Re: [PATCH 1/2] run-command: Remove set_nonblocking

[Junio C Hamano <gitster@pobox.com>]

Stefan Beller <sbeller@google.com> writes:

> strbuf_read_once can also operate on blocking file descriptors if we are
> sure they are ready. The poll (2) command however makes sure this is the
> case.
>
> Reading the manual for poll (2), there may be spurious returns indicating
> readiness but that is for network sockets only. Pipes should be unaffected.

Given the presence of "for example" in that bug section, I wouldn't
say "only" or "should be unaffected".

> By having this patch, we rely on the correctness of poll to return
> only pipes ready to read.

We rely on two things.  One is for poll to return only pipes that are 
non-empty.  The other is for read from a non-empty pipe not to block.

>
> This fixes compilation in Windows.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---

Thanks.  Let's apply these fixes on sb/submodule-parallel-fetch,
merge the result to 'next' and have people play with it.

>  run-command.c | 13 -------------
>  1 file changed, 13 deletions(-)
>
> diff --git a/run-command.c b/run-command.c
> index 0a3c24e..51d078c 100644
> --- a/run-command.c
> +++ b/run-command.c
> @@ -1006,17 +1006,6 @@ static void pp_cleanup(struct parallel_processes *pp)
>  	sigchain_pop_common();
>  }
>  
> -static void set_nonblocking(int fd)
> -{
> -	int flags = fcntl(fd, F_GETFL);
> -	if (flags < 0)
> -		warning("Could not get file status flags, "
> -			"output will be degraded");
> -	else if (fcntl(fd, F_SETFL, flags | O_NONBLOCK))
> -		warning("Could not set file status flags, "
> -			"output will be degraded");
> -}
> -
>  /* returns
>   *  0 if a new task was started.
>   *  1 if no new jobs was started (get_next_task ran out of work, non critical
> @@ -1052,8 +1041,6 @@ static int pp_start_one(struct parallel_processes *pp)
>  		return code ? -1 : 1;
>  	}
>  
> -	set_nonblocking(pp->children[i].process.err);
> -
>  	pp->nr_processes++;
>  	pp->children[i].in_use = 1;
>  	pp->pfd[i].fd = pp->children[i].process.err;