/*
 * This file is open source software, licensed to you under the terms
 * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership.  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.
 */

/*
 * Copyright (C) 2020 ScyllaDB.
 */

#include <chrono>

#include <seastar/testing/test_case.hh>
#include <seastar/testing/thread_test_case.hh>
#include <seastar/core/do_with.hh>
#include <seastar/core/loop.hh>
#include <seastar/core/sleep.hh>
#include <seastar/core/rwlock.hh>
#include <seastar/core/shared_mutex.hh>
#include <seastar/util/alloc_failure_injector.hh>
#include <boost/range/irange.hpp>

using namespace seastar;
using namespace std::chrono_literals;

SEASTAR_THREAD_TEST_CASE(test_rwlock) {
    rwlock l;

    l.for_write().lock().get();
    BOOST_REQUIRE(!l.try_write_lock());
    BOOST_REQUIRE(!l.try_read_lock());
    l.for_write().unlock();

    l.for_read().lock().get();
    BOOST_REQUIRE(!l.try_write_lock());
    BOOST_REQUIRE(l.try_read_lock());
    l.for_read().lock().get();
    l.for_read().unlock();
    l.for_read().unlock();
    l.for_read().unlock();

    BOOST_REQUIRE(l.try_write_lock());
    l.for_write().unlock();
}

SEASTAR_TEST_CASE(test_with_lock_mutable) {
    return do_with(rwlock(), [](rwlock& l) {
        return with_lock(l.for_read(), [p = std::make_unique<int>(42)] () mutable {});
    });
}

SEASTAR_TEST_CASE(test_rwlock_exclusive) {
    return do_with(rwlock(), unsigned(0), [] (rwlock& l, unsigned& counter) {
        return parallel_for_each(boost::irange(0, 10), [&l, &counter] (int idx) {
            return with_lock(l.for_write(), [&counter] {
                BOOST_REQUIRE_EQUAL(counter, 0u);
                ++counter;
                return sleep(1ms).then([&counter] {
                    --counter;
                    BOOST_REQUIRE_EQUAL(counter, 0u);
                });
            });
        });
    });
}

SEASTAR_TEST_CASE(test_rwlock_shared) {
    return do_with(rwlock(), unsigned(0), unsigned(0), [] (rwlock& l, unsigned& counter, unsigned& max) {
        return parallel_for_each(boost::irange(0, 10), [&l, &counter, &max] (int idx) {
            return with_lock(l.for_read(), [&counter, &max] {
                ++counter;
                max = std::max(max, counter);
                return sleep(1ms).then([&counter] {
                    --counter;
                });
            });
        }).finally([&counter, &max] {
            BOOST_REQUIRE_EQUAL(counter, 0u);
            BOOST_REQUIRE_NE(max, 0u);
        });
    });
}

SEASTAR_THREAD_TEST_CASE(test_rwlock_failed_func) {
    rwlock l;

    // verify that the rwlock is unlocked when func fails
    future<> fut = with_lock(l.for_read(), [] {
        throw std::runtime_error("injected");
    });
    BOOST_REQUIRE_THROW(fut.get(), std::runtime_error);

    fut = with_lock(l.for_write(), [] {
        throw std::runtime_error("injected");
    });
    BOOST_REQUIRE_THROW(fut.get(), std::runtime_error);

    BOOST_REQUIRE(l.try_write_lock());
    l.for_write().unlock();
}

SEASTAR_THREAD_TEST_CASE(test_failed_with_lock) {
    struct test_lock {
        future<> lock() noexcept {
            return make_exception_future<>(std::runtime_error("injected"));
        }
        void unlock() noexcept {
            BOOST_REQUIRE(false);
        }
    };

    test_lock l;

    // if l.lock() fails neither the function nor l.unlock()
    // should be called.
    BOOST_REQUIRE_THROW(with_lock(l, [] {
        BOOST_REQUIRE(false);
    }).get(), std::runtime_error);
}

SEASTAR_THREAD_TEST_CASE(test_shared_mutex) {
    shared_mutex sm;

    sm.lock().get();
    BOOST_REQUIRE(!sm.try_lock());
    BOOST_REQUIRE(!sm.try_lock_shared());
    sm.unlock();

    sm.lock_shared().get();
    BOOST_REQUIRE(!sm.try_lock());
    BOOST_REQUIRE(sm.try_lock_shared());
    sm.lock_shared().get();
    sm.unlock_shared();
    sm.unlock_shared();
    sm.unlock_shared();

    BOOST_REQUIRE(sm.try_lock());
    sm.unlock();
}

SEASTAR_TEST_CASE(test_shared_mutex_exclusive) {
    return do_with(shared_mutex(), unsigned(0), [] (shared_mutex& sm, unsigned& counter) {
        return parallel_for_each(boost::irange(0, 10), [&sm, &counter] (int idx) {
            return with_lock(sm, [&counter] {
                BOOST_REQUIRE_EQUAL(counter, 0u);
                ++counter;
                return sleep(1ms).then([&counter] {
                    --counter;
                    BOOST_REQUIRE_EQUAL(counter, 0u);
                });
            });
        });
    });
}

SEASTAR_TEST_CASE(test_shared_mutex_shared) {
    return do_with(shared_mutex(), unsigned(0), unsigned(0), [] (shared_mutex& sm, unsigned& counter, unsigned& max) {
        return parallel_for_each(boost::irange(0, 10), [&sm, &counter, &max] (int idx) {
            return with_shared(sm, [&counter, &max] {
                ++counter;
                max = std::max(max, counter);
                return sleep(1ms).then([&counter] {
                    --counter;
                });
            });
        }).finally([&counter, &max] {
            BOOST_REQUIRE_EQUAL(counter, 0u);
            BOOST_REQUIRE_NE(max, 0u);
        });
    });
}

SEASTAR_THREAD_TEST_CASE(test_shared_mutex_failed_func) {
    shared_mutex sm;

    // verify that the shared_mutex is unlocked when func fails
    future<> fut = with_shared(sm, [] {
        throw std::runtime_error("injected");
    });
    BOOST_REQUIRE_THROW(fut.get(), std::runtime_error);

    fut = with_lock(sm, [] {
        throw std::runtime_error("injected");
    });
    BOOST_REQUIRE_THROW(fut.get(), std::runtime_error);

    BOOST_REQUIRE(sm.try_lock());
    sm.unlock();
}

SEASTAR_THREAD_TEST_CASE(test_shared_mutex_failed_lock) {
#ifdef SEASTAR_ENABLE_ALLOC_FAILURE_INJECTION
    shared_mutex sm;

    // if l.lock() fails neither the function nor l.unlock()
    // should be called.
    sm.lock().get();
    seastar::memory::local_failure_injector().fail_after(0);
    BOOST_REQUIRE_THROW(with_shared(sm, [] {
        BOOST_REQUIRE(false);
    }).get(), std::bad_alloc);

    seastar::memory::local_failure_injector().fail_after(0);
    BOOST_REQUIRE_THROW(with_lock(sm, [] {
        BOOST_REQUIRE(false);
    }).get(), std::bad_alloc);
    sm.unlock();

    seastar::memory::local_failure_injector().cancel();
#endif // SEASTAR_ENABLE_ALLOC_FAILURE_INJECTION
}