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implement parallel checksumming

recursive
Stephen McQuay 4 years ago
parent
commit
802792d620
No known key found for this signature in database GPG Key ID: 1ABF428F71BAFC3D
2 changed files with 90 additions and 21 deletions
  1. +2
    -2
      check.go
  2. +88
    -19
      main.go

+ 2
- 2
check.go View File

@ -95,7 +95,7 @@ func check(files []string) chan error {
results := []<-chan error{}
for w := 0; w < *ngo; w++ {
results = append(results, compute(jobs))
results = append(results, verify(jobs))
}
return merge(results)
@ -125,7 +125,7 @@ func merge(cs []<-chan error) chan error {
return out
}
func compute(jobs chan work) chan error {
func verify(jobs chan work) chan error {
r := make(chan error)
go func() {
for job := range jobs {

+ 88
- 19
main.go View File

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

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