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
|
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lsp
import (
"sync"
"time"
)
type debounceFunc struct {
order uint64
done chan struct{}
}
type debouncer struct {
mu sync.Mutex
funcs map[string]*debounceFunc
}
func newDebouncer() *debouncer {
return &debouncer{
funcs: make(map[string]*debounceFunc),
}
}
// debounce waits timeout before running f, if no subsequent call is made with
// the same key in the intervening time. If a later call to debounce with the
// same key occurs while the original call is blocking, the original call will
// return immediately without running its f.
//
// If order is specified, it will be used to order calls logically, so calls
// with lesser order will not cancel calls with greater order.
func (d *debouncer) debounce(key string, order uint64, timeout time.Duration, f func()) {
if timeout == 0 {
// Degenerate case: no debouncing.
f()
return
}
// First, atomically acquire the current func, cancel it, and insert this
// call into d.funcs.
d.mu.Lock()
current, ok := d.funcs[key]
if ok && current.order > order {
// If we have a logical ordering of events (as is the case for snapshots),
// don't overwrite a later event with an earlier event.
d.mu.Unlock()
return
}
if ok {
close(current.done)
}
done := make(chan struct{})
next := &debounceFunc{
order: order,
done: done,
}
d.funcs[key] = next
d.mu.Unlock()
// Next, wait to be cancelled or for our wait to expire. There is a race here
// that we must handle: our timer could expire while another goroutine holds
// d.mu.
select {
case <-done:
case <-time.After(timeout):
d.mu.Lock()
if d.funcs[key] != next {
// We lost the race: another event has arrived for the key and started
// waiting. We could reasonably choose to run f at this point, but doing
// nothing is simpler.
d.mu.Unlock()
return
}
delete(d.funcs, key)
d.mu.Unlock()
f()
}
}
|
