1// untested sections: 1
2
3package gexec
4
5import (
6	"io"
7	"sync"
8)
9
10/*
11PrefixedWriter wraps an io.Writer, emitting the passed in prefix at the beginning of each new line.
12This can be useful when running multiple gexec.Sessions concurrently - you can prefix the log output of each
13session by passing in a PrefixedWriter:
14
15gexec.Start(cmd, NewPrefixedWriter("[my-cmd] ", GinkgoWriter), NewPrefixedWriter("[my-cmd] ", GinkgoWriter))
16*/
17type PrefixedWriter struct {
18	prefix        []byte
19	writer        io.Writer
20	lock          *sync.Mutex
21	atStartOfLine bool
22}
23
24func NewPrefixedWriter(prefix string, writer io.Writer) *PrefixedWriter {
25	return &PrefixedWriter{
26		prefix:        []byte(prefix),
27		writer:        writer,
28		lock:          &sync.Mutex{},
29		atStartOfLine: true,
30	}
31}
32
33func (w *PrefixedWriter) Write(b []byte) (int, error) {
34	w.lock.Lock()
35	defer w.lock.Unlock()
36
37	toWrite := []byte{}
38
39	for _, c := range b {
40		if w.atStartOfLine {
41			toWrite = append(toWrite, w.prefix...)
42		}
43
44		toWrite = append(toWrite, c)
45
46		w.atStartOfLine = c == '\n'
47	}
48
49	_, err := w.writer.Write(toWrite)
50	if err != nil {
51		return 0, err
52	}
53
54	return len(b), nil
55}
56