mirror of https://github.com/tidwall/tile38.git
115 lines
1.8 KiB
Go
115 lines
1.8 KiB
Go
package expire
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import (
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"sync"
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"time"
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)
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// Item is a something that can expire
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type Item interface {
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Expires() time.Time
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}
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// List of expireable items
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type List struct {
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mu sync.Mutex
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queue queue
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bgrun bool
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Expired func(item Item)
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}
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// Push an item onto the queue
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func (list *List) Push(item Item) {
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unix := item.Expires().UnixNano()
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list.mu.Lock()
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if !list.bgrun {
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list.bgrun = true
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go list.bg()
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}
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list.queue.push(unix, item)
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list.mu.Unlock()
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}
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func (list *List) bg() {
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now := time.Now().UnixNano()
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for {
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list.mu.Lock()
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if list.queue.len == 0 {
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list.bgrun = false
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list.mu.Unlock()
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break
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}
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if now > list.queue.peek().unix { // now.After(list.queue.peek().unix)
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n := list.queue.pop()
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list.mu.Unlock()
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if list.Expired != nil {
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list.Expired(n.item)
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}
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} else {
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list.mu.Unlock()
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time.Sleep(time.Second / 10)
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now = time.Now().UnixNano()
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}
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}
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}
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type qnode struct {
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unix int64
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item Item
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}
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type queue struct {
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nodes []qnode
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len int
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size int
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}
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func (q *queue) push(unix int64, item Item) {
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if q.nodes == nil {
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q.nodes = make([]qnode, 2)
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} else {
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q.nodes = append(q.nodes, qnode{})
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}
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i := q.len + 1
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j := i / 2
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for i > 1 && q.nodes[j].unix > unix {
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q.nodes[i] = q.nodes[j]
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i = j
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j = j / 2
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}
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q.nodes[i].unix = unix
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q.nodes[i].item = item
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q.len++
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}
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func (q *queue) peek() qnode {
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if q.len == 0 {
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return qnode{}
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}
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return q.nodes[1]
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}
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func (q *queue) pop() qnode {
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if q.len == 0 {
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return qnode{}
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}
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n := q.nodes[1]
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q.nodes[1] = q.nodes[q.len]
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q.len--
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var j, k int
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i := 1
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for i != q.len+1 {
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k = q.len + 1
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j = 2 * i
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if j <= q.len && q.nodes[j].unix < q.nodes[k].unix {
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k = j
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}
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if j+1 <= q.len && q.nodes[j+1].unix < q.nodes[k].unix {
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k = j + 1
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}
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q.nodes[i] = q.nodes[k]
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i = k
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}
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return n
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}
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