File indexing completed on 2024-05-19 09:36:34
0001 /* 0002 Copyright (C) 2018 Andreas Hartmetz <ahartmetz@gmail.com> 0003 0004 This library is free software; you can redistribute it and/or 0005 modify it under the terms of the GNU Library General Public 0006 License as published by the Free Software Foundation; either 0007 version 2 of the License, or (at your option) any later version. 0008 0009 This library is distributed in the hope that it will be useful, 0010 but WITHOUT ANY WARRANTY; without even the implied warranty of 0011 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 0012 Library General Public License for more details. 0013 0014 You should have received a copy of the GNU Library General Public License 0015 along with this library; see the file COPYING.LGPL. If not, write to 0016 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 0017 Boston, MA 02110-1301, USA. 0018 0019 Alternatively, this file is available under the Mozilla Public License 0020 Version 1.1. You may obtain a copy of the License at 0021 http://www.mozilla.org/MPL/ 0022 */ 0023 0024 #ifndef IIOEVENTSOURCE_H 0025 #define IIOEVENTSOURCE_H 0026 0027 #include "iovaluetypes.h" 0028 #include "types.h" 0029 0030 class IIoEventListener; 0031 0032 // TODO: explain the context for this - layered sources and listeners and such 0033 0034 // There is one subtle problem that needs to be solved regarding IIoEventListener::fileDescriptor(). 0035 // Event sources are expected to use some kind of hash / map FileDescriptor -> IIoEventListener, so 0036 // an IIoEventListener cannot unregister after closing the file descriptor. Even keeping the old 0037 // value around doesn't help - the file descriptor could be reused very soon by any other part of the 0038 // current process. 0039 // So the lowest level implementation of close() must immediately unregister the IIoEventListener 0040 // leading to the I/O operation leading to the close(). That lowest level IIoEventListener must also 0041 // unregister itself, etc, up to the highest level IIoEventSource (usually EventDispatcherPrivate). 0042 0043 class IIoEventSource 0044 { 0045 public: 0046 virtual ~IIoEventSource(); 0047 0048 // Contract: an IIoEventSource may have different IIoEventListeners listening to read and write 0049 // As a further restriction, a listener must always remove I/O interest from its old source 0050 // before enabling it on its new source. 0051 void addIoListener(IIoEventListener *iol); 0052 void removeIoListener(IIoEventListener *iol); 0053 0054 protected: 0055 // add / remove only make sense for stateful APIs such as Linux epoll, so they don't have to be 0056 // implemented - the defaults just call updateIoInterestInternal(). 0057 virtual void addIoListenerInternal(IIoEventListener *iol, uint32 ioRw); 0058 virtual void removeIoListenerInternal(IIoEventListener *iol); 0059 virtual void updateIoInterestInternal(IIoEventListener *iol, uint32 ioRw) = 0; 0060 0061 private: 0062 friend class IIoEventListener; 0063 // called from IIoEventListener when its m_ioInterest changed 0064 void updateIoInterest(IIoEventListener *iol); 0065 }; 0066 0067 #endif // IIOEVENTSOURCE_H