Move deque.hpp into core and refactor

rt/include/typon/core/continuation.hpp

@@ -4,6 +4,7 @@
 #include <atomic>
 #include <concepts>
 #include <coroutine>
+#include <cstddef>
 #include <cstdint>
 #include <exception>
 #include <limits>
@@ -87,6 +88,8 @@ namespace typon
 
     Continuation() noexcept {}
 
+    Continuation(std::nullptr_t null) noexcept : _data(null) {}
+
     template <typename Promise>
     Continuation(std::coroutine_handle<Promise> coroutine) noexcept
       : _data(&(coroutine.promise()._data))
@@ -112,6 +115,11 @@ namespace typon
       _data->_coroutine.resume();
     }
 
+    operator bool() noexcept
+    {
+      return _data;
+    }
+
     operator std::coroutine_handle<>() noexcept
     {
       return _data->_coroutine;

rt/include/typon/fundamental/deque.hpp → rt/include/typon/core/deque.hpp

@@ -7,114 +7,128 @@
 #include <type_traits>
 #include <utility>
 
-#include <typon/fundamental/optional.hpp>
 #include <typon/fundamental/ring_buffer.hpp>
 
 
-namespace typon::fdt::lock_free
+namespace typon
 {
 
-  template <typename T>
-  struct deque
+  struct Deque
   {
-    using array_type = ring_buffer<T>;
-    using pop_type = fdt::optional<T>;
-
-    using u8 = typename ring_buffer<T>::u8;
-    using u64 = typename ring_buffer<T>::u64;
-
-    static constexpr unsigned char Abort {1};
-    static constexpr unsigned char Resize {2};
+    using ring_buffer = fdt::lock_free::ring_buffer<Continuation>;
+    using u64 = ring_buffer::u64;
 
     using enum std::memory_order;
 
     std::atomic<u64> _top {1};
     std::atomic<u64> _bottom {1};
-    std::atomic<array_type *> _array;
+    std::atomic<ring_buffer *> _buffer { new ring_buffer(3) };
+    std::coroutine_handle<> _coroutine;
+    std::atomic<bool> _resumable;
 
-    deque(u8 bits = 3) noexcept : _array(new array_type(bits)) {}
+    Deque() noexcept {}
 
-    ~deque()
+    Deque(std::coroutine_handle<> coroutine) noexcept
+      : _coroutine(coroutine)
+      , _resumable(true)
+    {}
+
+    ~Deque()
     {
-      delete _array.load(relaxed);
+      delete _buffer.load(relaxed);
     }
 
-    void push(T x) noexcept
+    void push(Continuation x) noexcept
     {
       u64 bottom = _bottom.load(relaxed);
       u64 top = _top.load(acquire);
-      auto array = _array.load(relaxed);
-      if (bottom - top > array->capacity() - 1)
+      ring_buffer * buffer = _buffer.load(relaxed);
+      if (bottom - top > buffer->capacity() - 1)
       {
-        array = array->grow(top, bottom);
-        _array.store(array);
+        buffer = buffer->grow(top, bottom);
+        _buffer.store(buffer);
       }
-      array->put(bottom, x);
+      buffer->put(bottom, x);
       std::atomic_thread_fence(release);
       _bottom.store(bottom + 1, relaxed);
     }
 
-    optional<T> pop() noexcept
+    bool pop() noexcept
     {
       u64 bottom = _bottom.load(relaxed) - 1;
-      auto array = _array.load(relaxed);
       _bottom.store(bottom, relaxed);
       std::atomic_thread_fence(seq_cst);
       u64 top = _top.load(relaxed);
-      if (top <= bottom)
+      if (top < bottom)
       {
+        return true;
+      }
       if (top == bottom)
       {
-          if (!_top.compare_exchange_strong(top, top + 1, seq_cst, relaxed))
-          {
+        bool win = _top.compare_exchange_strong(top, top + 1, seq_cst, relaxed);
         _bottom.store(bottom + 1, relaxed);
-            return array->_next ? optional<T>(Resize) : optional<T>();
+        return win;
       }
       _bottom.store(bottom + 1, relaxed);
-        }
-        T x = array->get(bottom);
-        if (array->_next && array->capacity() > (bottom - top) * 4)
-        {
-          return { x, Resize };
-        }
-        return { x };
-      }
-      _bottom.store(bottom + 1, relaxed);
-      return array->_next ? optional<T>(Resize) : optional<T>();
+      return false;
     }
 
-    optional<T> steal() noexcept
+    Continuation steal() noexcept
     {
       u64 top = _top.load(acquire);
       std::atomic_thread_fence(seq_cst);
       u64 bottom = _bottom.load(acquire);
-      // Use acquire instead of consume (semantics under revision).
-      auto array = _array.load(acquire);
+      ring_buffer * buffer = _buffer.load(consume);
       if (top < bottom)
       {
-        T x = array->get(top);
+        Continuation x = buffer->get(top);
         if (!_top.compare_exchange_strong(top, top + 1, seq_cst, relaxed))
         {
-          return { Abort };
+          return { nullptr };
+        }
+        return x;
       }
-        if (array->_next && array->capacity() > (bottom - top) * 4)
+      return { nullptr };
+    }
+
+    Continuation pop_top() noexcept
     {
-          return { x, Resize };
+      u64 top = _top.load(relaxed);
+      u64 bottom = _bottom.load(relaxed);
+      auto buffer = _buffer.load(relaxed);
+      if (top < bottom)
+      {
+        Continuation x = buffer->get(top);
+        _top.store(top + 1, relaxed);
+        return x;
       }
-        return { x };
+      return { nullptr };
     }
-      return array->_next ? optional<T>(Resize) : optional<T>();
+
+    void suspend(std::coroutine_handle<> coroutine) noexcept
+    {
+      _resumable.store(false);
+      _coroutine = coroutine;
+    }
+
+    void resume() noexcept
+    {
+      _coroutine.resume();
     }
 
-    array_type * shrink() noexcept
+    ring_buffer * reclaim() noexcept
     {
       u64 bottom = _bottom.load(relaxed);
       u64 top = _top.load(relaxed);
-      auto array = _array.load(relaxed);
-      if (auto next = array->shrink(top, bottom))
+      auto buffer = _buffer.load(relaxed);
+      u64 capacity = buffer->capacity();
+      if (bottom < top + (capacity >> 2))
+      {
+        if (auto next = buffer->shrink(top, bottom))
         {
-        _array.store(next, relaxed);
-        return array;
+          _buffer.store(next, relaxed);
+          return buffer;
+        }
       }
       return nullptr;
     }

rt/include/typon/core/fork.hpp

@@ -51,11 +51,11 @@ namespace typon
         {
           std::coroutine_handle<> await_suspend(std::coroutine_handle<promise_type> coroutine) noexcept
           {
-            if (auto continuation = Scheduler::pop())
+            auto continuation = coroutine.promise()._continuation;
+            if (Scheduler::pop())
             {
-              return *continuation;
+              return continuation;
             }
-            auto & continuation = coroutine.promise()._continuation;
             u64 n = continuation.n().fetch_sub(1, std::memory_order_acq_rel);
             if (n == 1)
             {

rt/include/typon/core/future.hpp

@@ -8,8 +8,8 @@
 
 #include <typon/fundamental/scope.hpp>
 
+#include <typon/core/deque.hpp>
 #include <typon/core/scheduler.hpp>
-#include <typon/core/work_deque.hpp>
 
 
 namespace typon
@@ -45,7 +45,7 @@ namespace typon
       auto state = _state.exchange(ready, std::memory_order_acq_rel);
       if (state != no_waiter)
       {
-        Scheduler::enable(reinterpret_cast<WorkDeque *>(state));
+        Scheduler::enable(reinterpret_cast<Deque *>(state));
       }
     }
 
@@ -92,7 +92,7 @@ namespace typon
       auto state = _state.exchange(ready, std::memory_order_acq_rel);
       if (state != no_waiter)
       {
-        Scheduler::enable(reinterpret_cast<WorkDeque *>(state));
+        Scheduler::enable(reinterpret_cast<Deque *>(state));
       }
     }
 
@@ -133,7 +133,7 @@ namespace typon
       auto state = _state.exchange(ready, std::memory_order_acq_rel);
       if (state != no_waiter)
       {
-        Scheduler::enable(reinterpret_cast<WorkDeque *>(state));
+        Scheduler::enable(reinterpret_cast<Deque *>(state));
       }
     }
 
@@ -172,7 +172,7 @@ namespace typon
       auto state = _state.exchange(ready, std::memory_order_acq_rel);
       if (state != no_waiter)
       {
-        Scheduler::enable(reinterpret_cast<WorkDeque *>(state));
+        Scheduler::enable(reinterpret_cast<Deque *>(state));
       }
     }
 

rt/include/typon/core/scheduler.hpp

@@ -8,15 +8,13 @@
 #include <thread>
 #include <vector>
 
-#include <typon/fundamental/deque.hpp>
 #include <typon/fundamental/event_count.hpp>
 #include <typon/fundamental/garbage_collector.hpp>
-#include <typon/fundamental/optional.hpp>
 #include <typon/fundamental/random.hpp>
 
 #include <typon/core/continuation.hpp>
+#include <typon/core/deque.hpp>
 #include <typon/core/worker.hpp>
-#include <typon/core/work_deque.hpp>
 
 
 namespace typon
@@ -25,7 +23,6 @@ namespace typon
   struct Scheduler
   {
     using uint = unsigned int;
-    using Task = typename fdt::lock_free::deque<Continuation>::pop_type;
     using Work = Worker::Work;
     using garbage_collector = fdt::lock_free::garbage_collector;
 
@@ -41,7 +38,7 @@ namespace typon
     {
       Scheduler & scheduler = get();
       uint id = fdt::random::random() % scheduler._concurrency;
-      scheduler._worker[id].add(new WorkDeque(task, true));
+      scheduler._worker[id].add(new Deque(task));
       scheduler._notifyer.notify_one();
     }
 
@@ -50,26 +47,23 @@ namespace typon
       get()._worker[thread_id]._active.load()->push(task);
     }
 
-    static Task pop() noexcept
+    static bool pop() noexcept
     {
       Scheduler & scheduler = get();
-      WorkDeque * active = scheduler._worker[thread_id]._active.load();
-      Task task = active->pop();
-      if (task.get_flags() == fdt::lock_free::deque<Continuation>::Resize)
-      {
-        if (auto array = active->shrink())
+      Deque * active = scheduler._worker[thread_id]._active.load();
+      bool result = active->pop();
+      if (auto array = active->reclaim())
       {
         scheduler._gc.retire(array);
       }
-      }
-      return task;
+      return result;
     }
 
-    static WorkDeque * suspend(std::coroutine_handle<> coroutine) noexcept
+    static Deque * suspend(std::coroutine_handle<> coroutine) noexcept
     {
       Scheduler & scheduler = get();
       Worker & worker = scheduler._worker[thread_id];
-      WorkDeque * deque = worker._active.load();
+      Deque * deque = worker._active.load();
       worker._active.store(nullptr);
       deque->suspend(coroutine);
       for (uint i = 0; i < scheduler._concurrency * 2; i++)
@@ -84,7 +78,7 @@ namespace typon
       return deque;
     }
 
-    static void enable(WorkDeque * deque) noexcept
+    static void enable(Deque * deque) noexcept
     {
       deque->_resumable.store(true);
       get()._notifyer.notify_one();
@@ -143,7 +137,11 @@ namespace typon
           _notifyer.notify_one();
         }
       }
-      _worker[thread_id].resume(work, _gc);
+      auto garbage = _worker[thread_id].resume(work);
+      if (garbage)
+      {
+        _gc.retire(garbage);
+      }
       _actives.fetch_sub(1);
     }
 

rt/include/typon/core/work_deque.hpp

-#ifndef TYPON_CORE_WORK_DEQUE_HPP_INCLUDED
-#define TYPON_CORE_WORK_DEQUE_HPP_INCLUDED
-
-#include <atomic>
-#include <coroutine>
-
-#include <typon/fundamental/deque.hpp>
-
-#include <typon/core/continuation.hpp>
-
-
-namespace typon
-{
-
-  struct WorkDeque
-  {
-    fdt::lock_free::deque<Continuation> _deque;
-    std::coroutine_handle<> _coroutine;
-    std::atomic<bool> _resumable;
-
-    WorkDeque() noexcept {}
-
-    WorkDeque(std::coroutine_handle<> coroutine, bool resumable) noexcept
-      : _coroutine(coroutine)
-      , _resumable(resumable)
-    {}
-
-    void push(Continuation x) noexcept
-    {
-      _deque.push(std::move(x));
-    }
-
-    auto pop() noexcept
-    {
-      return _deque.pop();
-    }
-
-    auto steal() noexcept
-    {
-      return _deque.steal();
-    }
-
-    void suspend(std::coroutine_handle<> coroutine) noexcept
-    {
-      _resumable.store(false);
-      _coroutine = coroutine;
-    }
-
-    void resume() noexcept
-    {
-      _coroutine.resume();
-    }
-
-    auto shrink() noexcept
-    {
-      return _deque.shrink();
-    }
-
-  };
-
-}
-
-
-#endif // TYPON_CORE_WORK_DEQUE_HPP_INCLUDED

rt/include/typon/core/worker.hpp

@@ -8,11 +8,9 @@
 #include <vector>
 
 #include <typon/fundamental/garbage_collector.hpp>
-#include <typon/fundamental/optional.hpp>
 #include <typon/fundamental/random.hpp>
 
 #include <typon/core/continuation.hpp>
-#include <typon/core/work_deque.hpp>
 
 
 namespace typon
@@ -28,13 +26,13 @@ namespace typon
       State _state;
       union
       {
-        WorkDeque * _deque;
+        Deque * _deque;
         Continuation _task;
       };
 
       Work() noexcept : _state(Empty) {}
 
-      Work(WorkDeque * deque) noexcept : _state(Resumable), _deque(deque) {}
+      Work(Deque * deque) noexcept : _state(Resumable), _deque(deque) {}
 
       Work(Continuation task) noexcept : _state(Stolen), _task(task) {}
 
@@ -45,8 +43,8 @@ namespace typon
     };
 
     std::mutex _mutex;
-    std::atomic<WorkDeque *> _active {nullptr};
-    std::vector<WorkDeque *> _pool;
+    std::atomic<Deque *> _active {nullptr};
+    std::vector<Deque *> _pool;
 
     ~Worker()
     {
@@ -60,7 +58,7 @@ namespace typon
       }
     }
 
-    void resume(Work & work, fdt::lock_free::garbage_collector & gc) noexcept
+    Deque * resume(Work & work) noexcept
     {
       auto active = _active.load();
       if (work._state == Work::Resumable)
@@ -69,26 +67,27 @@ namespace typon
         work._deque->resume();
         if (active)
         {
-          gc.retire(active);
+          return active;
         }
       }
       else
       {
         if (!active)
         {
-          _active.store(new WorkDeque());
+          _active.store(new Deque());
         }
         work._task.resume();
       }
+      return nullptr;
     }
 
-    void add(WorkDeque * deque) noexcept
+    void add(Deque * deque) noexcept
     {
       std::lock_guard lock(_mutex);
       _pool.push_back(deque);
     }
 
-    bool try_add(WorkDeque * deque) noexcept
+    bool try_add(Deque * deque) noexcept
     {
       if (!_mutex.try_lock())
       {
@@ -117,26 +116,23 @@ namespace typon
       {
         if (auto task = active->steal())
         {
-          task->thefts()++;
-          return *task;
+          task.thefts()++;
+          return task;
         }
         return {};
       }
       auto deque = _pool[index];
       if (!deque->_resumable.load())
       {
-        auto task = deque->steal();
-        if (task.get_flags() == fdt::lock_free::deque<Continuation>::Resize)
+        auto task = deque->pop_top();
+        if (auto garbage = deque->reclaim())
         {
-          if (auto array = deque->shrink())
-          {
-            delete array;
-          }
+          delete garbage;
         }
         if (task)
         {
-          task->thefts()++;
-          return *task;
+          task.thefts()++;
+          return task;
         }
         return {};
       }
@@ -147,7 +143,6 @@ namespace typon
       _pool.pop_back();
       return deque;
     }
-
   };
 
 }

rt/include/typon/fundamental/optional.hpp

-#ifndef TYPON_FUNDAMENTAL_OPTIONAL_HPP_INCLUDED
-#define TYPON_FUNDAMENTAL_OPTIONAL_HPP_INCLUDED
-
-#include <type_traits>
-
-
-namespace typon::fdt
-{
-
-  template <typename T>
-    requires std::is_trivially_copyable_v<T>
-  struct optional
-  {
-    unsigned char _state;
-    union
-    {
-      T _value;
-    };
-
-    optional() noexcept : _state(0) {}
-
-    optional(T value) noexcept : _state(1), _value(value) {}
-
-    optional(unsigned char flags) noexcept : _state(flags << 1) {}
-
-    optional(T value, unsigned char flags) noexcept
-      : _state((flags << 1) | 1)
-      , _value(value)
-    {}
-
-    ~optional()
-    {
-      if (_state & 1)
-      {
-        std::destroy_at(std::addressof(_value));
-      }
-    }
-
-    operator bool() noexcept
-    {
-      return _state & 1;
-    }
-
-    unsigned char get_flags() noexcept
-    {
-      return _state >> 1;
-    }
-
-    void set_flags(unsigned char flags) noexcept
-    {
-      _state = (flags << 1) | (_state & 1);
-    }
-
-    T * operator->() noexcept
-    {
-      return std::addressof(_value);
-    }
-
-    T & operator*() noexcept
-    {
-      return _value;
-    }
-  };
-
-}
-
-
-#endif // TYPON_FUNDAMENTAL_OPTIONAL_HPP_INCLUDED

rt/include/typon/fundamental/ring_buffer.hpp

@@ -14,6 +14,7 @@ namespace typon::fdt::lock_free
 
   template <typename T>
     requires std::is_trivially_copyable_v<T>
+    && std::is_trivially_destructible_v<T>
   struct ring_buffer
   {
     using u8 = std::uint_least8_t;