-
Notifications
You must be signed in to change notification settings - Fork 0
/
cmdplx.go
173 lines (152 loc) · 4.92 KB
/
cmdplx.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
package cmdplx
import (
"bufio"
"io"
"os/exec"
"sync"
)
const (
Stdout = 1
Stderr = 2
)
type Line struct {
cmd *exec.Cmd // from which command
// Error when reading from the command's output.
// If error exists, Text and From are left unset
err error
text string // line content
from int // from stdout or stderr
}
// Get the current command
func (l *Line) Cmd() *exec.Cmd { return l.cmd }
// Get the error occured in reading from stdout or stderr
func (l *Line) Err() error { return l.err }
// Get the current line text
func (l *Line) Text() string { return l.text }
// Check to see the current line is from Stderr or Stdout
func (l *Line) From() int { return l.from }
type Status struct {
cmd *exec.Cmd // which command
err error // error
}
// Get the current command
func (s *Status) Cmd() *exec.Cmd { return s.cmd }
// Get the error
func (s *Status) Err() error { return s.err }
// Multiplex multiple commands' stdout and stderr.
type multiplexer struct {
cmds []*exec.Cmd // commands to run
lines chan *Line // channel to receive commands' output line by line
exited chan *Status // channel to receive commands' Wait() error
started chan *Status // channel to receive commands' Start() error
wg *sync.WaitGroup
}
// Start all the commands
//
// Stdout and stderr will be scanned line by line and the result will be
// sent to the lines channel(unbuffered).
// Start status is sent to the started channel.
// Exit status is sent to the exited channel.
// Started and exited channel are buffered channels with the same the size of the input commands
//
// The returning channels will all get CLOSED when commands are finished
func Start(cmds []*exec.Cmd) (
lines <-chan *Line,
started <-chan *Status,
exited <-chan *Status) {
lines, started, exited = newMultiplexer(cmds).startAll()
return
}
// Create new multiplexer
func newMultiplexer(cmds []*exec.Cmd) *multiplexer {
plx := &multiplexer{cmds: cmds}
plx.lines = make(chan *Line)
plx.wg = &sync.WaitGroup{}
count := len(plx.cmds)
plx.exited = make(chan *Status, count)
plx.started = make(chan *Status, count)
return plx
}
func (plx *multiplexer) startAll() (
lines <-chan *Line,
started <-chan *Status,
exited <-chan *Status) {
for _, c := range plx.cmds {
plx.wg.Add(1)
go plx.start(c)
}
go func() {
plx.wg.Wait()
close(plx.lines)
close(plx.started)
close(plx.exited)
}()
return plx.lines, plx.started, plx.exited
}
// Run a command.
// Start status is sent to started channel and exit status is sent exited channel.
// Stdout and stderr will be scanned line by line and sent to lines lines channel.
func (plx *multiplexer) start(c *exec.Cmd) {
defer plx.wg.Done()
var (
stdout io.ReadCloser
stderr io.ReadCloser
)
status := &Status{
cmd: c,
err: nil,
}
if stdout, status.err = c.StdoutPipe(); status.err != nil {
plx.started <- status
return
}
if stderr, status.err = c.StderrPipe(); status.err != nil {
plx.started <- status
return
}
if status.err = c.Start(); status.err != nil {
plx.started <- status
return
}
outScan, errScan := bufio.NewScanner(stdout), bufio.NewScanner(stderr)
var wg sync.WaitGroup
wg.Add(2)
go func() {
defer wg.Done()
for outScan.Scan() {
plx.lines <- &Line{
cmd: c,
text: outScan.Text(),
from: Stdout,
}
}
if err := errScan.Err(); err != nil {
plx.lines <- &Line{
cmd: c,
err: err,
}
}
}()
go func() {
defer wg.Done()
for errScan.Scan() {
plx.lines <- &Line{
cmd: c,
text: errScan.Text(),
from: Stderr,
}
}
if err := outScan.Err(); err != nil {
plx.lines <- &Line{
cmd: c,
err: err,
}
}
}()
wg.Wait()
err := c.Wait()
plx.exited <- &Status{
cmd: c,
err: err,
}
}