khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 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 | |
| 15 | package v2store |
| 16 | |
| 17 | import "container/heap" |
| 18 | |
| 19 | // An TTLKeyHeap is a min-heap of TTLKeys order by expiration time |
| 20 | type ttlKeyHeap struct { |
| 21 | array []*node |
| 22 | keyMap map[*node]int |
| 23 | } |
| 24 | |
| 25 | func newTtlKeyHeap() *ttlKeyHeap { |
| 26 | h := &ttlKeyHeap{keyMap: make(map[*node]int)} |
| 27 | heap.Init(h) |
| 28 | return h |
| 29 | } |
| 30 | |
| 31 | func (h ttlKeyHeap) Len() int { |
| 32 | return len(h.array) |
| 33 | } |
| 34 | |
| 35 | func (h ttlKeyHeap) Less(i, j int) bool { |
| 36 | return h.array[i].ExpireTime.Before(h.array[j].ExpireTime) |
| 37 | } |
| 38 | |
| 39 | func (h ttlKeyHeap) Swap(i, j int) { |
| 40 | // swap node |
| 41 | h.array[i], h.array[j] = h.array[j], h.array[i] |
| 42 | |
| 43 | // update map |
| 44 | h.keyMap[h.array[i]] = i |
| 45 | h.keyMap[h.array[j]] = j |
| 46 | } |
| 47 | |
| 48 | func (h *ttlKeyHeap) Push(x interface{}) { |
| 49 | n, _ := x.(*node) |
| 50 | h.keyMap[n] = len(h.array) |
| 51 | h.array = append(h.array, n) |
| 52 | } |
| 53 | |
| 54 | func (h *ttlKeyHeap) Pop() interface{} { |
| 55 | old := h.array |
| 56 | n := len(old) |
| 57 | x := old[n-1] |
| 58 | // Set slice element to nil, so GC can recycle the node. |
| 59 | // This is due to golang GC doesn't support partial recycling: |
| 60 | // https://github.com/golang/go/issues/9618 |
| 61 | old[n-1] = nil |
| 62 | h.array = old[0 : n-1] |
| 63 | delete(h.keyMap, x) |
| 64 | return x |
| 65 | } |
| 66 | |
| 67 | func (h *ttlKeyHeap) top() *node { |
| 68 | if h.Len() != 0 { |
| 69 | return h.array[0] |
| 70 | } |
| 71 | return nil |
| 72 | } |
| 73 | |
| 74 | func (h *ttlKeyHeap) pop() *node { |
| 75 | x := heap.Pop(h) |
| 76 | n, _ := x.(*node) |
| 77 | return n |
| 78 | } |
| 79 | |
| 80 | func (h *ttlKeyHeap) push(x interface{}) { |
| 81 | heap.Push(h, x) |
| 82 | } |
| 83 | |
| 84 | func (h *ttlKeyHeap) update(n *node) { |
| 85 | index, ok := h.keyMap[n] |
| 86 | if ok { |
| 87 | heap.Remove(h, index) |
| 88 | heap.Push(h, n) |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | func (h *ttlKeyHeap) remove(n *node) { |
| 93 | index, ok := h.keyMap[n] |
| 94 | if ok { |
| 95 | heap.Remove(h, index) |
| 96 | } |
| 97 | } |