/// <summary>
/// Internal method to create the value changed observable
/// </summary>
/// <param name="key"></param>
/// <param name="filter"></param>
/// <returns></returns>
private static IObservable <Unit> CreateKeyValuesChangedObservable(IntPtr key, RegistryNotifyFilter filter)
{
return(Observable.Create <Unit>(
obs =>
{
var eventNotify = new AutoResetEvent(false);
var result = Advapi32Api.RegNotifyChangeKeyValue(key, true, filter, eventNotify.SafeWaitHandle.DangerousGetHandle(), true);
if (result != 0)
{
obs.OnError(new Win32Exception(Marshal.GetLastWin32Error()));
}
return new CompositeDisposable(
eventNotify,
SetCallbackWhenSignalled(eventNotify,
() => {
obs.OnNext(Unit.Default);
obs.OnCompleted();
}));
}).Repeat());
}
/// <summary>
/// Create an observable to monitor for registry changes
/// </summary>
/// <param name="hKey">IntPtr</param>
/// <param name="subKey">string</param>
/// <param name="registrationScheduler">IScheduler</param>
/// <param name="filter">RegistryNotifyFilter</param>
/// <returns>IObservable</returns>
public static IObservable <Unit> ObserveChanges(IntPtr hKey, string subKey, IScheduler registrationScheduler = null, RegistryNotifyFilter filter = RegistryNotifyFilter.ChangeLastSet)
{
return(Observable.Create <Unit>(
obs =>
{
try
{
var result = Advapi32Api.RegOpenKeyEx(hKey, subKey, RegistryOpenOptions.None, RegistryKeySecurityAccessRights.Read, out var registryKey);
if (result != 0)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return new CompositeDisposable(
CreateKeyValuesChangedObservable(registryKey, filter).SubscribeOn(registrationScheduler ?? Scheduler.CurrentThread).Subscribe(obs),
Disposable.Create(() => Advapi32Api.RegCloseKey(registryKey)));
}
catch (Win32Exception e)
{
obs.OnError(e);
return Disposable.Empty;
}
}));
}
