aos/common/mutex_test.cc

#include "aos/common/mutex.h"

#include <math.h>
#include <pthread.h>
#include <sched.h>

#include <chrono>
#include <thread>

#include "gtest/gtest.h"

#include "aos/common/die.h"
#include "aos/common/time.h"
#include "aos/common/util/death_test_log_implementation.h"
#include "aos/common/util/thread.h"
#include "aos/linux_code/ipc_lib/aos_sync.h"
#include "aos/linux_code/ipc_lib/core_lib.h"
#include "aos/testing/test_logging.h"
#include "aos/testing/test_shm.h"

namespace aos {
namespace testing {

namespace chrono = ::std::chrono;
namespace this_thread = ::std::this_thread;

class MutexTest : public ::testing::Test {
 public:
  Mutex test_mutex_;

 protected:
  void SetUp() override {
    ::aos::testing::EnableTestLogging();
    SetDieTestMode(true);
  }
};

typedef MutexTest MutexDeathTest;
typedef MutexTest MutexLockerTest;
typedef MutexTest MutexLockerDeathTest;
typedef MutexTest IPCMutexLockerTest;
typedef MutexTest IPCMutexLockerDeathTest;
typedef MutexTest IPCRecursiveMutexLockerTest;

TEST_F(MutexTest, TryLock) {
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());
  EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

TEST_F(MutexTest, Lock) {
  ASSERT_FALSE(test_mutex_.Lock());
  EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

TEST_F(MutexTest, Unlock) {
  ASSERT_FALSE(test_mutex_.Lock());
  EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
  test_mutex_.Unlock();
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

// Sees what happens with multiple unlocks.
TEST_F(MutexDeathTest, RepeatUnlock) {
  logging::Init();
  ASSERT_FALSE(test_mutex_.Lock());
  test_mutex_.Unlock();
  EXPECT_DEATH(
      {
        logging::AddImplementation(new util::DeathTestLogImplementation());
        test_mutex_.Unlock();
      },
      ".*multiple unlock.*");
}

// Sees what happens if you unlock without ever locking (or unlocking) it.
TEST_F(MutexDeathTest, NeverLock) {
  logging::Init();
  EXPECT_DEATH(
      {
        logging::AddImplementation(new util::DeathTestLogImplementation());
        test_mutex_.Unlock();
      },
      ".*multiple unlock.*");
}

// Tests that locking a mutex multiple times from the same thread fails nicely.
TEST_F(MutexDeathTest, RepeatLock) {
  EXPECT_DEATH(
      {
        logging::AddImplementation(new util::DeathTestLogImplementation());
        ASSERT_FALSE(test_mutex_.Lock());
        ASSERT_FALSE(test_mutex_.Lock());
      },
      ".*multiple lock.*");
}

// Tests that Lock behaves correctly when the previous owner exits with the lock
// held (which is the same as dying any other way).
TEST_F(MutexTest, OwnerDiedDeathLock) {
  testing::TestSharedMemory my_shm;
  Mutex *mutex =
      static_cast<Mutex *>(shm_malloc_aligned(sizeof(Mutex), alignof(Mutex)));
  new (mutex) Mutex();

  util::FunctionThread::RunInOtherThread([&]() {
    ASSERT_FALSE(mutex->Lock());
  });
  EXPECT_TRUE(mutex->Lock());

  mutex->Unlock();
  mutex->~Mutex();
}

// Tests that TryLock behaves correctly when the previous owner dies.
TEST_F(MutexTest, OwnerDiedDeathTryLock) {
  testing::TestSharedMemory my_shm;
  Mutex *mutex =
      static_cast<Mutex *>(shm_malloc_aligned(sizeof(Mutex), alignof(Mutex)));
  new (mutex) Mutex();

  util::FunctionThread::RunInOtherThread([&]() {
    ASSERT_FALSE(mutex->Lock());
  });
  EXPECT_EQ(Mutex::State::kOwnerDied, mutex->TryLock());

  mutex->Unlock();
  mutex->~Mutex();
}

// TODO(brians): Test owner dying by being SIGKILLed and SIGTERMed.

// This sequence of mutex operations used to mess up the robust list and cause
// one of the mutexes to not get owner-died like it should.
TEST_F(MutexTest, DontCorruptRobustList) {
  // I think this was the allocator lock in the original failure.
  Mutex mutex1;
  // This one should get owner-died afterwards (iff the kernel accepts the
  // robust list and uses it). I think it was the task_death_notification lock
  // in the original failure.
  Mutex mutex2;

  util::FunctionThread::RunInOtherThread([&]() {
    ASSERT_FALSE(mutex1.Lock());
    ASSERT_FALSE(mutex2.Lock());
    mutex1.Unlock();
  });

  EXPECT_EQ(Mutex::State::kLocked, mutex1.TryLock());
  EXPECT_EQ(Mutex::State::kOwnerDied, mutex2.TryLock());

  mutex1.Unlock();
  mutex2.Unlock();
}

namespace {

class AdderThread : public ::aos::util::Thread {
 public:
  AdderThread(int *counter, Mutex *mutex,
              monotonic_clock::duration sleep_before_time,
              monotonic_clock::duration sleep_after_time)
      : counter_(counter),
        mutex_(mutex),
        sleep_before_time_(sleep_before_time),
        sleep_after_time_(sleep_after_time) {}

 private:
  virtual void Run() override {
    this_thread::sleep_for(sleep_before_time_);
    MutexLocker locker(mutex_);
    ++(*counter_);
    this_thread::sleep_for(sleep_after_time_);
  }

  int *const counter_;
  Mutex *const mutex_;
  const monotonic_clock::duration sleep_before_time_, sleep_after_time_;
};

}  // namespace

// Verifies that ThreadSanitizer understands that a contended mutex establishes
// a happens-before relationship.
TEST_F(MutexTest, ThreadSanitizerContended) {
  int counter = 0;
  AdderThread threads[2]{
      {&counter, &test_mutex_, chrono::milliseconds(200),
       chrono::milliseconds(0)},
      {&counter, &test_mutex_, chrono::milliseconds(0),
       chrono::milliseconds(0)},
  };
  for (auto &c : threads) {
    c.Start();
  }
  for (auto &c : threads) {
    c.WaitUntilDone();
  }
  EXPECT_EQ(2, counter);
}

// Verifiers that ThreadSanitizer understands how a mutex works.
// For some reason this used to fail when the other tests didn't...
// The loops make it fail more reliably when it's going to.
TEST_F(MutexTest, ThreadSanitizerMutexLocker) {
  for (int i = 0; i < 100; ++i) {
    int counter = 0;
    ::std::thread thread([&counter, this]() {
      for (int i = 0; i < 300; ++i) {
        MutexLocker locker(&test_mutex_);
        ++counter;
      }
    });
    for (int i = 0; i < 300; ++i) {
      MutexLocker locker(&test_mutex_);
      --counter;
    }
    thread.join();
    EXPECT_EQ(0, counter);
  }
}

// Verifies that ThreadSanitizer understands that an uncontended mutex
// establishes a happens-before relationship.
TEST_F(MutexTest, ThreadSanitizerUncontended) {
  int counter = 0;
  AdderThread threads[2]{
      {&counter, &test_mutex_, chrono::milliseconds(0),
       chrono::milliseconds(0)},
      {&counter, &test_mutex_, chrono::milliseconds(200),
       chrono::milliseconds(0)}, };
  for (auto &c : threads) {
    c.Start();
  }
  for (auto &c : threads) {
    c.WaitUntilDone();
  }
  EXPECT_EQ(2, counter);
}

namespace {

class LockerThread : public util::Thread {
 public:
  LockerThread(Mutex *mutex, bool lock, bool unlock)
      : mutex_(mutex), lock_(lock), unlock_(unlock) {}

 private:
  virtual void Run() override {
    if (lock_) ASSERT_FALSE(mutex_->Lock());
    if (unlock_) mutex_->Unlock();
  }

  Mutex *const mutex_;
  const bool lock_, unlock_;
};

}  // namespace

// Makes sure that we don't SIGSEGV or something with multiple threads.
TEST_F(MutexTest, MultiThreadedLock) {
  LockerThread t(&test_mutex_, true, true);
  t.Start();
  ASSERT_FALSE(test_mutex_.Lock());
  test_mutex_.Unlock();
  t.Join();
}

TEST_F(MutexLockerTest, Basic) {
  {
    aos::MutexLocker locker(&test_mutex_);
    EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
  }
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

// Tests that MutexLocker behaves correctly when the previous owner dies.
TEST_F(MutexLockerDeathTest, OwnerDied) {
  testing::TestSharedMemory my_shm;
  Mutex *mutex =
      static_cast<Mutex *>(shm_malloc_aligned(sizeof(Mutex), alignof(Mutex)));
  new (mutex) Mutex();

  util::FunctionThread::RunInOtherThread([&]() {
    ASSERT_FALSE(mutex->Lock());
  });
  EXPECT_DEATH(
      {
        logging::AddImplementation(new util::DeathTestLogImplementation());
        MutexLocker locker(mutex);
      },
      ".*previous owner of mutex [^ ]+ died.*");

  mutex->~Mutex();
}

TEST_F(IPCMutexLockerTest, Basic) {
  {
    aos::IPCMutexLocker locker(&test_mutex_);
    EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
    EXPECT_FALSE(locker.owner_died());
  }
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

// Tests what happens when the caller doesn't check if the previous owner died
// with an IPCMutexLocker.
TEST_F(IPCMutexLockerDeathTest, NoCheckOwnerDied) {
  EXPECT_DEATH({ aos::IPCMutexLocker locker(&test_mutex_); },
               "nobody checked if the previous owner of mutex [^ ]+ died.*");
}

TEST_F(IPCRecursiveMutexLockerTest, Basic) {
  {
    aos::IPCRecursiveMutexLocker locker(&test_mutex_);
    EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
    EXPECT_FALSE(locker.owner_died());
  }
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

// Tests actually locking a mutex recursively with IPCRecursiveMutexLocker.
TEST_F(IPCRecursiveMutexLockerTest, RecursiveLock) {
  {
    aos::IPCRecursiveMutexLocker locker(&test_mutex_);
    EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
    {
      aos::IPCRecursiveMutexLocker locker(&test_mutex_);
      EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
      EXPECT_FALSE(locker.owner_died());
    }
    EXPECT_EQ(Mutex::State::kLockFailed, test_mutex_.TryLock());
    EXPECT_FALSE(locker.owner_died());
  }
  EXPECT_EQ(Mutex::State::kLocked, test_mutex_.TryLock());

  test_mutex_.Unlock();
}

// Tests that IPCMutexLocker behaves correctly when the previous owner dies.
TEST_F(IPCMutexLockerTest, OwnerDied) {
  testing::TestSharedMemory my_shm;
  Mutex *mutex =
      static_cast<Mutex *>(shm_malloc_aligned(sizeof(Mutex), alignof(Mutex)));
  new (mutex) Mutex();

  util::FunctionThread::RunInOtherThread([&]() {
    ASSERT_FALSE(mutex->Lock());
  });
  {
    aos::IPCMutexLocker locker(mutex);
    EXPECT_EQ(Mutex::State::kLockFailed, mutex->TryLock());
    EXPECT_TRUE(locker.owner_died());
  }
  EXPECT_EQ(Mutex::State::kLocked, mutex->TryLock());

  mutex->Unlock();
  mutex->~Mutex();
}

}  // namespace testing
}  // namespace aos