implement parallel checksumming
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parent
b11c4701c3
commit
802792d620
4
check.go
4
check.go
@ -95,7 +95,7 @@ func check(files []string) chan error {
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results := []<-chan error{}
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for w := 0; w < *ngo; w++ {
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results = append(results, compute(jobs))
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results = append(results, verify(jobs))
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}
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return merge(results)
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@ -125,7 +125,7 @@ func merge(cs []<-chan error) chan error {
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return out
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}
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func compute(jobs chan work) chan error {
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func verify(jobs chan work) chan error {
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r := make(chan error)
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go func() {
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for job := range jobs {
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109
main.go
109
main.go
@ -7,9 +7,11 @@ import (
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"crypto/sha512"
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"flag"
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"fmt"
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"hash"
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"io"
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"os"
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"runtime"
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"sync"
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)
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var algo = flag.String("a", "sha1", "algorithm to use")
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@ -30,51 +32,118 @@ func main() {
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os.Exit(1)
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}
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case false:
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if err := hsh(files); err != nil {
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fmt.Fprintf(os.Stderr, "%v\n", err)
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c := 0
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for res := range hsh(files) {
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if res.err != nil {
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c++
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fmt.Fprintf(os.Stderr, "%v\n", res.err)
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} else {
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fmt.Printf("%v\n", res.msg)
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}
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}
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if c > 0 {
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os.Exit(1)
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}
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}
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}
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func hsh(files []string) error {
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h := sha256.New()
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type hashr func() hash.Hash
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func hsh(files []string) chan result {
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var h hashr
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switch *algo {
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case "sha1", "1":
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h = sha1.New()
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h = sha1.New
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case "sha256", "256":
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h = sha256.New()
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h = sha256.New
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case "sha512", "512":
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h = sha512.New()
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h = sha512.New
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case "md5":
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h = md5.New()
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h = md5.New
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default:
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return fmt.Errorf("unsupported algorithm: %v", *algo)
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r := make(chan result)
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go func() {
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r <- result{err: fmt.Errorf("unsupported algorithm: %v", *algo)}
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}()
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return r
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}
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if len(files) == 0 {
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_, err := io.Copy(h, os.Stdin)
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hsh := h()
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_, err := io.Copy(hsh, os.Stdin)
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if err != nil {
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fmt.Fprintf(os.Stderr, "%v\n", err)
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os.Exit(1)
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}
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fmt.Printf("%x -\n", h.Sum(nil))
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} else {
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fmt.Printf("%x -\n", hsh.Sum(nil))
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return nil
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}
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jobs := make(chan work)
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go func() {
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for _, name := range files {
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f, err := os.Open(name)
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jobs <- work{cs: checksum{filename: name}}
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}
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close(jobs)
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}()
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res := []<-chan result{}
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for w := 0; w < *ngo; w++ {
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res = append(res, compute(h, jobs))
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}
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return rmerge(res)
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}
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type result struct {
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msg string
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err error
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}
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func compute(h hashr, jobs chan work) chan result {
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hsh := h()
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r := make(chan result)
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go func() {
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for job := range jobs {
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f, err := os.Open(job.cs.filename)
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if err != nil {
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fmt.Fprintf(os.Stderr, "%v\n", err)
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r <- result{err: err}
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continue
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}
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h.Reset()
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_, err = io.Copy(h, f)
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hsh.Reset()
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_, err = io.Copy(hsh, f)
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f.Close()
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if err != nil {
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fmt.Fprintf(os.Stderr, "%v\n", err)
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r <- result{err: err}
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continue
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}
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fmt.Printf("%x %s\n", h.Sum(nil), name)
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r <- result{msg: fmt.Sprintf("%x %s", hsh.Sum(nil), job.cs.filename)}
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}
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}
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return nil
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close(r)
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}()
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return r
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}
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func rmerge(cs []<-chan result) chan result {
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out := make(chan result)
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var wg sync.WaitGroup
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output := func(c <-chan result) {
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for n := range c {
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out <- n
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}
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wg.Done()
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}
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wg.Add(len(cs))
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for _, c := range cs {
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go output(c)
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}
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go func() {
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wg.Wait()
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close(out)
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}()
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return out
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}
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