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// SPDX-License-Identifier: GPL-3.0-or-later
package file
import (
"context"
"fmt"
"os"
"path/filepath"
"strings"
"time"
"github.com/netdata/netdata/go/go.d.plugin/agent/confgroup"
"github.com/netdata/netdata/go/go.d.plugin/logger"
"github.com/fsnotify/fsnotify"
)
type (
Watcher struct {
*logger.Logger
paths []string
reg confgroup.Registry
watcher *fsnotify.Watcher
cache cache
refreshEvery time.Duration
}
cache map[string]time.Time
)
func (c cache) lookup(path string) (time.Time, bool) { v, ok := c[path]; return v, ok }
func (c cache) has(path string) bool { _, ok := c.lookup(path); return ok }
func (c cache) remove(path string) { delete(c, path) }
func (c cache) put(path string, modTime time.Time) { c[path] = modTime }
func NewWatcher(reg confgroup.Registry, paths []string) *Watcher {
d := &Watcher{
Logger: log,
paths: paths,
reg: reg,
watcher: nil,
cache: make(cache),
refreshEvery: time.Minute,
}
return d
}
func (w *Watcher) String() string {
return w.Name()
}
func (w *Watcher) Name() string {
return "file watcher"
}
func (w *Watcher) Run(ctx context.Context, in chan<- []*confgroup.Group) {
w.Info("instance is started")
defer func() { w.Info("instance is stopped") }()
watcher, err := fsnotify.NewWatcher()
if err != nil {
w.Errorf("fsnotify watcher initialization: %v", err)
return
}
w.watcher = watcher
defer w.stop()
w.refresh(ctx, in)
tk := time.NewTicker(w.refreshEvery)
defer tk.Stop()
for {
select {
case <-ctx.Done():
return
case <-tk.C:
w.refresh(ctx, in)
case event := <-w.watcher.Events:
// TODO: check if event.Has will do
if event.Name == "" || isChmodOnly(event) || !w.fileMatches(event.Name) {
break
}
if event.Has(fsnotify.Create) && w.cache.has(event.Name) {
// vim "backupcopy=no" case, already collected after Rename event.
break
}
if event.Has(fsnotify.Rename) {
// It is common to modify files using vim.
// When writing to a file a backup is made. "backupcopy" option tells how it's done.
// Default is "no": rename the file and write a new one.
// This is cheap attempt to not send empty group for the old file.
time.Sleep(time.Millisecond * 100)
}
w.refresh(ctx, in)
case err := <-w.watcher.Errors:
if err != nil {
w.Warningf("watch: %v", err)
}
}
}
}
func (w *Watcher) fileMatches(file string) bool {
for _, pattern := range w.paths {
if ok, _ := filepath.Match(pattern, file); ok {
return true
}
}
return false
}
func (w *Watcher) listFiles() (files []string) {
for _, pattern := range w.paths {
if matches, err := filepath.Glob(pattern); err == nil {
files = append(files, matches...)
}
}
return files
}
func (w *Watcher) refresh(ctx context.Context, in chan<- []*confgroup.Group) {
select {
case <-ctx.Done():
return
default:
}
var groups []*confgroup.Group
seen := make(map[string]bool)
for _, file := range w.listFiles() {
fi, err := os.Lstat(file)
if err != nil {
w.Warningf("lstat '%s': %v", file, err)
continue
}
if !fi.Mode().IsRegular() {
continue
}
seen[file] = true
if v, ok := w.cache.lookup(file); ok && v.Equal(fi.ModTime()) {
continue
}
w.cache.put(file, fi.ModTime())
if group, err := parse(w.reg, file); err != nil {
w.Warningf("parse '%s': %v", file, err)
} else if group == nil {
groups = append(groups, &confgroup.Group{Source: file})
} else {
for _, cfg := range group.Configs {
cfg.SetProvider("file watcher")
cfg.SetSourceType(configSourceType(file))
cfg.SetSource(fmt.Sprintf("discoverer=file_watcher,file=%s", file))
}
groups = append(groups, group)
}
}
for name := range w.cache {
if seen[name] {
continue
}
w.cache.remove(name)
groups = append(groups, &confgroup.Group{Source: name})
}
send(ctx, in, groups)
w.watchDirs()
}
func (w *Watcher) watchDirs() {
for _, path := range w.paths {
if idx := strings.LastIndex(path, "/"); idx > -1 {
path = path[:idx]
} else {
path = "./"
}
if err := w.watcher.Add(path); err != nil {
w.Errorf("start watching '%s': %v", path, err)
}
}
}
func (w *Watcher) stop() {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// closing the watcher deadlocks unless all events and errors are drained.
go func() {
for {
select {
case <-w.watcher.Errors:
case <-w.watcher.Events:
case <-ctx.Done():
return
}
}
}()
_ = w.watcher.Close()
}
func isChmodOnly(event fsnotify.Event) bool {
return event.Op^fsnotify.Chmod == 0
}
func send(ctx context.Context, in chan<- []*confgroup.Group, groups []*confgroup.Group) {
if len(groups) == 0 {
return
}
select {
case <-ctx.Done():
case in <- groups:
}
}
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