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Add coroutine spinlock #2123

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66 changes: 66 additions & 0 deletions lib/inc/drogon/utils/coroutine.h
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#include <algorithm>
#include <atomic>
#include <cassert>
#include <chrono>
#include <condition_variable>
#include <coroutine>
#include <exception>
Expand Down Expand Up @@ -987,4 +988,69 @@ class Mutex final
CoroMutexAwaiter *waiters_;
};

class SpinLock final
{
public:
explicit SpinLock(std::int32_t count = 1024) noexcept
: spinCount_(count), locked_(false)
{
}

bool try_lock() noexcept
{
return !locked_.exchange(true, std::memory_order_acquire);
}

Task<> coro_lock() noexcept
{
auto counter = spinCount_;
while (!try_lock())
{
while (locked_.load(std::memory_order_relaxed))
{
if (counter-- <= 0)
{
trantor::EventLoop *loop =
trantor::EventLoop::getEventLoopOfCurrentThread();
assert(loop != nullptr);
co_await sleepCoro(loop, std::chrono::milliseconds(1));
counter = spinCount_;
}
}
}
co_return;
}

void lock() noexcept
{
auto counter = spinCount_;
while (!try_lock())
{
while (locked_.load(std::memory_order_relaxed))
{
if (counter-- <= 0)
{
std::this_thread::yield();
counter = spinCount_;
}
}
}
}

void unlock() noexcept
{
locked_.store(false, std::memory_order_release);
}

Task<std::unique_lock<SpinLock>> scoped_lock() noexcept
{
co_await coro_lock();
co_return std::unique_lock<SpinLock>{*this, std::adopt_lock};
}

private:
int32_t spinCount_;
std::atomic_bool locked_;
};

} // namespace drogon
29 changes: 29 additions & 0 deletions lib/tests/unittests/CoroutineTest.cc
Original file line number Diff line number Diff line change
Expand Up @@ -245,3 +245,32 @@ DROGON_TEST(Mutex)
pool.getLoop(i)->quit();
pool.wait();
}

DROGON_TEST(SpinLock)
{
trantor::EventLoopThreadPool pool{3};
pool.start();
SpinLock spin_lock;
async_run([&]() -> Task<> {
co_await switchThreadCoro(pool.getLoop(0));
auto guard = co_await spin_lock.scoped_lock();
co_await sleepCoro(pool.getLoop(1), std::chrono::seconds(2));
co_return;
});
std::this_thread::sleep_for(std::chrono::milliseconds(100));
std::promise<void> done;
async_run([&]() -> Task<> {
co_await switchThreadCoro(pool.getLoop(2));
auto id = std::this_thread::get_id();
co_await spin_lock.coro_lock();
CHECK(id == std::this_thread::get_id());
spin_lock.unlock();
CHECK(id == std::this_thread::get_id());
done.set_value();
co_return;
});
done.get_future().wait();
for (int16_t i = 0; i < 3; i++)
pool.getLoop(i)->quit();
pool.wait();
}
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