README.md

Golang local cache

Implementation of simple local cache.

Features & todos:

• prevents "dogpile effect"
• check data expiration time
• lru policy
• cache hit and enviction stats

Cache limitations:

• keys are always int
• get function returns multiple values
• set function sets multiple keys at once
• to prevent dog pile effect queueKey should be manually set

How to use

Create cache instance

import "github.com/sima-land/go-local-cache"
c := cache.New()

Create getter function. Its preferred way to fill the cache because in case of "dog pile" effect getter will be called once.

getter := func(keys Keys) (Result, error) {
	r := Result{}
	for _, k := range keys {
		// haavy call to database
		r[k] = db.GetByID(k)		
	}
	return r, nil
}

Obtain data from cache. If there is no data in the cache getter will be called.

Note:

1. Next call is concurrently safe
2. If too many go-routines in our application are trying to call this getter with same queue key (user-1) then only first call will actually be done

result, err := c.Get(int[]{1}, getter, "user-1")

QueueKey param explain

You can simple use entity name and id as queueKey param of Get function. Eg:

result, err := c.Get(int[]{1}, userGetter, "user-1")
result, err := c.Get(int[]{1}, productGetter, "product-1")

Or if you need to get a page of product's block whole page. If keys 1,2 are in cache but other keys are not then:

1. Keys 1 and 2 will be get from cache
2. Getter will be called for keys 3,4,5 and 6
3. If another getter with same queue key "product-1" was called before and first one will be used instead

result, err := c.Get(int[]{1,2,3,4,5,6}, userGetter, "product-page-1")

Options

Cache has a variety of configuration options:

c := cache.New(cache.Options{
		MaxEntries: 1000000, // Specify max number items in cache
		TTL: time.Hour, // Time to live for cache entries
	})

Test

MacBook 2,7 GHz Intel Core i5

BenchmarkCache_Get-4      500000              2274 ns/op
BenchmarkCache_Get-4      500000              2335 ns/op