watcher: Add file deleted by accident

See #7972

diff --git a/watcher/batcher.go b/watcher/batcher.go
new file mode 100644 (file)
index 0000000..12c5194
--- /dev/null
+++ b/watcher/batcher.go
@@ -0,0 +1,73 @@
+// Copyright 2020 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package watcher
+
+import (
+       "time"
+
+       "github.com/fsnotify/fsnotify"
+)
+
+// Batcher batches file watch events in a given interval.
+type Batcher struct {
+       *fsnotify.Watcher
+       interval time.Duration
+       done     chan struct{}
+
+       Events chan []fsnotify.Event // Events are returned on this channel
+}
+
+// New creates and starts a Batcher with the given time interval.
+func New(interval time.Duration) (*Batcher, error) {
+       watcher, err := fsnotify.NewWatcher()
+
+       batcher := &Batcher{}
+       batcher.Watcher = watcher
+       batcher.interval = interval
+       batcher.done = make(chan struct{}, 1)
+       batcher.Events = make(chan []fsnotify.Event, 1)
+
+       if err == nil {
+               go batcher.run()
+       }
+
+       return batcher, err
+}
+
+func (b *Batcher) run() {
+       tick := time.Tick(b.interval)
+       evs := make([]fsnotify.Event, 0)
+OuterLoop:
+       for {
+               select {
+               case ev := <-b.Watcher.Events:
+                       evs = append(evs, ev)
+               case <-tick:
+                       if len(evs) == 0 {
+                               continue
+                       }
+                       b.Events <- evs
+                       evs = make([]fsnotify.Event, 0)
+               case <-b.done:
+                       break OuterLoop
+               }
+       }
+       close(b.done)
+}
+
+// Close stops the watching of the files.
+func (b *Batcher) Close() {
+       b.done <- struct{}{}
+       b.Watcher.Close()
+}