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98 lines
2.0 KiB
Go
98 lines
2.0 KiB
Go
package main
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import (
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"flag"
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"fmt"
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"math/rand"
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"os"
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"time"
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)
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var (
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fname string
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fappend bool
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reopen bool
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freq float64
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)
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// generates a pseudorandom string of length n that is composed of alphanumeric
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// characters.
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func randomString(n int) string {
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var alpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
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buf := make([]byte, n)
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for i := 0; i < len(buf); i++ {
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buf[i] = alpha[rand.Intn(len(alpha)-1)]
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}
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return string(buf)
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}
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func outFile() (*os.File, error) {
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if fname == "" {
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return os.Stdout, nil
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}
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options := os.O_WRONLY | os.O_CREATE
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if fappend {
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options |= os.O_APPEND
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} else {
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options |= os.O_TRUNC
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}
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return os.OpenFile(fname, options, 0644)
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}
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func reopenWrite(c chan string) {
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for line := range c {
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f, err := outFile()
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if err != nil {
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fmt.Printf("ERROR: unable to open outfile: %v", err)
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continue
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}
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if _, err := f.WriteString(line); err != nil {
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fmt.Printf("ERROR: unable to write line: %v", err)
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}
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f.Close()
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}
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}
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func regularWrite(c chan string) {
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f, err := outFile()
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if err != nil {
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fmt.Printf("ERROR: unable to open outfile: %v", err)
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return
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}
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defer f.Close()
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for line := range c {
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if _, err := f.WriteString(line); err != nil {
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fmt.Printf("ERROR: unable to write line: %v", err)
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}
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}
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}
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func writeLines(c chan string) {
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if reopen {
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go reopenWrite(c)
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} else {
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go regularWrite(c)
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}
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}
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func main() {
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flag.Parse()
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c := make(chan string)
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writeLines(c)
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for t := range time.Tick(time.Duration(1e9 / freq)) {
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c <- fmt.Sprintf("%v %v %v\n", t.UnixNano(), randomString(32), randomString(32))
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}
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}
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func init() {
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flag.StringVar(&fname, "file", "", "destination file to which random data will be written")
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flag.BoolVar(&fappend, "append", false, "append to file instead of truncating file on open")
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flag.BoolVar(&reopen, "reopen", false, "reopen file handle on every write instead of using a persistent handle")
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flag.Float64Var(&freq, "freq", 1, "frequency in hz at which lines will be written")
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rand.Seed(time.Now().UnixNano())
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}
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