Added timed waiting operations to the generic backend.

Author: Lastique

include/boost/atomic/detail/wait_ops_generic.hpp

@@ -3,20 +3,31 @@
  * (See accompanying file LICENSE_1_0.txt or copy at
  * http://www.boost.org/LICENSE_1_0.txt)
  *
- * Copyright (c) 2020 Andrey Semashev
+ * Copyright (c) 2020-2025 Andrey Semashev
  */
 /*!
  * \file   atomic/detail/wait_ops_generic.hpp
  *
  * This header contains generic (lock-based) implementation of the waiting/notifying atomic operations.
+ *
+ * This backend is used when lock-free atomic operations are available but native waiting/notifying operations are not.
  */
 
 #ifndef BOOST_ATOMIC_DETAIL_WAIT_OPS_GENERIC_HPP_INCLUDED_
 #define BOOST_ATOMIC_DETAIL_WAIT_OPS_GENERIC_HPP_INCLUDED_
 
 #include <cstddef>
+#include <chrono>
 #include <boost/memory_order.hpp>
+#include <boost/atomic/wait_result.hpp>
 #include <boost/atomic/detail/config.hpp>
+#if !defined(BOOST_WINDOWS)
+#include <time.h>
+#include <type_traits>
+#include <boost/atomic/posix_clock_traits_fwd.hpp>
+#include <boost/atomic/detail/has_posix_clock_traits.hpp>
+#endif
+#include <boost/atomic/detail/chrono.hpp>
 #include <boost/atomic/detail/pause.hpp>
 #include <boost/atomic/detail/lock_pool.hpp>
 #include <boost/atomic/detail/wait_operations_fwd.hpp>
@@ -38,19 +49,19 @@ template< typename Base >
 struct wait_operations_generic< Base, false > :
     public Base
 {
-    typedef Base base_type;
-    typedef typename base_type::storage_type storage_type;
-    typedef lock_pool::scoped_lock< base_type::storage_alignment, true > scoped_lock;
-    typedef lock_pool::scoped_wait_state< base_type::storage_alignment > scoped_wait_state;
+    using base_type = Base;
+    using storage_type = typename base_type::storage_type;
+    using scoped_lock = lock_pool::scoped_lock< base_type::storage_alignment, true >;
+    using scoped_wait_state = lock_pool::scoped_wait_state< base_type::storage_alignment >;
 
-    static BOOST_CONSTEXPR_OR_CONST bool always_has_native_wait_notify = false;
+    static constexpr bool always_has_native_wait_notify = false;
 
-    static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) BOOST_NOEXCEPT
+    static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) noexcept
     {
         return false;
     }
 
-    static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) BOOST_NOEXCEPT
+    static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) noexcept
     {
         storage_type new_val = base_type::load(storage, order);
         if (new_val == old_val)
@@ -67,13 +78,119 @@ struct wait_operations_generic< Base, false > :
         return new_val;
     }
 
-    static BOOST_FORCEINLINE void notify_one(storage_type volatile& storage) BOOST_NOEXCEPT
+private:
+    template< typename Clock >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until_fallback(storage_type const volatile& storage, storage_type old_val, typename Clock::time_point timeout, typename Clock::time_point now, memory_order order)
+        noexcept(noexcept(Clock::now()))
+    {
+        wait_result< storage_type > res{ base_type::load(storage, order), false };
+        if (res.value == old_val)
+        {
+            scoped_wait_state wait_state(&storage);
+            while (res.value == old_val)
+            {
+                const std::chrono::nanoseconds nsec = atomics::detail::chrono::ceil< std::chrono::nanoseconds >(timeout - now);
+                if (nsec.count() <= 0)
+                {
+                    res.timeout = true;
+                    break;
+                }
+
+                wait_state.wait_for(nsec);
+
+                now = Clock::now();
+                res.value = base_type::load(storage, order);
+            }
+        }
+
+        return res;
+    }
+
+#if !defined(BOOST_WINDOWS)
+
+    template< typename Clock >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until_abs_timeout(storage_type const volatile& storage, storage_type old_val, typename Clock::time_point timeout, memory_order order) noexcept
+    {
+        wait_result< storage_type > res{ base_type::load(storage, order), false };
+        if (res.value == old_val)
+        {
+            scoped_wait_state wait_state(&storage);
+            const timespec abs_timeout(posix_clock_traits< Clock >::to_timespec(timeout));
+            if (BOOST_LIKELY(abs_timeout.tv_sec >= 0))
+            {
+                while (res.value == old_val)
+                {
+                    res.timeout = wait_state.wait_until(posix_clock_traits< Clock >::clock_id, abs_timeout);
+                    res.value = base_type::load(storage, order);
+
+                    if (res.timeout)
+                        goto timeout_expired;
+                }
+            }
+            else
+            {
+            timeout_expired:
+                res.timeout = !(res.value == old_val);
+            }
+        }
+
+        return res;
+    }
+
+    template< typename Clock >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until_dispatch(storage_type const volatile& storage, storage_type old_val, typename Clock::time_point timeout, memory_order order, std::true_type) noexcept
+    {
+        return wait_until_abs_timeout< Clock >(storage, old_val, timeout, order);
+    }
+
+    template< typename Clock >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until_dispatch(storage_type const volatile& storage, storage_type old_val, typename Clock::time_point timeout, memory_order order, std::false_type)
+        noexcept(noexcept(Clock::now()))
+    {
+        return wait_until_fallback< Clock >(storage, old_val, timeout, Clock::now(), order);
+    }
+
+public:
+    template< typename Clock, typename Duration >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until(storage_type const volatile& storage, storage_type old_val, std::chrono::time_point< Clock, Duration > timeout, memory_order order)
+        noexcept(noexcept(wait_until_dispatch< Clock >(storage, old_val, timeout, order, std::integral_constant< bool, has_posix_clock_traits< Clock >::value >())))
+    {
+        return wait_until_dispatch< Clock >(storage, old_val, timeout, order, std::integral_constant< bool, has_posix_clock_traits< Clock >::value >());
+    }
+
+#else // !defined(BOOST_WINDOWS)
+
+public:
+    template< typename Clock, typename Duration >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until(storage_type const volatile& storage, storage_type old_val, std::chrono::time_point< Clock, Duration > timeout, memory_order order)
+        noexcept(noexcept(wait_until_fallback< Clock >(storage, old_val, timeout, Clock::now(), order)))
+    {
+        return wait_until_fallback< Clock >(storage, old_val, timeout, Clock::now(), order);
+    }
+
+#endif // !defined(BOOST_WINDOWS)
+
+    template< typename Rep, typename Period >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_for(storage_type const volatile& storage, storage_type old_val, std::chrono::duration< Rep, Period > timeout, memory_order order) noexcept
+    {
+        const std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
+        return wait_until_fallback< std::chrono::steady_clock >(storage, old_val, now + timeout, now, order);
+    }
+
+    static BOOST_FORCEINLINE void notify_one(storage_type volatile& storage) noexcept
     {
         scoped_lock lock(&storage);
         lock_pool::notify_one(lock.get_lock_state(), &storage);
     }
 
-    static BOOST_FORCEINLINE void notify_all(storage_type volatile& storage) BOOST_NOEXCEPT
+    static BOOST_FORCEINLINE void notify_all(storage_type volatile& storage) noexcept
     {
         scoped_lock lock(&storage);
         lock_pool::notify_all(lock.get_lock_state(), &storage);
@@ -87,19 +204,23 @@ struct wait_operations_generic< Base, true > :
     typedef Base base_type;
     typedef typename base_type::storage_type storage_type;
 
-    static BOOST_CONSTEXPR_OR_CONST bool always_has_native_wait_notify = false;
+    static constexpr bool always_has_native_wait_notify = false;
+
+private:
+    static constexpr unsigned int fast_loop_count = 16u;
 
-    static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) BOOST_NOEXCEPT
+public:
+    static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) noexcept
     {
         return false;
     }
 
-    static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) BOOST_NOEXCEPT
+    static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) noexcept
     {
         storage_type new_val = base_type::load(storage, order);
         if (new_val == old_val)
         {
-            for (unsigned int i = 0u; i < 16u; ++i)
+            for (unsigned int i = 0u; i < fast_loop_count; ++i)
             {
                 atomics::detail::pause();
                 new_val = base_type::load(storage, order);
@@ -119,11 +240,72 @@ struct wait_operations_generic< Base, true > :
         return new_val;
     }
 
-    static BOOST_FORCEINLINE void notify_one(storage_type volatile&) BOOST_NOEXCEPT
+private:
+    template< typename Clock >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until_impl(storage_type const volatile& storage, storage_type old_val, typename Clock::time_point timeout, typename Clock::time_point now, memory_order order)
+        noexcept(noexcept(Clock::now()))
+    {
+        wait_result< storage_type > res{ base_type::load(storage, order), false };
+        if (res.value == old_val)
+        {
+            for (unsigned int i = 0u; i < fast_loop_count; ++i)
+            {
+                if ((now - timeout).count() >= 0)
+                {
+                    res.timeout = true;
+                    goto finish;
+                }
+
+                atomics::detail::pause();
+                now = Clock::now();
+
+                res.value = base_type::load(storage, order);
+                if (res.value != old_val)
+                    goto finish;
+            }
+
+            do
+            {
+                if ((now - timeout).count() >= 0)
+                {
+                    res.timeout = true;
+                    goto finish;
+                }
+
+                atomics::detail::wait_some();
+                now = Clock::now();
+                res.value = base_type::load(storage, order);
+            }
+            while (res.value == old_val);
+        }
+
+    finish:
+        return res;
+    }
+
+public:
+    template< typename Clock, typename Duration >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_until(storage_type const volatile& storage, storage_type old_val, std::chrono::time_point< Clock, Duration > timeout, memory_order order)
+        noexcept(noexcept(wait_until_impl< Clock >(storage, old_val, timeout, Clock::now(), order)))
+    {
+        return wait_until_impl< Clock >(storage, old_val, timeout, Clock::now(), order);
+    }
+
+    template< typename Rep, typename Period >
+    static BOOST_FORCEINLINE wait_result< storage_type >
+    wait_for(storage_type const volatile& storage, storage_type old_val, std::chrono::duration< Rep, Period > timeout, memory_order order) noexcept
+    {
+        const std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
+        return wait_until_impl< std::chrono::steady_clock >(storage, old_val, now + timeout, now, order);
+    }
+
+    static BOOST_FORCEINLINE void notify_one(storage_type volatile&) noexcept
     {
     }
 
-    static BOOST_FORCEINLINE void notify_all(storage_type volatile&) BOOST_NOEXCEPT
+    static BOOST_FORCEINLINE void notify_all(storage_type volatile&) noexcept
     {
     }
 };