blob: dc99e707b3670a047431fbe0f90af6739735bba3 (
plain) (
blame)
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
|
package gui
// sharedVal is a concurrent interface to a piece of shared data.
//
// A client can read the data by sending a channel via request, and the stored value will
// be sent back via the channel. The client is responsible for closing the channel.
//
// The stored value can be changed by sending the new value via set. Requests block until
// the first value is received on set.
//
// A sharedVal should be closed after use.
type sharedVal[T any] struct {
request chan<- chan T
set chan<- T
}
func newSharedVal[T any]() sharedVal[T] {
request := make(chan chan T)
set := make(chan T)
go func() {
val := <-set // wait for initial value
for {
select {
case v, ok := <-set:
if !ok { // closed
return
}
val = v
case req, ok := <-request:
if !ok { // closed
return
}
go func() { // don't wait for client to receive
req <- val
}()
}
}
}()
return sharedVal[T]{request, set}
}
// get makes a synchronous request and returns the stored value.
func (sv sharedVal[T]) get() T {
c := make(chan T)
defer close(c)
sv.request <- c
return <-c
}
func (sv sharedVal[T]) close() {
close(sv.request)
close(sv.set)
}
|