1// Copyright 2015 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package store
16
17import (
18	"container/heap"
19)
20
21// An TTLKeyHeap is a min-heap of TTLKeys order by expiration time
22type ttlKeyHeap struct {
23	array  []*node
24	keyMap map[*node]int
25}
26
27func newTtlKeyHeap() *ttlKeyHeap {
28	h := &ttlKeyHeap{keyMap: make(map[*node]int)}
29	heap.Init(h)
30	return h
31}
32
33func (h ttlKeyHeap) Len() int {
34	return len(h.array)
35}
36
37func (h ttlKeyHeap) Less(i, j int) bool {
38	return h.array[i].ExpireTime.Before(h.array[j].ExpireTime)
39}
40
41func (h ttlKeyHeap) Swap(i, j int) {
42	// swap node
43	h.array[i], h.array[j] = h.array[j], h.array[i]
44
45	// update map
46	h.keyMap[h.array[i]] = i
47	h.keyMap[h.array[j]] = j
48}
49
50func (h *ttlKeyHeap) Push(x interface{}) {
51	n, _ := x.(*node)
52	h.keyMap[n] = len(h.array)
53	h.array = append(h.array, n)
54}
55
56func (h *ttlKeyHeap) Pop() interface{} {
57	old := h.array
58	n := len(old)
59	x := old[n-1]
60	// Set slice element to nil, so GC can recycle the node.
61	// This is due to golang GC doesn't support partial recycling:
62	// https://github.com/golang/go/issues/9618
63	old[n-1] = nil
64	h.array = old[0 : n-1]
65	delete(h.keyMap, x)
66	return x
67}
68
69func (h *ttlKeyHeap) top() *node {
70	if h.Len() != 0 {
71		return h.array[0]
72	}
73	return nil
74}
75
76func (h *ttlKeyHeap) pop() *node {
77	x := heap.Pop(h)
78	n, _ := x.(*node)
79	return n
80}
81
82func (h *ttlKeyHeap) push(x interface{}) {
83	heap.Push(h, x)
84}
85
86func (h *ttlKeyHeap) update(n *node) {
87	index, ok := h.keyMap[n]
88	if ok {
89		heap.Remove(h, index)
90		heap.Push(h, n)
91	}
92}
93
94func (h *ttlKeyHeap) remove(n *node) {
95	index, ok := h.keyMap[n]
96	if ok {
97		heap.Remove(h, index)
98	}
99}
100