Home / cs-notes / Architecture / Components / Netty / EventLoop / NioEventLoop / processSelectedKeys

    private void processSelectedKeys() {
        if (selectedKeys != null) {
            processSelectedKeysOptimized();
        } else {
            processSelectedKeysPlain(selector.selectedKeys());
        }
    }

    private void processSelectedKeysOptimized() {
        for (int i = 0; i < selectedKeys.size; ++i) {
            final SelectionKey k = selectedKeys.keys[i];
            // null out entry in the array to allow to have it GC'ed once the Channel close
            // See https://github.com/netty/netty/issues/2363
            selectedKeys.keys[i] = null;

            final Object a = k.attachment();

            if (a instanceof AbstractNioChannel) {
                processSelectedKey(k, (AbstractNioChannel) a);
            } else {
                @SuppressWarnings("unchecked")
                NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
                processSelectedKey(k, task);
            }
            ...
        }
    }

    private void processSelectedKeysPlain(Set<SelectionKey> selectedKeys) {
        // check if the set is empty and if so just return to not create garbage by
        // creating a new Iterator every time even if there is nothing to process.
        // See https://github.com/netty/netty/issues/597
        if (selectedKeys.isEmpty()) {
            return;
        }

        Iterator<SelectionKey> i = selectedKeys.iterator();
        for (;;) {
            final SelectionKey k = i.next();
            final Object a = k.attachment();
            i.remove();

            if (a instanceof AbstractNioChannel) {
                processSelectedKey(k, (AbstractNioChannel) a);
            } else {
                @SuppressWarnings("unchecked")
                NioTask<SelectableChannel> task = (NioTask<SelectableChannel>) a;
                processSelectedKey(k, task);
            }
            ...
        }
    }