C++ PG_PROTOCOL_MAJOR函数代码示例

static Source *
CreateRemoteSource(const char *path, TupleDesc desc)
{
	RemoteSource *self = (RemoteSource *) palloc0(sizeof(RemoteSource));
	self->base.close = (SourceCloseProc) RemoteSourceClose;

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
	{
		/* new way */
		StringInfoData	buf;
		int16			format;
		int				nattrs;
		int				i;

		self->base.read = (SourceReadProc) RemoteSourceRead;

		/* count valid fields */
		for (nattrs = 0, i = 0; i < desc->natts; i++)
		{
			if (desc->attrs[i]->attisdropped)
				continue;
			nattrs++;
		}

		format = (IsBinaryCopy() ? 1 : 0);
		pq_beginmessage(&buf, 'G');
		pq_sendbyte(&buf, format);		/* overall format */
		pq_sendint(&buf, nattrs, 2);
		for (i = 0; i < nattrs; i++)
			pq_sendint(&buf, format, 2);		/* per-column formats */
		pq_endmessage(&buf);
		self->buffer = makeStringInfo();
	}
	else if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 2)
	{
		self->base.read = (SourceReadProc) RemoteSourceReadOld;

		/* old way */
		if (IsBinaryCopy())
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			errmsg("COPY BINARY is not supported to stdout or from stdin")));
		pq_putemptymessage('G');
	}
	else
	{
		self->base.read = (SourceReadProc) RemoteSourceReadOld;

		/* very old way */
		if (IsBinaryCopy())
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			errmsg("COPY BINARY is not supported to stdout or from stdin")));
		pq_putemptymessage('D');
	}
	/* We *must* flush here to ensure FE knows it can send. */
	pq_flush();

	return (Source *) self;
}

/* ----------------
 *		ReadyForQuery - tell dest that we are ready for a new query
 *
 *		The ReadyForQuery message is sent in protocol versions 2.0 and up
 *		so that the FE can tell when we are done processing a query string.
 *		In versions 3.0 and up, it also carries a transaction state indicator.
 *
 *		Note that by flushing the stdio buffer here, we can avoid doing it
 *		most other places and thus reduce the number of separate packets sent.
 * ----------------
 */
void
ReadyForQuery(CommandDest dest)
{
	switch (dest)
	{
		case DestRemote:
		case DestRemoteExecute:
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
			{
				StringInfoData buf;

				pq_beginmessage(&buf, 'Z');
				pq_sendbyte(&buf, TransactionBlockStatusCode());
				pq_endmessage(&buf);
			}
			else if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 2)
				pq_putemptymessage('Z');
			/* Flush output at end of cycle in any case. */
			pq_flush();
			break;

		case DestNone:
		case DestDebug:
		case DestSPI:
		case DestTuplestore:
		case DestIntoRel:
		case DestCopyOut:
			break;
	}
}

static void
SendResultDescriptionMessage(AttributeDefinition *attrs, int natts)
{
	int			proto = PG_PROTOCOL_MAJOR(FrontendProtocol);
	int			i;
	StringInfoData buf;

	pq_beginmessage(&buf, 'T'); /* tuple descriptor message type */
	pq_sendint(&buf, natts, 2);	/* # of attrs in tuples */

	for (i = 0; i < natts; ++i)
	{
		pq_sendstring(&buf, attrs[i].name);
		/* column ID info appears in protocol 3.0 and up */
		if (proto >= 3)
		{
			pq_sendint(&buf, 0, 4);
			pq_sendint(&buf, 0, 2);
		}
		/* If column is a domain, send the base type and typmod instead */
		pq_sendint(&buf, attrs[i].typid, sizeof(Oid));
		pq_sendint(&buf, attrs[i].typlen, sizeof(int16));
		/* typmod appears in protocol 2.0 and up */
		if (proto >= 2)
			pq_sendint(&buf, attrs[i].typmod, sizeof(int32));
		/* format info appears in protocol 3.0 and up */
		if (proto >= 3)
			pq_sendint(&buf, 0, 2);
	}

	pq_endmessage(&buf);
}

/*
 * Send NOTIFY message to my front end.
 */
static void
NotifyMyFrontEnd(char *relname, int32 listenerPID)
{
	if (whereToSendOutput == DestRemote)
	{
		StringInfoData buf;

		pq_beginmessage(&buf, 'A');
		pq_sendint(&buf, listenerPID, sizeof(int32));
		pq_sendstring(&buf, relname);
		if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
		{
			/* XXX Add parameter string here later */
			pq_sendstring(&buf, "");
		}
		pq_endmessage(&buf);

		/*
		 * NOTE: we do not do pq_flush() here.	For a self-notify, it will
		 * happen at the end of the transaction, and for incoming notifies
		 * ProcessIncomingNotify will do it after finding all the notifies.
		 */
	}
	else
		elog(INFO, "NOTIFY for %s", relname);
}

/* --------------------------------
 *		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;
}

/* ----------------
 *		NullCommand - tell dest that an empty query string was recognized
 *
 *		In FE/BE protocol version 1.0, this hack is necessary to support
 *		libpq's crufty way of determining whether a multiple-command
 *		query string is done.  In protocol 2.0 it's probably not really
 *		necessary to distinguish empty queries anymore, but we still do it
 *		for backwards compatibility with 1.0.  In protocol 3.0 it has some
 *		use again, since it ensures that there will be a recognizable end
 *		to the response to an Execute message.
 * ----------------
 */
void
NullCommand(CommandDest dest)
{
	switch (dest)
	{
		case DestRemote:
		case DestRemoteExecute:

			/*
			 * tell the fe that we saw an empty query string.  In protocols
			 * before 3.0 this has a useless empty-string message body.
			 */
			if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
				pq_putemptymessage('I');
			else
				pq_puttextmessage('I', "");
			break;

		case DestNone:
		case DestDebug:
		case DestSPI:
		case DestTuplestore:
		case DestIntoRel:
		case DestCopyOut:
			break;
	}
}

/*
 * SendRowDescriptionMessage --- send a RowDescription message to the frontend
 *
 * Notes: the TupleDesc has typically been manufactured by ExecTypeFromTL()
 * or some similar function; it does not contain a full set of fields.
 * The targetlist will be NIL when executing a utility function that does
 * not have a plan.  If the targetlist isn't NIL then it is a Query node's
 * targetlist; it is up to us to ignore resjunk columns in it.  The formats[]
 * array pointer might be NULL (if we are doing Describe on a prepared stmt);
 * send zeroes for the format codes in that case.
 */
void
SendRowDescriptionMessage(TupleDesc typeinfo, List *targetlist, int16 *formats)
{
	Form_pg_attribute *attrs = typeinfo->attrs;
	int			natts = typeinfo->natts;
	int			proto = PG_PROTOCOL_MAJOR(FrontendProtocol);
	int			i;
	StringInfoData buf;
	ListCell   *tlist_item = list_head(targetlist);

	pq_beginmessage(&buf, 'T'); /* tuple descriptor message type */
	pq_sendint(&buf, natts, 2); /* # of attrs in tuples */

	for (i = 0; i < natts; ++i)
	{
		Oid			atttypid = attrs[i]->atttypid;
		int32		atttypmod = attrs[i]->atttypmod;

		pq_sendstring(&buf, NameStr(attrs[i]->attname));
		/* column ID info appears in protocol 3.0 and up */
		if (proto >= 3)
		{
			/* Do we have a non-resjunk tlist item? */
			while (tlist_item &&
				   ((TargetEntry *) lfirst(tlist_item))->resjunk)
				tlist_item = lnext(tlist_item);
			if (tlist_item)
			{
				TargetEntry *tle = (TargetEntry *) lfirst(tlist_item);

				pq_sendint(&buf, tle->resorigtbl, 4);
				pq_sendint(&buf, tle->resorigcol, 2);
				tlist_item = lnext(tlist_item);
			}
			else
			{
				/* No info available, so send zeroes */
				pq_sendint(&buf, 0, 4);
				pq_sendint(&buf, 0, 2);
			}
		}
		/* If column is a domain, send the base type and typmod instead */
		atttypid = getBaseTypeAndTypmod(atttypid, &atttypmod);
		pq_sendint(&buf, (int) atttypid, sizeof(atttypid));
		pq_sendint(&buf, attrs[i]->attlen, sizeof(attrs[i]->attlen));
		/* typmod appears in protocol 2.0 and up */
		if (proto >= 2)
			pq_sendint(&buf, atttypmod, sizeof(atttypmod));
		/* format info appears in protocol 3.0 and up */
		if (proto >= 3)
		{
			if (formats)
				pq_sendint(&buf, formats[i], 2);
			else
				pq_sendint(&buf, 0, 2);
		}
	}
	pq_endmessage(&buf);
}

static int
pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
{
	int			ret;
	char	   *crypt_pwd = NULL;
	const char *pwd_to_send;

	/* Encrypt the password if needed. */

	switch (areq)
	{
		case AUTH_REQ_MD5:
			{
				char	   *crypt_pwd2;

				/* Allocate enough space for two MD5 hashes */
				crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
				if (!crypt_pwd)
				{
					printfPQExpBuffer(&conn->errorMessage,
									  libpq_gettext("out of memory\n"));
					return STATUS_ERROR;
				}

				crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
				if (!pg_md5_encrypt(password, conn->pguser,
									strlen(conn->pguser), crypt_pwd2))
				{
					free(crypt_pwd);
					return STATUS_ERROR;
				}
				if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), conn->md5Salt,
									sizeof(conn->md5Salt), crypt_pwd))
				{
					free(crypt_pwd);
					return STATUS_ERROR;
				}

				pwd_to_send = crypt_pwd;
				break;
			}
		case AUTH_REQ_PASSWORD:
			pwd_to_send = password;
			break;
		default:
			return STATUS_ERROR;
	}
	/* Packet has a message type as of protocol 3.0 */
	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
		ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
	else
		ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
	if (crypt_pwd)
		free(crypt_pwd);
	return ret;
}

static void
printtup_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
{
	DR_printtup *myState = (DR_printtup *) self;
	Portal		portal = myState->portal;

	/* create buffer to be used for all messages */
	initStringInfo(&myState->buf);

	/*
	 * Create a temporary memory context that we can reset once per row to
	 * recover palloc'd memory.  This avoids any problems with leaks inside
	 * datatype output routines, and should be faster than retail pfree's
	 * anyway.
	 */
	myState->tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
												"printtup",
												ALLOCSET_DEFAULT_SIZES);

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
	{
		/*
		 * Send portal name to frontend (obsolete cruft, gone in proto 3.0)
		 *
		 * If portal name not specified, use "blank" portal.
		 */
		const char *portalName = portal->name;

		if (portalName == NULL || portalName[0] == '\0')
			portalName = "blank";

		pq_puttextmessage('P', portalName);
	}

	/*
	 * If we are supposed to emit row descriptions, then send the tuple
	 * descriptor of the tuples.
	 */
	if (myState->sendDescrip)
		SendRowDescriptionMessage(&myState->buf,
								  typeinfo,
								  FetchPortalTargetList(portal),
								  portal->formats);

	/* ----------------
	 * We could set up the derived attr info at this time, but we postpone it
	 * until the first call of printtup, for 2 reasons:
	 * 1. We don't waste time (compared to the old way) if there are no
	 *	  tuples at all to output.
	 * 2. Checking in printtup allows us to handle the case that the tuples
	 *	  change type midway through (although this probably can't happen in
	 *	  the current executor).
	 * ----------------
	 */
}

/* --------------------------------
 *		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.
 *
 *		returns 0 if OK, EOF if trouble
 * --------------------------------
 */
int
pq_putmessage(char msgtype, const char *s, size_t len)
{
	if (DoingCopyOut)
	{
		return EOF;
	}

	if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
	{
		if (!pq_send_mutex_lock())
		{
			return EOF;
		}
	}

	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;

	if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
		pthread_mutex_unlock(&send_mutex);

	return 0;

fail:
	if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
		pthread_mutex_unlock(&send_mutex);

	return EOF;
}

/*
 * SendRowDescriptionMessage --- send a RowDescription message to the frontend
 *
 * Notes: the TupleDesc has typically been manufactured by ExecTypeFromTL()
 * or some similar function; it does not contain a full set of fields.
 * The targetlist will be NIL when executing a utility function that does
 * not have a plan.  If the targetlist isn't NIL then it is a Query node's
 * targetlist; it is up to us to ignore resjunk columns in it.  The formats[]
 * array pointer might be NULL (if we are doing Describe on a prepared stmt);
 * send zeroes for the format codes in that case.
 */
void
SendRowDescriptionMessage(StringInfo buf, TupleDesc typeinfo,
						  List *targetlist, int16 *formats)
{
	int			natts = typeinfo->natts;
	int			proto = PG_PROTOCOL_MAJOR(FrontendProtocol);

	/* tuple descriptor message type */
	pq_beginmessage_reuse(buf, 'T');
	/* # of attrs in tuples */
	pq_sendint16(buf, natts);

	if (proto >= 3)
		SendRowDescriptionCols_3(buf, typeinfo, targetlist, formats);
	else
		SendRowDescriptionCols_2(buf, typeinfo, targetlist, formats);

	pq_endmessage_reuse(buf);
}

static void
printtup_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
{
	DR_printtup *myState = (DR_printtup *) self;
	Portal		portal = myState->portal;

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
	{
		/*
		 * Send portal name to frontend (obsolete cruft, gone in proto 3.0)
		 *
		 * If portal name not specified, use "blank" portal.
		 */
		const char *portalName = portal->name;

		if (portalName == NULL || portalName[0] == '\0')
			portalName = "blank";

		pq_puttextmessage('P', portalName);
	}

	/*
	 * If we are supposed to emit row descriptions, then send the tuple
	 * descriptor of the tuples.
	 */
	if (myState->sendDescrip)
		SendRowDescriptionMessage(typeinfo,
								  FetchPortalTargetList(portal),
								  portal->formats);

	/* ----------------
	 * We could set up the derived attr info at this time, but we postpone it
	 * until the first call of printtup, for 2 reasons:
	 * 1. We don't waste time (compared to the old way) if there are no
	 *	  tuples at all to output.
	 * 2. Checking in printtup allows us to handle the case that the tuples
	 *	  change type midway through (although this probably can't happen in
	 *	  the current executor).
	 * ----------------
	 */
}

static void
send_buffer()
{
    if (buffer_len > 0)
    {
	StringInfoData msgbuf;
	char *cursor = buffer;

	while (--buffer_len > 0)
	{
	    if (*cursor == '\0')
		*cursor = '\n';
	    cursor++;
	}

	if (*cursor != '\0')
	        ereport(ERROR,
		        (errcode(ERRCODE_INTERNAL_ERROR),
			 errmsg("internal error"),
		         errdetail("Wrong message format detected")));

	pq_beginmessage(&msgbuf, 'N');

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
	{
		pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_PRIMARY);
		pq_sendstring(&msgbuf, buffer);
		pq_sendbyte(&msgbuf, '\0');
	}
	else
	{
		*cursor++ = '\n';
		*cursor = '\0';
		pq_sendstring(&msgbuf, buffer);
	}

	pq_endmessage(&msgbuf);
	pq_flush();
    }
}

/*
 * pqPutMsgStart: begin construction of a message to the server
 *
 * msg_type is the message type byte, or 0 for a message without type byte
 * (only startup messages have no type byte)
 *
 * force_len forces the message to have a length word; otherwise, we add
 * a length word if protocol 3.
 *
 * Returns 0 on success, EOF on error
 *
 * The idea here is that we construct the message in conn->outBuffer,
 * beginning just past any data already in outBuffer (ie, at
 * outBuffer+outCount).  We enlarge the buffer as needed to hold the message.
 * When the message is complete, we fill in the length word (if needed) and
 * then advance outCount past the message, making it eligible to send.
 *
 * The state variable conn->outMsgStart points to the incomplete message's
 * length word: it is either outCount or outCount+1 depending on whether
 * there is a type byte.  If we are sending a message without length word
 * (pre protocol 3.0 only), then outMsgStart is -1.  The state variable
 * conn->outMsgEnd is the end of the data collected so far.
 */
int
pqPutMsgStart(char msg_type, bool force_len, PGconn *conn)
{
	int			lenPos;
	int			endPos;

	/* allow room for message type byte */
	if (msg_type)
		endPos = conn->outCount + 1;
	else
		endPos = conn->outCount;

	/* do we want a length word? */
	if (force_len || PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
	{
		lenPos = endPos;
		/* allow room for message length */
		endPos += 4;
	}
	else
		lenPos = -1;

	/* make sure there is room for message header */
	if (pqCheckOutBufferSpace(endPos, conn))
		return EOF;
	/* okay, save the message type byte if any */
	if (msg_type)
		conn->outBuffer[conn->outCount] = msg_type;
	/* set up the message pointers */
	conn->outMsgStart = lenPos;
	conn->outMsgEnd = endPos;
	/* length word, if needed, will be filled in by pqPutMsgEnd */

	if (conn->Pfdebug)
		fprintf(conn->Pfdebug, "To backend> Msg %c\n",
				msg_type ? msg_type : ' ');

	return 0;
}

/* ----------------
 *		Initialize: create a DestReceiver for printtup
 * ----------------
 */
DestReceiver *
printtup_create_DR(CommandDest dest, Portal portal)
{
	DR_printtup *self = (DR_printtup *) palloc(sizeof(DR_printtup));

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
		self->pub.receiveSlot = printtup;
	else
	{
		/*
		 * In protocol 2.0 the Bind message does not exist, so there is no way
		 * for the columns to have different print formats; it's sufficient to
		 * look at the first one.
		 */
		if (portal->formats && portal->formats[0] != 0)
			self->pub.receiveSlot = printtup_internal_20;
		else
			self->pub.receiveSlot = printtup_20;
	}
	self->pub.rStartup = printtup_startup;
	self->pub.rShutdown = printtup_shutdown;
	self->pub.rDestroy = printtup_destroy;
	self->pub.mydest = dest;

	self->portal = portal;

	/*
	 * Send T message automatically if DestRemote, but not if
	 * DestRemoteExecute
	 */
	self->sendDescrip = (dest == DestRemote);

	self->attrinfo = NULL;
	self->nattrs = 0;
	self->myinfo = NULL;

	return (DestReceiver *) self;
}