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// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package store
import (
"container/heap"
)
// An TTLKeyHeap is a min-heap of TTLKeys order by expiration time
type ttlKeyHeap struct {
array []*node
keyMap map[*node]int
}
func newTtlKeyHeap() *ttlKeyHeap {
h := &ttlKeyHeap{keyMap: make(map[*node]int)}
heap.Init(h)
return h
}
func (h ttlKeyHeap) Len() int {
return len(h.array)
}
func (h ttlKeyHeap) Less(i, j int) bool {
return h.array[i].ExpireTime.Before(h.array[j].ExpireTime)
}
func (h ttlKeyHeap) Swap(i, j int) {
// swap node
h.array[i], h.array[j] = h.array[j], h.array[i]
// update map
h.keyMap[h.array[i]] = i
h.keyMap[h.array[j]] = j
}
func (h *ttlKeyHeap) Push(x interface{}) {
n, _ := x.(*node)
h.keyMap[n] = len(h.array)
h.array = append(h.array, n)
}
func (h *ttlKeyHeap) Pop() interface{} {
old := h.array
n := len(old)
x := old[n-1]
// Set slice element to nil, so GC can recycle the node.
// This is due to golang GC doesn't support partial recycling:
// https://github.com/golang/go/issues/9618
old[n-1] = nil
h.array = old[0 : n-1]
delete(h.keyMap, x)
return x
}
func (h *ttlKeyHeap) top() *node {
if h.Len() != 0 {
return h.array[0]
}
return nil
}
func (h *ttlKeyHeap) pop() *node {
x := heap.Pop(h)
n, _ := x.(*node)
return n
}
func (h *ttlKeyHeap) push(x interface{}) {
heap.Push(h, x)
}
func (h *ttlKeyHeap) update(n *node) {
index, ok := h.keyMap[n]
if ok {
heap.Remove(h, index)
heap.Push(h, n)
}
}
func (h *ttlKeyHeap) remove(n *node) {
index, ok := h.keyMap[n]
if ok {
heap.Remove(h, index)
}
}