calm

Documentation

Overview

Package calm provides panic recovery that converts panics into errors with stack traces and an errclass.Panic classification.

Index

• func Unpanic(f func() error) (err error)

Examples

• Unpanic

Functions

func Unpanic

func Unpanic(f func() error) (err error)

Unpanic executes the given function catching any panic and returning it as an error with stack trace and an errclass.Panic classification. WARNING: It is not possible to recover from a panic in a goroutine spawned by `f()`. Users should ensure that any goroutines created by `f()` are likewise guarded against panics.

Example

package main

import (
	"bytes"
	"fmt"
	"log/slog"
	"regexp"

	"github.com/wood-jp/xerrors"
	"github.com/wood-jp/xerrors/calm"
)

func newLogger(buf *bytes.Buffer) *slog.Logger {
	return slog.New(slog.NewJSONHandler(buf, &slog.HandlerOptions{
		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
			if a.Key == slog.TimeKey && len(groups) == 0 {
				return slog.Attr{}
			}
			return a
		},
	}))
}

var (
	reSource = regexp.MustCompile(`"source":"[^"]*"`)
	reLine   = regexp.MustCompile(`"line":\d+`)
)

func normalizeStack(s string) string {
	s = reSource.ReplaceAllString(s, `"source":"..."`)
	s = reLine.ReplaceAllString(s, `"line":0`)
	return s
}

func main() {
	var buf bytes.Buffer
	err := calm.Unpanic(func() error {
		panic("something went wrong")
	})
	newLogger(&buf).Error("recovered panic", xerrors.Log(err))
	fmt.Print(normalizeStack(buf.String()))
}

Output:
{"level":"ERROR","msg":"recovered panic","error":{"error":"panic: something went wrong","error_detail":{"stacktrace":[{"func":"github.com/wood-jp/xerrors/calm_test.ExampleUnpanic.func1","line":0,"source":"..."},{"func":"github.com/wood-jp/xerrors/calm.Unpanic","line":0,"source":"..."},{"func":"github.com/wood-jp/xerrors/calm_test.ExampleUnpanic","line":0,"source":"..."},{"func":"main.main","line":0,"source":"..."}],"class":"panic"}}}