-/*
- * This file is part of the GROMACS molecular simulation package.
- *
- * Copyright (c) 2017,2018,2019,2020, by the GROMACS development team, led by
- * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
- * and including many others, as listed in the AUTHORS file in the
- * top-level source directory and at http://www.gromacs.org.
- *
- * GROMACS is free software; you can redistribute it and/or
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-/*! \internal \file
- * \brief Tests for gmx::Mutex
- *
- * These tests ensure that basic mutual-exclusion properties hold.
- * Note that no testing can prove there isn't a bug, but if one
- * exists, then these tests might expose one.
- *
- * In particular, try_lock can be implemented differently on different
- * platforms, or with different default mutex types, so we should
- * check that the behaviour continues to conform with the thread-MPI
- * documentation.
- *
- * \author Mark Abraham <mark.j.abraham@gmail.com>
- * \ingroup module_utility
- */
-
-#include "gmxpre.h"
-
-#include "gromacs/utility/mutex.h"
-
-#include "config.h"
-
-#include <future>
-
-#include <gtest/gtest.h>
-
-
-namespace gmx
-{
-namespace test
-{
-namespace
-{
-
-//! Convenience definition.
-using Lock = gmx::lock_guard<Mutex>;
-
-TEST(MutexBasicTest, CanBeMade)
-{
- Mutex m;
-}
-
-TEST(MutexBasicTest, CanBeLocked)
-{
- Mutex m;
- ASSERT_NO_THROW(m.lock());
- m.unlock();
-}
-
-TEST(MutexBasicTest, CanBeTryLocked)
-{
- Mutex m;
- ASSERT_TRUE(m.try_lock());
- m.unlock();
-}
-
-TEST(MutexBasicTest, CanBeUsedInLockGuard)
-{
- Mutex m;
- Lock g(m);
-}
-
-//! A shared value for a mutex to protect
-int g_sharedValue;
-//! A mutex to protect a shared value
-Mutex g_sharedValueMutex;
-
-//! Function type for asynchronous tasks.
-using TaskType = std::function<int(void)>;
-
-//! A task that just does work.
-int updateSharedValue()
-{
- return ++g_sharedValue;
-}
-
-//! A task that does work after it gets the mutex.
-int updateSharedValueWithLock()
-{
- Lock guard(g_sharedValueMutex);
- return updateSharedValue();
-}
-
-//! A task that does work only if it can get the mutex immediately.
-int updateSharedValueWithTryLock()
-{
- // Special return value to signal when work was not done because
- // the lock was not acquired.
- int result = -1;
- if (g_sharedValueMutex.try_lock())
- {
- result = updateSharedValue();
- g_sharedValueMutex.unlock();
- }
- return result;
-}
-
-/*! \brief Parameterized test fixture.
- *
- * Checks that different launch policies work. In further tests of
- * mutual exclusion, we need to specify std::thread::async, to require
- * that a thread actually launched. The default policy permits the
- * std:: implementation to avoid launching a thread, and at least the
- * behaviour of thread-MPI try_lock also varies with the threading
- * implementation underlying it. */
-class DifferentTasksTest : public ::testing::TestWithParam<TaskType>
-{
-public:
- DifferentTasksTest() { g_sharedValue = 0; }
- //! Check the results
- void checkResults()
- {
- int result = 0;
- EXPECT_NO_THROW(result = futureResult_.get()) << "Future should not contain an exception";
- EXPECT_EQ(1, result) << "Task should have run";
- EXPECT_EQ(1, g_sharedValue) << "Shared value should be updated";
- }
- //! Contains the result the task returns.
- std::future<int> futureResult_;
-};
-
-TEST_P(DifferentTasksTest, StdAsyncWorksWithDefaultPolicy)
-{
- auto task = GetParam();
- EXPECT_NO_THROW(futureResult_ = std::async(task)) << "Async should succeed";
- checkResults();
-}
-
-TEST_P(DifferentTasksTest, StdAsyncWorksWithAsyncLaunchPolicy)
-{
- auto task = GetParam();
- EXPECT_NO_THROW(futureResult_ = std::async(std::launch::async, task)) << "Async should succeed";
- checkResults();
-}
-
-TEST_P(DifferentTasksTest, StdAsyncWorksWithDeferredLaunchPolicy)
-{
- auto task = GetParam();
- EXPECT_NO_THROW(futureResult_ = std::async(std::launch::deferred, task))
- << "Async should succeed";
- checkResults();
-}
-
-// Test that the different launch policies work with the different tasks
-INSTANTIATE_TEST_CASE_P(WithAndWithoutMutex,
- DifferentTasksTest,
- ::testing::Values(updateSharedValue,
- updateSharedValueWithLock,
- updateSharedValueWithTryLock));
-
-TEST(MutexTaskTest, MutualExclusionWorksWithLock)
-{
- g_sharedValue = 0;
- std::future<int> result;
- {
- // Hold the mutex, launch a lock attempt on another
- // thread, check that the shared value isn't changed, then
- // release the mutex by leaving the scope, after which the
- // other thread's lock can get the mutex.
- Lock guard(g_sharedValueMutex);
- result = std::async(std::launch::async, updateSharedValueWithLock);
- EXPECT_EQ(0, g_sharedValue) << "Task should not have run yet";
- }
- EXPECT_EQ(1, result.get()) << "Task should have run";
- EXPECT_EQ(1, g_sharedValue) << "Shared value should be updated";
-}
-
-TEST(MutexTaskTest, MutualExclusionWorksWithTryLockOnOtherThread)
-{
- g_sharedValue = 0;
- {
- // Hold the mutex, launch a try_lock attempt on another
- // thread, check that the shared value isn't changed, then
- // make sure the try_lock attempt has returned, double check
- // that the shared value isn't changed, and release the mutex
- // by leaving the scope.
- Lock guard(g_sharedValueMutex);
- auto result = std::async(std::launch::async, updateSharedValueWithTryLock);
- EXPECT_EQ(0, g_sharedValue) << "Data race detected";
- EXPECT_EQ(-1, result.get()) << "The try_lock should fail";
- EXPECT_EQ(0, g_sharedValue) << "Task should not have run";
- }
- EXPECT_EQ(0, g_sharedValue) << "Mutex release can't affect the protected value";
-}
-
-TEST(MutexTaskTest, MutualExclusionWorksWithTryLockOnSameThread)
-{
- g_sharedValue = 0;
- int finalSharedValue = GMX_NATIVE_WINDOWS ? 1 : 0;
- {
- // Hold the mutex and launch a try_lock attempt on this
- // thread. Behaviour then varies with the implementation
- // underlying thread-MPI.
- Lock guard(g_sharedValueMutex);
- int result = updateSharedValueWithTryLock();
- if (GMX_NATIVE_WINDOWS)
- {
- EXPECT_EQ(1, result) << "The try_lock should succeed";
- EXPECT_EQ(finalSharedValue, g_sharedValue) << "Task should have run";
- }
- else
- {
- EXPECT_EQ(-1, result) << "The try_lock should fail";
- EXPECT_EQ(finalSharedValue, g_sharedValue) << "Task should not have run";
- }
- }
- EXPECT_EQ(finalSharedValue, g_sharedValue) << "Mutex release can't affect the protected value";
-}
-
-} // namespace
-} // namespace test
-} // namespace gmx