forked from msazurestackworkloads/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
delaying_deliverer.go
183 lines (158 loc) · 4.79 KB
/
delaying_deliverer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
/*
Copyright 2016 The Kubernetes 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.
*/
// TODO: consider moving it to a more generic package.
package util
import (
"container/heap"
"time"
)
const (
// TODO: Investigate what capacity is right.
delayingDelivererUpdateChanCapacity = 1000
)
// DelayingDelivererItem is structure delivered by DelayingDeliverer to the
// target channel.
type DelayingDelivererItem struct {
// Key under which the value was added to deliverer.
Key string
// Value of the item.
Value interface{}
// When the item should be delivered.
DeliveryTime time.Time
}
type delivererHeap struct {
keyPosition map[string]int
data []*DelayingDelivererItem
}
// Functions required by container.Heap.
func (dh *delivererHeap) Len() int { return len(dh.data) }
func (dh *delivererHeap) Less(i, j int) bool {
return dh.data[i].DeliveryTime.Before(dh.data[j].DeliveryTime)
}
func (dh *delivererHeap) Swap(i, j int) {
dh.keyPosition[dh.data[i].Key] = j
dh.keyPosition[dh.data[j].Key] = i
dh.data[i], dh.data[j] = dh.data[j], dh.data[i]
}
func (dh *delivererHeap) Push(x interface{}) {
item := x.(*DelayingDelivererItem)
dh.data = append(dh.data, item)
dh.keyPosition[item.Key] = len(dh.data) - 1
}
func (dh *delivererHeap) Pop() interface{} {
n := len(dh.data)
item := dh.data[n-1]
dh.data = dh.data[:n-1]
delete(dh.keyPosition, item.Key)
return item
}
// A structure that pushes the items to the target channel at a given time.
type DelayingDeliverer struct {
// Channel to deliver the data when their time comes.
targetChannel chan *DelayingDelivererItem
// Store for data
heap *delivererHeap
// Channel to feed the main goroutine with updates.
updateChannel chan *DelayingDelivererItem
// To stop the main goroutine.
stopChannel chan struct{}
}
func NewDelayingDeliverer() *DelayingDeliverer {
return NewDelayingDelivererWithChannel(make(chan *DelayingDelivererItem, 100))
}
func NewDelayingDelivererWithChannel(targetChannel chan *DelayingDelivererItem) *DelayingDeliverer {
return &DelayingDeliverer{
targetChannel: targetChannel,
heap: &delivererHeap{
keyPosition: make(map[string]int),
data: make([]*DelayingDelivererItem, 0),
},
updateChannel: make(chan *DelayingDelivererItem, delayingDelivererUpdateChanCapacity),
stopChannel: make(chan struct{}),
}
}
// Deliver all items due before or equal to timestamp.
func (d *DelayingDeliverer) deliver(timestamp time.Time) {
for d.heap.Len() > 0 {
if timestamp.Before(d.heap.data[0].DeliveryTime) {
return
}
item := heap.Pop(d.heap).(*DelayingDelivererItem)
d.targetChannel <- item
}
}
func (d *DelayingDeliverer) run() {
for {
now := time.Now()
d.deliver(now)
nextWakeUp := now.Add(time.Hour)
if d.heap.Len() > 0 {
nextWakeUp = d.heap.data[0].DeliveryTime
}
sleepTime := nextWakeUp.Sub(now)
select {
case <-time.After(sleepTime):
break // just wake up and process the data
case item := <-d.updateChannel:
if position, found := d.heap.keyPosition[item.Key]; found {
if item.DeliveryTime.Before(d.heap.data[position].DeliveryTime) {
d.heap.data[position] = item
heap.Fix(d.heap, position)
}
// Ignore if later.
} else {
heap.Push(d.heap, item)
}
case <-d.stopChannel:
return
}
}
}
// Starts the DelayingDeliverer.
func (d *DelayingDeliverer) Start() {
go d.run()
}
// Stops the DelayingDeliverer. Undelivered items are discarded.
func (d *DelayingDeliverer) Stop() {
close(d.stopChannel)
}
// Delivers value at the given time.
func (d *DelayingDeliverer) DeliverAt(key string, value interface{}, deliveryTime time.Time) {
d.updateChannel <- &DelayingDelivererItem{
Key: key,
Value: value,
DeliveryTime: deliveryTime,
}
}
// Delivers value after the given delay.
func (d *DelayingDeliverer) DeliverAfter(key string, value interface{}, delay time.Duration) {
d.DeliverAt(key, value, time.Now().Add(delay))
}
// Gets target channel of the deliverer.
func (d *DelayingDeliverer) GetTargetChannel() chan *DelayingDelivererItem {
return d.targetChannel
}
// Starts Delaying deliverer with a handler listening on the target channel.
func (d *DelayingDeliverer) StartWithHandler(handler func(*DelayingDelivererItem)) {
go func() {
for {
select {
case item := <-d.targetChannel:
handler(item)
case <-d.stopChannel:
return
}
}
}()
d.Start()
}