Re: Is there any way for non-blocking IO with phobos?

[Kagamin via Digitalmars-d-learn]

On Tuesday, 13 November 2018 at 13:52:57 UTC, Sobaya wrote:
But I don't know how many lines are sent from the server for an 
input, so readln function blocks.


Read lines in another thread and send them to the main thread 
with std.concurrency.

Re: Is there any way for non-blocking IO with phobos?

[Rémy Mouëza via Digitalmars-d-learn]

On Tuesday, 13 November 2018 at 13:52:57 UTC, Sobaya wrote:

I want to connect to a server and communicate with ssh.

So I tried to spawn the process of ssh using pipeProcess 
function, and read/write with its pipe's stdin and stdout.


But I don't know how many lines are sent from the server for an 
input, so readln function blocks.


I think this can be solved with non-blocking IO, but I cannot 
find how do I use non-blocking IO with phobos.


Please give me any ideas.

Thanks.


I had some success with the "hasdata" package available on 
code.dlang.org:

https://code.dlang.org/packages/hasdata

Below is a sample program that I have tested on Linux:
--
/+ dub.sdl:
name "non-blocking-io"
description "A non blocking IO example using hasdata."
authors "Rémy J. A. Mouëza"
license "MIT"
dependency "hasdata" version="~>1.1.0"
-- sourcePaths "."
configuration "application" {
targetType "executable"
}
+/
// Written in the D programming language: http://dlang.org
import std.process;
import std.string;
import std.range;
import std.stdio;

import core.thread;

import hasdata;


struct NonBlockingPs {
/// The underlying vlc process.
ProcessPipes ps;
alias ps this;

immutable bufsize = 8;

this (string [] args...) {
this.ps = pipeProcess (args,
Redirect.stdin  |
Redirect.stdout |
Redirect.stderrToStdout);
}

~this () {
if (! ps.pid.tryWait.terminated) {
ps.pid.kill ();
}
}

string [] readlines () {
string lines;
string line;
char [bufsize] buffer;

try {
int loop = 16;

while (loop -- > 0 && ps.stdout.hasData) {
line = cast (string) ps.stdout.rawRead (buffer);

if (! line.empty) {
lines ~= line;
}
}
}
catch (Exception e) {
"Exception: %s".writeln (e);
}
return lines.splitLines ();
}
}


void main () {

NonBlockingPs ps = NonBlockingPs ("bash", "-c", `
for i in {1..10}; do
printf "hello %02d" $i
sleep 1
done
`);

while (! ps.pid.tryWait.terminated) {
string [] text = ps.readlines ();

if (text.empty) {
"Nothing to read for now".writeln;
}
else {
"=> %s".writefln (text.join ("\n => "));
}
Thread.getThis ().sleep (500.dur!"msecs");
}
}
--

And here is the output of its execution (launched with `dub 
nbio.d` -- as I named the file `nbio.d`):


Nothing to read for now
=> hello 01
Nothing to read for now
=> hello 02
Nothing to read for now
=> hello 03
Nothing to read for now
=> hello 04
Nothing to read for now
=> hello 05
Nothing to read for now
=> hello 06
Nothing to read for now
=> hello 07
Nothing to read for now
=> hello 08
Nothing to read for now
=> hello 09
Nothing to read for now
=> hello 10
Nothing to read for now

Re: Is there any way for non-blocking IO with phobos?

[Steven Schveighoffer via Digitalmars-d-learn]

On 11/13/18 8:52 AM, Sobaya wrote:

I want to connect to a server and communicate with ssh.

So I tried to spawn the process of ssh using pipeProcess function, and 
read/write with its pipe's stdin and stdout.


But I don't know how many lines are sent from the server for an input, 
so readln function blocks.


I think this can be solved with non-blocking IO, but I cannot find how 
do I use non-blocking IO with phobos.


Please give me any ideas.


Phobos process pipes use std.stdio.File and therefore FILE * as 
underlying mechanism. I don't think you can do this non-blocking.


You could extract the FILE *, and extract the file descriptor, and do it 
manually. Only way I can think of.


-Steve

Is there any way for non-blocking IO with phobos?

[Sobaya via Digitalmars-d-learn]

I want to connect to a server and communicate with ssh.

So I tried to spawn the process of ssh using pipeProcess 
function, and read/write with its pipe's stdin and stdout.


But I don't know how many lines are sent from the server for an 
input, so readln function blocks.


I think this can be solved with non-blocking IO, but I cannot 
find how do I use non-blocking IO with phobos.


Please give me any ideas.

Thanks.