[jira] [Created] (MESOS-6484) Memory leak in `Future::after()`

["Alexander Rojas (JIRA)" <ji...@apache.org>]

Alexander Rojas created MESOS-6484:
--------------------------------------

             Summary: Memory leak in `Future<T>::after()`
                 Key: MESOS-6484
                 URL: https://issues.apache.org/jira/browse/MESOS-6484
             Project: Mesos
          Issue Type: Bug
          Components: libprocess
    Affects Versions: 1.1.0
            Reporter: Alexander Rojas


The problem arises when one tries to associate an {{after()}} call to copied futures. The following test case is enough to reproduce the issue:

{code}
class Policy
{
public:
  virtual Try<Duration> timeout() = 0;
  virtual Duration totalTimeout() = 0;

  virtual ~Policy() {}
};

class MockPolicy : public Policy
{
public:
  virtual ~MockPolicy() {}

  MOCK_METHOD0(timeout, Try<Duration>());
  MOCK_METHOD0(totalTimeout, Duration());
};

template <typename ResultType>
process::Future<ResultType> retry(
    const std::function<Future<ResultType>()>& action,
    const std::shared_ptr<Policy>& policy)
{
  CHECK(policy != nullptr);

  Try<Duration> timeout = policy->timeout();
  if (timeout.isError()) {
    return Future<ResultType>::failed(timeout.error());
  }

  return action()
    .after(timeout.get(), [action, policy](const Future<ResultType>&) {
      return retry<ResultType>(action, policy);
    });
}

TEST(FutureTest, Retry)
{
  auto policy = std::make_shared<MockPolicy>();

  EXPECT_CALL(*policy, timeout())
      .WillRepeatedly(Return(Milliseconds(1)));

  unsigned callCount = 0;
  auto future = retry<Nothing>([&callCount]() -> Future<Nothing> {
      ++callCount;
      if (callCount < 4) {
        return Future<Nothing>();
      }
      return Nothing();
    },
    policy);

  AWAIT_READY(future);
  EXPECT_EQ(1, policy.use_count());
{code}

In the test, one would expect that there is only one active reference to {{policy}}, therefore the expectation {{EXPECT_EQ(1, policy.use_count())}}. However, if after is triggered more than once, each extra call adds one undeleted reference to {{policy}}.



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