仅当文件自上次调用os.Lstat以来已更改时才调用os.Lstat

Question

I'm trying to write a program, calcsize, that calculates the size of all sub directories. I want to create a cache of the result and only re-walk the directory if it has changed since the last time I've run the program.

Something like:

./calcsize
//outputs 
/absolute/file/path1/ 1000 Bytes
/absolute/file/path2/ 2000 Bytes

I'm already walking the dirs with my own walk implementation because the built in go filepath.Walk is already calling Lstat on every file.

Is there any way to know if a directory or set of files has changed without calling Lstat on every file? Maybe a system call I'm not aware of?

Answer 1

In general, no. However you might want to look at: https://github.com/mattn/go-zglob/blob/master/fastwalk/fastwalk_unix.go

And using that data you can skip some of the stat calls, if you only care about files.