegisterOnEvicted(func(key, value interface{}) {
		fmt.Printf("Cache Key %v Evicted\n", key)
	})

	cache.RegisterOnExpired(func(key, value interface{}) {
		fmt.Printf("Cache Key %v Expired, Removing it from cache\n", key)
		// use delete directly when your application 
		// guarantee no other goroutine can store items with the same key.
		// Peek also invoke lazy expiry. 
		// 
		// Note this should done only with safe cache.
		cache.Peek(key) 
	})	

	for i:= 0 ; i < 10 ; i++ {
        cache.StoreWithTTL(i, i, time.Microsecond)
	}

	time.Sleep(time.Second)
	fmt.Println(cache.Len())
}

Contributing

1. Fork it
2. Download your fork to your PC (git clone https://github.com/your_username/libcache && cd libcache)
3. Create your feature branch (git checkout -b my-new-feature)
4. Make changes and add them (git add .)
5. Commit your changes (git commit -m 'Add some feature')
6. Push to the branch (git push origin my-new-feature)
7. Create new pull request

License

Libcache is released under the MIT license. See LICENSE