In-memory cache

Task description is here

Performance and implementation

This cache implementation is based on the sync.Map.
The solutions based on a hash table promise operations add, get and remove performed in constant (O[1]) time.
For this library, I initially took sync.Mutex + map[string]interface{}, however it showed problems with concurrent deletion of elements and poor performance when deleting itself.
At the same time sync.Map performed well in these cases (the library, which is taken for performance comparison, was based on sync.Map).
As a result, I choice sync.Map and I ended up with exactly the same library as the one taken as an example.
Loser.

Example

Installation:

go get -u github.com/p12s/in-memory-cache

Using:

package main

import (
	"fmt"
	"time"
	cache "github.com/p12s/in-memory-cache"
)

func main() {
	cleanExpiredPeriod := 1 * time.Second
	cache := cache.New(cleanExpiredPeriod)
	fmt.Println(cache.Get("userId"))	// doesn't exist - return "nil"

	cache.Set("userId", 42)
	fmt.Println(cache.Get("userId"))	// 42

	cache.SetWithExpire("number", 43, time.Second * 10)
	fmt.Println(cache.Get("number"))	// 43
	time.Sleep(time.Second * 11)
	fmt.Println(cache.Get("number"))	// nil

	cache.Delete("userId")
	fmt.Println(cache.Get("userId"))	// <nil>
}

Сomparison with other same solution

For comparison, let's take any of the package from awesome-go, for example, In-memory cache.

Package	Method	quantity	ns/op	B/op	allocs/op	fast %
Cache
	New	6379844	166.9	368	6
	Set/SetWithExpire	6264136	192.4	40	2
	Get	420062818	2.911	0	0
	Delete	855741927	1.385	0	0
This package
	New	6436862	175.6	368	6	~
	Set/SetWithExpire	5521599	199.7	56	3	~
	Get	424934931	2.824	0	0	~
	Delete	842618384	1.417	0	0	~