github.com/kovansky/hugo@v0.92.3-0.20220224232819-63076e4ff19f/watcher/batcher.go (about)

     1  // Copyright 2020 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package watcher
    15  
    16  import (
    17  	"time"
    18  
    19  	"github.com/fsnotify/fsnotify"
    20  	"github.com/gohugoio/hugo/watcher/filenotify"
    21  )
    22  
    23  // Batcher batches file watch events in a given interval.
    24  type Batcher struct {
    25  	filenotify.FileWatcher
    26  	interval time.Duration
    27  	done     chan struct{}
    28  
    29  	Events chan []fsnotify.Event // Events are returned on this channel
    30  }
    31  
    32  // New creates and starts a Batcher with the given time interval.
    33  // It will fall back to a poll based watcher if native isn's supported.
    34  // To always use polling, set poll to true.
    35  func New(intervalBatcher, intervalPoll time.Duration, poll bool) (*Batcher, error) {
    36  	var err error
    37  	var watcher filenotify.FileWatcher
    38  
    39  	if poll {
    40  		watcher = filenotify.NewPollingWatcher(intervalPoll)
    41  	} else {
    42  		watcher, err = filenotify.New(intervalPoll)
    43  	}
    44  
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  
    49  	batcher := &Batcher{}
    50  	batcher.FileWatcher = watcher
    51  	batcher.interval = intervalBatcher
    52  	batcher.done = make(chan struct{}, 1)
    53  	batcher.Events = make(chan []fsnotify.Event, 1)
    54  
    55  	if err == nil {
    56  		go batcher.run()
    57  	}
    58  
    59  	return batcher, nil
    60  }
    61  
    62  func (b *Batcher) run() {
    63  	tick := time.Tick(b.interval)
    64  	evs := make([]fsnotify.Event, 0)
    65  OuterLoop:
    66  	for {
    67  		select {
    68  		case ev := <-b.FileWatcher.Events():
    69  			evs = append(evs, ev)
    70  		case <-tick:
    71  			if len(evs) == 0 {
    72  				continue
    73  			}
    74  			b.Events <- evs
    75  			evs = make([]fsnotify.Event, 0)
    76  		case <-b.done:
    77  			break OuterLoop
    78  		}
    79  	}
    80  	close(b.done)
    81  }
    82  
    83  // Close stops the watching of the files.
    84  func (b *Batcher) Close() {
    85  	b.done <- struct{}{}
    86  	b.FileWatcher.Close()
    87  }