ListenerWritabilityMonitor Class — netty Architecture

Source Code

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2RemoteFlowController.java lines 668–766

    private final class ListenerWritabilityMonitor extends WritabilityMonitor implements Http2StreamVisitor {
        private final Listener listener;

        ListenerWritabilityMonitor(Listener listener) {
            this.listener = listener;
        }

        @Override
        public boolean visit(Http2Stream stream) throws Http2Exception {
            FlowState state = state(stream);
            if (isWritable(state) != state.markedWritability()) {
                notifyWritabilityChanged(state);
            }
            return true;
        }

        @Override
        void windowSize(FlowState state, int initialWindowSize) {
            super.windowSize(state, initialWindowSize);
            try {
                checkStateWritability(state);
            } catch (Http2Exception e) {
                throw new RuntimeException("Caught unexpected exception from window", e);
            }
        }

        @Override
        void incrementWindowSize(FlowState state, int delta) throws Http2Exception {
            super.incrementWindowSize(state, delta);
            checkStateWritability(state);
        }

        @Override
        void initialWindowSize(int newWindowSize) throws Http2Exception {
            super.initialWindowSize(newWindowSize);
            if (isWritableConnection()) {
                // If the write operation does not occur we still need to check all streams because they
                // may have transitioned from writable to not writable.
                checkAllWritabilityChanged();
            }
        }

        @Override
        void enqueueFrame(FlowState state, FlowControlled frame) throws Http2Exception {
            super.enqueueFrame(state, frame);
            checkConnectionThenStreamWritabilityChanged(state);
        }

        @Override
        void stateCancelled(FlowState state) {
            try {
                checkConnectionThenStreamWritabilityChanged(state);
            } catch (Http2Exception e) {
                throw new RuntimeException("Caught unexpected exception from checkAllWritabilityChanged", e);
            }
        }

        @Override
        void channelWritabilityChange() throws Http2Exception {
            if (connectionState.markedWritability() != isChannelWritable()) {
                checkAllWritabilityChanged();
            }
        }

        private void checkStateWritability(FlowState state) throws Http2Exception {
            if (isWritable(state) != state.markedWritability()) {
                if (state == connectionState) {
                    checkAllWritabilityChanged();
                } else {
                    notifyWritabilityChanged(state);
                }
            }
        }

        private void notifyWritabilityChanged(FlowState state) {
            state.markedWritability(!state.markedWritability());
            try {
                listener.writabilityChanged(state.stream);
            } catch (Throwable cause) {
                logger.error("{} Caught Throwable from listener.writabilityChanged for {}",
                        ctx.channel(), state.stream, cause);