added pidfile, hup handling, truncate option

randomizr.go

@@ -5,14 +5,17 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
+	"os/signal"
+	"syscall"
 	"time"
 )
 
 var (
 	fname     string
-	fappend bool
+	ftruncate bool
 	reopen    bool
 	freq      float64
+	pidfile   string
 )
 
 // generates a pseudorandom string of length n that is composed of alphanumeric
@@ -31,10 +34,10 @@ func outFile() (*os.File, error) {
 		return os.Stdout, nil
 	}
 	options := os.O_WRONLY | os.O_CREATE
-    if fappend {
+	if ftruncate {
-        options |= os.O_APPEND
-    } else {
 		options |= os.O_TRUNC
+	} else {
+		options |= os.O_APPEND
 	}
 
 	return os.OpenFile(fname, options, 0644)
@@ -55,17 +58,26 @@ func reopenWrite(c chan string) {
 }
 
 func regularWrite(c chan string) {
+	hup := make(chan os.Signal, 1)
+	signal.Notify(hup, syscall.SIGHUP, syscall.SIGUSR1)
+
+START:
 	f, err := outFile()
 	if err != nil {
 		fmt.Printf("ERROR: unable to open outfile: %v", err)
 		return
 	}
-	defer f.Close()
 
-	for line := range c {
+	for {
+		select {
+		case line := <-c:
 			if _, err := f.WriteString(line); err != nil {
 				fmt.Printf("ERROR: unable to write line: %v", err)
 			}
+		case <-hup:
+			f.Close()
+			goto START
+		}
 	}
 }
 
@@ -77,8 +89,21 @@ func writeLines(c chan string) {
 	}
 }
 
+func writePid() {
+	if pidfile == "" {
+		return
+	}
+	f, err := os.OpenFile(pidfile, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "ERROR unable to open pidfile: %v", err)
+		return
+	}
+	fmt.Fprintf(f, "%d\n", os.Getpid())
+}
+
 func main() {
 	flag.Parse()
+	writePid()
 	c := make(chan string)
 
 	writeLines(c)
@@ -90,8 +115,9 @@ func main() {
 
 func init() {
 	flag.StringVar(&fname, "file", "", "destination file to which random data will be written")
-	flag.BoolVar(&fappend, "append", false, "append to file instead of truncating file on open")
+	flag.StringVar(&pidfile, "pidfile", "", "file to which a pid is written")
+	flag.BoolVar(&ftruncate, "truncate", false, "truncate file on opening instead of appending")
 	flag.BoolVar(&reopen, "reopen", false, "reopen file handle on every write instead of using a persistent handle")
-	flag.Float64Var(&freq, "freq", 1, "frequency in hz at which lines will be written")
+	flag.Float64Var(&freq, "freq", 10, "frequency in hz at which lines will be written")
 	rand.Seed(time.Now().UnixNano())
 }