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- package middleware
-
- // The original work was derived from Goji's middleware, source:
- // https://github.com/zenazn/goji/tree/master/web/middleware
-
- import (
- "bytes"
- "errors"
- "fmt"
- "net/http"
- "os"
- "runtime/debug"
- "strings"
- )
-
- // Recoverer is a middleware that recovers from panics, logs the panic (and a
- // backtrace), and returns a HTTP 500 (Internal Server Error) status if
- // possible. Recoverer prints a request ID if one is provided.
- //
- // Alternatively, look at https://github.com/pressly/lg middleware pkgs.
- func Recoverer(next http.Handler) http.Handler {
- fn := func(w http.ResponseWriter, r *http.Request) {
- defer func() {
- if rvr := recover(); rvr != nil && rvr != http.ErrAbortHandler {
-
- logEntry := GetLogEntry(r)
- if logEntry != nil {
- logEntry.Panic(rvr, debug.Stack())
- } else {
- PrintPrettyStack(rvr)
- }
-
- w.WriteHeader(http.StatusInternalServerError)
- }
- }()
-
- next.ServeHTTP(w, r)
- }
-
- return http.HandlerFunc(fn)
- }
-
- func PrintPrettyStack(rvr interface{}) {
- debugStack := debug.Stack()
- s := prettyStack{}
- out, err := s.parse(debugStack, rvr)
- if err == nil {
- os.Stderr.Write(out)
- } else {
- // print stdlib output as a fallback
- os.Stderr.Write(debugStack)
- }
- }
-
- type prettyStack struct {
- }
-
- func (s prettyStack) parse(debugStack []byte, rvr interface{}) ([]byte, error) {
- var err error
- useColor := true
- buf := &bytes.Buffer{}
-
- cW(buf, false, bRed, "\n")
- cW(buf, useColor, bCyan, " panic: ")
- cW(buf, useColor, bBlue, "%v", rvr)
- cW(buf, false, bWhite, "\n \n")
-
- // process debug stack info
- stack := strings.Split(string(debugStack), "\n")
- lines := []string{}
-
- // locate panic line, as we may have nested panics
- for i := len(stack) - 1; i > 0; i-- {
- lines = append(lines, stack[i])
- if strings.HasPrefix(stack[i], "panic(0x") {
- lines = lines[0 : len(lines)-2] // remove boilerplate
- break
- }
- }
-
- // reverse
- for i := len(lines)/2 - 1; i >= 0; i-- {
- opp := len(lines) - 1 - i
- lines[i], lines[opp] = lines[opp], lines[i]
- }
-
- // decorate
- for i, line := range lines {
- lines[i], err = s.decorateLine(line, useColor, i)
- if err != nil {
- return nil, err
- }
- }
-
- for _, l := range lines {
- fmt.Fprintf(buf, "%s", l)
- }
- return buf.Bytes(), nil
- }
-
- func (s prettyStack) decorateLine(line string, useColor bool, num int) (string, error) {
- line = strings.TrimSpace(line)
- if strings.HasPrefix(line, "\t") || strings.Contains(line, ".go:") {
- return s.decorateSourceLine(line, useColor, num)
- } else if strings.HasSuffix(line, ")") {
- return s.decorateFuncCallLine(line, useColor, num)
- } else {
- if strings.HasPrefix(line, "\t") {
- return strings.Replace(line, "\t", " ", 1), nil
- } else {
- return fmt.Sprintf(" %s\n", line), nil
- }
- }
- }
-
- func (s prettyStack) decorateFuncCallLine(line string, useColor bool, num int) (string, error) {
- idx := strings.LastIndex(line, "(")
- if idx < 0 {
- return "", errors.New("not a func call line")
- }
-
- buf := &bytes.Buffer{}
- pkg := line[0:idx]
- // addr := line[idx:]
- method := ""
-
- if idx := strings.LastIndex(pkg, string(os.PathSeparator)); idx < 0 {
- if idx := strings.Index(pkg, "."); idx > 0 {
- method = pkg[idx:]
- pkg = pkg[0:idx]
- }
- } else {
- method = pkg[idx+1:]
- pkg = pkg[0 : idx+1]
- if idx := strings.Index(method, "."); idx > 0 {
- pkg += method[0:idx]
- method = method[idx:]
- }
- }
- pkgColor := nYellow
- methodColor := bGreen
-
- if num == 0 {
- cW(buf, useColor, bRed, " -> ")
- pkgColor = bMagenta
- methodColor = bRed
- } else {
- cW(buf, useColor, bWhite, " ")
- }
- cW(buf, useColor, pkgColor, "%s", pkg)
- cW(buf, useColor, methodColor, "%s\n", method)
- // cW(buf, useColor, nBlack, "%s", addr)
- return buf.String(), nil
- }
-
- func (s prettyStack) decorateSourceLine(line string, useColor bool, num int) (string, error) {
- idx := strings.LastIndex(line, ".go:")
- if idx < 0 {
- return "", errors.New("not a source line")
- }
-
- buf := &bytes.Buffer{}
- path := line[0 : idx+3]
- lineno := line[idx+3:]
-
- idx = strings.LastIndex(path, string(os.PathSeparator))
- dir := path[0 : idx+1]
- file := path[idx+1:]
-
- idx = strings.Index(lineno, " ")
- if idx > 0 {
- lineno = lineno[0:idx]
- }
- fileColor := bCyan
- lineColor := bGreen
-
- if num == 1 {
- cW(buf, useColor, bRed, " -> ")
- fileColor = bRed
- lineColor = bMagenta
- } else {
- cW(buf, false, bWhite, " ")
- }
- cW(buf, useColor, bWhite, "%s", dir)
- cW(buf, useColor, fileColor, "%s", file)
- cW(buf, useColor, lineColor, "%s", lineno)
- if num == 1 {
- cW(buf, false, bWhite, "\n")
- }
- cW(buf, false, bWhite, "\n")
-
- return buf.String(), nil
- }
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