-
Notifications
You must be signed in to change notification settings - Fork 1
/
topkcounter.go
249 lines (221 loc) · 6.38 KB
/
topkcounter.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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
package topkcounter
import (
"encoding/binary"
"errors"
"github.com/channelmeter/topkcounter/list"
)
type bucket struct {
counterList *list.List // counterList<counter>
count int64
}
type TopKCounter struct {
capacity int64
counterMap map[string]*list.Element // map[string]<Counter>
bucketList *list.List // bucketList<bucket>
}
type counter struct {
bucketNode *list.Element // *bucket
count int64
error int64
item string
}
type Counted interface {
Count() int
Value() string
}
func newCounter(bucketNode *list.Element, item string) *counter {
return &counter{
bucketNode: bucketNode,
item: item,
count: 0,
error: 0,
}
}
func (c *counter) Count() int {
return int(c.count)
}
func (c *counter) Value() string {
return c.item
}
func newBucket(count int64) *bucket {
return &bucket{
counterList: list.New(),
count: count,
}
}
func NewTopKCounter(capacity int64) *TopKCounter {
return &TopKCounter{
capacity: capacity,
counterMap: make(map[string]*list.Element),
bucketList: list.New(),
}
}
func (c *TopKCounter) Offer(item string) bool {
return c.OfferN(item, 1)
}
func (c *TopKCounter) OfferN(item string, increment int) bool {
r, _ := c.OfferReturnAll(item, increment)
return r
}
func (c *TopKCounter) OfferReturnDropped(item string, increment int) string {
_, r := c.OfferReturnAll(item, increment)
return r
}
func (c *TopKCounter) Size() int {
return len(c.counterMap)
}
func (c *TopKCounter) OfferReturnAll(item string, increment int) (bool, string) {
counterNode, itemExists := c.counterMap[item]
var droppedItem string
if !itemExists {
if int64(c.Size()) < c.capacity {
counterNode = (c.bucketList.PushFront(newBucket(0)).Value.(*bucket)).counterList.PushBack(newCounter(c.bucketList.Front(), item))
} else {
bucketMin := c.bucketList.Front().Value.(*bucket)
counterNode = bucketMin.counterList.Back()
counter := counterNode.Value.(*counter)
droppedItem = counter.item
delete(c.counterMap, droppedItem)
counter.item = item
counter.error = bucketMin.count
}
c.counterMap[item] = counterNode
}
c.incrementCounter(counterNode, increment)
return !itemExists, droppedItem
}
func (c *TopKCounter) incrementCounter(counterNode *list.Element, increment int) {
counter := counterNode.Value.(*counter)
oldNode := counter.bucketNode
_bucket := oldNode.Value.(*bucket)
_bucket.counterList.Remove(counterNode)
counter.count += int64(increment)
bucketNodePrev := oldNode
bucketNodeNext := bucketNodePrev.Next()
for bucketNodeNext != nil {
bucketNext := bucketNodeNext.Value.(*bucket)
if counter.count == bucketNext.count {
bucketNext.counterList.PushFrontElement(counterNode) // Attach count_i to Bucket_i^+'s child-list
break
} else if counter.count > bucketNext.count {
bucketNodePrev = bucketNodeNext
bucketNodeNext = bucketNodePrev.Next() // Continue hunting for an appropriate bucket
} else {
// A new bucket has to be created
bucketNodeNext = nil
}
}
if bucketNodeNext == nil {
bucketNext := newBucket(counter.count)
bucketNext.counterList.PushFrontElement(counterNode)
bucketNodeNext = c.bucketList.InsertAfter(bucketNext, bucketNodePrev) //bucketList.addAfter(bucketNodePrev, bucketNext);
}
counter.bucketNode = bucketNodeNext
if _bucket.counterList.Len() == 0 {
c.bucketList.Remove(oldNode) // Detach Bucket_i from the Stream-Summary
}
}
func (c *TopKCounter) Peek(k int) []string {
topK := make([]string, 0, k)
for bNode := c.bucketList.Back(); bNode != nil; bNode = bNode.Prev() {
b := bNode.Value.(*bucket)
for a := b.counterList.Back(); a != nil; a = a.Prev() {
if len(topK) == k {
return topK
}
topK = append(topK, a.Value.(*counter).item)
}
}
return topK
}
func (c *TopKCounter) TopK(k int) []Counted {
topK := make([]Counted, 0, k)
for bNode := c.bucketList.Back(); bNode != nil; bNode = bNode.Prev() {
b := bNode.Value.(*bucket)
for a := b.counterList.Back(); a != nil; a = a.Prev() {
if len(topK) == k {
return topK
}
topK = append(topK, Counted(a.Value.(*counter)))
}
}
return topK
}
func NewTopKCounterBytes(buf []byte) (c *TopKCounter, err error) {
defer func() {
if r := recover(); r != nil {
switch x := r.(type) {
case string:
err = errors.New(x)
case error:
err = x
default:
err = errors.New("Deserialization failed.")
}
c = nil
}
}()
capacity := int64(binary.LittleEndian.Uint64(buf))
bucketListLen := int(binary.LittleEndian.Uint64(buf[8:]))
p := 16
counterMap := make(map[string]*list.Element)
bucketList := list.New()
for i := 0; i < bucketListLen; i++ {
count := int64(binary.LittleEndian.Uint64(buf[p:]))
buck := newBucket(count)
listLen := int(binary.LittleEndian.Uint64(buf[p+8:]))
p += 16
buckElem := bucketList.PushBack(buck)
counterList := list.New()
buck.counterList = counterList
for j := 0; j < listLen; j++ {
ctr := &counter{}
ctr.count = int64(binary.LittleEndian.Uint64(buf[p:]))
ctr.error = int64(binary.LittleEndian.Uint64(buf[p+8:]))
itemLen := int(binary.LittleEndian.Uint64(buf[p+16:]))
p += 24
ctr.item = string(buf[p : p+itemLen])
p += itemLen
ctr.bucketNode = buckElem
ctrElem := counterList.PushBack(ctr)
counterMap[ctr.item] = ctrElem
}
}
return &TopKCounter{
capacity: capacity,
counterMap: counterMap,
bucketList: bucketList,
}, nil
}
func (c *TopKCounter) Bytes() []byte {
buffLen := 0
for n := c.bucketList.Front(); n != nil; n = n.Next() {
buck := n.Value.(*bucket)
buffLen += 16
for m := buck.counterList.Front(); m != nil; m = m.Next() {
buffLen += 24 + len([]byte(m.Value.(*counter).item))
}
}
buf := make([]byte, 8*2+buffLen+1)
binary.LittleEndian.PutUint64(buf, uint64(c.capacity))
binary.LittleEndian.PutUint64(buf[8:], uint64(c.bucketList.Len()))
p := 16
for n := c.bucketList.Front(); n != nil; n = n.Next() {
buck := n.Value.(*bucket)
binary.LittleEndian.PutUint64(buf[p:], uint64(buck.count))
binary.LittleEndian.PutUint64(buf[p+8:], uint64(buck.counterList.Len()))
p += 16
for m := buck.counterList.Front(); m != nil; m = m.Next() {
ctr := m.Value.(*counter)
itemLen := len([]byte(ctr.item))
binary.LittleEndian.PutUint64(buf[p:], uint64(ctr.count))
binary.LittleEndian.PutUint64(buf[p+8:], uint64(ctr.error))
binary.LittleEndian.PutUint64(buf[p+16:], uint64(itemLen))
p += 24
copy(buf[p:], ctr.item)
p += itemLen
}
}
buf[p] = 0
return buf
}