自学教程：C++ CheckConnection函数代码示例

void StepManiaLanServer::UpdateClients(){	//Go through all the clients and check to see if it is being used.	//If so then try to get a backet and parse the data.	for (unsigned int x = 0; x < Client.size(); ++x)		if (CheckConnection(x) && (Client[x]->GetData(Packet) >= 0))			ParseData(Packet, x);}

/* * Set values for sequence */intSetValGTM(char *seqname, GTM_Sequence nextval, bool iscalled){	GTM_SequenceKeyData seqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	return conn ? set_val(conn, &seqkey, nextval, iscalled) : -1;}

/* * Alter a sequence on the GTM */intAlterSequenceGTM(char *seqname, GTM_Sequence increment, GTM_Sequence minval,				 GTM_Sequence maxval, GTM_Sequence startval, GTM_Sequence lastval, bool cycle, bool is_restart){	GTM_SequenceKeyData seqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	return conn ? alter_sequence(conn, &seqkey, increment, minval, maxval, startval, lastval, cycle, is_restart) : 0;}

void JohanCity::UpdateTime(float dt) {	clock->Start();		// Optimized version of power checking...	CheckPower(); // crawls from power plant outward...		// Optimized version of water checking...	CheckWater(); // crawls from water source outward...		// TODO: optimize?	CheckConnection();	checktilems = clock->Reset() * 1000.0f;		// Then apply tile info to buildings	CheckBuildingRequisites();		checkbuildingms = clock->Reset() * 1000.0f;	// Done checking for required items? Spend the RCI	for(int i = 0;i < tiles.size();i++) {		for(int j = 0;j < tiles[i].size();j++) {			TileType type = tiles[i][j]->type;			if(type == ttResidential || type == ttCommercial || type == ttIndustrial) {				tiles[i][j]->UpdateTime(dt);			}						// Undo checks (so they won't get invalid)?			tiles[i][j]->checkid = -1;//			tiles[i][j]->powered = false;//			tiles[i][j]->watered = false;//			tiles[i][j]->connected = false;		}	}		updatetilems = clock->Reset() * 1000.0f;		for(std::list<Building*>::iterator i = buildings.begin();i != buildings.end();i++) {		Building* building = *i;		building->UpdateTime(dt);	}		updatebuildingms = clock->Reset() * 1000.0f;		snprintf(timingreport,256,		"Check tile time: %.2f ms/r/nCheck building time: %.2f ms/r/nUpdate tile time: %.2f ms/r/nUpdate building time: %.2f ms/r/n",		checktilems,		checkbuildingms,		updatetilems,		updatebuildingms);		UpdateBuffers();}

/* * Drop the sequence depending the key type * * Type of Sequence name use in key; *		GTM_SEQ_FULL_NAME, full name of sequence *		GTM_SEQ_DB_NAME, DB name part of sequence key */intDropSequenceGTM(char *name, GTM_SequenceKeyType type){	GTM_SequenceKeyData seqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(name) + 1;	seqkey.gsk_key = name;	seqkey.gsk_type = type;	return conn ? close_sequence(conn, &seqkey) : -1;}

/* * Create a sequence on the GTM. */intCreateSequenceGTM(char *seqname, GTM_Sequence increment, GTM_Sequence minval,				  GTM_Sequence maxval, GTM_Sequence startval, bool cycle){	GTM_SequenceKeyData seqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	return conn ? open_sequence(conn, &seqkey, increment, minval, maxval, startval, cycle) : 0;}

/* * Rename the sequence */intRenameSequenceGTM(char *seqname, const char *newseqname){	GTM_SequenceKeyData seqkey, newseqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	newseqkey.gsk_keylen = strlen(newseqname) + 1;	newseqkey.gsk_key = (char *) newseqname;	return conn ? rename_sequence(conn, &seqkey, &newseqkey) : -1;}

/* * Report BARRIER */intReportBarrierGTM(char *barrier_id){	if (!gtm_backup_barrier)		return;	CheckConnection();	if (!conn)		return EOF;	return(report_barrier(conn, barrier_id));}

GTM_SnapshotGetSnapshotGTM(GlobalTransactionId gxid, bool canbe_grouped){	GTM_Snapshot ret_snapshot = NULL;	CheckConnection();	if (conn)		ret_snapshot = get_snapshot(conn, gxid, canbe_grouped);	if (ret_snapshot == NULL)	{		CloseGTM();		InitGTM();	}	return ret_snapshot;}

void NetworkThread::Run(){	while(ReceiveMessages())	{		if(myPacket && !myPacket.endOfPacket())		{			ParseMessages();			myPacket.clear();		}				CheckConnection();				sf::sleep(sf::milliseconds(100));	}}

GetNextValGTM(char *seqname)#endif{	GTM_Sequence ret = -1;	GTM_SequenceKeyData seqkey;#ifdef XCP	char   *coordName = IS_PGXC_COORDINATOR ? PGXCNodeName : MyCoordName;	int		coordPid = IS_PGXC_COORDINATOR ? MyProcPid : MyCoordPid;	int		status;#endif	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;#ifdef XCP	if (conn)		status = get_next(conn, &seqkey, coordName,						  coordPid, range, &ret, rangemax);	else		status = GTM_RESULT_COMM_ERROR;	/* retry once */	if (status == GTM_RESULT_COMM_ERROR)	{		CloseGTM();		InitGTM();		if (conn)			status = get_next(conn, &seqkey, coordName, coordPid,							  range, &ret, rangemax);	}	if (status != GTM_RESULT_OK)		ereport(ERROR,				(errcode(ERRCODE_INTERNAL_ERROR),				 errmsg("%s", GTMPQerrorMessage(conn))));#else	if (conn)		ret = get_next(conn, &seqkey);	if (ret < 0)	{		CloseGTM();		InitGTM();	}#endif	return ret;}

/* * AcceptResult * * Checks whether a result is valid, giving an error message if necessary; * and ensures that the connection to the backend is still up. * * Returns true for valid result, false for error state. */static boolAcceptResult(const PGresult *result){	bool		OK;	if (!result)		OK = false;	else		switch (PQresultStatus(result))		{			case PGRES_COMMAND_OK:			case PGRES_TUPLES_OK:			case PGRES_EMPTY_QUERY:			case PGRES_COPY_IN:			case PGRES_COPY_OUT:			case PGRES_COPY_BOTH:				/* Fine, do nothing */				OK = true;				break;			case PGRES_BAD_RESPONSE:			case PGRES_NONFATAL_ERROR:			case PGRES_FATAL_ERROR:				OK = false;				break;			default:				OK = false;				psql_error("unexpected PQresultStatus (%d)",						   PQresultStatus(result));				break;		}	if (!OK)	{		const char *error = PQerrorMessage(pset.db);		if (strlen(error))			psql_error("%s", error);		CheckConnection();	}	return OK;}

/* Update is run regulary and we gather the state of the Wiiremote and see if the user have pressed on a button or moved the wiiremote   This could have been done with callbacks instead but it doesn't look nice in C++*/void CWiiRemote::Update(){  if (m_DisconnectWhenPossible)  {//If the user have choosen to disconnect or lost comunication    DisconnectNow(true);    m_DisconnectWhenPossible = false;  }#ifdef CWIID_OLD  if(m_connected)  {//Here we check if the connection is suddenly broken    if (!CheckConnection())    {      DisconnectNow(true);      return;    }  }#endif}

/* * Get the next sequence value */GTM_SequenceGetNextValGTM(char *seqname){	GTM_Sequence ret = -1;	GTM_SequenceKeyData seqkey;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	if (conn)		ret =  get_next(conn, &seqkey);	if (ret < 0)	{		CloseGTM();		InitGTM();	}	return ret;}

/* * Set values for sequence */intSetValGTM(char *seqname, GTM_Sequence nextval, bool iscalled){	GTM_SequenceKeyData seqkey;#ifdef XCP	char   *coordName = IS_PGXC_COORDINATOR ? PGXCNodeName : MyCoordName;	int		coordPid = IS_PGXC_COORDINATOR ? MyProcPid : MyCoordPid;#endif	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;#ifdef XCP	return conn ? set_val(conn, &seqkey, coordName, coordPid, nextval, iscalled) : -1;#else	return conn ? set_val(conn, &seqkey, nextval, iscalled) : -1;#endif}

/* * ProcessCopyResult: if command was a COPY FROM STDIN/TO STDOUT, handle it * * Note: Utility function for use by SendQuery() only. * * Returns true if the query executed successfully, false otherwise. */static boolProcessCopyResult(PGresult *results){	bool		success = false;	if (!results)		return false;	switch (PQresultStatus(results))	{		case PGRES_TUPLES_OK:		case PGRES_COMMAND_OK:		case PGRES_EMPTY_QUERY:			/* nothing to do here */			success = true;			break;		case PGRES_COPY_OUT:			SetCancelConn();			success = handleCopyOut(pset.db, pset.queryFout);			ResetCancelConn();			break;		case PGRES_COPY_IN:			SetCancelConn();			success = handleCopyIn(pset.db, pset.cur_cmd_source,								   PQbinaryTuples(results));			ResetCancelConn();			break;		default:			break;	}	/* may need this to recover from conn loss during COPY */	if (!CheckConnection())		return false;	return success;}

/* * ProcessCopyResult: if command was a COPY FROM STDIN/TO STDOUT, handle it * * Note: Utility function for use by SendQuery() only. * * Returns true if the query executed successfully, false otherwise. */static boolProcessCopyResult(PGresult *results){	bool		success = false;	if (!results)		return false;	switch (PQresultStatus(results))	{		case PGRES_TUPLES_OK:		case PGRES_COMMAND_OK:		case PGRES_EMPTY_QUERY:			/* nothing to do here */			success = true;			break;		case PGRES_COPY_OUT:			success = handleCopyOut(pset.db, pset.queryFout);			break;		case PGRES_COPY_IN:			if (pset.cur_cmd_interactive && !QUIET())				puts(gettext("Enter data to be copied followed by a newline./n"							 "End with a backslash and a period on a line by itself."));			success = handleCopyIn(pset.db, pset.cur_cmd_source,			  pset.cur_cmd_interactive ? get_prompt(PROMPT_COPY) : NULL);			break;		default:			break;	}	/* may need this to recover from conn loss during COPY */	if (!CheckConnection())		return false;	return success;}

intPrepareTranGTM(GlobalTransactionId gxid){	int ret;	if (!GlobalTransactionIdIsValid(gxid))		return 0;	CheckConnection();	ret = prepare_transaction(conn, gxid);	/*	 * If something went wrong (timeout), try and reset GTM connection. 	 * We will close the transaction locally anyway, and closing GTM will force	 * it to be closed on GTM.	 */	if (ret < 0)	{		CloseGTM();		InitGTM();	}	return ret;}

bool cSQL::SendCommand(const String &request){#ifdef NODB   return true;#endif   if (!CheckConnection())   {      return false;   }   try   {      if (mEnableLog)         log.push_back(Time().TimeString() + "---" + request);      cmd->CommandText = request;      cmd->Execute();      return true;   }   catch (Exception &exception)   {      return false;   }}

GlobalTransactionIdBeginTranGTM(GTM_Timestamp *timestamp){	GlobalTransactionId  xid = InvalidGlobalTransactionId;	CheckConnection();	// TODO Isolation level	if (conn)		xid =  begin_transaction(conn, GTM_ISOLATION_RC, timestamp);	/* If something went wrong (timeout), try and reset GTM connection 	 * and retry. This is safe at the beginning of a transaction.	 */	if (!TransactionIdIsValid(xid))	{		CloseGTM();		InitGTM();		if (conn)			xid = begin_transaction(conn, GTM_ISOLATION_RC, timestamp);	}	return xid;}

int main(){ DBusServer* server;	DBusConnection* connection;	DBusError error;	char* address;			dbus_error_init(&error);	server = dbus_server_listen("tcp:host=localhost,port=8085", &error);		if(!server)	{		std_log(LOG_FILENAME_LINE, "Error :: %s/n%s",error.name,error.message);		std_log(LOG_FILENAME_LINE, "Fail");		create_xml(1);		return 1;	}		address = dbus_server_get_address(server);	std_log(LOG_FILENAME_LINE, "Address :; %s",address);			connection = dbus_connection_open_private("tcp:host=localhost,port=8085", &error);	if(!CheckConnection(connection, &error))		return 1;		dbus_connection_close(connection);	dbus_connection_unref(connection);	dbus_shutdown();		dbus_server_disconnect(server);			std_log(LOG_FILENAME_LINE, "SUCCESS");		create_xml(0);	return 0;}

/* * Register Given Node * Connection for registering is just used once then closed */intRegisterGTM(GTM_PGXCNodeType type, GTM_PGXCNodePort port, char *datafolder){	int ret;	CheckConnection();	if (!conn)		return EOF;	ret = node_register(conn, type, port, PGXCNodeName, datafolder);	/* If something went wrong, retry once */	if (ret < 0)	{		CloseGTM();		InitGTM();		if (conn)			ret = node_register(conn, type, port, PGXCNodeName, datafolder);	}	return ret;}

/* * Get the next sequence value */GTM_SequenceGetNextValGTM(char *seqname){	GTM_Sequence ret = -1;	GTM_SequenceKeyData seqkey;	int	status;	CheckConnection();	seqkey.gsk_keylen = strlen(seqname) + 1;	seqkey.gsk_key = seqname;	if (conn)		status =  get_next(conn, &seqkey, &ret);	if (status != GTM_RESULT_OK)	{		CloseGTM();		InitGTM();		ereport(ERROR,				(errcode(ERRCODE_INTERNAL_ERROR),				 errmsg("%s", GTMPQerrorMessage(conn))));	}	return ret;}

GlobalTransactionIdBeginTranAutovacuumGTM(void){	GlobalTransactionId  xid = InvalidGlobalTransactionId;	CheckConnection();	// TODO Isolation level	if (conn)		xid =  begin_transaction_autovacuum(conn, GTM_ISOLATION_RC);	/*	 * If something went wrong (timeout), try and reset GTM connection and retry.	 * This is safe at the beginning of a transaction.	 */	if (!TransactionIdIsValid(xid))	{		CloseGTM();		InitGTM();		if (conn)			xid =  begin_transaction_autovacuum(conn, GTM_ISOLATION_RC);	}	return xid;}

intCommitTranGTM(GlobalTransactionId gxid, int waited_xid_count,		GlobalTransactionId *waited_xids){	int ret;	if (!GlobalTransactionIdIsValid(gxid))		return 0;	CheckConnection();#ifdef XCP	ret = -1;	if (conn)#endif	ret = commit_transaction(conn, gxid, waited_xid_count, waited_xids);	/*	 * If something went wrong (timeout), try and reset GTM connection.	 * We will close the transaction locally anyway, and closing GTM will force	 * it to be closed on GTM.	 */	if (ret < 0)	{		CloseGTM();		InitGTM();#ifdef XCP		if (conn)			ret = commit_transaction(conn, gxid, waited_xid_count, waited_xids);#endif	}	/* Close connection in case commit is done by autovacuum worker or launcher */	if (IsAutoVacuumWorkerProcess() || IsAutoVacuumLauncherProcess())		CloseGTM();	currentGxid = InvalidGlobalTransactionId;	return ret;}

/* * AcceptResult * * Checks whether a result is valid, giving an error message if necessary; * resets cancelConn as needed, and ensures that the connection to the backend * is still up. * * Returns true for valid result, false for error state. */static boolAcceptResult(const PGresult *result){	bool		OK = true;	ResetCancelConn();	if (!result)		OK = false;	else		switch (PQresultStatus(result))		{			case PGRES_COMMAND_OK:			case PGRES_TUPLES_OK:			case PGRES_EMPTY_QUERY:			case PGRES_COPY_IN:				/* Fine, do nothing */				break;			case PGRES_COPY_OUT:				/* keep cancel connection for copy out state */				SetCancelConn();				break;			default:				OK = false;				break;		}	if (!OK)	{		psql_error("%s", PQerrorMessage(pset.db));		CheckConnection();	}	return OK;}

/* * For a prepared transaction, commit the gxid used for PREPARE TRANSACTION * and for COMMIT PREPARED. */intCommitPreparedTranGTM(GlobalTransactionId gxid, GlobalTransactionId prepared_gxid){	int ret = 0;	if (!GlobalTransactionIdIsValid(gxid) || !GlobalTransactionIdIsValid(prepared_gxid))		return ret;	CheckConnection();	ret = commit_prepared_transaction(conn, gxid, prepared_gxid);	/*	 * If something went wrong (timeout), try and reset GTM connection.	 * We will close the transaction locally anyway, and closing GTM will force	 * it to be closed on GTM.	 */	if (ret < 0)	{		CloseGTM();		InitGTM();	}	currentGxid = InvalidGlobalTransactionId;	return ret;}

intRollbackTranGTM(GlobalTransactionId gxid){	int ret = -1;	if (!GlobalTransactionIdIsValid(gxid))		return 0;	CheckConnection();	if (conn)		ret = abort_transaction(conn, gxid);	/*	 * If something went wrong (timeout), try and reset GTM connection. 	 * We will abort the transaction locally anyway, and closing GTM will force	 * it to end on GTM.	 */	if (ret < 0)	{		CloseGTM();		InitGTM();	}	return ret;}