src/base/uncontended_mutex.test.cc

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#include <gtest/gtest.h>
#include <mutex>
#include <thread>
#include <vector>

#include "base/uncontended_mutex.hh"

using namespace gem5;

TEST(UncontendedMutex, Lock)
{
    int data = 0;
    UncontendedMutex m;

    std::thread t1([&] () {
        std::lock_guard<UncontendedMutex> g(m);
        // Simulate += operation with a racing change between read and write.
        int tmp = data;
        std::this_thread::sleep_for(std::chrono::milliseconds(200));
        data = tmp + 1;
    });

    std::thread t2([&] () {
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        std::lock_guard<UncontendedMutex> g(m);
        data = data + 1;
    });

    std::thread t3([&] () {
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        std::lock_guard<UncontendedMutex> g(m);
        data = data + 1;
    });
    t1.join();
    t2.join();
    t3.join();

    EXPECT_EQ(data, 3);
}

TEST(UncontendedMutex, HeavyContention)
{
    int num_of_iter = 1000;
    int num_of_thread = 1000;
    std::vector<std::thread> threads;

    int data = 0;
    UncontendedMutex m;

    for (int t = 0 ; t < num_of_thread; ++t) {
        threads.emplace_back([&] () {
            for (int k = 0; k < num_of_iter; ++k) {
                std::lock_guard<UncontendedMutex> g(m);
                data++;
            }
        });
    }

    for (auto& t : threads) {
        t.join();
    }
    EXPECT_EQ(data, num_of_iter * num_of_thread);
}