lru

README

lru

A lru is an asynchronous LRU cache (generic version).

• based on golang map structure
• prevents infinite cache growth
• designed for asynchronous use

Usage

For example, caching the output of the ioutil.ReadFile function to reduce disk I/O.

package main

import (
	"log"
	"os"

	"github.com/codeation/lru"
)

func readFileContent(key string) ([]byte, error) {
	log.Println("read once")
	return os.ReadFile(key)
}

func main() {
	cache := lru.NewCache(1024, readFileContent)
	for i := 0; i < 10; i++ {
		data, err := cache.Get("input.txt")
		if err != nil {
			log.Fatal(err)
		}
		log.Printf("file size is %d\n", len(data))
	}
}

The lru.NewCache parameter is the number of cache items until the last used item is removed from the cache. The second parameter is a func to get the value for the specified key and error.

The parameter of cache.Get func is a key (filename in this case). An error is returned when the function returns an error.

Documentation

Overview

Package lru implements asynchronous LRU cache.

Index

• type LRU
  • func New[K comparable, V any](capacity int, fn func(K) (V, error)) *LRU[K, V]
  • func (c *LRU[K, V]) Get(key K) (V, error)
  • func (c *LRU[K, V]) Reset()
• type SyncLRU
  • func NewSyncLRU[K comparable, V any](capacity int, fn func(K) (V, error)) *SyncLRU[K, V]
  • func (c *SyncLRU[K, V]) Get(key K) (V, error)
  • func (c *SyncLRU[K, V]) Reset()

Types

type LRU

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

LRU is a plain LRU cache.

func New

func New[K comparable, V any](capacity int, fn func(K) (V, error)) *LRU[K, V]

New creates an LRU cache with the specified capacity. f is a callback function for getting a value by key, which is called if there is no value in the cache.

func (*LRU[K, V]) Get

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

Get returns the cached value for the key, or waits for the callback function to return a value.

func (*LRU[K, V]) Reset

func (c *LRU[K, V]) Reset()

Reset resets cache contents.

type SyncLRU

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

SyncLRU is a LRU cache for concurrent use.

func NewSyncLRU

func NewSyncLRU[K comparable, V any](capacity int, fn func(K) (V, error)) *SyncLRU[K, V]

NewSyncLRU creates an LRU cache with the specified capacity. f is a callback function for getting a value by key, which is called if there is no value in the cache. The callback function will be called once for concurrent Get requests with the same key.

func (*SyncLRU[K, V]) Get

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

Get returns the cached value for the key, or waits for the callback function to return a value.

func (*SyncLRU[K, V]) Reset

func (c *SyncLRU[K, V]) Reset()

Reset resets cache contents.