[fiber] Implement std concurrency interfaces

src/modm/processing/fiber/barrier.hpp

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2023, Niklas Hauser
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#pragma once
+
+#include "fiber.hpp"
+
+namespace modm::fiber
+{
+
+/// @ingroup modm_processing_fiber
+/// @{
+
+/// Implements the `std::barrier` interface for fibers.
+/// @see https://en.cppreference.com/w/cpp/thread/barrier
+template< class CompletionFunction = decltype([](){}) >
+class barrier
+{
+	barrier(const barrier&) = delete;
+	barrier& operator=(const barrier&) = delete;
+	using count_t = uint16_t;
+
+	const CompletionFunction completion;
+	volatile count_t expected;
+	volatile count_t count;
+	volatile count_t sequence{};
+public:
+	using arrival_token = count_t;
+	constexpr explicit barrier(std::ptrdiff_t expected,
+							   CompletionFunction f = CompletionFunction())
+	: completion(std::move(f)), expected(expected), count(expected) {}
+
+	[[nodiscard]] static constexpr std::ptrdiff_t
+	max() { return count_t(-1); }
+
+	[[nodiscard]] arrival_token
+	arrive(std::ptrdiff_t n=1)
+	{
+		count_t last_arrival{sequence};
+		count -= n;
+		if (count == 0)
+		{
+			count = expected;
+			sequence++;
+			completion();
+		}
+		return last_arrival;
+	}
+
+	void
+	wait(arrival_token&& arrival) const
+	{
+		while (arrival == sequence) modm::this_fiber::yield();
+	}
+
+	void
+	arrive_and_wait()
+	{
+		wait(arrive());
+	}
+
+	void
+	arrive_and_drop()
+	{
+		expected--;
+		arrive();
+	}
+};
+
+/// @}
+
+}

src/modm/processing/fiber/condition_variable.hpp

@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2023, Niklas Hauser
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#pragma once
+
+#include "fiber.hpp"
+#include <atomic>
+#include <condition_variable>
+
+namespace modm::fiber
+{
+
+/// @ingroup modm_processing_fiber
+/// @{
+
+/// Implements the `std::condition_variable_any` interface for fibers.
+/// @see https://en.cppreference.com/w/cpp/thread/condition_variable
+class condition_variable_any
+{
+	condition_variable_any(const condition_variable_any&) = delete;
+	condition_variable_any& operator=(const condition_variable_any&) = delete;
+
+	std::atomic<uint16_t> sequence{};
+public:
+	constexpr condition_variable_any() = default;
+
+	void inline
+	notify_one()
+	{
+		sequence++;
+	}
+
+	void inline
+	notify_any()
+	{
+		sequence++;
+	}
+
+
+	template< class Lock >
+	void
+	wait(Lock& lock)
+	{
+		lock.unlock();
+		const auto my_sequence = sequence.load();
+		while(my_sequence == sequence.load()) modm::this_fiber::yield();
+		lock.lock();
+	}
+
+	template< class Lock, class Predicate >
+	void
+	wait(Lock& lock, Predicate&& pred)
+	{
+		while (not pred()) wait(lock);
+	}
+
+	template< class Lock, class Predicate >
+	bool
+	wait(Lock& lock, std::stop_token stoken, Predicate pred)
+	{
+		while (not stoken.stop_requested())
+		{
+			if (pred()) return true;
+			wait(lock);
+		}
+		return pred();
+	}
+
+
+	template< class Lock, class Rep, class Period >
+	std::cv_status
+	wait_for(Lock& lock, std::chrono::duration<Rep, Period> rel_time)
+	{
+		lock.unlock();
+		const auto condition = [this, my_sequence = sequence.load()]()
+							   { return my_sequence != sequence.load(); };
+		const bool result = this_fiber::poll_for(rel_time, condition);
+		lock.lock();
+		return result ? std::cv_status::no_timeout : std::cv_status::timeout;
+	}
+
+	template< class Lock, class Rep, class Period, class Predicate >
+	bool
+	wait_for(Lock& lock, std::chrono::duration<Rep, Period> rel_time, Predicate&& pred)
+	{
+		while (not pred())
+		{
+			if (wait_for(lock, rel_time) == std::cv_status::timeout)
+				return pred();
+		}
+		return true;
+	}
+
+	template< class Lock, class Rep, class Period, class Predicate >
+	bool
+	wait_for(Lock& lock, std::stop_token stoken,
+			 std::chrono::duration<Rep, Period> rel_time, Predicate&& pred)
+	{
+		while (not stoken.stop_requested())
+		{
+			if (pred()) return true;
+			if (wait_for(lock, rel_time) == std::cv_status::timeout)
+				return pred();
+		}
+		return pred();
+	}
+
+
+	template< class Lock, class Clock, class Duration >
+	std::cv_status
+	wait_until(Lock& lock, std::chrono::time_point<Clock, Duration> abs_time)
+	{
+		lock.unlock();
+		const auto condition = [this, my_sequence = sequence.load()]()
+							   { return my_sequence != sequence.load(); };
+		const bool result = this_fiber::poll_until(abs_time, condition);
+		lock.lock();
+		return result ? std::cv_status::no_timeout : std::cv_status::timeout;
+	}
+
+	template< class Lock, class Clock, class Duration, class Predicate >
+	bool
+	wait_until(Lock& lock, std::chrono::time_point<Clock, Duration> abs_time, Predicate&& pred)
+	{
+		while (not pred())
+		{
+			if (wait_until(lock, abs_time) == std::cv_status::timeout)
+				return pred();
+		}
+		return true;
+	}
+
+	template< class Lock, class Clock, class Duration, class Predicate >
+	bool
+	wait_until(Lock& lock, std::stop_token stoken,
+			   std::chrono::time_point<Clock, Duration> abs_time, Predicate&& pred)
+	{
+		while (not stoken.stop_requested())
+		{
+			if (pred()) return true;
+			if (wait_until(lock, abs_time) == std::cv_status::timeout)
+				return pred();
+		}
+		return pred();
+	}
+};
+
+// There is no specialization for std::unique_lock.
+using condition_variable = condition_variable_any;
+
+/// @}
+
+}

src/modm/processing/fiber/latch.hpp

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2023, Niklas Hauser
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#pragma once
+
+#include "fiber.hpp"
+#include <atomic>
+
+namespace modm::fiber
+{
+
+/// @ingroup modm_processing_fiber
+/// @{
+
+/// Implements the `std::latch` interface for fibers.
+/// @see https://en.cppreference.com/w/cpp/thread/latch
+class latch
+{
+	latch(const latch&) = delete;
+	latch& operator=(const latch&) = delete;
+
+	using count_t = uint16_t;
+	std::atomic<count_t> count;
+public:
+	constexpr explicit
+	latch(std::ptrdiff_t expected)
+	: count(expected) {}
+
+	[[nodiscard]] static constexpr std::ptrdiff_t
+	max() { return count_t(-1); }
+
+	void inline
+	count_down(std::ptrdiff_t n=1)
+	{
+		count -= n;
+	}
+
+	[[nodiscard]] bool inline
+	try_wait() const
+	{
+		return count.load() == 0;
+	}
+
+	void inline
+	wait() const
+	{
+		while(not try_wait()) modm::this_fiber::yield();
+	}
+
+	void inline
+	arrive_and_wait(std::ptrdiff_t n=1)
+	{
+		count_down(n);
+		wait();
+	}
+};
+
+/// @}
+
+}

src/modm/processing/fiber/module.lb

@@ -21,7 +21,7 @@ def is_enabled(env):
         not env.has_module(":processing:protothread")
 
 def prepare(module, options):
-    module.depends(":processing:timer")
+    module.depends(":processing:timer", ":architecture:atomic")
 
     module.add_query(
         EnvironmentQuery(name="__enabled", factory=is_enabled))
@@ -77,3 +77,11 @@ def build(env):
     env.copy("task.hpp")
     env.copy("functions.hpp")
     env.copy("fiber.hpp")
+
+    env.copy("mutex.hpp")
+    env.copy("shared_mutex.hpp")
+    env.copy("semaphore.hpp")
+    env.copy("latch.hpp")
+    env.copy("barrier.hpp")
+    # FIXME: Not in avrlibc++
+    # env.copy("condition_variable.hpp")