/*
 * Copyright 2015 Nest Labs, Inc.
 *
 * 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.
 */

// Test bed for folly/Cancellation.h

#include <folly/Cancellation.h>
#include <gtest/gtest.h>
#include <future>

using ::folly::Cancellation;

/* Tests the basic operation of the construct */
TEST(Cancellation, BasicFunction)
{
    Cancellation c;
    EXPECT_FALSE(c.is_cancelled());
    c.cancel();
    EXPECT_TRUE(c.is_cancelled());
}

/* Independently constructed objects shall not share state */
TEST(Cancellation, Independence)
{
    Cancellation c0;
    Cancellation c1;
    EXPECT_FALSE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c0.cancel();
    EXPECT_TRUE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
}

/* Objects using copy constructor shall have a common state */
TEST(Cancellation, CopyConstructor)
{
    Cancellation c0;
    Cancellation c1(c0);
    EXPECT_FALSE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c0.cancel();
    EXPECT_TRUE(c0.is_cancelled());
    EXPECT_TRUE(c1.is_cancelled());
}

/* Objects using assignment operator shall have a common state */
TEST(Cancellation, AssignmentOperator0)
{
    Cancellation c0;
    Cancellation c1;
    c0 = c1;
    EXPECT_FALSE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c0.cancel();
    EXPECT_TRUE(c0.is_cancelled());
    EXPECT_TRUE(c1.is_cancelled());
}

/* Objects using assignment operator shall have a common state, even after calling cancel() */
TEST(Cancellation, AssignmentOperator1)
{
    Cancellation c0;
    Cancellation c1;
    EXPECT_FALSE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c1.cancel();
    c0 = c1;
    EXPECT_TRUE(c0.is_cancelled());
    EXPECT_TRUE(c1.is_cancelled());
}

/* Objects using move operator shall transfer state */
TEST(Cancellation, MoveConstructor0)
{
    Cancellation c0;
    EXPECT_FALSE(c0.is_cancelled());
    Cancellation c1(std::move(c0));
    EXPECT_FALSE(c1.is_cancelled());
}

/* Objects using move operator shall transfer state */
TEST(Cancellation, MoveConstructor1)
{
    Cancellation c0;
    EXPECT_FALSE(c0.is_cancelled());
    c0.cancel();
    EXPECT_TRUE(c0.is_cancelled());
    Cancellation c1(std::move(c0));
    EXPECT_TRUE(c1.is_cancelled());
}

/* Objects using move assignment shall transfer state */
TEST(Cancellation, MoveAssignment0)
{
    Cancellation c0;
    EXPECT_FALSE(c0.is_cancelled());
    Cancellation c1;
    c1.cancel();
    EXPECT_TRUE(c1.is_cancelled());
    c1 = std::move(c0);
    EXPECT_FALSE(c1.is_cancelled());
}

/* Objects using move assignment shall transfer state */
TEST(Cancellation, MoveAssignment1)
{
    Cancellation c0;
    Cancellation c1;
    EXPECT_FALSE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c0.cancel();
    EXPECT_TRUE(c0.is_cancelled());
    EXPECT_FALSE(c1.is_cancelled());
    c0 = std::move(c1);
    EXPECT_FALSE(c0.is_cancelled());
}

/* CancellationSharedState shall be a basic lockable type */
TEST(CancellationSharedState, LockableInterface)
{
    folly::detail::CancellationSharedState cp;
    cp.lock();
    cp.unlock();
    EXPECT_TRUE(true);
}

/* CancellationStateLock shall acquire lock if not cancelled */
TEST(CancellationSharedState, StateLockAcquire)
{
    Cancellation c;
    EXPECT_FALSE(c.is_cancelled());
    auto h = c.hold_state();
    EXPECT_TRUE(h.owns_lock());
    EXPECT_TRUE(static_cast<bool>(h));
}

/* CancellationStateLock shall not acquire lock if cancelled */
TEST(CancellationSharedState, StateLockDenied)
{
    Cancellation c;
    c.cancel();
    EXPECT_TRUE(c.is_cancelled());
    auto h = c.hold_state();
    EXPECT_FALSE(h.owns_lock());
    EXPECT_FALSE(static_cast<bool>(h));
}

/* Multiple CancellationStateLock's may be held without blocking */
TEST(CancellationStateLock, MultiReader)
{
    Cancellation c;
    auto h0 = c.hold_state();
    EXPECT_TRUE((bool)h0);
    auto h1 = c.hold_state();
    EXPECT_TRUE((bool)h1);
    EXPECT_FALSE(c.is_cancelled());
    h0.unlock();
    EXPECT_FALSE(h0);
    h1.unlock();
    EXPECT_FALSE(h1);
    c.cancel();
}

/* CancellationStateLock shall be RAII */
TEST(CancellationStateLock, RAII)
{
    Cancellation c;
    {
        auto h = c.hold_state();
        EXPECT_TRUE((bool)h);
    }
    c.cancel();
    {
        auto h = c.hold_state();
        EXPECT_FALSE(h);
    }
}

/* cancel operation shall block a cancel until all holds release */
TEST(CancellationStateLock, BlocksCancel)
{
    Cancellation c;
    auto h0 = c.hold_state();
    auto h1 = c.hold_state();
    auto h2 = c.hold_state();
    auto h3 = c.hold_state();
    auto h4 = c.hold_state();

    EXPECT_TRUE((bool)h0);
    EXPECT_TRUE((bool)h1);
    EXPECT_TRUE((bool)h2);
    EXPECT_TRUE((bool)h3);
    EXPECT_TRUE((bool)h4);
    EXPECT_FALSE(c.is_cancelled());

    std::mutex mx;
    std::condition_variable cond;
    bool ready = false;
    auto fut = std::async(std::launch::async,
                          [&] {
                              std::unique_lock<std::mutex> lock(mx);
                              ready = true;
                              cond.notify_one();
                              lock.unlock();

                              c.cancel();
                          });

    std::unique_lock<std::mutex> lock(mx);
    while (!ready) {
        cond.wait(lock);
    }
    lock.unlock();

    /* while adding a sleep right here would ensure that the remote thread
     * is blocked... defer that to the BlocksMultiCancel test
     */

    EXPECT_FALSE(c.is_cancelled());
    h0.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h1.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h2.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h3.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h4.unlock();

    /* state is indeterminate until thread completes */

    fut.wait();

    EXPECT_TRUE(c.is_cancelled());
}

/* cancel operation shall block multiple cancellations until all holds release */
TEST(CancellationStateLock, BlocksMultiCancel)
{
    Cancellation c;
    auto h0 = c.hold_state();
    auto h1 = c.hold_state();
    auto h2 = c.hold_state();
    auto h3 = c.hold_state();
    auto h4 = c.hold_state();

    EXPECT_TRUE((bool)h0);
    EXPECT_TRUE((bool)h1);
    EXPECT_TRUE((bool)h2);
    EXPECT_TRUE((bool)h3);
    EXPECT_TRUE((bool)h4);
    EXPECT_FALSE(c.is_cancelled());

    std::mutex mx;
    std::condition_variable cond;
    unsigned ready {0};
    auto lam = [&] {
        std::unique_lock<std::mutex> lock(mx);
        ++ready;
        cond.notify_one();
        lock.unlock();

        c.cancel();
    };
    auto fut0 = std::async(std::launch::async, lam);
    auto fut1 = std::async(std::launch::async, lam);
    auto fut2 = std::async(std::launch::async, lam);
    auto fut3 = std::async(std::launch::async, lam);
    auto fut4 = std::async(std::launch::async, lam);

    std::unique_lock<std::mutex> lock(mx);
    while (ready < 5) {
        cond.wait(lock);
    }
    lock.unlock();

    /* try to ensure remote threads are /really/ blocked */
    usleep(40000);

    EXPECT_FALSE(c.is_cancelled());
    h0.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h1.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h2.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h3.unlock();
    EXPECT_FALSE(c.is_cancelled());
    h4.unlock();

    fut0.wait();
    EXPECT_TRUE(c.is_cancelled());
    fut1.wait();
    fut2.wait();
    fut3.wait();
    fut4.wait();

    EXPECT_TRUE(c.is_cancelled());
}