textwriter.mx raw

   1  // Copyright 2023 The Go Authors. All rights reserved.
   2  // Use of this source code is governed by a BSD-style
   3  // license that can be found in the LICENSE file.
   4  
   5  package raw
   6  
   7  import (
   8  	"fmt"
   9  	"io"
  10  
  11  	"internal/trace/version"
  12  )
  13  
  14  // TextWriter emits the text format of a trace.
  15  type TextWriter struct {
  16  	w io.Writer
  17  	v version.Version
  18  }
  19  
  20  // NewTextWriter creates a new write for the trace text format.
  21  func NewTextWriter(w io.Writer, v version.Version) (*TextWriter, error) {
  22  	_, err := fmt.Fprintf(w, "Trace Go1.%d\n", v)
  23  	if err != nil {
  24  		return nil, err
  25  	}
  26  	return &TextWriter{w: w, v: v}, nil
  27  }
  28  
  29  // WriteEvent writes a single event to the stream.
  30  func (w *TextWriter) WriteEvent(e Event) error {
  31  	// Check version.
  32  	if e.Version != w.v {
  33  		return fmt.Errorf("mismatched version between writer (go 1.%d) and event (go 1.%d)", w.v, e.Version)
  34  	}
  35  
  36  	// Write event.
  37  	_, err := fmt.Fprintln(w.w, e.String())
  38  	return err
  39  }
  40