internal_flush(void)
{
	static int	last_reported_send_errno = 0;

	char	   *bufptr = PqSendBuffer + PqSendStart;
	char	   *bufend = PqSendBuffer + PqSendPointer;

	while (bufptr < bufend)
	{
		int			r;

		r = secure_write(MyProcPort, bufptr, bufend - bufptr);

		if (r <= 0)
		{
			if (errno == EINTR)
				continue;		/* Ok if we were interrupted */

			/*
			 * Ok if no data writable without blocking, and the socket is in
			 * non-blocking mode.
			 */
			if (errno == EAGAIN ||
				errno == EWOULDBLOCK)
			{
				return 0;
			}

			/*
			 * Careful: an ereport() that tries to write to the client would
			 * cause recursion to here, leading to stack overflow and core
			 * dump!  This message must go *only* to the postmaster log.
			 *
			 * If a client disconnects while we're in the midst of output, we
			 * might write quite a bit of data before we get to a safe query
			 * abort point.  So, suppress duplicate log messages.
			 */
			if (errno != last_reported_send_errno)
			{
				last_reported_send_errno = errno;
				ereport(COMMERROR,
						(errcode_for_socket_access(),
						 errmsg("could not send data to client: %m")));
			}

			/*
			 * We drop the buffered data anyway so that processing can
			 * continue, even though we'll probably quit soon. We also set a
			 * flag that'll cause the next CHECK_FOR_INTERRUPTS to terminate
			 * the connection.
			 */
			PqSendStart = PqSendPointer = 0;
			ClientConnectionLost = 1;
			InterruptPending = 1;
			return EOF;
		}

		last_reported_send_errno = 0;	/* reset after any successful send */
		bufptr += r;
		PqSendStart += r;
	}

	PqSendStart = PqSendPointer = 0;
	return 0;
}
Unknown