Copy subdirectories concurrently

[Adrian Stanciu]

I am trying to achieve this using sync.WaitGroups based on the example from golang.org sync package.

var wg sync.WaitGroup // this is global

func CopyWebFiles(source, dest string) (err error) {

files, err := os.Open(source)

file, err := files.Readdir(0)

if err != nil {

fmt.Printf("Error reading directory %s: %s\n", source, err)

return err

}

for _, f := range file {

if f.IsDir() {

wg.Add(1)

go func() {

                                defer wg.Done()

copy.CopyDir(source+"\\"+f.Name(), dest+"\\"+f.Name())

}()

} else {

copy.CopyFile(source+"\\"+f.Name(), dest+"\\"+f.Name())

}

}

return nil

}

func main() {

CopyWebFiles(config.Location+"\\WebFiles", config.Destination)

wg.Wait()

}

But the problem is it doesn't copy only one directory instead of 9. If I print the directory copied before defer wg.Done() it says the same directory, so does that means that copies the same directory 9 times ? 

I don't really understand what my problem is, can someone help me figure it out ?

[Dan Kortschak]

f doesn't bind necessarily until after the loop completes. Add f := f after the for line or make the goroutine func take an argument.

--
You received this message because you are subscribed to the Google Groups "golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

[Adrian Stanciu]

Thanks, that did the trick.

[Dave Cheney]

On 31 Jan 2014, at 7:26, Adrian Stanciu <adrians...@gmail.com> wrote:

I am trying to achieve this using sync.WaitGroups based on the example from golang.org sync package.

var wg sync.WaitGroup // this is global

func CopyWebFiles(source, dest string) (err error) {

files, err := os.Open(source)

Err is lost here

file, err := files.Readdir(0)

Don't assume the state if files here, it could be nil and your program may panic. 

if err != nil {

fmt.Printf("Error reading directory %s: %s\n", source, err)

return err

}

for _, f := range file {

if f.IsDir() {

wg.Add(1)

go func() {

                                defer wg.Done()

copy.CopyDir(source+"\\"+f.Name(), dest+"\\"+f.Name())

}()

} else {

copy.CopyFile(source+"\\"+f.Name(), dest+"\\"+f.Name())

}

}

return nil

}

func main() {

CopyWebFiles(config.Location+"\\WebFiles", config.Destination)

wg.Wait()

}

But the problem is it doesn't copy only one directory instead of 9. If I print the directory copied before defer wg.Done() it says the same directory, so does that means that copies the same directory 9 times ? 

I don't really understand what my problem is, can someone help me figure it out ?

--