+/** This class is a basic I/O handler class.
+ * Any object which wishes to receive basic I/O events
+ * from the socketengine must derive from this class and
+ * implement the HandleEvent() method. The derived class
+ * must then be added to SocketEngine using the method
+ * SocketEngine::AddFd(), after which point the derived
+ * class will receive events to its HandleEvent() method.
+ * The derived class should also implement one of Readable()
+ * and Writeable(). In the current implementation, only
+ * Readable() is used. If this returns true, the socketengine
+ * inserts a readable socket. If it is false, the socketengine
+ * inserts a writeable socket. The derived class should never
+ * change the value this function returns without first
+ * deleting the socket from the socket engine. The only
+ * requirement beyond this for an event handler is that it
+ * must have a file descriptor. What this file descriptor
+ * is actually attached to is completely up to you.
+ */
+class CoreExport EventHandler : public Extensible
+{
+ protected:
+ /** File descriptor.
+ * All events which can be handled
+ * must have a file descriptor.
+ * This allows you to add events for
+ * sockets, fifo's, pipes, and various
+ * other forms of IPC.
+ */
+ int fd;
+ public:
+ /** Get the current file descriptor
+ * @return The file descriptor of this handler
+ */
+ int GetFd();
+
+ /** Set a new file desciptor
+ * @param FD The new file descriptor. Do not
+ * call this method without first deleting the
+ * object from the SocketEngine if you have
+ * added it to a SocketEngine instance.
+ */
+ void SetFd(int FD);
+
+ /** Constructor
+ */
+ EventHandler() {}
+
+ /** Destructor
+ */
+ virtual ~EventHandler() {}
+
+ /** Override this function to indicate readability.
+ * @return This should return true if the function
+ * wishes to receive EVENT_READ events. Do not change
+ * what this function returns while the event handler
+ * is still added to a SocketEngine instance!
+ * If this function is unimplemented, the base class
+ * will return true.
+ *
+ * NOTE: You cannot set both Readable() and
+ * Writeable() to true. If you wish to receive
+ * a write event for your object, you must call
+ * SocketEngine::WantWrite() instead. This will
+ * trigger your objects next EVENT_WRITE type event.
+ */
+ virtual bool Readable();
+
+ /** Override this function to indicate writeability.
+ * @return This should return true if the function
+ * wishes to receive EVENT_WRITE events. Do not change
+ * what this function returns while the event handler
+ * is still added to a SocketEngine instance!
+ * If this function is unimplemented, the base class
+ * will return false.
+ *
+ * NOTE: You cannot set both Readable() and
+ * Writeable() to true. If you wish to receive
+ * a write event for your object, you must call
+ * SocketEngine::WantWrite() instead. This will
+ * trigger your objects next EVENT_WRITE type event.
+ */
+ virtual bool Writeable();
+
+ /** Process an I/O event.
+ * You MUST implement this function in your derived
+ * class, and it will be called whenever read or write
+ * events are received, depending on what your functions
+ * Readable() and Writeable() returns and wether you
+ * previously made a call to SocketEngine::WantWrite().
+ * @param et either one of EVENT_READ for read events,
+ * and EVENT_WRITE for write events.
+ */
+ virtual void HandleEvent(EventType et, int errornum = 0) = 0;
+
+#ifdef WINDOWS
+
+ /** "Fake" file descriptor. This is windows-specific.
+ */
+ int m_internalFd;
+
+ /** Pointer to read event. We delete this so the buffer can't be used
+ * after the socket is deleted, and so it doesn't leak memory
+ */
+ void* m_readEvent;
+ /** Pointer to a write event.
+ */
+ void* m_writeEvent;
+ /** Pointer to an accept event.
+ */
+ void* m_acceptEvent;
+
+#endif
+};
+
+/** Provides basic file-descriptor-based I/O support.