forked from eapache/channels
/
resizable_channel.go
97 lines (86 loc) · 2.26 KB
/
resizable_channel.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
package channels
import "github.com/eapache/queue"
// ResizableChannel implements the Channel interface with a resizable buffer between the input and the output.
// The channel initially has a buffer size of 1, but can be resized by calling Resize().
//
// Resizing to a buffer capacity of None is, unfortunately, not supported and will panic
// (see https://github.com/eapache/channels/issues/1).
// Resizing back and forth between a finite and infinite buffer is fully supported.
type ResizableChannel struct {
input, output chan interface{}
resize chan BufferCap
size BufferCap
buffer *queue.Queue
}
func NewResizableChannel() *ResizableChannel {
ch := &ResizableChannel{make(chan interface{}), make(chan interface{}), make(chan BufferCap), 1, queue.New()}
go ch.magicBuffer()
return ch
}
func (ch *ResizableChannel) In() chan<- interface{} {
return ch.input
}
func (ch *ResizableChannel) Out() <-chan interface{} {
return ch.output
}
func (ch *ResizableChannel) Len() int {
return ch.buffer.Length()
}
func (ch *ResizableChannel) Cap() BufferCap {
return ch.size
}
func (ch *ResizableChannel) Close() {
close(ch.input)
}
func (ch *ResizableChannel) Resize(newSize BufferCap) {
if newSize == None {
panic("channels: ResizableChannel does not support unbuffered behaviour")
}
if newSize < 0 && newSize != Infinity {
panic("channels: invalid negative size trying to resize channel")
}
ch.resize <- newSize
}
func (ch *ResizableChannel) shutdown() {
for ch.buffer.Length() > 0 {
ch.output <- ch.buffer.Peek()
ch.buffer.Remove()
}
close(ch.output)
close(ch.resize)
}
func (ch *ResizableChannel) magicBuffer() {
for {
if ch.buffer.Length() == 0 {
select {
case elem, open := <-ch.input:
if open {
ch.buffer.Add(elem)
} else {
ch.shutdown()
return
}
case ch.size = <-ch.resize:
}
} else if ch.size != Infinity && ch.buffer.Length() >= int(ch.size) {
select {
case ch.output <- ch.buffer.Peek():
ch.buffer.Remove()
case ch.size = <-ch.resize:
}
} else {
select {
case elem, open := <-ch.input:
if open {
ch.buffer.Add(elem)
} else {
ch.shutdown()
return
}
case ch.output <- ch.buffer.Peek():
ch.buffer.Remove()
case ch.size = <-ch.resize:
}
}
}
}