-
Notifications
You must be signed in to change notification settings - Fork 453
/
executor.go
254 lines (215 loc) · 6.89 KB
/
executor.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
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package panicmon
import (
"errors"
"io"
"os"
"os/exec"
"os/signal"
"strconv"
"syscall"
)
// StatusCode represents the exit code of a process.
type StatusCode int
// String returns the string representation of the status code.
func (r StatusCode) String() string {
return strconv.Itoa(int(r))
}
// An Executor is responsible for executing a command and forwarding signals
// received by the parent to the spawned process. It reports process/signal
// events via the ProcessHandler/SignalHandler interfaces it is created with.
type Executor interface {
// Run executes a command as defined by args.
Run(args []string) (StatusCode, error)
}
// executor is the underlying implementation of Executor.
type executor struct {
// channel on which os will send received signals
sigC chan os.Signal
// channel to shut down signal handler
closeC chan struct{}
// channel that will be closed when the executor has finished closing
closeDone chan struct{}
handler Handler
stdout io.Writer
stderr io.Writer
env []string
}
// ExecutorOptions specifies options for creating a new executor.
type ExecutorOptions struct {
// Handler for signal and process events.
Handler Handler
// If ListenSigs is non-empty than only the signals specified will be
// listened to / forwarded. Default (empty) will cause all signals to be
// listened to, and all signals except SIGCHLD will be forwarded to the
// child.
Signals []os.Signal
// By default panicmon directs the child's stdout/stderr to its own in order
// to seamlessly wrap the process. This behavior can be overridden by
// specifying an io.Writer to send the child's stdout/stderr to. If either
// is nil the parent's will be used. Output can be silenced by setting either
// to ioutil.Discard.
Stdout io.Writer
Stderr io.Writer
// By default panicmon uses the existing processes environment variables
// when launching child processes. Set Env if you'd like to specify you're
// own environment variables to spawn with, on how to use this option see
// os/exec.Cmd.
Env []string
}
// Validate ensures that an ExecutorOpts type is valid. Specifically, it will
// set ProcessHandler and SignalHandler to noop handlers if either of them are
// nil.
func (opts *ExecutorOptions) Validate() {
if opts.Handler.ProcessHandler == nil {
opts.Handler.ProcessHandler = NoopProcessHandler{}
}
if opts.Handler.SignalHandler == nil {
opts.Handler.SignalHandler = NoopSignalHandler{}
}
}
// NewDefaultExecutorOpts returns an ExecutorOpts that will listen to / forward
// all signals (except SIGCHLD) but will use noop handlers for signal/process
// events.
func NewDefaultExecutorOpts() ExecutorOptions {
return ExecutorOptions{
Handler: Handler{
ProcessHandler: NoopProcessHandler{},
SignalHandler: NoopSignalHandler{},
},
}
}
// NewExecutor returns an executor configured according to opts (after calling
// opts.Validate()).
func NewExecutor(opts ExecutorOptions) Executor {
opts.Validate()
ex := &executor{
sigC: make(chan os.Signal, 2),
closeC: make(chan struct{}),
closeDone: make(chan struct{}),
handler: opts.Handler,
stdout: opts.Stdout,
stderr: opts.Stderr,
env: opts.Env,
}
signal.Notify(ex.sigC, opts.Signals...)
return ex
}
func (ex *executor) Run(args []string) (StatusCode, error) {
ex.handler.ProcessStarted(ProcessStartEvent{Args: args})
result, err := ex.execCmd(args)
if result.failedAtStartup && err != nil {
ex.handler.ProcessFailed(ProcessFailedEvent{
Args: args,
Err: err,
})
return result.statusCode, err
}
ex.handler.ProcessExited(ProcessExitedEvent{
Args: args,
Code: result.statusCode,
Err: err,
})
return result.statusCode, err
}
type execResult struct {
failedAtStartup bool
statusCode StatusCode
}
// execCmd spawns a command according to args and passes any signals received
// by the parent process to the spawned process. It returns a bool indicating
// whether the process failed at startup or after starting, the status code of
// the failed process, and an error capturing further information.
func (ex *executor) execCmd(args []string) (execResult, error) {
result := execResult{true, StatusCode(0)}
if len(args) == 0 {
return result, errors.New("args cannot be empty")
}
cmd := exec.Command(args[0], args[1:]...)
if ex.stdout == nil {
cmd.Stdout = os.Stdout
} else {
cmd.Stdout = ex.stdout
}
if ex.stderr == nil {
cmd.Stderr = os.Stderr
} else {
cmd.Stderr = ex.stderr
}
if ex.env != nil {
cmd.Env = ex.env
}
cmd.SysProcAttr = execSyscallAttr
if err := cmd.Start(); err != nil {
return result, err
}
// i.e. indicate we made it past process startup
result.failedAtStartup = false
go ex.passSignals(cmd.Process)
defer ex.close()
// if cmd.Wait returns a nil error it means the process exited with 0
err := cmd.Wait()
if err == nil {
return result, nil
}
// if exited uncleanly, capture status code to report
status := cmd.ProcessState.Sys().(syscall.WaitStatus)
result.statusCode = StatusCode(status.ExitStatus())
return result, err
}
func (ex *executor) close() {
close(ex.closeC)
}
func (ex *executor) closeAndWait() {
ex.close()
<-ex.closeDone
}
// passSignals forwards all signals (except SIGCHLD) received on sigC to the
// process running at proc.
func (ex *executor) passSignals(proc *os.Process) {
for {
select {
case sig := <-ex.sigC:
if sig.(syscall.Signal) == syscall.SIGCHLD {
continue
}
ex.handler.SignalReceived(SignalReceivedEvent{
Signal: sig,
ChildPid: proc.Pid,
})
if err := proc.Signal(sig); err != nil {
ex.handler.SignalFailed(SignalFailedEvent{
Signal: sig,
ChildPid: proc.Pid,
Err: err,
})
continue
}
ex.handler.SignalPassed(SignalPassedEvent{
Signal: sig,
ChildPid: proc.Pid,
})
case <-ex.closeC:
close(ex.closeDone)
return
}
}
}