DefaultHttp2RemoteFlowController Class — netty Architecture

Source Code

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2RemoteFlowController.java lines 43–767

public class DefaultHttp2RemoteFlowController implements Http2RemoteFlowController {
    private static final InternalLogger logger =
            InternalLoggerFactory.getInstance(DefaultHttp2RemoteFlowController.class);
    private static final int MIN_WRITABLE_CHUNK = 32 * 1024;
    private final Http2Connection connection;
    private final Http2Connection.PropertyKey stateKey;
    private final StreamByteDistributor streamByteDistributor;
    private final FlowState connectionState;
    private int initialWindowSize = DEFAULT_WINDOW_SIZE;
    private WritabilityMonitor monitor;
    private ChannelHandlerContext ctx;

    public DefaultHttp2RemoteFlowController(Http2Connection connection) {
        this(connection, (Listener) null);
    }

    public DefaultHttp2RemoteFlowController(Http2Connection connection,
                                            StreamByteDistributor streamByteDistributor) {
        this(connection, streamByteDistributor, null);
    }

    public DefaultHttp2RemoteFlowController(Http2Connection connection, final Listener listener) {
        this(connection, new WeightedFairQueueByteDistributor(connection), listener);
    }

    public DefaultHttp2RemoteFlowController(Http2Connection connection,
                                            StreamByteDistributor streamByteDistributor,
                                            final Listener listener) {
        this.connection = checkNotNull(connection, "connection");
        this.streamByteDistributor = checkNotNull(streamByteDistributor, "streamWriteDistributor");

        // Add a flow state for the connection.
        stateKey = connection.newKey();
        connectionState = new FlowState(connection.connectionStream());
        connection.connectionStream().setProperty(stateKey, connectionState);

        // Monitor may depend upon connectionState, and so initialize after connectionState
        listener(listener);
        monitor.windowSize(connectionState, initialWindowSize);

        // Register for notification of new streams.
        connection.addListener(new Http2ConnectionAdapter() {
            @Override
            public void onStreamAdded(Http2Stream stream) {
                // If the stream state is not open then the stream is not yet eligible for flow controlled frames and
                // only requires the ReducedFlowState. Otherwise the full amount of memory is required.
                stream.setProperty(stateKey, new FlowState(stream));
            }

            @Override
            public void onStreamActive(Http2Stream stream) {
                // If the object was previously created, but later activated then we have to ensure the proper
                // initialWindowSize is used.
                monitor.windowSize(state(stream), initialWindowSize);
            }

            @Override
            public void onStreamClosed(Http2Stream stream) {
                // Any pending frames can never be written, cancel and
                // write errors for any pending frames.
                state(stream).cancel(STREAM_CLOSED, null);
            }

            @Override
            public void onStreamHalfClosed(Http2Stream stream) {
                if (HALF_CLOSED_LOCAL == stream.state()) {
                    /*
                     * When this method is called there should not be any
                     * pending frames left if the API is used correctly. However,
                     * it is possible that a erroneous application can sneak
                     * in a frame even after having already written a frame with the
                     * END_STREAM flag set, as the stream state might not transition
                     * immediately to HALF_CLOSED_LOCAL / CLOSED due to flow control
                     * delaying the write.
                     *
                     * This is to cancel any such illegal writes.
                     */
                    state(stream).cancel(STREAM_CLOSED, null);
                }
            }
        });