mirror of https://bitbucket.org/ausocean/av.git
80 lines
2.1 KiB
Go
80 lines
2.1 KiB
Go
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/*
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DESCRIPTION
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watcher.go provides a tool for watching a file for modifications and
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performing an action when the file is modified.
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AUTHORS
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Saxon A. Nelson-Milton <saxon@ausocean.org>
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LICENSE
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Copyright (C) 2022 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
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*/
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package main
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import (
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"fmt"
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"path"
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"bitbucket.org/ausocean/utils/logging"
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"github.com/fsnotify/fsnotify"
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)
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// watchFile watches a file for modifications and calls onWrite when the file
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// is modified. Technically, the directory is watched instead of the file.
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// This is because watching the file itself will cause problems if changes
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// are done atomically.
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// See fsnotify documentation:
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// https://godocs.io/github.com/fsnotify/fsnotify#hdr-Watching_files
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func watchFile(file string, onWrite func(), l logging.Logger) error {
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watcher, err := fsnotify.NewWatcher()
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if err != nil {
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return fmt.Errorf("could not create watcher: %w", err)
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}
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go func() {
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for {
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select {
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case event, ok := <-watcher.Events:
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if !ok {
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l.Warning("watcher events chan closed, terminating")
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return
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}
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if event.Op&fsnotify.Write == fsnotify.Write && event.Name == file {
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l.Info("file modification event", "file", file)
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onWrite()
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}
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case err, ok := <-watcher.Errors:
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if !ok {
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l.Warning("watcher error chan closed, terminating")
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return
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}
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l.Error("file watcher error", "error", err)
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}
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}
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}()
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// Watch the directory over the file.
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err = watcher.Add(path.Dir(file))
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if err != nil {
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return fmt.Errorf("could not add file %s to watcher: %w", file, err)
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}
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return nil
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}
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