doWriteMessage() — netty Function Reference

Architecture documentation for the doWriteMessage() function in NioSctpChannel.java from the netty codebase.

Function java Buffer Telemetry

Entity Profile

Buffer→ Telemetry→ doWriteMessage() — netty Function Reference

Dependency Diagram

graph TD
  1c8038e5_17d1_9428_0f33_fc8c0cfe4928["doWriteMessage()"]
  ce6c049a_7822_1e77_29fc_0d83a1e2ef54["NioSctpChannel"]
  1c8038e5_17d1_9428_0f33_fc8c0cfe4928 -->|defined in| ce6c049a_7822_1e77_29fc_0d83a1e2ef54
  style 1c8038e5_17d1_9428_0f33_fc8c0cfe4928 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

transport-sctp/src/main/java/io/netty/channel/sctp/nio/NioSctpChannel.java lines 311–347

    @Override
    protected boolean doWriteMessage(Object msg, ChannelOutboundBuffer in) throws Exception {
        SctpMessage packet = (SctpMessage) msg;
        ByteBuf data = packet.content();
        int dataLen = data.readableBytes();
        if (dataLen == 0) {
            return true;
        }

        ByteBuffer nioData;
        int javaVersion = PlatformDependent.javaVersion();
        if (javaVersion >= 22 && javaVersion < 25 && data.isDirect() ||
                !data.isDirect() || data.nioBufferCount() != 1) {
            // Ensure that we only use a single, direct ByteBuffer when doing SCTP IO.
            // If the ByteBuf is composite, or is on-heap, we do a copy.
            // On Java 22 through 24, we additionally need to avoid using ByteBuffer instances that are
            // backed by MemorySegments, because of https://bugs.openjdk.org/browse/JDK-8357268
            if (outputCopy == null || outputCopy.capacity() < dataLen) {
                outputCopy = ByteBuffer.allocateDirect(dataLen);
            }
            outputCopy.clear();
            outputCopy.limit(dataLen);
            data.readBytes(outputCopy);
            outputCopy.flip();
            nioData = outputCopy;
        } else {
            nioData = data.nioBuffer();
        }

        final MessageInfo mi = MessageInfo.createOutgoing(association(), null, packet.streamIdentifier());
        mi.payloadProtocolID(packet.protocolIdentifier());
        mi.streamNumber(packet.streamIdentifier());
        mi.unordered(packet.isUnordered());

        final int writtenBytes = javaChannel().send(nioData, mi);
        return writtenBytes > 0;
    }