che-1518 Fix creation zombie prosess when user closes terminal.

[AndrienkoAleksandr]

Fix creation zombie processes when user closes terminal by close button or prints command exit in the terminal without launched another processes.

Signed-off-by: Aleksandr Andrienko aandrienko@codenvy.com

[AndrienkoAleksandr]

@evoevodin @garagatyi review please.

[voievodin]

defer conn.Close()

[voievodin]

go fmt file

[voievodin]

Ok for me, @garagatyi please take a look

[garagatyi]

LGTM

[voievodin]

What do you think about the next concept:

type onceCloser struct {
    sync.Mutex
    waitGroup *sync.WaitGroup
    isDone    bool
    close     func()
}

func (wc *onceCloser) done() {
    defer wc.Unlock()
    wc.Lock()
    if wc.isDone {
        wc.isDone = true
        wc.close()
        wc.waitGroup.Done()
    }
}

then you can create 2 closers for connection and pty file:

    wg := &sync.WaitGroup{}
    fileCloser := &onceCloser{waitGroup: wg, close: func() { closeReader(reader, wp.PtyFile) }}
    connCloser := &onceCloser{waitGroup: wg, close: func() { conn.Close() }}

and pass those closers to methods that redirect data

    //read output from terminal
    go sendPtyOutputToConnection(conn, reader, connCloser)
    //write input to terminal
    go sendConnectionInputToPty(conn, reader, wp.PtyFile, fileCloser)

and obviously inside those method do defer closer.done()

after the process is finished wp.Cmd.Wait() returned use

waitAndClose(time.Second * 5, wg, fileCloser, connCloser)

which is

func waitAndClose(howLong time.Duration, wg *sync.WaitGroup, closers ...*onceCloser) {
    c := make(chan bool)
    go func() {
        defer close(c)
        wg.Wait()
    }()
    select {
    case <-c:
    case <- time.After(howLong):
        for _, closer := range closers {
            closer.done()
        }
    }
}