Restlet 2.1.7 - NPE in org.restlet.ext.httpclient.internal.HttpMethodCall.getStatusCode

[davsclaus]

There is a NPE when you use a restlet http client to call a remote rest service, and you have a connect timeout, and that triggers a timeout.

And if your restlet http client uses asynchronous mode, then the callback in the handle is not called because of this NPE.

This causes our client code to never get notified of this, and therefore hang.

The NPE is

Mar 19, 2014 9:40:06 AM org.restlet.engine.adapter.ClientAdapter$1 handle
WARNING: Unexpected error or exception inside the user call back
java.lang.NullPointerException
    at org.restlet.ext.httpclient.internal.HttpMethodCall.getStatusCode(HttpMethodCall.java:271)
    at org.restlet.engine.adapter.ClientAdapter$1.handle(ClientAdapter.java:93)
    at org.restlet.ext.httpclient.internal.HttpMethodCall.sendRequest(HttpMethodCall.java:368)
    at org.restlet.engine.adapter.ClientAdapter.commit(ClientAdapter.java:90)
    at org.restlet.engine.adapter.HttpClientHelper.handle(HttpClientHelper.java:112)
    at org.restlet.Client.handle(Client.java:180)
    at org.restlet.Restlet.handle(Restlet.java:351)
    at org.restlet.Restlet.handle(Restlet.java:364)
    at org.apache.camel.component.restlet.RestletProducer.process(RestletProducer.java:87)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
    at org.apache.camel.processor.UnitOfWorkProducer.process(UnitOfWorkProducer.java:73)
    at org.apache.camel.impl.ProducerCache$2.doInProducer(ProducerCache.java:378)
    at org.apache.camel.impl.ProducerCache$2.doInProducer(ProducerCache.java:346)
    at org.apache.camel.impl.ProducerCache.doInProducer(ProducerCache.java:242)
    at org.apache.camel.impl.ProducerCache.sendExchange(ProducerCache.java:346)
    at org.apache.camel.impl.ProducerCache.send(ProducerCache.java:201)
    at org.apache.camel.impl.DefaultProducerTemplate.send(DefaultProducerTemplate.java:128)
    at org.apache.camel.impl.DefaultProducerTemplate.send(DefaultProducerTemplate.java:115)
    at org.apache.camel.impl.DefaultProducerTemplate.sendBodyAndHeader(DefaultProducerTemplate.java:182)
    at org.apache.camel.impl.DefaultProducerTemplate.requestBodyAndHeader(DefaultProducerTemplate.java:301)
    at org.apache.camel.impl.DefaultProducerTemplate.requestBodyAndHeader(DefaultProducerTemplate.java:337)
    at org.apache.camel.component.restlet.RestletProducerTimeoutTest.testRestletProducerGet(RestletProducerTimeoutTest.java:29)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:202)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:65)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

And the problem is that getStatusLine returns null, because of the timeout issue

workload: 1h

[davsclaus]

We set these timeout values

        client.getContext().getParameters().add("socketTimeout", String.valueOf(endpoint.getSocketTimeout()));
        client.getContext().getParameters().add("socketConnectTimeoutMs", String.valueOf(endpoint.getSocketTimeout()));

For example to 10000 (10 sec) and if the remote REST server takes longer to respond, we get this NPE.

[davsclaus]

And this is our restlet http client code from Apache Camel, that uses the client and the async api

        LOG.debug("Sending request: {} for exchangeId: {}", request, exchange.getExchangeId());
        client.handle(request, new Uniform() {
            @Override
            public void handle(Request request, Response response) {
                LOG.debug("Received response: {} for exchangeId: {}", response, exchange.getExchangeId());
                try {
                    if (response != null) {
                        Integer respCode = response.getStatus().getCode();
                        if (respCode > 207 && throwException) {
                            exchange.setException(populateRestletProducerException(exchange, response, respCode));
                        } else {
                            binding.populateExchangeFromRestletResponse(exchange, response);
                        }
                    }
                } catch (Exception e) {
                    exchange.setException(e);
                } finally {
                    callback.done(false);
                }
            }
        });

eg the handle method is not invoked, because of the NPE and therefore we cannot react and call our callback in the finally block.

[jlouvel]

Thanks Claus for the detailled report. @thboileau can we try to fix this for 2.2.0 and 2.3 M1?

[jlouvel]

Moved to 2.2.1.

[jlouvel]

We'll start by preventing the NPE and see if it works

[thboileau]

Thanks a lot Claus for reporting this issue and for the detail report!

I've updated the code in order to:

• return a 1001 status code (communication error such as timeout)
• prevent NPE on both call to getStatusLine
• prevent NPE when converting null to int...

This update is now part of 2.2 branch and master branch (2.3 release)