| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package file |
| 4 | |
| 5 | import ( |
| 6 | "context" |
| 7 | "fmt" |
| 8 | "os" |
| 9 | "path/filepath" |
| 10 | "strings" |
| 11 | "time" |
| 12 | |
| 13 | "github.com/netdata/netdata/go/plugins/logger" |
| 14 | "github.com/netdata/netdata/go/plugins/plugin/framework/confgroup" |
| 15 | |
| 16 | "github.com/fsnotify/fsnotify" |
| 17 | ) |
| 18 | |
| 19 | type ( |
| 20 | Watcher struct { |
| 21 | *logger.Logger |
| 22 | |
| 23 | paths []string |
| 24 | reg confgroup.Registry |
| 25 | watcher *fsnotify.Watcher |
| 26 | cache cache |
| 27 | refreshEvery time.Duration |
| 28 | eventSettle time.Duration |
| 29 | } |
| 30 | cache map[string]time.Time |
| 31 | ) |
| 32 | |
| 33 | func (c cache) lookup(path string) (time.Time, bool) { v, ok := c[path]; return v, ok } |
| 34 | func (c cache) has(path string) bool { _, ok := c.lookup(path); return ok } |
| 35 | func (c cache) remove(path string) { delete(c, path) } |
| 36 | func (c cache) put(path string, modTime time.Time) { c[path] = modTime } |
| 37 | |
| 38 | func NewWatcher(reg confgroup.Registry, paths []string) *Watcher { |
| 39 | d := &Watcher{ |
| 40 | Logger: log, |
| 41 | paths: paths, |
| 42 | reg: reg, |
| 43 | watcher: nil, |
| 44 | cache: make(cache), |
| 45 | refreshEvery: time.Minute, |
| 46 | eventSettle: 100 * time.Millisecond, |
| 47 | } |
| 48 | return d |
| 49 | } |
| 50 | |
| 51 | func (w *Watcher) String() string { |
| 52 | return w.Name() |
| 53 | } |
| 54 | |
| 55 | func (w *Watcher) Name() string { |
| 56 | return "file watcher" |
| 57 | } |
| 58 | |
| 59 | func (w *Watcher) Run(ctx context.Context, in chan<- []*confgroup.Group) { |
| 60 | w.Info("instance is started") |
| 61 | defer func() { w.Info("instance is stopped") }() |
| 62 | |
| 63 | watcher, err := fsnotify.NewWatcher() |
| 64 | if err != nil { |
| 65 | w.Errorf("fsnotify watcher initialization: %v", err) |
| 66 | return |
| 67 | } |
| 68 | |
| 69 | w.watcher = watcher |
| 70 | defer w.stop() |
| 71 | w.refresh(ctx, in) |
| 72 | |
| 73 | tk := time.NewTicker(w.refreshEvery) |
| 74 | defer tk.Stop() |
| 75 | |
| 76 | for { |
| 77 | select { |
| 78 | case <-ctx.Done(): |
| 79 | return |
| 80 | case <-tk.C: |
| 81 | w.refresh(ctx, in) |
| 82 | case event := <-w.watcher.Events: |
| 83 | // TODO: check if event.Has will do |
| 84 | if event.Name == "" || isChmodOnly(event) || !w.fileMatches(event.Name) { |
| 85 | break |
| 86 | } |
| 87 | if event.Has(fsnotify.Create) && w.cache.has(event.Name) { |
| 88 | // vim "backupcopy=no" case, already collected after Rename event. |
| 89 | break |
| 90 | } |
| 91 | w.waitFileEventSettle(event) |
| 92 | w.refresh(ctx, in) |
| 93 | case err := <-w.watcher.Errors: |
| 94 | if err != nil { |
| 95 | w.Warningf("watch: %v", err) |
| 96 | } |
| 97 | } |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | func (w *Watcher) fileMatches(file string) bool { |
| 102 | for _, pattern := range w.paths { |
| 103 | if ok, _ := filepath.Match(pattern, file); ok { |
| 104 | return true |
| 105 | } |
| 106 | } |
| 107 | return false |
| 108 | } |
| 109 | |
| 110 | func (w *Watcher) listFiles() (files []string) { |
| 111 | for _, pattern := range w.paths { |
| 112 | if matches, err := filepath.Glob(pattern); err == nil { |
| 113 | files = append(files, matches...) |
| 114 | } |
| 115 | } |
| 116 | return files |
| 117 | } |
| 118 | |
| 119 | func (w *Watcher) refresh(ctx context.Context, in chan<- []*confgroup.Group) { |
| 120 | select { |
| 121 | case <-ctx.Done(): |
| 122 | return |
| 123 | default: |
| 124 | } |
| 125 | var groups []*confgroup.Group |
| 126 | seen := make(map[string]bool) |
| 127 | |
| 128 | for _, file := range w.listFiles() { |
| 129 | fi, err := os.Lstat(file) |
| 130 | if err != nil { |
| 131 | w.Warningf("lstat '%s': %v", file, err) |
| 132 | continue |
| 133 | } |
| 134 | |
| 135 | if !fi.Mode().IsRegular() { |
| 136 | continue |
| 137 | } |
| 138 | |
| 139 | seen[file] = true |
| 140 | if v, ok := w.cache.lookup(file); ok && v.Equal(fi.ModTime()) { |
| 141 | continue |
| 142 | } |
| 143 | w.cache.put(file, fi.ModTime()) |
| 144 | |
| 145 | if group, err := parse(w.reg, file); err != nil { |
| 146 | w.Warningf("parse '%s': %v", file, err) |
| 147 | } else if group == nil { |
| 148 | groups = append(groups, &confgroup.Group{Source: file}) |
| 149 | } else { |
| 150 | for _, cfg := range group.Configs { |
| 151 | cfg.SetProvider("file watcher") |
| 152 | cfg.SetSourceType(configSourceType(file)) |
| 153 | cfg.SetSource(fmt.Sprintf("discoverer=file_watcher,file=%s", file)) |
| 154 | } |
| 155 | groups = append(groups, group) |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | for name := range w.cache { |
| 160 | if seen[name] { |
| 161 | continue |
| 162 | } |
| 163 | w.cache.remove(name) |
| 164 | groups = append(groups, &confgroup.Group{Source: name}) |
| 165 | } |
| 166 | |
| 167 | send(ctx, in, groups) |
| 168 | |
| 169 | w.watchDirs() |
| 170 | } |
| 171 | |
| 172 | func (w *Watcher) watchDirs() { |
| 173 | for _, path := range w.paths { |
| 174 | if idx := strings.LastIndex(path, "/"); idx > -1 { |
| 175 | path = path[:idx] |
| 176 | } else { |
| 177 | path = "./" |
| 178 | } |
| 179 | if err := w.watcher.Add(path); err != nil { |
| 180 | w.Errorf("start watching '%s': %v", path, err) |
| 181 | } |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | func (w *Watcher) stop() { |
| 186 | ctx, cancel := context.WithCancel(context.Background()) |
| 187 | defer cancel() |
| 188 | |
| 189 | // closing the watcher deadlocks unless all events and errors are drained. |
| 190 | go func() { |
| 191 | for { |
| 192 | select { |
| 193 | case <-w.watcher.Errors: |
| 194 | case <-w.watcher.Events: |
| 195 | case <-ctx.Done(): |
| 196 | return |
| 197 | } |
| 198 | } |
| 199 | }() |
| 200 | |
| 201 | _ = w.watcher.Close() |
| 202 | } |
| 203 | |
| 204 | func (w *Watcher) waitFileEventSettle(event fsnotify.Event) { |
| 205 | if w.eventSettle <= 0 { |
| 206 | return |
| 207 | } |
| 208 | if event.Has(fsnotify.Create) || event.Has(fsnotify.Write) || event.Has(fsnotify.Rename) { |
| 209 | // Give editors and os.WriteFile() a chance to finish truncating/replacing the file |
| 210 | // before we snapshot it, otherwise transient empty reads can be cached as real updates. |
| 211 | time.Sleep(w.eventSettle) |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | func isChmodOnly(event fsnotify.Event) bool { |
| 216 | return event.Op^fsnotify.Chmod == 0 |
| 217 | } |
| 218 | |
| 219 | func send(ctx context.Context, in chan<- []*confgroup.Group, groups []*confgroup.Group) { |
| 220 | if len(groups) == 0 { |
| 221 | return |
| 222 | } |
| 223 | select { |
| 224 | case <-ctx.Done(): |
| 225 | case in <- groups: |
| 226 | } |
| 227 | } |