testWritabilityChanged() — netty Function Reference

Source Code

transport/src/test/java/io/netty/channel/ReentrantChannelTest.java lines 43–110

    @Test
    public void testWritabilityChanged() throws Exception {

        LocalAddress addr = new LocalAddress("testWritabilityChanged");

        ServerBootstrap sb = getLocalServerBootstrap();
        sb.bind(addr).sync().channel();

        Bootstrap cb = getLocalClientBootstrap();

        setInterest(Event.WRITE, Event.FLUSH, Event.WRITABILITY);

        Channel clientChannel = cb.connect(addr).sync().channel();
        clientChannel.config().setWriteBufferLowWaterMark(512);
        clientChannel.config().setWriteBufferHighWaterMark(1024);

        // What is supposed to happen from this point:
        //
        // 1. Because this write attempt has been made from a non-I/O thread,
        //    ChannelOutboundBuffer.pendingWriteBytes will be increased before
        //    write() event is really evaluated.
        //    -> channelWritabilityChanged() will be triggered,
        //       because the Channel became unwritable.
        //
        // 2. The write() event is handled by the pipeline in an I/O thread.
        //    -> write() will be triggered.
        //
        // 3. Once the write() event is handled, ChannelOutboundBuffer.pendingWriteBytes
        //    will be decreased.
        //    -> channelWritabilityChanged() will be triggered,
        //       because the Channel became writable again.
        //
        // 4. The message is added to the ChannelOutboundBuffer and thus
        //    pendingWriteBytes will be increased again.
        //    -> channelWritabilityChanged() will be triggered.
        //
        // 5. The flush() event causes the write request in theChannelOutboundBuffer
        //    to be removed.
        //    -> flush() and channelWritabilityChanged() will be triggered.
        //
        // Note that the channelWritabilityChanged() in the step 4 can occur between
        // the flush() and the channelWritabilityChanged() in the step 5, because
        // the flush() is invoked from a non-I/O thread while the other are from
        // an I/O thread.

        ChannelFuture future = clientChannel.write(createTestBuf(2000));

        clientChannel.flush();
        future.sync();

        clientChannel.close().sync();

        assertLog(
                // Case 1:
                "WRITABILITY: writable=false\n" +
                "WRITE\n" +
                "WRITABILITY: writable=false\n" +
                "WRITABILITY: writable=false\n" +
                "FLUSH\n" +
                "WRITABILITY: writable=true\n",
                // Case 2:
                "WRITABILITY: writable=false\n" +
                "WRITE\n" +
                "WRITABILITY: writable=false\n" +
                "FLUSH\n" +
                "WRITABILITY: writable=true\n" +
                "WRITABILITY: writable=true\n");
    }