diff --git a/main.go b/main.go index 82415ba..4267533 100644 --- a/main.go +++ b/main.go @@ -12,8 +12,11 @@ import ( var options struct { pidfile string + lineBuf int } +// writes out a message and then exits with the status coded provided by +// status. Since bail calls os.Exit, defered functions are not run. func bail(status int, template string, args ...interface{}) { if status == 0 { fmt.Fprintf(os.Stdout, template, args...) @@ -23,18 +26,23 @@ func bail(status int, template string, args ...interface{}) { os.Exit(status) } +// writes out the current process's pid to a file func writePid() error { f, err := os.OpenFile(options.pidfile, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644) if err != nil { return err } + defer f.Close() + if _, err := fmt.Fprintln(f, os.Getpid()); err != nil { return err } - f.Close() return nil } +// writes lines to the file handled by the fileopener f as they appear on the +// channel c. when huppend receives a hup process, the fileopener f is +// reopened. func writelines(f *fileOpener, c chan []byte) { hup := make(chan os.Signal, 1) signal.Notify(hup, syscall.SIGHUP) @@ -65,6 +73,8 @@ func writelines(f *fileOpener, c chan []byte) { } } +// a fileopener wraps a file and provides a helper for reopening the file by +// path. type fileOpener struct { *os.File fname string @@ -81,6 +91,10 @@ func (f *fileOpener) Open() error { return nil } +// closes and reopens the file found at the fileopener's specified path. If +// the original file has moved, reopen will cause the fileopener to change which +// inode it points to. If the original file has been moved or deleted, and a +// new file has not been created in its place, func (f *fileOpener) Reopen() error { if err := f.Close(); err != nil { return fmt.Errorf("fileOpener unable to reopen file: %v", err) @@ -120,7 +134,7 @@ func main() { bail(1, "unable to write pidfile: %v", err) } - c := make(chan []byte) + c := make(chan []byte, options.lineBuf) go writelines(f, c) r := bufio.NewReader(os.Stdin) @@ -140,4 +154,5 @@ func main() { func init() { flag.StringVar(&options.pidfile, "pidfile", "./huppend.pid", "pidfile") + flag.IntVar(&options.lineBuf, "linebuf", 200, "number of lines allowed to be in memory before writer is blocked") }