聊聊dubbo的TimeoutFilter

序

本文主要研究一下dubbo的TimeoutFilter

ListenableFilter

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

public abstract class ListenableFilter implements Filter {

    protected Listener listener = null;

    public Listener listener() {
        return listener;
    }
}

• ListenableFilter聲明實現Filter接口，它主要定義了listener()方法

TimeoutFilter

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

@Activate(group = CommonConstants.PROVIDER)
public class TimeoutFilter extends ListenableFilter {

    private static final Logger logger = LoggerFactory.getLogger(TimeoutFilter.class);

    private static final String TIMEOUT_FILTER_START_TIME = "timeout_filter_start_time";

    public TimeoutFilter() {
        super.listener = new TimeoutListener();
    }

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        invocation.setAttachment(TIMEOUT_FILTER_START_TIME, String.valueOf(System.currentTimeMillis()));
        return invoker.invoke(invocation);
    }

    static class TimeoutListener implements Listener {

        @Override
        public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
            String startAttach = invocation.getAttachment(TIMEOUT_FILTER_START_TIME);
            if (startAttach != null) {
                long elapsed = System.currentTimeMillis() - Long.valueOf(startAttach);
                if (invoker.getUrl() != null && elapsed > invoker.getUrl().getMethodParameter(invocation.getMethodName(), "timeout", Integer.MAX_VALUE)) {
                    if (logger.isWarnEnabled()) {
                        logger.warn("invoke time out. method: " + invocation.getMethodName() + " arguments: " + Arrays.toString(invocation.getArguments()) + " , url is " + invoker.getUrl() + ", invoke elapsed " + elapsed + " ms.");
                    }
                }
            }
        }

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

        }
    }
}

• TimeoutFilter繼承了ListenableFilter，其構造器初始化的listener爲TimeoutListener；invoke方法先記錄開始執行的時間，以後執行結束時會回調Listener的onResponse或onError方法；TimeoutListener的onResponse會取出timeout_filter_start_time值，若是存在則計算執行耗時，在設置了有效timeout且耗時大於該timeout時，會打印warn日誌

小結

TimeoutFilter繼承了ListenableFilter，其構造器初始化的listener爲TimeoutListener；invoke方法先記錄開始執行的時間，以後執行結束時會回調Listener的onResponse或onError方法；TimeoutListener的onResponse會取出timeout_filter_start_time值，若是存在則計算執行耗時，在設置了有效timeout且耗時大於該timeout時，會打印warn日誌

doc

• TimeoutFilter