Function PQconnectPoll

src/interfaces/libpq/fe-connect.c:2321–3965

---------------- * PQconnectPoll * * Poll an asynchronous connection. * * Returns a PostgresPollingStatusType. * Before calling this function, use select(2) to determine when data * has arrived.. * * You must call PQfinish whether or not this fails. * * This function and PQconnectStart are intended to allow connections to be * made without blocking the execution of your program on rem

 * ----------------
 */
PostgresPollingStatusType
PQconnectPoll(PGconn *conn)
{
	bool		reset_connection_state_machine = false;
	bool		need_new_connection = false;
	PGresult   *res;
	char		sebuf[PG_STRERROR_R_BUFLEN];
	int			optval;

	if (conn == NULL)
		return PGRES_POLLING_FAILED;

	/* Get the new data */
	switch (conn->status)
	{
			/*
			 * We really shouldn't have been polled in these two cases, but we
			 * can handle it.
			 */
		case CONNECTION_BAD:
			return PGRES_POLLING_FAILED;
		case CONNECTION_OK:
			return PGRES_POLLING_OK;

			/* These are reading states */
		case CONNECTION_AWAITING_RESPONSE:
		case CONNECTION_AUTH_OK:
		case CONNECTION_CHECK_WRITABLE:
		case CONNECTION_CONSUME:
		case CONNECTION_CHECK_STANDBY:
			{
				/* Load waiting data */
				int			n = pqReadData(conn);

				if (n < 0)
					goto error_return;
				if (n == 0)
					return PGRES_POLLING_READING;

				break;
			}

			/* These are writing states, so we just proceed. */
		case CONNECTION_STARTED:
		case CONNECTION_MADE:
			break;

			/* Special cases: proceed without waiting. */
		case CONNECTION_SSL_STARTUP:
		case CONNECTION_NEEDED:
		case CONNECTION_GSS_STARTUP:
		case CONNECTION_CHECK_TARGET:
			break;

		default:
			appendPQExpBufferStr(&conn->errorMessage,
								 libpq_gettext("invalid connection state, probably indicative of memory corruption\n"));
			goto error_return;