diff --git a/stack.go b/stack.go index ddc8c30..81f8856 100644 --- a/stack.go +++ b/stack.go @@ -1,7 +1,6 @@ package errors import ( - "bytes" "fmt" "io" "path" @@ -11,6 +10,8 @@ import ( ) // Frame represents a program counter inside a stack frame. +// For historical reasons if Frame is interpreted as a uintptr +// its value represents the program counter + 1. type Frame uintptr // pc returns the program counter for this frame; @@ -61,29 +62,24 @@ func (f Frame) name() string { // GOPATH separated by \n\t (\n\t) // %+v equivalent to %+s:%d func (f Frame) Format(s fmt.State, verb rune) { - f.format(s, s, verb) -} - -// format allows stack trace printing calls to be made with a bytes.Buffer. -func (f Frame) format(w io.Writer, s fmt.State, verb rune) { switch verb { case 's': switch { case s.Flag('+'): - io.WriteString(w, f.name()) - io.WriteString(w, "\n\t") - io.WriteString(w, f.file()) + io.WriteString(s, f.name()) + io.WriteString(s, "\n\t") + io.WriteString(s, f.file()) default: - io.WriteString(w, path.Base(f.file())) + io.WriteString(s, path.Base(f.file())) } case 'd': - io.WriteString(w, strconv.Itoa(f.line())) + io.WriteString(s, strconv.Itoa(f.line())) case 'n': - io.WriteString(w, funcname(f.name())) + io.WriteString(s, funcname(f.name())) case 'v': - f.format(w, s, 's') - io.WriteString(w, ":") - f.format(w, s, 'd') + f.Format(s, 's') + io.WriteString(s, ":") + f.Format(s, 'd') } } @@ -99,50 +95,37 @@ type StackTrace []Frame // // %+v Prints filename, function, and line number for each Frame in the stack. func (st StackTrace) Format(s fmt.State, verb rune) { - var b bytes.Buffer switch verb { case 'v': switch { case s.Flag('+'): - b.Grow(len(st) * stackMinLen) for _, f := range st { - b.WriteByte('\n') - f.format(&b, s, verb) + io.WriteString(s, "\n") + f.Format(s, verb) } case s.Flag('#'): - fmt.Fprintf(&b, "%#v", []Frame(st)) + fmt.Fprintf(s, "%#v", []Frame(st)) default: - st.formatSlice(&b, s, verb) + st.formatSlice(s, verb) } case 's': - st.formatSlice(&b, s, verb) + st.formatSlice(s, verb) } - io.Copy(s, &b) } // formatSlice will format this StackTrace into the given buffer as a slice of // Frame, only valid when called with '%s' or '%v'. -func (st StackTrace) formatSlice(b *bytes.Buffer, s fmt.State, verb rune) { - b.WriteByte('[') - if len(st) == 0 { - b.WriteByte(']') - return - } - - b.Grow(len(st) * (stackMinLen / 4)) - st[0].format(b, s, verb) - for _, fr := range st[1:] { - b.WriteByte(' ') - fr.format(b, s, verb) +func (st StackTrace) formatSlice(s fmt.State, verb rune) { + io.WriteString(s, "[") + for i, f := range st { + if i > 0 { + io.WriteString(s, " ") + } + f.Format(s, verb) } - b.WriteByte(']') + io.WriteString(s, "]") } -// stackMinLen is a best-guess at the minimum length of a stack trace. It -// doesn't need to be exact, just give a good enough head start for the buffer -// to avoid the expensive early growth. -const stackMinLen = 96 - // stack represents a stack of program counters. type stack []uintptr diff --git a/stack_test.go b/stack_test.go index 172a57d..1acd719 100644 --- a/stack_test.go +++ b/stack_test.go @@ -133,7 +133,7 @@ func TestStackTrace(t *testing.T) { "\t.+/github.com/pkg/errors/stack_test.go:131", // this is the stack of New }, }, { - func() error { noinline(); return New("ooh") }(), []string{ + func() error { return New("ooh") }(), []string{ `github.com/pkg/errors.TestStackTrace.func1` + "\n\t.+/github.com/pkg/errors/stack_test.go:136", // this is the stack of New "github.com/pkg/errors.TestStackTrace\n" + @@ -248,7 +248,3 @@ func caller() Frame { frame, _ := frames.Next() return Frame(frame.PC) } - -//go:noinline -// noinline prevents the caller being inlined -func noinline() {}