blob: 80cf78b48e55470564654684d7a8d69f232648bd [file] [log] [blame]
// 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 (
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.
// First, atomically acquire the current func, cancel it, and insert this
// call into d.funcs.
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.
if ok {
done := make(chan struct{})
next := &debounceFunc{
order: order,
done: done,
d.funcs[key] = next
// 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
select {
case <-done:
case <-time.After(timeout):
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.
delete(d.funcs, key)