Disposer.ut.cpp

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// The Reactive C++ Toolbox.
// Copyright (C) 2013-2019 Swirly Cloud Limited
// Copyright (C) 2021 Reactive Markets Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include "Disposer.hpp"
 
#include <boost/test/unit_test.hpp>
 
#include <stdexcept>
 
using namespace std;
using namespace toolbox;
 
namespace {
struct Disposer : BasicDisposer<Disposer> {
    using BasicDisposer<Disposer>::is_dispose_deferred;
    using BasicDisposer<Disposer>::is_locked;
    using BasicDisposer<Disposer>::lock_this;
    void dispose_now(CyclTime now) noexcept
    {
        // Ensure that dispose_now can safely call dispose.
        // This could happen if dispose_now invoked a callback.
        dispose(now);
        ++disposed;
    }
    int disposed{0};
};
 
// These helpers are not inlined into the test cases, so the guard is released by the code that
// runs while an exception unwinds their frame, as when a send throws inside a guard.
[[gnu::noinline]] void throw_error()
{
    throw runtime_error{"error"};
}
 
[[gnu::noinline]] void throw_while_locked(Disposer& d, CyclTime now)
{
    const auto lock = d.lock_this(now);
    throw_error();
}
 
[[gnu::noinline]] void dispose_and_throw_while_locked(Disposer& d, CyclTime now)
{
    const auto lock = d.lock_this(now);
    d.dispose(now);
    throw_error();
}
} // namespace
 
BOOST_AUTO_TEST_SUITE(DisposerSuite)
 
BOOST_AUTO_TEST_CASE(DisposerCase)
{
    const auto now = CyclTime::now();
    Disposer d;
    BOOST_CHECK(!d.is_locked());
    BOOST_CHECK(!d.is_dispose_deferred());
    BOOST_CHECK_EQUAL(d.disposed, 0);
    {
        auto lock = d.lock_this(now);
        BOOST_CHECK(d.is_locked());
        BOOST_CHECK(!d.is_dispose_deferred());
    }
    BOOST_CHECK(!d.is_locked());
    BOOST_CHECK(!d.is_dispose_deferred());
    BOOST_CHECK_EQUAL(d.disposed, 0);
    {
        auto outer_lock = d.lock_this(now);
        BOOST_CHECK(d.is_locked());
        {
            auto inner_lock = d.lock_this(now);
            BOOST_CHECK(!d.is_dispose_deferred());
            d.dispose(now);
            BOOST_CHECK(d.is_locked());
            BOOST_CHECK(d.is_dispose_deferred());
            BOOST_CHECK_EQUAL(d.disposed, 0);
        }
        // And again.
        d.dispose(now);
        BOOST_CHECK(d.is_locked());
        BOOST_CHECK(d.is_dispose_deferred());
        BOOST_CHECK_EQUAL(d.disposed, 0);
    }
    BOOST_CHECK_EQUAL(d.disposed, 1);
}
 
BOOST_AUTO_TEST_CASE(DisposerUnwindCase)
{
    // An exception that unwinds through the guard must release it. GCC 14 at -O1 and above
    // deleted this release when the dispose path wrote the count twice.
    const auto now = CyclTime::now();
    Disposer d;
    BOOST_CHECK_THROW(throw_while_locked(d, now), runtime_error);
    BOOST_CHECK(!d.is_locked());
    BOOST_CHECK(!d.is_dispose_deferred());
    d.dispose(now);
    BOOST_CHECK_EQUAL(d.disposed, 1);
}
 
BOOST_AUTO_TEST_CASE(DisposerUnwindDeferredCase)
{
    // A disposal deferred by the guard runs once when an exception unwinds through it, and the
    // object then stays locked so that it is not disposed a second time.
    const auto now = CyclTime::now();
    Disposer d;
    BOOST_CHECK_THROW(dispose_and_throw_while_locked(d, now), runtime_error);
    BOOST_CHECK_EQUAL(d.disposed, 1);
    BOOST_CHECK(d.is_locked());
    d.dispose(now);
    BOOST_CHECK_EQUAL(d.disposed, 1);
}
 
BOOST_AUTO_TEST_SUITE_END()