readthrough

README

readthrough

Overview

This library is to implement read-through cache quickly in your application.

In order to improve the application performance, we sometimes implement caching. But it takes time because we need to implement a cache accessor, integrate it to your business logic, unit tests and integration tests of it. This library is to get a quick win to improve your application performance without changing your application code much, by a simple read-through cache.

Also you can implement your own caching (e.g. redis or memcache) to customize this library.

Installation

import "github.com/dakimura/readthrough"

Usage

The usage of this library is to just wrap a slow function that you want to improve performance like as follows:

rt := readthrough.Through{Proxy: readthrough.NewInMemoryProxy()}

value, _ := rt.Get("cacheKey", someSlowFunction)

When someSlowFunction is called with the cacheKey, the returned values are cached with cacheKey. So the cached value will be returned immediately when the function is called again.

Note: We assume that your application has a slow function which returns (interface{}, error) .

func someSlowFunction() (interface{}, error) {
	// example
	time.Sleep(3 * time.Second)
	return "hoge", nil
}

If the returned values are not (interface{}, error) please wrap the function and make another function which returns (interface{}, error) .

Example Code

package main

import (
	"fmt"
	"github.com/dakimura/readthrough"
	"time"
)

var rt = readthrough.Through{Proxy: readthrough.NewInMemoryProxy()}

func main() {
	fmt.Println("before try... current time: " + time.Now().String())

	cacheKey := "hello"
	// 1st try takes 3 seconds
	value, _ := rt.Get(cacheKey, someSlowFunction)
	fmt.Println(value.(string))

	// 2nd try takes almost 0 second
	value, _ = rt.Get(cacheKey, someSlowFunction)
	fmt.Println(value.(string))
}

func someSlowFunction() (interface{}, error) {
	time.Sleep(3 * time.Second)
	return "current time: " + time.Now().String(), nil
}

Output:

before try... current time: 2019-09-30 19:02:02.941276 +0900 JST m=+0.000198594
current time: 2019-09-30 19:02:05.943923 +0900 JST m=+3.002818374
current time: 2019-09-30 19:02:05.943923 +0900 JST m=+3.002818374

Original Proxy

In the examples above, proxy.NewInMemoryProxy() is used for the proxy storage. If you want to use another storage for the cache, please implement your own proxy.Proxy implementation.

proxy/proxy.go

// Proxy behaves as a read-through cache for an origin (DB, API server, etc)
type Proxy interface {
	Get(key string) (bool, interface{}, error)
	Set(key string, val interface{}) error
}

Documentation

Index

• type InMemoryProxy
  • func (p *InMemoryProxy) Get(key string) (bool, interface{}, error)
  • func (p *InMemoryProxy) Set(key string, val interface{}) error
• type Proxy
  • func NewInMemoryProxy() Proxy
• type Through
  • func (rt *Through) Get(key string, req func() (interface{}, error)) (interface{}, error)

Types

type InMemoryProxy

type InMemoryProxy struct {
	// contains filtered or unexported fields
}

InMemoryProxy sets the value in the map object as a cache

func (*InMemoryProxy) Get

func (p *InMemoryProxy) Get(key string) (bool, interface{}, error)

Get checks if the cache is stored in the map object and returns true and the value if the cache is set It returns false if the value is not set

func (*InMemoryProxy) Set

func (p *InMemoryProxy) Set(key string, val interface{}) error

Set sets a value to the map object as a caches

type Proxy

type Proxy interface {
	Get(key string) (bool, interface{}, error)
	Set(key string, val interface{}) error
}

Proxy behaves as a read-through cache for an origin (DB, API server, etc)

func NewInMemoryProxy

func NewInMemoryProxy() Proxy

NewInMemoryProxy creates an InMemory Proxy object

type Through

type Through struct {
	Proxy Proxy
}

Through is accessor for a read-through cache proxy and an origin

func (*Through) Get

func (rt *Through) Get(key string, req func() (interface{}, error)) (interface{}, error)

Get reads a value through the proxy and set the cache