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// 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 debounceEvent struct {
order uint64
done chan struct{}
}
type debouncer struct {
mu sync.Mutex
events map[string]*debounceEvent
}
func newDebouncer() *debouncer {
return &debouncer{
events: make(map[string]*debounceEvent),
}
}
// debounce returns a channel that receives a boolean reporting whether,
// by the time the delay channel receives a value, this call is (or will be)
// the most recent call with the highest order number for its key.
func (d *debouncer) debounce(key string, order uint64, delay <-chan time.Time) <-chan bool {
okc := make(chan bool, 1)
d.mu.Lock()
if prev, ok := d.events[key]; ok {
if prev.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()
okc <- false
return okc
}
close(prev.done)
}
done := make(chan struct{})
next := &debounceEvent{
order: order,
done: done,
}
d.events[key] = next
d.mu.Unlock()
go func() {
ok := false
select {
case <-delay:
d.mu.Lock()
if d.events[key] == next {
ok = true
delete(d.events, key)
} else {
// The event was superseded before we acquired d.mu.
}
d.mu.Unlock()
case <-done:
}
okc <- ok
}()
return okc
}
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