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recursive.go
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recursive.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 monitor
import (
"fmt"
"os"
"path/filepath"
"github.com/fsnotify/fsnotify"
"github.com/joeshaw/multierror"
"github.com/elastic/elastic-agent-libs/logp"
)
type recursiveWatcher struct {
inner *fsnotify.Watcher
tree FileTree
eventC chan fsnotify.Event
done chan bool
addC chan string
addErrC chan error
log *logp.Logger
isExcludedPath func(path string) bool
}
func newRecursiveWatcher(inner *fsnotify.Watcher, isExcludedPath func(path string) bool) *recursiveWatcher {
return &recursiveWatcher{
inner: inner,
tree: FileTree{},
eventC: make(chan fsnotify.Event, 1),
addC: make(chan string),
addErrC: make(chan error),
log: logp.NewLogger(moduleName),
isExcludedPath: isExcludedPath,
}
}
func (watcher *recursiveWatcher) Start() error {
watcher.done = make(chan bool, 1)
go watcher.forwardEvents()
return nil
}
func (watcher *recursiveWatcher) Add(path string) error {
if watcher.done != nil {
watcher.addC <- path
return <-watcher.addErrC
}
return watcher.addRecursive(path)
}
func (watcher *recursiveWatcher) Close() error {
if watcher.done != nil {
// has been Started(), goroutine takes care of cleanup
close(watcher.done)
return nil
}
// not started
return watcher.close()
}
func (watcher *recursiveWatcher) EventChannel() <-chan fsnotify.Event {
return watcher.eventC
}
func (watcher *recursiveWatcher) ErrorChannel() <-chan error {
return watcher.inner.Errors
}
func (watcher *recursiveWatcher) addRecursive(path string) error {
if watcher.isExcludedPath(path) {
return nil
}
var errs multierror.Errors
err := filepath.Walk(path, func(path string, info os.FileInfo, fnErr error) error {
if watcher.isExcludedPath(path) {
return nil
}
if fnErr != nil {
errs = append(errs, fmt.Errorf("error walking path '%s': %w", path, fnErr))
// If FileInfo is not nil, the directory entry can be processed
// even if there was some error
if info == nil {
return nil
}
}
var err error
if info.IsDir() {
if err = watcher.tree.AddDir(path); err == nil {
if err = watcher.inner.Add(path); err != nil {
errs = append(errs, fmt.Errorf("failed adding watcher to '%s': %w", path, err))
return nil
}
}
} else {
err = watcher.tree.AddFile(path)
}
return err
})
watcher.log.Debugw("Added recursive watch", "path", path)
if err != nil {
errs = append(errs, fmt.Errorf("failed to walk path '%s': %w", path, err))
}
return errs.Err()
}
func (watcher *recursiveWatcher) close() error {
close(watcher.eventC)
return watcher.inner.Close()
}
func (watcher *recursiveWatcher) deliver(ev fsnotify.Event) {
for {
select {
case <-watcher.done:
return
case path := <-watcher.addC:
watcher.addErrC <- watcher.addRecursive(path)
case watcher.eventC <- ev:
return
}
}
}
func (watcher *recursiveWatcher) forwardEvents() {
defer watcher.close()
for {
select {
case <-watcher.done:
return
case path := <-watcher.addC:
watcher.addErrC <- watcher.addRecursive(path)
case event, ok := <-watcher.inner.Events:
if !ok {
return
}
if event.Name == "" {
continue
}
switch event.Op {
case fsnotify.Create:
err := watcher.addRecursive(event.Name)
if err != nil {
watcher.inner.Errors <- fmt.Errorf("failed to add created path '%s': %w", event.Name, err)
}
err = watcher.tree.Visit(event.Name, PreOrder, func(path string, _ bool) error {
watcher.deliver(fsnotify.Event{
Name: path,
Op: event.Op,
})
return nil
})
if err != nil {
watcher.inner.Errors <- fmt.Errorf("failed to visit created path '%s': %w", event.Name, err)
}
case fsnotify.Remove:
err := watcher.tree.Visit(event.Name, PostOrder, func(path string, _ bool) error {
watcher.deliver(fsnotify.Event{
Name: path,
Op: event.Op,
})
return nil
})
if err != nil {
watcher.inner.Errors <- fmt.Errorf("failed to visit removed path '%s': %w", event.Name, err)
}
err = watcher.tree.Remove(event.Name)
if err != nil {
watcher.inner.Errors <- fmt.Errorf("failed to visit removed path '%s': %w", event.Name, err)
}
// Handling rename (move) as a special case to give this recursion
// the same semantics as macOS FSEvents:
// - Removal of a dir notifies removal for all files inside it
// - Moving a dir away sends only one notification for this dir
case fsnotify.Rename:
err := watcher.tree.Remove(event.Name)
if err != nil {
watcher.inner.Errors <- fmt.Errorf("failed to remove path '%s': %w", event.Name, err)
}
fallthrough
default:
watcher.deliver(event)
}
}
}
}