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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