Question

I am new to a non-blocking IO in Java. I have a question – will a readiness of a non-blocking channel be lost by the selector, if a new packet from a server will arrive after we completed reading from the channel, but before we removed a selection key for this channel from selector? Example code here:

        Selector selector;

        // ......

        while (true) {
            selector.select();
            Set<SelectionKey> set = selector.selectedKeys();

            Iterator<SelectionKey> iterator = set.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                SocketChannel channel = (SocketChannel) key.channel();
                ByteBuffer byteBuffer = ByteBuffer.allocate(GOOD_ENOUGH_CAPACITY);
                while (channel.read(byteBuffer) > 0) ;

                // HERE ! What happen if server started to write new message here?
                // Will this channel be selected on next selector.select() ?

                iterator.remove();

            }
        }

Answer 1

Yes, key will be selected. You must use method

key.cancel(); 

to remove key from selector