92 lines
1.8 KiB
Go
92 lines
1.8 KiB
Go
package internal
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import (
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"bytes"
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"fmt"
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"net/http"
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"runtime"
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"strings"
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)
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type StackTracer struct {
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CustomFn func(...interface{})
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Err error
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}
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// Error implements error interface.
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func (s StackTracer) Error() string {
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if s.Err == nil {
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return ""
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}
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return s.Err.Error()
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}
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// Unwrap implements the interface needed by errors.Unwrap.
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func (s StackTracer) Unwrap() error {
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return s.Err
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}
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// CheckStackTracer checks for specific error returned by
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// NewNotFoundResponder function or Trace Responder method.
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func CheckStackTracer(req *http.Request, err error) error {
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if nf, ok := err.(StackTracer); ok {
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if nf.CustomFn != nil {
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pc := make([]uintptr, 128)
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npc := runtime.Callers(2, pc)
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pc = pc[:npc]
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var mesg bytes.Buffer
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var netHTTPBegin, netHTTPEnd bool
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// Start recording at first net/http call if any...
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for {
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frames := runtime.CallersFrames(pc)
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var lastFn string
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for {
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frame, more := frames.Next()
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if !netHTTPEnd {
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if netHTTPBegin {
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netHTTPEnd = !strings.HasPrefix(frame.Function, "net/http.")
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} else {
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netHTTPBegin = strings.HasPrefix(frame.Function, "net/http.")
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}
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}
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if netHTTPEnd {
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if lastFn != "" {
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if mesg.Len() == 0 {
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if nf.Err != nil {
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mesg.WriteString(nf.Err.Error())
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} else {
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fmt.Fprintf(&mesg, "%s %s", req.Method, req.URL)
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}
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mesg.WriteString("\nCalled from ")
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} else {
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mesg.WriteString("\n ")
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}
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fmt.Fprintf(&mesg, "%s()\n at %s:%d", lastFn, frame.File, frame.Line)
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}
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}
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lastFn = frame.Function
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if !more {
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break
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}
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}
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// At least one net/http frame found
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if mesg.Len() > 0 {
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break
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}
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netHTTPEnd = true // retry without looking at net/http frames
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}
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nf.CustomFn(mesg.String())
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}
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err = nf.Err
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}
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return err
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}
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