memnix / memnix-rest

import (

	"sync"

	"time"

	"github.com/memnix/memnix-rest/config"

)

// Cache is a thread-safe map with expiration times.

// It's used for caching in memory.

type Cache struct {

	c     map[string]int64 // map of cache items

	mu    sync.RWMutex     // mutex for the map

	close chan struct{}

}

// New creates a new cache that asynchronously cleans

// expired entries after the given time passes.

func New() *Cache {

	cache := &Cache{

		close: make(chan struct{}),

		c:     make(map[string]int64),

		mu:    sync.RWMutex{},

	}

	go func() {

		ticker := time.NewTicker(config.CleaningInterval)

		defer ticker.Stop()

		for {

			select {

			case <-ticker.C:

				now := time.Now().UnixNano()

				for k, v := range cache.c {

					if v > 0 && v < now {

						cache.mu.Lock()

						delete(cache.c, k)

						cache.mu.Unlock()

					}

				}

			case <-cache.close:

				return

			}

		}

	}()

	return cache

}

// Close stops the cache's cleaning goroutine.

func (c *Cache) Close() {

	c.close <- struct{}{}

	close(c.close)

	c.c = nil

}

// Set sets the value of the given key.

func (c *Cache) Set(key string, duration time.Duration) {

	var expires int64

	if duration > 0 {

		expires = time.Now().Add(duration).UnixNano()

	}

	c.mu.Lock()

	defer c.mu.Unlock()

	c.c[key] = expires

}

// Exists returns true if the given key exists.

func (c *Cache) Exists(key string) bool {

	c.mu.RLock()

	defer c.mu.RUnlock()

	expires, ok := c.c[key]

	if !ok {

		return false

	}

	if expires > 0 && expires < time.Now().UnixNano() {

		return false

	}

	return true

}

// Delete deletes the given key.

// DeleteAll deletes all keys.

func (c *Cache) DeleteAll() {

	c.mu.Lock()

	defer c.mu.Unlock()

	c.c = make(map[string]int64)

}