/// <summary>
/// Must be called before any COM call.
/// </summary>
/// <typeparam name="T">The interface to used when making the call.</typeparam>
/// <param name="parent">Parent COM object</param>
/// <param name="methodName">Name of the method.</param>
/// <param name="isRequiredInterface">if set to <c>true</c> interface is an required interface and and exception is thrown on error.</param>
/// <returns></returns>
protected T BeginComCall <T>(object parent, string methodName, bool isRequiredInterface) where T : class
{
Utils.Trace(Utils.TraceMasks.ExternalSystem, "{0} called.", methodName);
lock (lock_)
{
outstandingCalls_++;
if (parent == null)
{
if (isRequiredInterface)
{
throw new NotConnectedException();
}
}
T comObject = parent as T;
if (comObject == null)
{
if (isRequiredInterface)
{
throw new NotSupportedException(Utils.Format("OPC Interface '{0}' is a required interface but not supported by the server.", typeof(T).Name));
}
else
{
Utils.Trace(Utils.TraceMasks.ExternalSystem, "OPC Interface '{0}' is not supported by server but it is only an optional one.", typeof(T).Name);
}
}
DCOMCallWatchdog.Set();
return(comObject);
}
}
/// <summary>
/// Must be called in the finally block after making a COM call.
/// </summary>
/// <param name="methodName">Name of the method.</param>
protected void EndComCall(string methodName)
{
Utils.Trace(Utils.TraceMasks.ExternalSystem, "{0} completed.", methodName);
lock (lock_)
{
outstandingCalls_--;
DCOMCallWatchdog.Reset();
}
}
/// <summary>
/// Disables ability to cancel synchronous calls to the server
/// </summary>
public void DisableDCOMCallCancellation()
{
DCOMCallWatchdog.Disable();
}
/// <summary>
/// Allows for cancellation of DCOM interface method calls to the server. By default DCOM interface calls will wait the default DCOM timeout
/// to fail - this method allows for tighter control of the timeout to wait before cancelling the call. This is most useful during connect or any operation
/// where it is not practical to wait 1+ minute(s) for the DCOM call to fail. Note that DCOM calls can only be controlled on a COM Single Threaded Apartment thread -
/// use the [STAThread] attribute on your application entry point or use Thread SetThreadApartment before the thread the server is operating on is created to STA.
/// </summary>
/// <param name="timeout">The synchronous call timeout</param>
public void EnableDCOMCallCancellation(TimeSpan timeout = default)
{
DCOMCallWatchdog.Enable(timeout);
}
