line_hook.go

// Copyright (c) 2021 Terminus, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package common

import (
	"fmt"
	"runtime"
	"strings"

	"github.com/sirupsen/logrus"
)

type LineHook struct {
	Field     string
	Skip      int
	levels    []logrus.Level
	Formatter func(file, function string, line int) string
}

func (hook *LineHook) Levels() []logrus.Level {
	return hook.levels
}

func (hook *LineHook) Fire(entry *logrus.Entry) error {
	entry.Data[hook.Field] = hook.Formatter(findCaller(hook.Skip))
	return nil
}

func NewLineHook(levels ...logrus.Level) *LineHook {
	hook := LineHook{
		Field:  "source",
		Skip:   5,
		levels: levels,
		Formatter: func(file, function string, line int) string {
			return fmt.Sprintf("%s:%d", file, line)
		},
	}
	if len(hook.levels) == 0 {
		hook.levels = logrus.AllLevels
	}

	return &hook
}

func findCaller(skip int) (string, string, int) {
	var (
		pc       uintptr
		file     string
		function string
		line     int
	)
	for i := 0; i < 10; i++ {
		pc, file, line = getCaller(skip + i)
		if !strings.HasPrefix(file, "logrus") {
			break
		}
	}
	if pc != 0 {
		frames := runtime.CallersFrames([]uintptr{pc})
		frame, _ := frames.Next()
		function = frame.Function
	}

	return file, function, line
}

func getCaller(skip int) (uintptr, string, int) {
	pc, file, line, ok := runtime.Caller(skip)
	if !ok {
		return 0, "", 0
	}

	n := 0
	for i := len(file) - 1; i > 0; i-- {
		if file[i] == '/' {
			n += 1
			if n >= 2 {
				file = file[i+1:]
				break
			}
		}
	}

	return pc, file, line
}