• opla (11/11) Nov 16 2015 Does anyone know if it's possible to monitor the events that
• Justin Whear (22/37) Nov 16 2015 You can use poll on the file descriptor (which can be gotten with

opla <opla opla.la> writes:

Does anyone know if it's possible to monitor the events that 
happen on the output stream of a piped process ?

I'm stuck on doc:

- https://www.win.tue.nl/~aeb/linux/lk/lk-12.html
- http://www.ibm.com/developerworks/library/l-ubuntu-inotify/
- http://linux.die.net/man/2/inotify_add_watch

inotify_add_watch second argument seems to be a file name. The 
only thing available is a std.stdio.File with a handle.

The goal is to create an asynchronous process with a least one 
notification that would happen when the process terminates, maybe 
when the output stream is written too.

Justin Whear <justin economicmodeling.com> writes:

On Mon, 16 Nov 2015 23:08:46 +0000, opla wrote:

 Does anyone know if it's possible to monitor the events that happen on
 the output stream of a piped process ?
 
 I'm stuck on doc:
 
 - https://www.win.tue.nl/~aeb/linux/lk/lk-12.html -
 http://www.ibm.com/developerworks/library/l-ubuntu-inotify/
 - http://linux.die.net/man/2/inotify_add_watch
 
 inotify_add_watch second argument seems to be a file name. The only
 thing available is a std.stdio.File with a handle.
 
 The goal is to create an asynchronous process with a least one
 notification that would happen when the process terminates, maybe when
 the output stream is written too.

You can use poll on the file descriptor (which can be gotten with 
File.fileno).  Basically something like this (untested):

while (ImWaiting)
{
	if (processPipes.stdout.eof)
	{
		// The child is done writing (has exited, generally 
speaking)
	}

	//TODO set up poll items
	pollfd pfd = { processPipes.stdout.fileno, POLLIN };

	// Use 0 for timeout so that we don't wait;  if you don't have 
anything else
	//  to do, you can use a real timeout value
	if (1 == poll(&pfd, 1, 0))
	{
		// New data is available on the child's stdout, do 
something with it
	}

	// Do other things, sleep, etc.
}