102 lines
2.1 KiB
Go
102 lines
2.1 KiB
Go
package main
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import (
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"bytes"
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"flag"
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"fmt"
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"io/ioutil"
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"os"
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"strings"
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"sync/atomic"
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"syscall"
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)
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const fileCount = 100
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type stats struct {
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renameOk int
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renameError int
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readOk int
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readError int
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readContentMismatch int
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}
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func usage() {
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fmt.Printf(`atomicrename creates %d "src" files in the current directory, renames
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them in random order over a single "dst" file while reading the "dst"
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file concurrently in a loop.
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Progress and errors are reported as they occour in addition to a summary
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printed at the end. cifs and fuse filesystems are known to fail, local
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filesystems and nfs seem ok.
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See https://github.com/hanwen/go-fuse/issues/398 for background info.
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`, fileCount)
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os.Exit(1)
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}
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func main() {
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flag.Usage = usage
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flag.Parse()
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hello := []byte("hello world")
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srcFiles := make(map[string]struct{})
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// prepare source files
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fmt.Print("creating files")
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for i := 0; i < fileCount; i++ {
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srcName := fmt.Sprintf("src.atomicrename.%d", i)
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srcFiles[srcName] = struct{}{}
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buf := bytes.Repeat([]byte("_"), i)
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buf = append(buf, hello...)
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if err := ioutil.WriteFile(srcName, buf, 0600); err != nil {
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panic(err)
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}
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fmt.Print(".")
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}
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fmt.Print("\n")
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// prepare destination file
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const dstName = "dst.atomicrename"
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if err := ioutil.WriteFile(dstName, hello, 0600); err != nil {
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panic(err)
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}
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var running int32 = 1
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stats := stats{}
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// read thread
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go func() {
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for atomic.LoadInt32(&running) == 1 {
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have, err := ioutil.ReadFile(dstName)
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if err != nil {
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fmt.Println(err)
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stats.readError++
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continue
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}
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if !strings.HasSuffix(string(have), string(hello)) {
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fmt.Printf("content mismatch: have %q\n", have)
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stats.readContentMismatch++
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continue
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}
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fmt.Printf("content ok len=%d\n", len(have))
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stats.readOk++
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}
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}()
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// rename thread = main thread
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for srcName := range srcFiles {
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if err := os.Rename(srcName, dstName); err != nil {
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fmt.Println(err)
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stats.renameError++
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}
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stats.renameOk++
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}
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// Signal the Read goroutine to stop when loop is done
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atomic.StoreInt32(&running, 0)
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syscall.Unlink(dstName)
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fmt.Printf("stats: %#v\n", stats)
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}
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