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
|
package pipe
import (
"context"
"sync"
"sync/atomic"
"github.com/pkg/errors"
)
type channel struct {
OnSendCompletion func()
value atomic.Value
lastValue *wrappedValue
}
type wrappedValue struct {
value interface{}
}
func (c *channel) Send(v interface{}) {
c.value.Store(&wrappedValue{value: v})
if c.OnSendCompletion != nil {
c.OnSendCompletion()
}
}
func (c *channel) Receive() (interface{}, bool) {
v := c.value.Load()
if v == nil || v.(*wrappedValue) == c.lastValue {
return nil, false
}
c.lastValue = v.(*wrappedValue)
return v.(*wrappedValue).value, true
}
type Pipe struct {
Sender Sender
Receiver Receiver
OnReceiveCompletion func()
OnSendCompletion func()
}
type Request struct {
Payload interface{}
Canceled bool
}
type Sender interface {
Request() Request
Update(v interface{})
Finalize(v interface{}, err error)
Status() Status
}
type Receiver interface {
Receive() bool
Cancel()
Status() Status
Request() interface{}
}
type Status struct {
Canceled bool
Completed bool
Err error
Value interface{}
}
func NewWithFunction(f func(context.Context) (interface{}, error)) (*Pipe, func()) {
p := New(Request{})
ctx, cancel := context.WithCancelCause(context.TODO())
p.OnReceiveCompletion = func() {
if req := p.Sender.Request(); req.Canceled {
cancel(errors.WithStack(context.Canceled))
}
}
return p, func() {
res, err := f(ctx)
if err != nil {
p.Sender.Finalize(nil, err)
return
}
p.Sender.Finalize(res, nil)
}
}
func New(req Request) *Pipe {
cancelCh := &channel{}
roundTripCh := &channel{}
pw := &sender{
req: req,
sendChannel: roundTripCh,
}
pr := &receiver{
req: req,
recvChannel: roundTripCh,
sendChannel: cancelCh,
}
p := &Pipe{
Sender: pw,
Receiver: pr,
}
cancelCh.OnSendCompletion = func() {
v, ok := cancelCh.Receive()
if ok {
pw.setRequest(v.(Request))
}
if p.OnReceiveCompletion != nil {
p.OnReceiveCompletion()
}
}
roundTripCh.OnSendCompletion = func() {
if p.OnSendCompletion != nil {
p.OnSendCompletion()
}
}
return p
}
type sender struct {
status Status
req Request
sendChannel *channel
mu sync.Mutex
}
func (pw *sender) Status() Status {
return pw.status
}
func (pw *sender) Request() Request {
pw.mu.Lock()
defer pw.mu.Unlock()
return pw.req
}
func (pw *sender) setRequest(req Request) {
pw.mu.Lock()
defer pw.mu.Unlock()
pw.req = req
}
func (pw *sender) Update(v interface{}) {
pw.status.Value = v
pw.sendChannel.Send(pw.status)
}
func (pw *sender) Finalize(v interface{}, err error) {
if v != nil {
pw.status.Value = v
}
pw.status.Err = err
pw.status.Completed = true
if errors.Is(err, context.Canceled) && pw.req.Canceled {
pw.status.Canceled = true
}
pw.sendChannel.Send(pw.status)
}
type receiver struct {
status Status
req Request
recvChannel *channel
sendChannel *channel
}
func (pr *receiver) Request() interface{} {
return pr.req.Payload
}
func (pr *receiver) Receive() bool {
v, ok := pr.recvChannel.Receive()
if !ok {
return false
}
pr.status = v.(Status)
return true
}
func (pr *receiver) Cancel() {
req := pr.req
if req.Canceled {
return
}
req.Canceled = true
pr.sendChannel.Send(req)
}
func (pr *receiver) Status() Status {
return pr.status
}
|
