ttl_key_heap.go

Documentation: go.etcd.io/etcd/server/v3/etcdserver/api/v2store

     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  }
    98
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