KQueueRecvByteAllocatorHandle Class — netty Architecture

Source Code

transport-classes-kqueue/src/main/java/io/netty/channel/kqueue/KQueueRecvByteAllocatorHandle.java lines 29–85

final class KQueueRecvByteAllocatorHandle extends DelegatingHandle implements ExtendedHandle {
    private final PreferredDirectByteBufAllocator preferredDirectByteBufAllocator =
            new PreferredDirectByteBufAllocator();

    private final UncheckedBooleanSupplier defaultMaybeMoreDataSupplier = new UncheckedBooleanSupplier() {
        @Override
        public boolean get() {
            return maybeMoreDataToRead();
        }
    };
    private boolean readEOF;
    private long numberBytesPending;

    KQueueRecvByteAllocatorHandle(ExtendedHandle handle) {
        super(handle);
    }

    @Override
    public ByteBuf allocate(ByteBufAllocator alloc) {
        // We need to ensure we always allocate a direct ByteBuf as we can only use a direct buffer to read via JNI.
        preferredDirectByteBufAllocator.updateAllocator(alloc);
        return delegate().allocate(preferredDirectByteBufAllocator);
    }

    @Override
    public boolean continueReading(UncheckedBooleanSupplier maybeMoreDataSupplier) {
        return readEOF || ((ExtendedHandle) delegate()).continueReading(maybeMoreDataSupplier);
    }

    @Override
    public boolean continueReading() {
        // We must override the supplier which determines if there maybe more data to read.
        return continueReading(defaultMaybeMoreDataSupplier);
    }

    void readEOF() {
        readEOF = true;
    }

    void numberBytesPending(long numberBytesPending) {
        this.numberBytesPending = numberBytesPending;
    }

    private boolean maybeMoreDataToRead() {
        /**
         * kqueue with EV_CLEAR flag set requires that we read until we consume "data" bytes
         * (see <a href="https://www.freebsd.org/cgi/man.cgi?kqueue">kqueue man</a>). However in order to
         * respect auto read we supporting reading to stop if auto read is off. If auto read is on we force reading to
         * continue to avoid a {@link StackOverflowError} between channelReadComplete and reading from the
         * channel. It is expected that the {@link #KQueueSocketChannel} implementations will track if all data was not
         * read, and will force a EVFILT_READ ready event.
         *
         * It is assumed EOF is handled externally by checking {@link #isReadEOF()}.
         */
        return lastBytesRead() == attemptedBytesRead();
    }
}