zircon/system/ulib/fbl/test/ref_ptr_tests.cpp

// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <fbl/alloc_checker.h>
#include <fbl/ref_counted.h>
#include <fbl/ref_ptr.h>
#include <stdio.h>
#include <unittest/unittest.h>

#include <utility>

namespace {

class RefCallCounter {
public:
    RefCallCounter();
    ~RefCallCounter();

    void AddRef();
    bool Release();

    void Adopt() {}

    int add_ref_calls() const { return add_ref_calls_; }
    int release_calls() const { return release_calls_; }

    static int destroy_calls() { return destroy_calls_; }
    static void operator delete(void* ptr) {}

private:
    int add_ref_calls_;
    int release_calls_;


    static int destroy_calls_;
};

int RefCallCounter::destroy_calls_ = 0u;

RefCallCounter::RefCallCounter()
    : add_ref_calls_(0u), release_calls_(0u) {}

RefCallCounter::~RefCallCounter() {
    destroy_calls_++;
}

void RefCallCounter::AddRef() {
    add_ref_calls_++;
}
bool RefCallCounter::Release() {
    release_calls_++;
    return add_ref_calls_ == release_calls_;
}

static_assert(std::is_standard_layout_v<fbl::RefPtr<RefCallCounter>>,
              "fbl::RefPtr<T>'s should have a standard layout.");

static bool ref_ptr_test() {
    BEGIN_TEST;
    using RefCallPtr = fbl::RefPtr<RefCallCounter>;

    RefCallCounter counter;
    RefCallPtr ptr = fbl::AdoptRef<RefCallCounter>(&counter);

    EXPECT_TRUE(&counter == ptr.get(), ".get() should point to object");
    EXPECT_TRUE(static_cast<bool>(ptr), "operator bool");
    EXPECT_TRUE(&counter == &(*ptr), "operator*");

    // Adoption should not manipulate the refcount.
    EXPECT_EQ(0, counter.add_ref_calls());
    EXPECT_EQ(0, counter.release_calls());
    EXPECT_EQ(0, RefCallCounter::destroy_calls());

    {
        RefCallPtr ptr2 = ptr;

        // Copying to a new RefPtr should call add once.
        EXPECT_EQ(1, counter.add_ref_calls());
        EXPECT_EQ(0, counter.release_calls());
        EXPECT_EQ(0, RefCallCounter::destroy_calls());
    }
    // Destroying the new RefPtr should release once.
    EXPECT_EQ(1, counter.add_ref_calls());
    EXPECT_EQ(1, counter.release_calls());
    EXPECT_EQ(1, RefCallCounter::destroy_calls());

    {
        RefCallPtr ptr2;

        EXPECT_TRUE(!static_cast<bool>(ptr2));

        ptr.swap(ptr2);

        // Swapping shouldn't cause any add or release calls, but should update
        // values.
        EXPECT_EQ(1, counter.add_ref_calls());
        EXPECT_EQ(1, counter.release_calls());
        EXPECT_EQ(1, RefCallCounter::destroy_calls());

        EXPECT_TRUE(!static_cast<bool>(ptr));
        EXPECT_TRUE(&counter == ptr2.get());

        ptr2.swap(ptr);
    }

    EXPECT_EQ(1, counter.add_ref_calls());
    EXPECT_EQ(1, counter.release_calls());
    EXPECT_EQ(1, RefCallCounter::destroy_calls());

    {
        RefCallPtr ptr2 = std::move(ptr);

        // Moving shouldn't cause any add or release but should update values.
        EXPECT_EQ(1, counter.add_ref_calls());
        EXPECT_EQ(1, counter.release_calls());
        EXPECT_EQ(1, RefCallCounter::destroy_calls());

        EXPECT_FALSE(static_cast<bool>(ptr));
        EXPECT_TRUE(&counter == ptr2.get());

        ptr2.swap(ptr);
    }

    // Reset should calls release and clear out the pointer.
    ptr.reset(nullptr);
    EXPECT_EQ(1, counter.add_ref_calls());
    EXPECT_EQ(2, counter.release_calls());
    EXPECT_EQ(1, RefCallCounter::destroy_calls());
    EXPECT_FALSE(static_cast<bool>(ptr));
    EXPECT_FALSE(ptr.get());

    END_TEST;
}

static bool ref_ptr_compare_test() {
    BEGIN_TEST;
    using RefCallPtr = fbl::RefPtr<RefCallCounter>;

    RefCallCounter obj1, obj2;

    RefCallPtr ptr1 = fbl::AdoptRef<RefCallCounter>(&obj1);
    RefCallPtr ptr2 = fbl::AdoptRef<RefCallCounter>(&obj2);
    RefCallPtr also_ptr1 = ptr1;
    RefCallPtr null_ref_ptr;

    EXPECT_TRUE(ptr1 == ptr1);
    EXPECT_FALSE(ptr1 != ptr1);

    EXPECT_FALSE(ptr1 == ptr2);
    EXPECT_TRUE(ptr1 != ptr2);

    EXPECT_TRUE(ptr1 == also_ptr1);
    EXPECT_FALSE(ptr1 != also_ptr1);

    EXPECT_TRUE(ptr1 != null_ref_ptr);
    EXPECT_TRUE(ptr1 != nullptr);
    EXPECT_TRUE(nullptr != ptr1);
    EXPECT_FALSE(ptr1 == null_ref_ptr);
    EXPECT_FALSE(ptr1 == nullptr);
    EXPECT_FALSE(nullptr == ptr1);

    EXPECT_TRUE(null_ref_ptr == nullptr);
    EXPECT_FALSE(null_ref_ptr != nullptr);
    EXPECT_TRUE(nullptr == null_ref_ptr);
    EXPECT_FALSE(nullptr != null_ref_ptr);

    END_TEST;
}

namespace upcasting {

class Stats {
public:
     Stats() { }
    ~Stats() { destroy_count_++; }

    static void Reset() {
        adopt_calls_   = 0;
        add_ref_calls_ = 0;
        release_calls_ = 0;
        destroy_count_ = 0;
    }

    void Adopt() { adopt_calls_++; }

    void AddRef() {
        ref_count_++;
        add_ref_calls_++;
    }

    bool Release() {
        ref_count_--;
        release_calls_++;
        return (ref_count_ <= 0);
    }

    static uint32_t adopt_calls()   { return adopt_calls_; }
    static uint32_t add_ref_calls() { return add_ref_calls_; }
    static uint32_t release_calls() { return release_calls_; }
    static uint32_t destroy_count() { return destroy_count_; }

private:
    int ref_count_ = 1;
    static uint32_t adopt_calls_;
    static uint32_t add_ref_calls_;
    static uint32_t release_calls_;
    static uint32_t destroy_count_;
};

uint32_t Stats::adopt_calls_   = 0;
uint32_t Stats::add_ref_calls_ = 0;
uint32_t Stats::release_calls_ = 0;
uint32_t Stats::destroy_count_ = 0;

class A : public Stats {
public:
    virtual ~A() { stuff = 0u; }

private:
    volatile uint32_t stuff;
};

class B {
public:
    ~B() { stuff = 1u; }

private:
    volatile uint32_t stuff;
};

class C : public A, public B {
public:
    ~C() { }
};

class D : public A {
public:
    virtual ~D() { stuff = 2u; }

private:
    volatile uint32_t stuff;
};

template <typename T>
struct custom_delete {
    inline void operator()(T* ptr) const {
        enum { type_must_be_complete = sizeof(T) };
        delete ptr;
    }
};

template <typename RefPtrType>
static bool handoff_lvalue_fn(const RefPtrType& ptr) {
    BEGIN_TEST;
    EXPECT_NONNULL(ptr);
    END_TEST;
}

template <typename RefPtrType>
static bool handoff_copy_fn(RefPtrType ptr) {
    BEGIN_TEST;
    EXPECT_NONNULL(ptr);
    END_TEST;
}

template <typename RefPtrType>
static bool handoff_rvalue_fn(RefPtrType&& ptr) {
    BEGIN_TEST;
    EXPECT_NONNULL(ptr);
    END_TEST;
}

class OverloadTestHelper {
public:
    enum class Result {
        None,
        ClassA,
        ClassB,
        ClassD,
    };

    void PassByCopy(fbl::RefPtr<A>) { result_ = Result::ClassA; }
    void PassByCopy(fbl::RefPtr<D>) { result_ = Result::ClassD; }

#if TEST_WILL_NOT_COMPILE || 0
    // Enabling this overload should cause the overload test to fail to compile
    // due to ambiguity (it does not know whether to cast fbl::RefPtr<C> to fbl::RefPtr<A>
    // or fbl::RefPtr<B>)
    void PassByCopy(fbl::RefPtr<B>) { result_ = Result::ClassB; }
#endif

    void PassByMove(fbl::RefPtr<A>&&) { result_ = Result::ClassA; }
    void PassByMove(fbl::RefPtr<D>&&) { result_ = Result::ClassD; }

#if TEST_WILL_NOT_COMPILE || 0
    // Enabling this overload should cause the overload test to fail to compile
    // due to ambiguity (it does not know whether to cast fbl::RefPtr<C> to fbl::RefPtr<A>
    // or fbl::RefPtr<B>)
    void PassByMove(fbl::RefPtr<B>&&) { result_ = Result::ClassB; }
#endif

    Result result() const { return result_; }

private:
    Result result_ = Result::None;
};

template <typename Base,
          typename Derived>
static bool do_test() {
    BEGIN_TEST;
    fbl::AllocChecker ac;

    fbl::RefPtr<Derived> derived_ptr;

    // Construct RefPtr<Base> with a copy and implicit cast
    Stats::Reset();
    derived_ptr = fbl::AdoptRef<Derived>(new (&ac) Derived());
    ASSERT_TRUE(ac.check());
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(0, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr(derived_ptr);

        EXPECT_NONNULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    // Construct RefPtr<Base> with a move and implicit cast
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr(std::move(derived_ptr));

        EXPECT_NULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    EXPECT_EQ(1, Stats::adopt_calls());
    EXPECT_EQ(1, Stats::add_ref_calls());
    EXPECT_EQ(2, Stats::release_calls());
    EXPECT_EQ(1, Stats::destroy_count());

    // Assign RefPtr<Base> at declaration time with a copy
    Stats::Reset();
    derived_ptr = fbl::AdoptRef<Derived>(new (&ac) Derived());
    ASSERT_TRUE(ac.check());
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(0, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr = derived_ptr;

        EXPECT_NONNULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    // Assign RefPtr<Base> at declaration time with a std::move
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr = std::move(derived_ptr);

        EXPECT_NULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    EXPECT_EQ(1, Stats::adopt_calls());
    EXPECT_EQ(1, Stats::add_ref_calls());
    EXPECT_EQ(2, Stats::release_calls());
    EXPECT_EQ(1, Stats::destroy_count());

    // Assign RefPtr<Base> after declaration with a copy
    Stats::Reset();
    derived_ptr = fbl::AdoptRef<Derived>(new (&ac) Derived());
    ASSERT_TRUE(ac.check());
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(0, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr;
        base_ptr = derived_ptr;

        EXPECT_NONNULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    // Assign RefPtr<Base> after declaration with a std::move
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        fbl::RefPtr<Base> base_ptr;
        base_ptr = std::move(derived_ptr);

        EXPECT_NULL(derived_ptr);
        EXPECT_NONNULL(base_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    EXPECT_EQ(1, Stats::adopt_calls());
    EXPECT_EQ(1, Stats::add_ref_calls());
    EXPECT_EQ(2, Stats::release_calls());
    EXPECT_EQ(1, Stats::destroy_count());

    // Pass the pointer to a function as an lvalue reference with an implicit cast
    Stats::Reset();
    derived_ptr = fbl::AdoptRef<Derived>(new (&ac) Derived());
    ASSERT_TRUE(ac.check());
    {
        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(0, Stats::add_ref_calls());
        EXPECT_EQ(0, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());

        // Note: counter to intuition, we actually do expect this to bump the
        // reference count regardless of what the target function does with the
        // reference-to-pointer passed to it.  We are not passing a const
        // reference to a RefPtr<Derived>; instead we are creating a temp
        // RefPtr<Base> (which is where the addref happens) and then passing a
        // refernce to *that* to the function.
        bool test_res = handoff_lvalue_fn<fbl::RefPtr<Base>>(derived_ptr);
        EXPECT_TRUE(test_res);

        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(1, Stats::add_ref_calls());
        EXPECT_EQ(1, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    // Pass the pointer to a function with a copy and implicit cast
    {
        bool test_res = handoff_copy_fn<fbl::RefPtr<Base>>(derived_ptr);
        EXPECT_TRUE(test_res);

        EXPECT_NONNULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(2, Stats::add_ref_calls());
        EXPECT_EQ(2, Stats::release_calls());
        EXPECT_EQ(0, Stats::destroy_count());
    }

    // Pass the pointer to a function as an rvalue reference and implicit cast
    {
        bool test_res = handoff_rvalue_fn<fbl::RefPtr<Base>>(std::move(derived_ptr));
        EXPECT_TRUE(test_res);

        EXPECT_NULL(derived_ptr);
        EXPECT_EQ(1, Stats::adopt_calls());
        EXPECT_EQ(2, Stats::add_ref_calls());
        EXPECT_EQ(3, Stats::release_calls());
        EXPECT_EQ(1, Stats::destroy_count());
    }

    END_TEST;
}

static bool ref_ptr_upcast_test() {
    BEGIN_TEST;
    bool test_res;

    // This should work.  C derives from A, A has a virtual destructor, and
    // everything is using the default deleter.
    test_res = do_test<A, C>();
    EXPECT_TRUE(test_res);

#if TEST_WILL_NOT_COMPILE || 0
    // This should not work.  C derives from B, but B has no virtual destructor.
    test_res = do_test<B, C>();
    EXPECT_FALSE(test_res);
#endif

#if TEST_WILL_NOT_COMPILE || 0
    // This should not work.  D has a virtual destructor, but it is not a base
    // class of C.
    test_res = do_test<D, C>();
    EXPECT_FALSE(test_res);
#endif

    // Test overload resolution.  Make a C and the try to pass it to
    // OverloadTestHelper's various overloaded methods.  The compiler should
    // know which version to pick, and it should pick the RefPtr<A> version, not
    // the RefPtr<D> version.  If the TEST_WILL_NOT_COMPILE check is enabled in
    // OverloadTestHelper, a RefPtr<B> version will be enabled as well.  This
    // should cause the build to break because of ambiguity.
    fbl::AllocChecker ac;
    fbl::RefPtr<C> ptr = fbl::AdoptRef(new (&ac) C());
    ASSERT_TRUE(ac.check());

    {
        // Test pass by copy first (so we can reuse our object)
        OverloadTestHelper helper;
        helper.PassByCopy(ptr);

        ASSERT_NONNULL(ptr);
        EXPECT_EQ(OverloadTestHelper::Result::ClassA, helper.result());

    }

    {
        // Now test pass by move.
        OverloadTestHelper helper;
        helper.PassByMove(std::move(ptr));

        EXPECT_NULL(ptr);
        EXPECT_EQ(OverloadTestHelper::Result::ClassA, helper.result());
    }

    END_TEST;
}

}  // namespace upcasting

static bool ref_ptr_adopt_null_test() {
    BEGIN_TEST;

    class C : public fbl::RefCounted<C> {
    };

    fbl::RefPtr<C> ptr = fbl::AdoptRef(static_cast<C*>(nullptr));
    EXPECT_NULL(ptr);
    END_TEST;
}

static bool ref_ptr_to_const_test() {
    BEGIN_TEST;

    class C : public fbl::RefCounted<C> {
    public:
        explicit C(int x) : x_(x) {}

        int get_x() const { return x_; }

    private:
        int x_;
    };

    fbl::AllocChecker ac;
    fbl::RefPtr<C> refptr = fbl::AdoptRef<C>(new (&ac) C(23));
    ASSERT_TRUE(ac.check());

    // Copy a ref-ptr to a ref-ptr-to-const.
    fbl::RefPtr<const C> const_refptr = refptr;
    // refptr should have been copied, not moved.
    ASSERT_NONNULL(refptr.get());

    // Call a const member function on a ref-ptr-to-const.
    EXPECT_NONNULL(const_refptr.get());
    EXPECT_EQ(const_refptr->get_x(), 23);

    // Move a ref-ptr to a ref-ptr-to-const.
    fbl::RefPtr<const C> moved_const_refptr = std::move(refptr);
    ASSERT_NONNULL(moved_const_refptr.get());
    // Now refptr should have been nulled out.
    ASSERT_NULL(refptr.get());

    // Move a ref-ptr-to-const into another ref-ptr-to-const.
    const_refptr.reset();
    ASSERT_NULL(const_refptr);
    const_refptr = std::move(moved_const_refptr);
    ASSERT_NONNULL(const_refptr);
    ASSERT_NULL(moved_const_refptr);

    END_TEST;
}

static bool ref_ptr_move_assign() {
    BEGIN_TEST;
    using RefCallPtr = fbl::RefPtr<RefCallCounter>;

    RefCallCounter counter1, counter2;
    RefCallPtr ptr1 = fbl::AdoptRef<RefCallCounter>(&counter1);
    RefCallPtr ptr2 = fbl::AdoptRef<RefCallCounter>(&counter2);

    EXPECT_NE(ptr1.get(), ptr2.get());
    EXPECT_NONNULL(ptr1);
    EXPECT_NONNULL(ptr2);

    ptr1 = std::move(ptr2);
    EXPECT_EQ(ptr1.get(), &counter2);
    EXPECT_NULL(ptr2);

    EXPECT_EQ(1, counter1.release_calls());
    EXPECT_EQ(0, counter2.release_calls());

    // Test self-assignment
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wself-move"
#endif
    ptr1 = std::move(ptr1);
#ifdef __clang__
#pragma clang diagnostic pop
#endif
    EXPECT_EQ(ptr1.get(), &counter2);
    EXPECT_EQ(0, counter2.release_calls());

    END_TEST;
}

}  // namespace

BEGIN_TEST_CASE(ref_ptr_tests)
RUN_NAMED_TEST("Ref Pointer", ref_ptr_test)
RUN_NAMED_TEST("Ref Pointer Comparison", ref_ptr_compare_test)
RUN_NAMED_TEST("Ref Pointer Upcast", upcasting::ref_ptr_upcast_test)
RUN_NAMED_TEST("Ref Pointer Adopt null", ref_ptr_adopt_null_test)
RUN_NAMED_TEST("Ref Pointer To Const", ref_ptr_to_const_test)
RUN_NAMED_TEST("Ref Pointer Move Assignment", ref_ptr_move_assign)
END_TEST_CASE(ref_ptr_tests)