How to detect lost net connection

[DRowell]

I'm working on an MFC C++ app that can connect to Oracle over the net and I need to detect (within 1-2 seconds) when the network connection has been lost.

I've tried several approaches in a worker thread:

I've tried NotifyChangeEventLog with WaitForSingleObject to catch additions to the System Event log. However TCPIP entries there relating to connection loss sometimes take as much as 8 seconds to show up.

I get better response using WMI to query for Win32_NetworkAdapter instance modification events with this query (it polls every 2 seconds):

select * from __InstanceModificationEvent within 2 where TargetInstance isa \"Win32_NetworkAdapter\" and PreviousInstance.NetConnectionStatus = 2 and TargetInstance.NetConnectionStatus <> 2

However, I see a CPU hit (~20% utilization every two seconds), and that seems rather expensive.

Does anyone know of another approach that is responsive and does not involve so much CPU work.

Thanks.

[VipulPathak]

How you connect to Oracle ? Can you post a small code snippet ?

Regards.

-Vipul Pathak ;

[DRowell]

I'm logging in using Oracle Objects For OLE (OO4O), Oracle's C++ API. Something like:

ODatabase m_oracleDatabase;

...

oresult orc = m_oracleDatabase.Open(
dbname, username, password, _defaultOpenMode);

It's not like I have a socket, and even if I did, we don't want to use pinging because it's often blocked for security reasons.

[j0nas]

Another approach is to implement a timeout... If there is no timeout options for the network functions you're dealing with, you can create/simulate a timeout by having blocking calls in a worker thread.