src/dawn/tests/unittests/MutexTests.cpp

// Copyright 2023 The Dawn & Tint Authors
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#include <memory>
#include <utility>

#include "dawn/common/Mutex.h"
#include "gtest/gtest.h"

namespace dawn {
namespace {

#if defined(DAWN_ENABLE_ASSERTS)
constexpr bool kAssertEnabled = true;
#else
constexpr bool kAssertEnabled = false;
#endif

class MutexTest : public ::testing::Test {
  protected:
    void SetUp() override {
        // IsLockedByCurrentThread() requires DAWN_ENABLE_ASSERTS flag enabled.
        if (!kAssertEnabled) {
            GTEST_SKIP() << "DAWN_ENABLE_ASSERTS is not enabled";
        }
    }

    Mutex mMutex;
};

// Test AutoLock automatically locks the mutex and unlocks it when out of scope.
TEST_F(MutexTest, AutoLock) {
    {
        Mutex::AutoLock autoLock(&mMutex);
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
    }
    EXPECT_FALSE(mMutex.IsLockedByCurrentThread());
}

// Test AutoLock move constructor transfers ownership of the lock.
TEST_F(MutexTest, AutoLockMoveConstructor) {
    {
        auto autoLock1 = std::make_unique<Mutex::AutoLock>(&mMutex);
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());

        // Move autoLock1 to autoLock2
        Mutex::AutoLock autoLock2(std::move(*autoLock1));

        // autoLock1 should no longer own the lock, so destroying it shouldn't unlock
        autoLock1.reset();
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
    }
    // autoLock2 is destroyed here, mutex should be unlocked
    EXPECT_FALSE(mMutex.IsLockedByCurrentThread());
}

// Test AutoLockAndHoldRef will keep the mutex alive
TEST_F(MutexTest, AutoLockAndHoldRef) {
    auto* mutex = new Mutex();
    EXPECT_EQ(mutex->GetRefCountForTesting(), 1u);
    {
        Mutex::AutoLockAndHoldRef autoLock(mutex);
        EXPECT_TRUE(mutex->IsLockedByCurrentThread());
        EXPECT_EQ(mutex->GetRefCountForTesting(), 2u);

        mutex->Release();
        EXPECT_EQ(mutex->GetRefCountForTesting(), 1u);
    }
}

// Name "*DeathTest" per https://google.github.io/googletest/advanced.html#death-test-naming
using MutexDeathTest = MutexTest;

// Double AutoLock calls should be cause assertion failure.
TEST_F(MutexDeathTest, DoubleLockCalls) {
    Mutex::AutoLock autoLock1(&mMutex);
    EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
    ASSERT_DEATH_IF_SUPPORTED({ Mutex::AutoLock autoLock2(&mMutex); }, "");
}

class RecursiveMutexTest : public ::testing::Test {
  protected:
    void SetUp() override {
        // IsLockedByCurrentThread() requires DAWN_ENABLE_ASSERTS flag enabled.
        if (!kAssertEnabled) {
            GTEST_SKIP() << "DAWN_ENABLE_ASSERTS is not enabled";
        }
    }

    RecursiveMutex mMutex;
};

// Test AutoLock automatically locks the mutex and unlocks it when out of scope.
TEST_F(RecursiveMutexTest, AutoLock) {
    {
        RecursiveMutex::AutoLock autoLock(&mMutex);
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
    }
    EXPECT_FALSE(mMutex.IsLockedByCurrentThread());
}

// Test that recursive AutoLock in same thread is valid.
TEST_F(RecursiveMutexTest, RecursiveAutoLock) {
    {
        RecursiveMutex::AutoLock autoLock1(&mMutex);
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
        RecursiveMutex::AutoLock autoLock2(&mMutex);
        EXPECT_TRUE(mMutex.IsLockedByCurrentThread());
    }
    EXPECT_FALSE(mMutex.IsLockedByCurrentThread());
}

}  // anonymous namespace
}  // namespace dawn