[Dubbo-2233] fix reference config cache issue #2233

[YoungHu]

What is the purpose of the change

fix issue #2233

Brief changelog

fix the referenceconfig cache null forever if no provider and then provider startup

Verifying this change

1. provider not startup
2. invoke with reference cache get null
3. provider startup
4. invoker with reference cache again get what you want

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[codecov-io]

Codecov Report

Merging #2347 into master will decrease coverage by 0.07%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master    #2347      +/-   ##
============================================
- Coverage     54.85%   54.78%   -0.08%     
+ Complexity     5241     5237       -4     
============================================
  Files           573      573              
  Lines         25456    25458       +2     
  Branches       4537     4538       +1     
============================================
- Hits          13965    13948      -17     
- Misses         9399     9415      +16     
- Partials       2092     2095       +3

Impacted Files	Coverage Δ	Complexity Δ
...pache/dubbo/config/utils/ReferenceConfigCache.java	77.55% <100%> (+0.95%)	12 <0> (+1)	⬆️
...apache/dubbo/rpc/protocol/dubbo/FutureAdapter.java	58.06% <0%> (-6.46%)	3% <0%> (ø)
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-4.17%)	3% <0%> (ø)
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	54.21% <0%> (-3.62%)	13% <0%> (-2%)
...he/dubbo/remoting/transport/netty/NettyServer.java	67.85% <0%> (-3.58%)	8% <0%> (-1%)
.../apache/dubbo/rpc/protocol/dubbo/DubboInvoker.java	68.33% <0%> (-3.34%)	11% <0%> (ø)
...a/org/apache/dubbo/monitor/dubbo/DubboMonitor.java	87.85% <0%> (-1.87%)	15% <0%> (ø)
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.2% <0%> (-1.48%)	29% <0%> (ø)
.../src/main/java/org/apache/dubbo/rpc/RpcStatus.java	57.89% <0%> (-1.06%)	18% <0%> (ø)
...apache/dubbo/rpc/protocol/dubbo/DubboProtocol.java	58.33% <0%> (-0.84%)	30% <0%> (-1%)
... and 2 more

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[diecui1202]

@YoungHu I try to reproduce the problem with the following client code,

        ReferenceConfig<DemoService> reference = new ReferenceConfig<>();
        reference.setApplication(new ApplicationConfig("first-dubbo-client"));
        reference.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
        reference.setInterface(DemoService.class);
        System.in.read(); // stop provider before continuing

        ReferenceConfigCache cache = ReferenceConfigCache.getCache();
        try {
            DemoService greetingsService = cache.get(reference);

            String message = greetingsService.sayHello("dubbo");
            System.out.println(message);
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.in.read(); // start provider before continuing

        DemoService greetingsService = cache.get(reference);
        // GreetingsService greetingsService = reference.get();
        String message = greetingsService.sayHello("dubbo");
        System.out.println(message);

With the newest master, it works. That means the second invocation succeed.

Is my client suitable for reproducing the problem ?

[YoungHu]

there is something wrong with your client code, first time you already up the provider, please check the test code i commit with this PR, you can find that test will failed without change the ReferenceConfigCache.java code

[diecui1202]

@YoungHu My mistake. But the following code can also get the right response.

        // not start provider, just run client 
        ReferenceConfig<DemoService> reference = new ReferenceConfig<>();
        reference.setApplication(new ApplicationConfig("first-dubbo-client"));
        reference.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
        reference.setInterface(DemoService.class);

        ReferenceConfigCache cache = ReferenceConfigCache.getCache();
        try {
            DemoService greetingsService = cache.get(reference);

            String message = greetingsService.sayHello("dubbo");
            System.out.println(message);
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.in.read(); // start provider before continuing

        DemoService greetingsService = cache.get(reference);
        // GreetingsService greetingsService = reference.get();
        String message = greetingsService.sayHello("dubbo");
        System.out.println(message);

So what's my code's problem ?

[YoungHu]

below is my code and test result, dubbo version is 2.6.2. why can't reproduce what I said, you may need find it out by yourself. because i can't get more information from you.

[diecui1202]

OK, thanks, I'll try it with the zk registry.

[diecui1202]

I use the newest master branch, it's ok. Refer to #1999

So could u please file a new PR?

[YoungHu]

confirmed this issue fix at master branch with #1999 ,close this one