FlowControlledHeaders Class — netty Architecture

Source Code

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2ConnectionEncoder.java lines 541–594

    private final class FlowControlledHeaders extends FlowControlledBase {
        private final Http2Headers headers;
        private final boolean hasPriority;
        private final int streamDependency;
        private final short weight;
        private final boolean exclusive;

        FlowControlledHeaders(Http2Stream stream, Http2Headers headers, boolean hasPriority,
                              int streamDependency, short weight, boolean exclusive,
                              int padding, boolean endOfStream, ChannelPromise promise) {
            super(stream, padding, endOfStream, promise.unvoid());
            this.headers = headers;
            this.hasPriority = hasPriority;
            this.streamDependency = streamDependency;
            this.weight = weight;
            this.exclusive = exclusive;
        }

        @Override
        public int size() {
            return 0;
        }

        @Override
        public void error(ChannelHandlerContext ctx, Throwable cause) {
            if (ctx != null) {
                lifecycleManager.onError(ctx, true, cause);
            }
            promise.tryFailure(cause);
        }

        @Override
        public void write(ChannelHandlerContext ctx, int allowedBytes) {
            boolean isInformational = validateHeadersSentState(stream, headers, connection.isServer(), endOfStream);
            // The code is currently requiring adding this listener before writing, in order to call onError() before
            // closeStreamLocal().
            promise.addListener(this);

            ChannelFuture f = sendHeaders(frameWriter, ctx, stream.id(), headers, hasPriority, streamDependency,
                    weight, exclusive, padding, endOfStream, promise);
            // Writing headers may fail during the encode state if they violate HPACK limits.
            Throwable failureCause = f.cause();
            if (failureCause == null) {
                // This just sets internal stream state which is used elsewhere in the codec and doesn't
                // necessarily mean the write will complete successfully.
                stream.headersSent(isInformational);
            }
        }

        @Override
        public boolean merge(ChannelHandlerContext ctx, Http2RemoteFlowController.FlowControlled next) {
            return false;
        }
    }