bucketInternal.go

package jac

import (
	"runtime"
	"time"
)

// back-end methods

// Return a declare bucketInternal with a given default expiration duration and cleanup
// interval. If the expiration duration is less than one (or NoExpiration),
// the items in the bucketInternal never expire (by default), and must be deleted
// manually. If the cleanup interval is less than one, expired items are not
// deleted from the bucketInternal before calling c.deleteExpired().
func declare(defaultExpiration, cleanupInterval time.Duration) *bucketInternalPtr {
	items := make(map[string]Item)
	return newCacheWithJanitor(defaultExpiration, cleanupInterval, items)
}

func (c *bucketInternal) set(k string, x interface{}, d time.Duration) {
	var e int64
	if d == DefaultExpiration {
		d = c.defaultExpiration
	}
	if d > 0 {
		e = time.Now().Add(d).UnixNano()
	}
	c.items[k] = Item{
		Object:     x,
		Expiration: e,
	}
}

func (c *bucketInternal) get(k string) (interface{}, bool) {
	item, found := c.items[k]
	if !found {
		return nil, false
	}
	// "Inlining" of expired
	if item.Expiration > 0 {
		if time.Now().UnixNano() > item.Expiration {
			return nil, false
		}
	}
	return item.Object, true
}

func (c *bucketInternal) delete(k string) (interface{}, bool) {
	if c.onEvicted != nil {
		if v, found := c.items[k]; found {
			delete(c.items, k)
			return v.Object, true
		}
	}
	delete(c.items, k)
	return nil, false
}

func (c *bucketInternal) deleteExpired() {
	var evictedItems []keyAndValue
	now := time.Now().UnixNano()
	c.mu.Lock()
	for k, v := range c.items {
		// "Inlining" of expired
		if v.Expiration > 0 && now > v.Expiration {
			ov, evicted := c.delete(k)
			if evicted {
				evictedItems = append(evictedItems, keyAndValue{k, ov})
			}
		}
	}
	c.mu.Unlock()
	for _, v := range evictedItems {
		c.onEvicted(v.key, v.value)
	}
}

func (c *bucketInternal) bucketItems() map[string]Item {
	c.mu.RLock()
	defer c.mu.RUnlock()
	m := make(map[string]Item, len(c.items))
	now := time.Now().UnixNano()
	for k, v := range c.items {
		// "Inlining" of expired
		if v.Expiration > 0 {
			if now > v.Expiration {
				continue
			}
		}
		m[k] = v
	}
	return m
}

func (j *janitor) run(c *bucketInternal) {
	ticker := time.NewTicker(j.Interval)
	for {
		select {
		case <-ticker.C:
			c.deleteExpired()
		case <-j.stop:
			ticker.Stop()
			return
		}
	}
}

func stopJanitor(c *bucketInternalPtr) {
	c.janitor.stop <- true
}

func runJanitor(c *bucketInternal, ci time.Duration) {
	j := &janitor{
		Interval: ci,
		stop:     make(chan bool),
	}
	c.janitor = j
	go j.run(c)
}

func newCache(de time.Duration, m map[string]Item) *bucketInternal {
	if de == 0 {
		de = -1
	}
	c := &bucketInternal{
		defaultExpiration: de,
		items:             m,
	}
	return c
}

func newCacheWithJanitor(de time.Duration, ci time.Duration, m map[string]Item) *bucketInternalPtr {
	c := newCache(de, m)
	// This trick ensures that the janitor goroutine (which--granted it
	// was enabled--is running deleteExpired on c forever) does not keep
	// the returned C object from being garbage collected. When it is
	// garbage collected, the finalizer stops the janitor goroutine, after
	// which c can be collected.
	C := &bucketInternalPtr{c}
	if ci > 0 {
		runJanitor(c, ci)
		runtime.SetFinalizer(C, stopJanitor)
	}
	return C
}

func (item Item) expired() bool {
	if item.Expiration == 0 {
		return false
	}
	return time.Now().UnixNano() > item.Expiration
}

func (c *Bucket) set(k, v string, t time.Duration, bck bool) {
	if k == "" {
		return
	}
	if c.writer != nil && bck {
		select {
		case c.writer <- backupData{
			data: [2]string{k, v},
			file: c.file,
		}:
		//default:
		case <-time.After(time.Duration(options.LoadDelayMs) * time.Millisecond):
			//println("lost")
		}
	}
	c.bucket.set(k, v, t)
}