pqcomm.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		 * message body so as not to lose communication sync.
		 */
		PG_TRY();
		{
			enlargeStringInfo(s, len);
		}
		PG_CATCH();
		{
			if (pq_discardbytes(len) == EOF)
				ereport(COMMERROR,
						(errcode(ERRCODE_PROTOCOL_VIOLATION),
						 errmsg("incomplete message from client")));
			PG_RE_THROW();
		}
		PG_END_TRY();

		/* And grab the message */
		if (pq_getbytes(s->data, len) == EOF)
		{
			ereport(COMMERROR,
					(errcode(ERRCODE_PROTOCOL_VIOLATION),
					 errmsg("incomplete message from client")));
			return EOF;
		}
		s->len = len;
		/* Place a trailing null per StringInfo convention */
		s->data[len] = '\0';
	}

	return 0;
}


/* --------------------------------
 *		pq_putbytes		- send bytes to connection (not flushed until pq_flush)
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_putbytes(const char *s, size_t len)
{
	int			res;

	/* Should only be called by old-style COPY OUT */
	Assert(DoingCopyOut);
	/* No-op if reentrant call */
	if (PqCommBusy)
		return 0;
	PqCommBusy = true;
	res = internal_putbytes(s, len);
	PqCommBusy = false;
	return res;
}

static int
internal_putbytes(const char *s, size_t len)
{
	size_t		amount;

	while (len > 0)
	{
		/* If buffer is full, then flush it out */
		if (PqSendPointer >= PQ_BUFFER_SIZE)
			if (internal_flush())
				return EOF;
		amount = PQ_BUFFER_SIZE - PqSendPointer;
		if (amount > len)
			amount = len;
		memcpy(PqSendBuffer + PqSendPointer, s, amount);
		PqSendPointer += amount;
		s += amount;
		len -= amount;
	}
	return 0;
}

/* --------------------------------
 *		pq_flush		- flush pending output
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_flush(void)
{
	int			res;

	/* No-op if reentrant call */
	if (PqCommBusy)
		return 0;
	PqCommBusy = true;
	res = internal_flush();
	PqCommBusy = false;
	return res;
}

static int
internal_flush(void)
{
	static int	last_reported_send_errno = 0;

	char	   *bufptr = PqSendBuffer;
	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 */

			/*
			 * 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.
			 */
			PqSendPointer = 0;
			return EOF;
		}

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

	PqSendPointer = 0;
	return 0;
}


/* --------------------------------
 * Message-level I/O routines begin here.
 *
 * These routines understand about the old-style COPY OUT protocol.
 * --------------------------------
 */


/* --------------------------------
 *		pq_putmessage	- send a normal message (suppressed in COPY OUT mode)
 *
 *		If msgtype is not '\0', it is a message type code to place before
 *		the message body.  If msgtype is '\0', then the message has no type
 *		code (this is only valid in pre-3.0 protocols).
 *
 *		len is the length of the message body data at *s.  In protocol 3.0
 *		and later, a message length word (equal to len+4 because it counts
 *		itself too) is inserted by this routine.
 *
 *		All normal messages are suppressed while old-style COPY OUT is in
 *		progress.  (In practice only a few notice messages might get emitted
 *		then; dropping them is annoying, but at least they will still appear
 *		in the postmaster log.)
 *
 *		We also suppress messages generated while pqcomm.c is busy.  This
 *		avoids any possibility of messages being inserted within other
 *		messages.  The only known trouble case arises if SIGQUIT occurs
 *		during a pqcomm.c routine --- quickdie() will try to send a warning
 *		message, and the most reasonable approach seems to be to drop it.
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_putmessage(char msgtype, const char *s, size_t len)
{
	if (DoingCopyOut || PqCommBusy)
		return 0;
	PqCommBusy = true;
	if (msgtype)
		if (internal_putbytes(&msgtype, 1))
			goto fail;
	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
	{
		uint32		n32;

		n32 = htonl((uint32) (len + 4));
		if (internal_putbytes((char *) &n32, 4))
			goto fail;
	}
	if (internal_putbytes(s, len))
		goto fail;
	PqCommBusy = false;
	return 0;

fail:
	PqCommBusy = false;
	return EOF;
}

/* --------------------------------
 *		pq_startcopyout - inform libpq that an old-style COPY OUT transfer
 *			is beginning
 * --------------------------------
 */
void
pq_startcopyout(void)
{
	DoingCopyOut = true;
}

/* --------------------------------
 *		pq_endcopyout	- end an old-style COPY OUT transfer
 *
 *		If errorAbort is indicated, we are aborting a COPY OUT due to an error,
 *		and must send a terminator line.  Since a partial data line might have
 *		been emitted, send a couple of newlines first (the first one could
 *		get absorbed by a backslash...)  Note that old-style COPY OUT does
 *		not allow binary transfers, so a textual terminator is always correct.
 * --------------------------------
 */
void
pq_endcopyout(bool errorAbort)
{
	if (!DoingCopyOut)
		return;
	if (errorAbort)
		pq_putbytes("\n\n\\.\n", 5);
	/* in non-error case, copy.c will have emitted the terminator line */
	DoingCopyOut = false;
}


/*
 * Support for TCP Keepalive parameters
 */

int
pq_getkeepalivesidle(Port *port)
{
#ifdef TCP_KEEPIDLE
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return 0;

	if (port->keepalives_idle != 0)
		return port->keepalives_idle;

	if (port->default_keepalives_idle == 0)
	{
		ACCEPT_TYPE_ARG3 size = sizeof(port->default_keepalives_idle);

		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPIDLE,
					   (char *) &port->default_keepalives_idle,
					   &size) < 0)
		{
			elog(LOG, "getsockopt(TCP_KEEPIDLE) failed: %m");
			port->default_keepalives_idle = -1; /* don't know */
		}
	}

	return port->default_keepalives_idle;
#else
	return 0;
#endif
}

int
pq_setkeepalivesidle(int idle, Port *port)
{
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return STATUS_OK;

#ifdef TCP_KEEPIDLE
	if (idle == port->keepalives_idle)
		return STATUS_OK;

	if (port->default_keepalives_idle <= 0)
	{
		if (pq_getkeepalivesidle(port) < 0)
		{
			if (idle == 0)
				return STATUS_OK;		/* default is set but unknown */
			else
				return STATUS_ERROR;
		}
	}

	if (idle == 0)
		idle = port->default_keepalives_idle;

	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPIDLE,
				   (char *) &idle, sizeof(idle)) < 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPIDLE) failed: %m");
		return STATUS_ERROR;
	}

	port->keepalives_idle = idle;
#else
	if (idle != 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPIDLE) not supported");
		return STATUS_ERROR;
	}
#endif

	return STATUS_OK;
}

int
pq_getkeepalivesinterval(Port *port)
{
#ifdef TCP_KEEPINTVL
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return 0;

	if (port->keepalives_interval != 0)
		return port->keepalives_interval;

	if (port->default_keepalives_interval == 0)
	{
		ACCEPT_TYPE_ARG3 size = sizeof(port->default_keepalives_interval);

		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPINTVL,
					   (char *) &port->default_keepalives_interval,
					   &size) < 0)
		{
			elog(LOG, "getsockopt(TCP_KEEPINTVL) failed: %m");
			port->default_keepalives_interval = -1;		/* don't know */
		}
	}

	return port->default_keepalives_interval;
#else
	return 0;
#endif
}

int
pq_setkeepalivesinterval(int interval, Port *port)
{
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return STATUS_OK;

#ifdef TCP_KEEPINTVL
	if (interval == port->keepalives_interval)
		return STATUS_OK;

	if (port->default_keepalives_interval <= 0)
	{
		if (pq_getkeepalivesinterval(port) < 0)
		{
			if (interval == 0)
				return STATUS_OK;		/* default is set but unknown */
			else
				return STATUS_ERROR;
		}
	}

	if (interval == 0)
		interval = port->default_keepalives_interval;

	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPINTVL,
				   (char *) &interval, sizeof(interval)) < 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPINTVL) failed: %m");
		return STATUS_ERROR;
	}

	port->keepalives_interval = interval;
#else
	if (interval != 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPINTVL) not supported");
		return STATUS_ERROR;
	}
#endif

	return STATUS_OK;
}

int
pq_getkeepalivescount(Port *port)
{
#ifdef TCP_KEEPCNT
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return 0;

	if (port->keepalives_count != 0)
		return port->keepalives_count;

	if (port->default_keepalives_count == 0)
	{
		ACCEPT_TYPE_ARG3 size = sizeof(port->default_keepalives_count);

		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPCNT,
					   (char *) &port->default_keepalives_count,
					   &size) < 0)
		{
			elog(LOG, "getsockopt(TCP_KEEPCNT) failed: %m");
			port->default_keepalives_count = -1;		/* don't know */
		}
	}

	return port->default_keepalives_count;
#else
	return 0;
#endif
}

int
pq_setkeepalivescount(int count, Port *port)
{
	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
		return STATUS_OK;

#ifdef TCP_KEEPCNT
	if (count == port->keepalives_count)
		return STATUS_OK;

	if (port->default_keepalives_count <= 0)
	{
		if (pq_getkeepalivescount(port) < 0)
		{
			if (count == 0)
				return STATUS_OK;		/* default is set but unknown */
			else
				return STATUS_ERROR;
		}
	}

	if (count == 0)
		count = port->default_keepalives_count;

	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPCNT,
				   (char *) &count, sizeof(count)) < 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPCNT) failed: %m");
		return STATUS_ERROR;
	}

	port->keepalives_count = count;
#else
	if (count != 0)
	{
		elog(LOG, "setsockopt(TCP_KEEPCNT) not supported");
		return STATUS_ERROR;
	}
#endif

	return STATUS_OK;
}