df91803297
This method reduces the likelihood of a race condition where you can add a (tracked) item to the cache, and the item isn't the item you thought it was.
108 lines
1.9 KiB
Go
108 lines
1.9 KiB
Go
package ccache
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import (
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"container/list"
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"sync/atomic"
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"time"
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)
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type Sized interface {
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Size() int64
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}
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type TrackedItem interface {
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Value() interface{}
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Release()
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Expired() bool
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TTL() time.Duration
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Expires() time.Time
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Extend(duration time.Duration)
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}
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type nilItem struct{}
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func (n *nilItem) Value() interface{} { return nil }
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func (n *nilItem) Release() {}
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func (i *nilItem) Expired() bool {
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return true
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}
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func (i *nilItem) TTL() time.Duration {
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return time.Minute
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}
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func (i *nilItem) Expires() time.Time {
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return time.Time{}
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}
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func (i *nilItem) Extend(duration time.Duration) {
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}
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var NilTracked = new(nilItem)
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type Item struct {
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key string
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group string
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promotions int32
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refCount int32
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expires int64
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size int64
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value interface{}
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element *list.Element
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}
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func newItem(key string, value interface{}, expires int64, track bool) *Item {
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size := int64(1)
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if sized, ok := value.(Sized); ok {
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size = sized.Size()
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}
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item := &Item{
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key: key,
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value: value,
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promotions: 0,
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size: size,
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expires: expires,
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}
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if track {
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item.refCount = 1
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}
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return item
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}
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func (i *Item) shouldPromote(getsPerPromote int32) bool {
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i.promotions += 1
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return i.promotions == getsPerPromote
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}
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func (i *Item) Value() interface{} {
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return i.value
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}
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func (i *Item) track() {
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atomic.AddInt32(&i.refCount, 1)
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}
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func (i *Item) Release() {
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atomic.AddInt32(&i.refCount, -1)
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}
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func (i *Item) Expired() bool {
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expires := atomic.LoadInt64(&i.expires)
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return expires < time.Now().UnixNano()
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}
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func (i *Item) TTL() time.Duration {
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expires := atomic.LoadInt64(&i.expires)
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return time.Nanosecond * time.Duration(expires-time.Now().UnixNano())
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}
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func (i *Item) Expires() time.Time {
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expires := atomic.LoadInt64(&i.expires)
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return time.Unix(0, expires)
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}
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func (i *Item) Extend(duration time.Duration) {
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atomic.StoreInt64(&i.expires, time.Now().Add(duration).UnixNano())
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}
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