Uncache a set of files (reimplementation of: https://dom.as/2009/06/26/uncache/)

uncache.go

package main

import (
	"fmt"
	"os"
	"path/filepath"

	"golang.org/x/sys/unix"
)

func uncache(path string) error {
	file, err := os.Open(path)
	if err != nil {
		return err
	}
	defer file.Close()

	return unix.Fadvise(int(file.Fd()), 0, 0, unix.FADV_DONTNEED)
}

func main() {
	numScanned := 0
	numUncached := 0

	for _, location := range os.Args[1:] {
		err := filepath.Walk(location, func(path string, fileInfo os.FileInfo, err error) error {
			if err != nil {
				return err
			}

			if fileInfo.IsDir() {
				return nil
			}

			numScanned++
			if err := uncache(path); err != nil {
				fmt.Printf("Failed to uncache '%s': %s\n", err)
			} else {
				fmt.Printf("Uncached '%s'\n", path)
				numUncached++
			}
			return nil
		})
		if err != nil {
			fmt.Printf("Errors walking '%s': %s\n", location, err)
		}
	}

	fmt.Printf("Scanned %d files\n", numScanned)
	fmt.Printf("Uncached %d files\n", numUncached)
}