Subject: Re: [PATCH 3/6] fetch-pack: refactor add_haves()

From: Junio C Hamano <[email-masked]>
Date: Thu, 08 Apr 2021 22:20:27 -0700

Jonathan Tan <[email-masked]> writes:

> A subsequent commit will need part, but not all, of the functionality in
> add_haves(), so move some of its functionality to its sole caller
> send_fetch_request().
>
> Signed-off-by: Jonathan Tan <[email-masked]>
> ---
>  fetch-pack.c | 28 ++++++++++++----------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/fetch-pack.c b/fetch-pack.c
> index 9f3901cdba..128ad47d2a 100644
> --- a/fetch-pack.c
> +++ b/fetch-pack.c
> @@ -1195,11 +1195,9 @@ static void add_common(struct strbuf *req_buf, struct oidset *common)
>  }
>  
>  static int add_haves(struct fetch_negotiator *negotiator,
> -		     int seen_ack,
>  		     struct strbuf *req_buf,
> -		     int *haves_to_send, int *in_vain)
> +		     int *haves_to_send)
>  {
> -	int ret = 0;
>  	int haves_added = 0;
>  	const struct object_id *oid;
>  
> @@ -1209,17 +1207,10 @@ static int add_haves(struct fetch_negotiator *negotiator,
>  			break;
>  	}
>  
> -	*in_vain += haves_added;
> -	if (!haves_added || (seen_ack && *in_vain >= MAX_IN_VAIN)) {
> -		/* Send Done */
> -		packet_buf_write(req_buf, "done\n");
> -		ret = 1;
> -	}
> -
>  	/* Increase haves to send on next round */
>  	*haves_to_send = next_flush(1, *haves_to_send);
>  
> -	return ret;
> +	return haves_added;
>  }

OK, so the helper used to

 - send out have's
 - increment *in_vain with the number of have's sent out
 - decide when to send done and send it
 - increase haves-to-send for the next round.

But the new version skips the second and third step, and let the
caller be responsible for in_vain management.  The only piece of
information the caller needs to do so from this function is the
number of have's we send out, so that is what we return from the
function.

> -	/* Add initial haves */
> -	ret = add_haves(negotiator, seen_ack, &req_buf,
> -			haves_to_send, in_vain);
> +	haves_added = add_haves(negotiator, &req_buf, haves_to_send);
> +	*in_vain += haves_added;
> +	if (!haves_added || (seen_ack && *in_vain >= MAX_IN_VAIN)) {
> +		/* Send Done */
> +		packet_buf_write(&req_buf, "done\n");
> +		done_sent = 1;
> +	}

And indeed, this caller does the *in_vain management add_haves()
used to do and give "done" as needed.

> @@ -1322,7 +1318,7 @@ static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
>  		die_errno(_("unable to write request to remote"));
>  
>  	strbuf_release(&req_buf);
> -	return ret;
> +	return done_sent;

And of course, the value returned by this function is if we sent
"done", which is far easier to see with the new variable name.

Again, very nicely done.