这篇文章主要介绍“dubbo的FailbackClusterInvoker有什么作用”，在日常操作中，相信很多人在dubbo的FailbackClusterInvoker有什么作用问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”dubbo的FailbackClusterInvoker有什么作用”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
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本文主要研究一下dubbo的FailbackClusterInvoker
FailbackClusterInvoker
dubbo-2.7.3/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/FailbackClusterInvoker.java
public class FailbackClusterInvoker extends AbstractClusterInvoker {
private static final Logger logger = LoggerFactory.getLogger(FailbackClusterInvoker.class);
private static final long RETRY_FAILED_PERIOD = 5;
private final int retries;
private final int failbackTasks;
private volatile Timer failTimer;
public FailbackClusterInvoker(Directory directory) {
super(directory);
int retriesConfig = getUrl().getParameter(RETRIES_KEY, DEFAULT_FAILBACK_TIMES);
if (retriesConfig <= 0) {
retriesConfig = DEFAULT_FAILBACK_TIMES;
}
int failbackTasksConfig = getUrl().getParameter(FAIL_BACK_TASKS_KEY, DEFAULT_FAILBACK_TASKS);
if (failbackTasksConfig <= 0) {
failbackTasksConfig = DEFAULT_FAILBACK_TASKS;
}
retries = retriesConfig;
failbackTasks = failbackTasksConfig;
}
private void addFailed(LoadBalance loadbalance, Invocation invocation, List> invokers, Invoker lastInvoker) {
if (failTimer == null) {
synchronized (this) {
if (failTimer == null) {
failTimer = new HashedWheelTimer(
new NamedThreadFactory("failback-cluster-timer", true),
1,
TimeUnit.SECONDS, 32, failbackTasks);
}
}
}
RetryTimerTask retryTimerTask = new RetryTimerTask(loadbalance, invocation, invokers, lastInvoker, retries, RETRY_FAILED_PERIOD);
try {
failTimer.newTimeout(retryTimerTask, RETRY_FAILED_PERIOD, TimeUnit.SECONDS);
} catch (Throwable e) {
logger.error("Failback background works error,invocation->" + invocation + ", exception: " + e.getMessage());
}
}
@Override
protected Result doInvoke(Invocation invocation, List> invokers, LoadBalance loadbalance) throws RpcException {
Invoker invoker = null;
try {
checkInvokers(invokers, invocation);
invoker = select(loadbalance, invocation, invokers, null);
return invoker.invoke(invocation);
} catch (Throwable e) {
logger.error("Failback to invoke method " + invocation.getMethodName() + ", wait for retry in background. Ignored exception: "
+ e.getMessage() + ", ", e);
addFailed(loadbalance, invocation, invokers, invoker);
return AsyncRpcResult.newDefaultAsyncResult(null, null, invocation); // ignore
}
}
@Override
public void destroy() {
super.destroy();
if (failTimer != null) {
failTimer.stop();
}
}
/**
* RetryTimerTask
*/
private class RetryTimerTask implements TimerTask {
private final Invocation invocation;
private final LoadBalance loadbalance;
private final List> invokers;
private final int retries;
private final long tick;
private Invoker lastInvoker;
private int retryTimes = 0;
RetryTimerTask(LoadBalance loadbalance, Invocation invocation, List> invokers, Invoker lastInvoker, int retries, long tick) {
this.loadbalance = loadbalance;
this.invocation = invocation;
this.invokers = invokers;
this.retries = retries;
this.tick = tick;
this.lastInvoker=lastInvoker;
}
@Override
public void run(Timeout timeout) {
try {
Invoker retryInvoker = select(loadbalance, invocation, invokers, Collections.singletonList(lastInvoker));
lastInvoker = retryInvoker;
retryInvoker.invoke(invocation);
} catch (Throwable e) {
logger.error("Failed retry to invoke method " + invocation.getMethodName() + ", waiting again.", e);
if ((++retryTimes) >= retries) {
logger.error("Failed retry times exceed threshold (" + retries + "), We have to abandon, invocation->" + invocation);
} else {
rePut(timeout);
}
}
}
private void rePut(Timeout timeout) {
if (timeout == null) {
return;
}
Timer timer = timeout.timer();
if (timer.isStop() || timeout.isCancelled()) {
return;
}
timer.newTimeout(timeout.task(), tick, TimeUnit.SECONDS);
}
}
}
FailbackClusterInvokerTest
dubbo-2.7.3/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/FailbackClusterInvokerTest.java
@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
public class FailbackClusterInvokerTest {
List> invokers = new ArrayList>();
URL url = URL.valueOf("test://test:11/test?retries=2&failbacktasks=2");
Invoker invoker = mock(Invoker.class);
RpcInvocation invocation = new RpcInvocation();
Directory 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(FailbackClusterInvokerTest.class);
invocation.setMethodName("method1");
invokers.add(invoker);
}
@AfterEach
public void tearDown() {
dic = null;
invocation = new RpcInvocation();
invokers.clear();
}
private void resetInvokerToException() {
given(invoker.invoke(invocation)).willThrow(new RuntimeException());
given(invoker.getUrl()).willReturn(url);
given(invoker.getInterface()).willReturn(FailbackClusterInvokerTest.class);
}
private void resetInvokerToNoException() {
given(invoker.invoke(invocation)).willReturn(result);
given(invoker.getUrl()).willReturn(url);
given(invoker.getInterface()).willReturn(FailbackClusterInvokerTest.class);
}
@Test
@Order(1)
public void testInvokeException() {
resetInvokerToException();
FailbackClusterInvoker invoker = new FailbackClusterInvoker(
dic);
invoker.invoke(invocation);
Assertions.assertNull(RpcContext.getContext().getInvoker());
DubboAppender.clear();
}
@Test
@Order(2)
public void testInvokeNoException() {
resetInvokerToNoException();
FailbackClusterInvoker invoker = new FailbackClusterInvoker(
dic);
Result ret = invoker.invoke(invocation);
Assertions.assertSame(result, ret);
}
@Test
@Order(3)
public void testNoInvoke() {
dic = mock(Directory.class);
given(dic.getUrl()).willReturn(url);
given(dic.list(invocation)).willReturn(null);
given(dic.getInterface()).willReturn(FailbackClusterInvokerTest.class);
invocation.setMethodName("method1");
invokers.add(invoker);
resetInvokerToNoException();
FailbackClusterInvoker invoker = new FailbackClusterInvoker(
dic);
LogUtil.start();
DubboAppender.clear();
invoker.invoke(invocation);
assertEquals(1, LogUtil.findMessage("Failback to invoke"));
LogUtil.stop();
}
@Disabled
@Test
@Order(4)
public void testARetryFailed() throws Exception {
//Test retries and
resetInvokerToException();
FailbackClusterInvoker invoker = new FailbackClusterInvoker(
dic);
LogUtil.start();
DubboAppender.clear();
invoker.invoke(invocation);
invoker.invoke(invocation);
invoker.invoke(invocation);
Assertions.assertNull(RpcContext.getContext().getInvoker());
// invoker.retryFailed();// when retry the invoker which get from failed map already is not the mocked invoker,so
//Ensure that the main thread is online
CountDownLatch countDown = new CountDownLatch(1);
countDown.await(15000L, TimeUnit.MILLISECONDS);
LogUtil.stop();
Assertions.assertEquals(4, LogUtil.findMessage(Level.ERROR, "Failed retry to invoke method"), "must have four error message ");
Assertions.assertEquals(2, LogUtil.findMessage(Level.ERROR, "Failed retry times exceed threshold"), "must have two error message ");
Assertions.assertEquals(1, LogUtil.findMessage(Level.ERROR, "Failback background works error"), "must have one error message ");
// it can be invoke successfully
}
}小结
FailbackClusterInvoker的构造器初始化了retriesConfig、failbackTasksConfig；doInvoke方法在catch到Throwable的时候，会执行addFailed方法，该方法会往HashedWheelTimer注册一个RetryTimerTask，delay为5秒；RetryTimerTask的run方法首先会通过select方法选择一个retryInvoker，然后进行重试，catch到Throwable时会递增retryTimes，不超出限制时执行rePut方法，重新注册RetryTimerTask
到此，关于“dubbo的FailbackClusterInvoker有什么作用”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联网站，小编会继续努力为大家带来更多实用的文章！
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