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io.go
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io.go
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package main
import (
"bytes"
"fmt"
"strings"
"sync"
"time"
)
// Time to wait for remaining IO after process exit.
const deadline time.Duration = 100 * time.Millisecond
// Top-level IO collector for SSH output
type IOCollector interface {
NewRemote(host string) *RemoteIO
Read()
}
// A single packet of output
type IOMessage struct {
data string
stream int
}
// Exists per host and sends IO to be aggregated back to IOCollector
type RemoteIO struct {
host string
collector chan *IOMessage
done chan error
}
func NewRemoteIO(host string) *RemoteIO {
return &RemoteIO{
host: host,
collector: make(chan *IOMessage),
done: make(chan error),
}
}
// Send data to stdout
func (remote *RemoteIO) Stdout(data []byte) {
remote.collector <- &IOMessage{
data: string(data),
stream: 1,
}
}
// Send data to stderr
func (remote *RemoteIO) Stderr(data []byte) {
remote.collector <- &IOMessage{
data: string(data),
stream: 2,
}
}
// Indicates an exit with return code
func (remote *RemoteIO) Exit(code int) {
remote.collector <- &IOMessage{
data: fmt.Sprintf("Exited with code: %d\n", code),
stream: -1,
}
}
// Indicates the client has terminated
func (remote *RemoteIO) Done(err error) {
remote.done <- err
}
// io.Writer to stdout for the specified RemoteIO
type stdoutWriter struct {
remote *RemoteIO
}
func (writer *stdoutWriter) Write(p []byte) (int, error) {
writer.remote.Stdout(p)
return len(p), nil
}
// io.Writer to stderr for the specified RemoteIO
type stderrWriter struct {
remote *RemoteIO
}
func (writer *stderrWriter) Write(p []byte) (int, error) {
writer.remote.Stderr(p)
return len(p), nil
}
// IOCollector that displays outputs one-at-a-time after each connection closes.
type RegularIOCollector struct {
results chan *IOResult
count int
}
// Full output from a remote connection
type IOResult struct {
host string
msgs []*IOMessage
result error
}
// Makes a RegularIOCollector
func NewRegularIOCollector() IOCollector {
return &RegularIOCollector{
results: make(chan *IOResult),
}
}
// Creates a new RemoteIO for the specified host
func (coll *RegularIOCollector) NewRemote(host string) *RemoteIO {
remote := NewRemoteIO(host)
coll.count++
go coll.process(remote)
return remote
}
// Collects and displays output from all RemoteIO's, then returns
func (coll *RegularIOCollector) Read() {
recvd := 0
for recvd < coll.count {
result := <-coll.results
fmt.Printf("\n===== Results from %s\n", result.host)
for _, x := range result.msgs {
fmt.Printf("%s", x.data)
}
if result.result != nil {
fmt.Printf("==> Failed with %s\n", result.result.Error())
}
recvd++
}
close(coll.results)
}
// Reads output from a single RemoteIO, sends it all back to collector when
// it is finished.
func (coll *RegularIOCollector) process(remote *RemoteIO) {
var msgs []*IOMessage
var result error
wait:
for {
select {
case msg := <-remote.collector:
msgs = append(msgs, msg)
case err := <-remote.done:
result = err
break wait
}
}
// Give the data streams some time to finish sending.
t := time.NewTimer(deadline)
wait2:
for {
select {
case msg := <-remote.collector:
msgs = append(msgs, msg)
if !t.Stop() {
<-t.C
}
t.Reset(deadline)
case <-t.C:
break wait2
}
}
coll.results <- &IOResult{
msgs: msgs,
host: remote.host,
result: result,
}
close(remote.collector)
close(remote.done)
}
// IOCollector that interleaves output from many remote hosts as it arrives.
type InterleavedIOCollector struct {
messages chan *IOMessage
waitgroup sync.WaitGroup
}
// Creates an InterleavedIOCollector
func NewInterleavedIOCollector() IOCollector {
return &InterleavedIOCollector{
messages: make(chan *IOMessage),
}
}
// Creates a RemoteIO that feeds the InterleavedIOCollector for the specified host.
func (coll *InterleavedIOCollector) NewRemote(host string) *RemoteIO {
remote := NewRemoteIO(host)
coll.waitgroup.Add(1)
go coll.process(remote)
return remote
}
// Collects and displays output from all RemoteIO's, then returns
func (coll *InterleavedIOCollector) Read() {
done := make(chan bool)
go func() {
coll.waitgroup.Wait()
done <- true
}()
for {
select {
case msg := <-coll.messages:
fmt.Println(msg.data)
case <-done:
close(coll.messages)
close(done)
return
}
}
}
// Reads output from a single RemoteIO and forwards it to the InterleavedIOCollector
func (coll *InterleavedIOCollector) process(remote *RemoteIO) {
defer coll.waitgroup.Done()
processor := &interleavedProcessor{
collector: coll,
remote: remote,
curStream: -1,
}
processor.process()
}
type interleavedProcessor struct {
collector *InterleavedIOCollector
remote *RemoteIO
curStream int
buf bytes.Buffer
}
func (proc *interleavedProcessor) process() {
var result error
wait:
for {
select {
case msg := <-proc.remote.collector:
proc.handle(msg)
case err := <-proc.remote.done:
result = err
break wait
}
}
// Give the data streams some time to finish sending.
t := time.NewTimer(deadline)
wait2:
for {
select {
case msg := <-proc.remote.collector:
proc.handle(msg)
if !t.Stop() {
<-t.C
}
t.Reset(deadline)
case <-t.C:
break wait2
}
}
if result != nil {
proc.handle(&IOMessage{
data: fmt.Sprintf("Failed with %s\n", result.Error()),
stream: -1,
})
}
proc.flush()
close(proc.remote.collector)
close(proc.remote.done)
}
func (proc *interleavedProcessor) handle(msg *IOMessage) {
if msg.stream != proc.curStream {
proc.flush()
proc.curStream = msg.stream
}
data := msg.data
for {
nl := strings.IndexByte(data, '\n')
if nl < 0 {
break
}
if proc.buf.Len() > 0 {
proc.buf.WriteString(data[:nl])
proc.flush()
} else {
proc.send(data[:nl])
}
data = data[nl+1:]
}
proc.buf.WriteString(data)
}
func (proc *interleavedProcessor) flush() {
if proc.buf.Len() > 0 {
proc.send(proc.buf.String())
proc.buf.Reset()
}
}
func (proc *interleavedProcessor) send(line string) {
var stream string
switch proc.curStream {
case 1:
stream = "out"
case 2:
stream = "err"
case -1:
stream = "***"
default:
stream = fmt.Sprintf("%03d", proc.curStream)
}
proc.collector.messages <- &IOMessage{
data: fmt.Sprintf("%s [%s]: %s", proc.remote.host, stream, line),
stream: proc.curStream,
}
}