Date: Wed, 28 Oct 2020 16:58:10 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	"Andrey M. Borodin" <x4mmm@yandex-team.ru>,
	=?utf-8?B?0JTQsNC90LjQuNC7INCX0LDRhdC70YvRgdGC0L7Qsg==?=
 <usernamedt@yandex-team.ru>
Subject: Re: libpq compression
Message-ID: <20201028195810.GA6732@alvherre.pgsql>
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On 2020-Oct-26, Konstantin Knizhnik wrote:

> +	while (bufptr < bufend || zpq_buffered(PqStream) != 0) /* has more data to flush or unsent data in internal compression buffer */
>  	{
> -		int			r;
> -
> -		r = secure_write(MyProcPort, bufptr, bufend - bufptr);
> -
> -		if (r <= 0)
> +		int		r;
> +		size_t  processed = 0;
> +		size_t  available = bufend - bufptr;
> +		r = PqStream
> +			? zpq_write(PqStream, bufptr, available, &processed)
> +			: secure_write(MyProcPort, bufptr, available);
> +		bufptr += processed;
> +		PqSendStart += processed;

This bit is surprising to me.  I thought the whole zpq_write() thing
should be hidden inside secure_write, so internal_flush would continue
to call just secure_write; and it is that routine's responsibility to
call zpq_write or be_tls_write or secure_raw_write etc according to
compile-time options and socket state.