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vardius/main.go

Last active Jun 2, 2020
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Go errors with stack trace
package main
import (
"bytes"
"errors"
"fmt"
"runtime"
)
type AppError struct {
trace string
err error
}
// Error returns the string representation of the error message.
func (e *AppError) Error() string {
return fmt.Sprintf("%s\n%s", e.trace, e.err)
}
func (e *AppError) Unwrap() error {
return e.err
}
// StackTrace returns the string representation of the error stack trace,
// includeTrace appends caller pcs frames to each error message if possible.
func (e *AppError) StackTrace() (string, error) {
var buf bytes.Buffer
if e.trace != "" {
if _, err := fmt.Fprintf(&buf, "%s", e.trace); err != nil {
return "", err
}
}
if e.err == nil {
return buf.String(), nil
}
var next *AppError
if errors.As(e.err, &next) {
stackTrace, err := next.StackTrace()
if err != nil {
return "", err
}
buf.WriteString(fmt.Sprintf("\n%s", stackTrace))
} else {
return fmt.Sprintf("%s\n%s", buf.String(), e.err), nil
}
return buf.String(), nil
}
func AppenStackTrace(err error) *AppError {
if err == nil {
panic("nil error provided")
}
var buf bytes.Buffer
frame := getFrame(2)
fmt.Fprintf(&buf, "%s", frame.File)
fmt.Fprintf(&buf, ":%d", frame.Line)
fmt.Fprintf(&buf, " %s", frame.Function)
return &AppError{
err: err,
trace: buf.String(),
}
}
func main() {
err := AppenStackTrace(testOne())
fmt.Printf("%s", err)
t, _ := err.StackTrace()
fmt.Printf("\n\n%s", t)
}
func testOne() error {
return fmt.Errorf("testOne: %w", AppenStackTrace(testTwo()))
}
func testTwo() error {
return fmt.Errorf("testTwo: %w", AppenStackTrace(testThree()))
}
func testThree() error {
return AppenStackTrace(fmt.Errorf("internal error"))
}
func getFrame(calldepth int) *runtime.Frame {
pc, file, line, ok := runtime.Caller(calldepth)
if !ok {
return nil
}
frame := &runtime.Frame{
PC: pc,
File: file,
Line: line,
}
funcForPc := runtime.FuncForPC(pc)
if funcForPc != nil {
frame.Func = funcForPc
frame.Function = funcForPc.Name()
frame.Entry = funcForPc.Entry()
}
return frame
}
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@vardius vardius commented May 31, 2020

Run this example on The Go Playground

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