Make shutdown faster in case of a long running event handler

[kovbal]

As detailed in issue #1 if changeEvent() takes a long time and new filesystem events keep happening, then the shutdown of the application is delayed.

This PR solves that problem by not processing entirely these events during shutdown.

[KevDi]

Thanks for that Pull Request. I tried it out but found another Problem (Sorry for that 😊).
If i know make the same steps as described in the Issue I end up waiting for the Program to close.
Now the Problem seems to stuck here:

while(hasPending() && (res = GetQueuedCompletionStatus(this->iocp.get(), &numOfBytes, &compKey, &ov, INFINITE)) != FALSE) {
   ...

It seems like the FsWatcher contains one WatchInfo with an PendingClose State and then calls GetQueuedCompletionStatus and then waits there forever because no events will be generated and put on the eventqueue as far as i can see.

[KevDi]

I did some further analysis to this and i think the root of the lies in the processEvent Function.
If the application is stopped but there are still files added to the directory the Number of Bytes transferred is not equal to zero so the WatchInfo is not ereased from the Map.
Inside the While Loop it's still pending but could not be closed because the Directory Handle is invalid.

[KevDi]

One Solution which works for me was to change the processEvent Function.

I just have added the following:

void FsWatcher::processEvent(DWORD numberOfBytesTrs, OVERLAPPED* overlapped) {
    ...
    if (this->shuttingDown) {
        watchInfoIt->second.state = WatchInfo::State::PendingClose;
    }
    
    if (watchInfoIt->second.state == WatchInfo::State::Listening) {
    ....
    }
    
    if (numberOfBytes == 0 || this->shuttingDown) {
        if (watchInfoIt->second.state == WatchInfo::State::PendingClose) {
           std::cout << "Erease WatchInfo " << watchInfoIt->second.rId << "\n";
           this->watchInfos.erase(watchInfoIt);
        } else {
           std::cout << "Error: " << GetLastError() << '\n';
           this->errorEvent(watchInfoIt->second.rId);
       }
       return;
    }
    ....
}