shouldFireChannelWritabilityChangedAfterRemoval() — netty Function Reference

Source Code

transport/src/test/java/io/netty/channel/PendingWriteQueueTest.java lines 92–139

    @Test
    public void shouldFireChannelWritabilityChangedAfterRemoval() {
        final AtomicReference<ChannelHandlerContext> ctxRef = new AtomicReference<ChannelHandlerContext>();
        final AtomicReference<PendingWriteQueue> queueRef = new AtomicReference<PendingWriteQueue>();
        final ByteBuf msg = Unpooled.copiedBuffer("test", CharsetUtil.US_ASCII);

        final EmbeddedChannel channel = new EmbeddedChannel(new ChannelInboundHandlerAdapter() {
            @Override
            public void handlerAdded(ChannelHandlerContext ctx) {
                ctxRef.set(ctx);
                queueRef.set(new PendingWriteQueue(ctx));
            }

            @Override
            public void channelWritabilityChanged(ChannelHandlerContext ctx) {
                final PendingWriteQueue queue = queueRef.get();

                final ByteBuf msg = (ByteBuf) queue.current();
                if (msg == null) {
                    return;
                }

                assertEquals(1, msg.refCnt());

                // This call will trigger another channelWritabilityChanged() event because the number of
                // pending bytes will go below the low watermark.
                //
                // If PendingWriteQueue.remove() did not remove the current entry before triggering
                // channelWritabilityChanged() event, we will end up with attempting to remove the same
                // element twice, resulting in the double release.
                queue.remove();

                assertEquals(0, msg.refCnt());
            }
        });

        channel.config().setWriteBufferLowWaterMark(1);
        channel.config().setWriteBufferHighWaterMark(3);

        final PendingWriteQueue queue = queueRef.get();

        // Trigger channelWritabilityChanged() by adding a message that's larger than the high watermark.
        queue.add(msg, channel.newPromise());

        channel.finish();

        assertEquals(0, msg.refCnt());
    }