[Go] 跨平台文件系统监控工具 fsnotify 应用举例

项目地址:https://github.com/fsnotify/fsnotify

fsnotify 能监控指定文件夹内 文件的修改情况,如 文件的 增加、删除、修改、重命名等操作。

官方给出了以下注意事项:

When a file is moved to another directory is it still being watched?

No (it shouldn't be, unless you are watching where it was moved to).

When I watch a directory, are all subdirectories watched as well?

No, you must add watches for any directory you want to watch (a recursive watcher is on the roadmap #18).

Do I have to watch the Error and Event channels in a separate goroutine?

As of now, yes. Looking into making this single-thread friendly (see howeyc #7)

Why am I receiving multiple events for the same file on OS X?

Spotlight indexing on OS X can result in multiple events (see howeyc #62). A temporary workaround is to add your folder(s) to the Spotlight Privacy settings until we have a native FSEvents implementation (see #11).

How many files can be watched at once?

There are OS-specific limits as to how many watches can be created:

  • Linux: /proc/sys/fs/inotify/max_user_watches contains the limit, reaching this limit results in a "no space left on device" error.
  • BSD / OSX: sysctl variables "kern.maxfiles" and "kern.maxfilesperproc", reaching these limits results in a "too many open files" error.

最为注意的一点是:

文件夹中的子文件夹,还需自己去添加监控,fsnotify 本身不提供递归循环监控功能!

应用举例

package main

import (
"github.com/fsnotify/fsnotify"
"log"
"runtime"
) func main() {
// 监控路径列表
paths := []string{
"/Users/jianbao/GoglandProjects/fiisoo/src/test/ch0",
"/Users/jianbao/GoglandProjects/fiisoo/src/test/ch1",
} watcher, err := fsnotify.NewWatcher()
if err != nil {
log.Fatalf("Failed to create watcher: %s", err)
}
defer watcher.Close() exit := make(chan bool) go func() {
for {
select {
case e := <-watcher.Events:
log.Println("修改文件:" + e.Name)
log.Println("修改类型:" + e.Op.String())
case err := <-watcher.Errors:
log.Printf("Watcher error: %s\n", err.Error()) // No need to exit here
}
}
}() log.Println("Initializing watcher...")
for _, path := range paths {
log.Printf("Watching: %s\n", path)
err = watcher.Add(path)
if err != nil {
log.Fatalf("Failed to watch directory: %s", err)
}
} <-exit // 用来 阻塞应用不退出,只能通过“杀死进程”的方式退出,如 按住 Ctrl + C 快捷键强制推出
runtime.Goexit()
}
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