Re: [Tarantool-patches] [PATCH 1/5] popen: Introduce a backend engine

[Konstantin Osipov <kostja.osipov@gmail.com>]

* Cyrill Gorcunov <gorcunov@gmail.com> [19/11/28 23:46]:
> +/**
> + * popen_write - write data to the child stdin
> + * @handle:	popen handle
> + * @buf:	data to write
> + * @count:	number of bytes to write
> + * @flags:	a flag representing stdin peer
> + *
> + * Returns number of bytes written or -1 on error.
> + */
> +ssize_t
> +popen_write(struct popen_handle *handle, void *buf,
> +	    size_t count, unsigned int flags)
> +{
> +	if (!popen_may_io(handle, STDIN_FILENO, flags))
> +		return -1;
> +
> +	say_debug("popen: %d: write idx %d",
> +		  handle->pid, STDIN_FILENO);
> +
> +	return write(handle->fds[STDIN_FILENO], buf, count);

I don't understand, is this blocking or not?

If this is blocking, where is it supposed to be called from?

Shouldn't you be using a non-blocking I/O like coio does?

Besides, even though I realize it's a pipe, so real world
return values may be different, but write() can return a partial
result even in blocking mode. Why did you choose to design an API
which will require caller to handle partial writes?


-- 
Konstantin Osipov, Moscow, Russia