util.go

package log

import (
	"runtime"
	"strconv"
	"strings"
)

// find outside caller
func getCaller() string {
	// fast lookup
	_, currentFile, currentLine, _ := runtime.Caller(3)
	return currentFile + ":" + strconv.Itoa(currentLine)
}

// trimOutPrefix removes all the characters before AND the prefix
// its return the original string if not found prefix in str
func trimOutPrefix(str, prefix string) string {
	i := strings.Index(str, prefix)
	if i < 0 {
		return str
	}
	return str[i+len(prefix):]
}

// trimToPrefix removes all the characters before the prefix
// its return the original string if not found prefix in str
func trimToPrefix(str, prefix string) string {
	i := strings.Index(str, prefix)
	if i < 0 {
		return str
	}
	return str[i:]
}

// getStack returns 10 closest stacktrace, included file paths and line numbers
// it will ignore all system path, path which is vendor is striped to /vendor/
// skip: number of stack ignored
// returns stack and function name
func GetStack(skip int) (string, string) {
	stack := make([]uintptr, 10)
	var sb strings.Builder
	// skip one system stack, the this current stack line
	length := runtime.Callers(4+skip, stack[:])
	funcname := ""
	first := -1
	for i := 0; i < length; i++ {
		pc := stack[i]
		// pc - 1 because the program counters we use are usually return addresses,
		// and we want to show the line that corresponds to the function call
		function := runtime.FuncForPC(pc - 1)
		if i == 0 {
			funcname = function.Name()
		}
		file, line := function.FileLine(pc - 1)
		file = trimToPrefix(file, "/vendor/")
		// dont report system path
		if isIgnorePath(file) {
			continue
		}

		// trim out common provider since most of go projects are hosted
		// in single host, there is no need to include them in the call stack
		// remove them help keeping the call stack smaller, navigatiing easier
		if !strings.HasPrefix(file, "/vendor") {
			file = trimOutPrefix(file, "/github.com/")
			file = trimOutPrefix(file, "/gitlab.com/")
			file = trimOutPrefix(file, "/gopkg.in/")
		}

		if first == -1 {
			first = i
		} else {
			sb.WriteString(" | ")
		}
		sb.WriteString(file + ":" + strconv.Itoa(line))
	}
	return sb.String(), funcname
}

func Stack() string {
	stack, _ := GetStack(0)
	return stack
}

// isIgnorePath indicates whether a path is just noise, that excluding the path does not
// affect error context
func isIgnorePath(path string) bool {
	if strings.HasPrefix(path, "/usr/local/go/src") {
		return true
	}

	if strings.HasPrefix(path, "/vendor/google.golang.org/") {
		return true
	}

	if strings.HasPrefix(path, "/vendor/github.com/gin-gonic") {
		return true
	}
	return false
}