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Prototypic test case for the race condition in DATAMONGO-686
/**
* @see DATAMONGO-686
*/
@SuppressWarnings("serial")
@Test
public void thereShouldBeNoRaceConditionWhenReusingQueryFromMultipleThreads() throws Exception {
Query query = new Query().addCriteria(where("_id").in("42"));
final CountDownLatch latch = new CountDownLatch(1);
final List<Object> observedValues = new ArrayList<Object>();
final DBObject queryObject = query.getQueryObject();
queryObject.put("_id", new BasicDBObject(((DBObject) queryObject.get("_id")).toMap()) {
@Override
public Object get(String key) {
if (key.endsWith("$in") && Thread.currentThread().getName().equals("t2")) {
// provokes the race-condition in
// org.springframework.data.mongodb.core.convert.QueryMapper.getMappedValue(Field, Object)
try {
latch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
Object result = super.get(key);
observedValues.add(result);
return result;
}
});
final List<Exception> exceptions = new ArrayList<Exception>();
Runnable code = new Runnable() {
@Override
public void run() {
try {
mapper.getMappedObject(queryObject, context.getPersistentEntity(Sample.class));
} catch (Exception ex) {
exceptions.add(ex);
}
latch.countDown();
}
};
Thread t1 = new Thread(code, "t1");
Thread t2 = new Thread(code, "t2");
t1.start();
t2.start();
t1.join();
t2.join();
assertThat(observedValues, is(not(empty())));
assertThat(observedValues.size(), is(2));
assertThat("Both observed values should be of the same type! But was: "
+ observedValues.get(0).getClass().getName() + " and " + observedValues.get(1).getClass().getName(),
observedValues.get(0).getClass().equals(observedValues.get(1).getClass()), is(true));
assertThat(exceptions.toString(), exceptions, is(empty()));
}
@thomasdarimont
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It results in the following stacktrace:

java.lang.AssertionError: [java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.lang.Iterable]
Expected: is an empty collection
but: <[java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.lang.Iterable]>
at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
at org.junit.Assert.assertThat(Assert.java:865)
at org.springframework.data.mongodb.core.convert.QueryMapperUnitTests.thereShouldBeNoRaceConditionWhenReusingQueryFromMultipleThreads(QueryMapperUnitTests.java:538)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
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.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.runners.ParentRunner.run(ParentRunner.java:309)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

@thomasdarimont
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java.lang.AssertionError: Both observed values should be of the same type! But was: java.util.Arrays$ArrayList and [Ljava.lang.Object;
Expected: is
but: was
at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
at org.junit.Assert.assertThat(Assert.java:865)
at org.springframework.data.mongodb.core.convert.QueryMapperUnitTests.thereShouldBeNoRaceConditionWhenReusingQueryFromMultipleThreads(QueryMapperUnitTests.java:547)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
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.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.runners.ParentRunner.run(ParentRunner.java:309)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

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