聊聊dubbo的FailfastClusterInvoker

序

本文主要研究一下dubbo的FailfastClusterInvoker

FailfastClusterInvoker

dubbo-2.7.3/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/FailfastClusterInvoker.java

public class FailfastClusterInvoker<T> extends AbstractClusterInvoker<T> {

    public FailfastClusterInvoker(Directory<T> directory) {
        super(directory);
    }

    @Override
    public Result doInvoke(Invocation invocation, List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {
        checkInvokers(invokers, invocation);
        Invoker<T> invoker = select(loadbalance, invocation, invokers, null);
        try {
            return invoker.invoke(invocation);
        } catch (Throwable e) {
            if (e instanceof RpcException && ((RpcException) e).isBiz()) { // biz exception.
                throw (RpcException) e;
            }
            throw new RpcException(e instanceof RpcException ? ((RpcException) e).getCode() : 0,
                    "Failfast invoke providers " + invoker.getUrl() + " " + loadbalance.getClass().getSimpleName()
                            + " select from all providers " + invokers + " for service " + getInterface().getName()
                            + " method " + invocation.getMethodName() + " on consumer " + NetUtils.getLocalHost()
                            + " use dubbo version " + Version.getVersion()
                            + ", but no luck to perform the invocation. Last error is: " + e.getMessage(),
                    e.getCause() != null ? e.getCause() : e);
        }
    }
}

• FailfastClusterInvoker的doInvoke在捕获到异常的时候包装为RpcException然后再抛出

FailfastClusterInvokerTest

dubbo-2.7.3/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/FailfastClusterInvokerTest.java

public class FailfastClusterInvokerTest {
    List<Invoker<FailfastClusterInvokerTest>> invokers = new ArrayList<Invoker<FailfastClusterInvokerTest>>();
    URL url = URL.valueOf("test://test:11/test");
    Invoker<FailfastClusterInvokerTest> invoker1 = mock(Invoker.class);
    RpcInvocation invocation = new RpcInvocation();
    Directory<FailfastClusterInvokerTest> dic;
    Result result = new AppResponse();

    /**
     * @throws java.lang.Exception
     */

    @BeforeEach
    public void setUp() throws Exception {

        dic = mock(Directory.class);

        given(dic.getUrl()).willReturn(url);
        given(dic.list(invocation)).willReturn(invokers);
        given(dic.getInterface()).willReturn(FailfastClusterInvokerTest.class);

        invocation.setMethodName("method1");

        invokers.add(invoker1);
    }

    private void resetInvoker1ToException() {
        given(invoker1.invoke(invocation)).willThrow(new RuntimeException());
        given(invoker1.getUrl()).willReturn(url);
        given(invoker1.getInterface()).willReturn(FailfastClusterInvokerTest.class);
    }

    private void resetInvoker1ToNoException() {
        given(invoker1.invoke(invocation)).willReturn(result);
        given(invoker1.getUrl()).willReturn(url);
        given(invoker1.getInterface()).willReturn(FailfastClusterInvokerTest.class);
    }

    @Test
    public void testInvokeException() {
        Assertions.assertThrows(RpcException.class, () -> {
            resetInvoker1ToException();
            FailfastClusterInvoker<FailfastClusterInvokerTest> invoker = new FailfastClusterInvoker<FailfastClusterInvokerTest>(dic);
            invoker.invoke(invocation);
            Assertions.assertSame(invoker1, RpcContext.getContext().getInvoker());
        });
    }

    @Test()
    public void testInvokeNoException() {

        resetInvoker1ToNoException();

        FailfastClusterInvoker<FailfastClusterInvokerTest> invoker = new FailfastClusterInvoker<FailfastClusterInvokerTest>(dic);
        Result ret = invoker.invoke(invocation);
        Assertions.assertSame(result, ret);
    }

    @Test()
    public void testNoInvoke() {
        dic = mock(Directory.class);

        given(dic.getUrl()).willReturn(url);
        given(dic.list(invocation)).willReturn(null);
        given(dic.getInterface()).willReturn(FailfastClusterInvokerTest.class);

        invocation.setMethodName("method1");

        invokers.add(invoker1);

        resetInvoker1ToNoException();

        FailfastClusterInvoker<FailfastClusterInvokerTest> invoker = new FailfastClusterInvoker<FailfastClusterInvokerTest>(dic);
        try {
            invoker.invoke(invocation);
            fail();
        } catch (RpcException expected) {
            assertFalse(expected.getCause() instanceof RpcException);
        }
    }

}

• FailfastClusterInvokerTest执行了testInvokeException、testInvokeNoException、testNoInvoke三种测试

小结

FailfastClusterInvoker的doInvoke在捕获到异常的时候包装为RpcException然后再抛出

doc

• FailfastClusterInvoker