[3.0] NPE when consumer invoke timeout

[zhangyz-hd]

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 3.0.2-SNAPSHOT
• Operating System version: ANY
• Java version: 8

Steps to reproduce this issue

服务调用timeout时，消费者端出现NPE日志

java.lang.NullPointerException
	at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcResult.decode(DecodeableRpcResult.java:122)
	at org.apache.dubbo.remoting.transport.DecodeHandler.decode(DecodeHandler.java:57)
	at org.apache.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:48)
	at org.apache.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:57)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.dubbo.common.threadlocal.InternalRunnable.run(InternalRunnable.java:41)
	at java.lang.Thread.run(Thread.java:748)

代码位置

    public void decode() throws Exception {
        if (!hasDecoded && channel != null && inputStream != null) {
            try {
                if (ConfigurationUtils.getSystemConfiguration().getBoolean(SERIALIZATION_SECURITY_CHECK_KEY, true)) {
                    Object serializationType_obj = invocation.get(SERIALIZATION_ID_KEY); // <------ invocation IS NULL!!
                    if (serializationType_obj != null) {
                        if ((byte) serializationType_obj != serializationType) {
                            throw new IOException("Unexpected serialization id:" + serializationType + " received from network, please check if the peer send the right id.");
                        }
                    }
                }
                decode(channel, inputStream);
            } catch (Throwable e) {

初步分析原因

超时时，消费者端TimeoutCheckTask创建了timeoutResponse，并调用了DefaultFuture.received

        private void notifyTimeout(DefaultFuture future) {
            // create exception response.
            Response timeoutResponse = new Response(future.getId());
            // set timeout status.
            timeoutResponse.setStatus(future.isSent() ? Response.SERVER_TIMEOUT : Response.CLIENT_TIMEOUT);
            timeoutResponse.setErrorMessage(future.getTimeoutMessage(true));
            // handle response.
            DefaultFuture.received(future.getChannel(), timeoutResponse, true);
        }

DefaultFuture.received内会先从FUTURES中删除该id

    public static void received(Channel channel, Response response, boolean timeout) {
        try {
            DefaultFuture future = FUTURES.remove(response.getId());
            if (future != null) {
                Timeout t = future.timeoutCheckTask;
                if (!timeout) {

当服务提供者返回调用结果时，DefaultFuture#FUTURES缓存的id已经被删除，从而导致DubboCodec#decodeBody中创建DecodeableRpcResult时，传入的invocation是null

// org.apache.dubbo.rpc.protocol.dubbo.DubboCodec#decodeBody
                        if (channel.getUrl().getParameter(DECODE_IN_IO_THREAD_KEY, DEFAULT_DECODE_IN_IO_THREAD)) {
                            result = new DecodeableRpcResult(channel, res, is,
                                    (Invocation) getRequestData(id), proto);
                            result.decode();
                        } else {
                            result = new DecodeableRpcResult(channel, res,
                                    new UnsafeByteArrayInputStream(readMessageData(is)),
                                    (Invocation) getRequestData(id), proto);
                        }

// org.apache.dubbo.remoting.exchange.codec.ExchangeCodec#getRequestData
    protected Object getRequestData(long id) {
        DefaultFuture future = DefaultFuture.getFuture(id);
        if (future == null) {
            return null;    //<----------(^_^)v
        }
        Request req = future.getRequest();
        if (req == null) {
            return null;
        }
        return req.getData();
    }

[wangchengming666]

I'll try to fix it.

[CrazyHZM]

Resolved in #8587