聊聊dubbo的ConsumerContextFilter

序

本文主要研究一下 dubbo 的 ConsumerContextFilter

ConsumerContextFilter

dubbo-2.7.2/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/filter/ConsumerContextFilter.java

@Activate(group = CONSUMER, order = -10000)
public class ConsumerContextFilter extends ListenableFilter {public ConsumerContextFilter() {super.listener = new ConsumerContextListener();
    }

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {RpcContext.getContext()
                .setInvoker(invoker)
                .setInvocation(invocation)
                .setLocalAddress(NetUtils.getLocalHost(), 0)
                .setRemoteAddress(invoker.getUrl().getHost(),
                        invoker.getUrl().getPort());
        if (invocation instanceof RpcInvocation) {((RpcInvocation) invocation).setInvoker(invoker);
        }
        try {RpcContext.removeServerContext();
            return invoker.invoke(invocation);
        } finally {RpcContext.removeContext();
        }
    }

    static class ConsumerContextListener implements Listener {
        @Override
        public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {RpcContext.getServerContext().setAttachments(appResponse.getAttachments());
        }

        @Override
        public void onError(Throwable t, Invoker<?> invoker, Invocation invocation) {}}
}

• ConsumerContextFilter 继承了 ListenableFilter，其 invoke 方法在 invoke 之前会给 RpcContext.getContext() 设置 invoker、invocation、localAddress、remoteAddress 并移除 serverContext；在 invoke 之后移除当前 context；其 listener 为 ConsumerContextListener，在 onResponse 的时候，会给 RpcContext.getServerContext() 设置 attachments

实例

dubbo-2.7.2/dubbo-rpc/dubbo-rpc-api/src/test/java/org/apache/dubbo/rpc/filter/ConsumerContextFilterTest.java

public class ConsumerContextFilterTest {Filter consumerContextFilter = new ConsumerContextFilter();

    @Test
    public void testSetContext() {URL url = URL.valueOf("test://test:11/test?group=dubbo&version=1.1");
        Invoker<DemoService> invoker = new MyInvoker<DemoService>(url);
        Invocation invocation = new MockInvocation();
        Result asyncResult = consumerContextFilter.invoke(invoker, invocation);
        asyncResult.thenApplyWithContext(result -> {assertEquals(invoker, RpcContext.getContext().getInvoker());
            assertEquals(invocation, RpcContext.getContext().getInvocation());
            assertEquals(NetUtils.getLocalHost() + ":0", RpcContext.getContext().getLocalAddressString());
            assertEquals("test:11", RpcContext.getContext().getRemoteAddressString());
            return result;
        });
    }
}

• 这里使用 asyncResult.thenApplyWithContext 来验证一下 RpcContext.getContext() 的 invoker、invocation、localhost、remoteAddress 值

小结

ConsumerContextFilter 继承了 ListenableFilter，其 invoke 方法在 invoke 之前会给 RpcContext.getContext() 设置 invoker、invocation、localAddress、remoteAddress 并移除 serverContext；在 invoke 之后移除当前 context；其 listener 为 ConsumerContextListener，在 onResponse 的时候，会给 RpcContext.getServerContext() 设置 attachments

doc

• ConsumerContextFilter