// +build debug package debug import ( "fmt" "log" "os" "path" "runtime" "strings" "sync" "syscall" ) var opts struct { tags map[string]bool breaks map[string]bool m sync.Mutex } var debugLogger = initDebugLogger() func initDebugLogger() (lgr *log.Logger) { opts.tags = make(map[string]bool) opts.breaks = make(map[string]bool) fmt.Fprintf(os.Stderr, "debug enabled\n") debugfile := os.Getenv("DEBUG_LOG") if debugfile != "" { fmt.Fprintf(os.Stderr, "debug log file %v\n", debugfile) // open logfile f, err := os.OpenFile(debugfile, os.O_WRONLY|os.O_APPEND, 0600) if err != nil && os.IsNotExist(err) { // create logfile f, err = os.OpenFile(debugfile, os.O_WRONLY|os.O_CREATE, 0600) } if err != nil { fmt.Fprintf(os.Stderr, "unable to open debug log file: %v\n", err) os.Exit(2) } // seek to the end _, err = f.Seek(2, 0) if err != nil { fmt.Fprintf(os.Stderr, "unable to seek to the end of %v: %v\n", debugfile, err) os.Exit(3) } // open logger lgr = log.New(f, "", log.LstdFlags) } // defaults opts.tags["break"] = true // initialize tags env := os.Getenv("DEBUG_TAGS") if len(env) > 0 { tags := []string{} for _, tag := range strings.Split(env, ",") { t := strings.TrimSpace(tag) val := true if t[0] == '-' { val = false t = t[1:] } else if t[0] == '+' { val = true t = t[1:] } // test pattern _, err := path.Match(t, "") if err != nil { fmt.Fprintf(os.Stderr, "error: invalid pattern %q: %v\n", t, err) os.Exit(5) } opts.tags[t] = val tags = append(tags, tag) } fmt.Fprintf(os.Stderr, "debug log enabled for: %v\n", tags) } // initialize break tags env = os.Getenv("DEBUG_BREAK") if len(env) > 0 { breaks := []string{} for _, tag := range strings.Split(env, ",") { t := strings.TrimSpace(tag) opts.breaks[t] = true breaks = append(breaks, t) } fmt.Fprintf(os.Stderr, "debug breaks enabled for: %v\n", breaks) } return } func Log(tag string, f string, args ...interface{}) { // synchronize log writes opts.m.Lock() defer opts.m.Unlock() dbgprint := func() { fmt.Fprintf(os.Stderr, "DEBUG["+tag+"]: "+f, args...) } if debugLogger != nil { debugLogger.Printf("["+tag+"] "+f, args...) } // check if tag is enabled directly if v, ok := opts.tags[tag]; ok { if v { dbgprint() } return } // check for globbing for k, v := range opts.tags { if m, _ := path.Match(k, tag); m { if v { dbgprint() } return } } // check if tag "all" is enabled if v, ok := opts.tags["all"]; ok && v { dbgprint() } } func Break(tag string) { // check if breaking is enabled if v, ok := opts.breaks[tag]; !ok || !v { return } _, file, line, _ := runtime.Caller(1) Log("break", "stopping process %d at %s (%v:%v)\n", os.Getpid(), tag, file, line) p, err := os.FindProcess(os.Getpid()) if err != nil { panic(err) } err = p.Signal(syscall.SIGSTOP) if err != nil { panic(err) } }