Operation.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2024, the clio developers.
 
    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#pragma once
 
#include "util/MoveTracker.hpp"
#include "util/Repeat.hpp"
#include "util/async/Concepts.hpp"
#include "util/async/Outcome.hpp"
#include "util/async/context/impl/Cancellation.hpp"
#include "util/async/context/impl/Timer.hpp"
 
#include <fmt/format.h>
 
#include <chrono>
#include <concepts>
#include <condition_variable>
#include <expected>
#include <functional>
#include <future>
#include <memory>
#include <mutex>
#include <optional>
 
namespace util::async {
namespace impl {
 
template <typename OutcomeType>
class BasicOperation {
protected:
    std::future<typename OutcomeType::DataType> future_;
 
public:
    using DataType = typename OutcomeType::DataType;
 
    explicit BasicOperation(OutcomeType* outcome) : future_{outcome->getStdFuture()}
    {
    }
 
    BasicOperation(BasicOperation&&) = default;
 
    BasicOperation(BasicOperation const&) = delete;
 
    [[nodiscard]] auto
    get()
    {
        return future_.get();
    }
 
    void
    wait()
    {
        future_.wait();
    }
};
 
template <typename CtxType, typename OpType>
struct BasicScheduledOperation : util::MoveTracker {
    class State {
        std::mutex m_;
        std::condition_variable ready_;
        std::optional<OpType> op_{std::nullopt};
 
    public:
        void
        emplace(auto&& op)
        {
            std::lock_guard const lock{m_};
            op_.emplace(std::forward<decltype(op)>(op));
            ready_.notify_all();
        }
 
        [[nodiscard]] OpType&
        get()
        {
            std::unique_lock lock{m_};
            ready_.wait(lock, [this] { return op_.has_value(); });
            return op_.value();
        }
    };
 
    std::shared_ptr<State> state = std::make_shared<State>();
    typename CtxType::Timer timer;
 
    BasicScheduledOperation(auto& executor, auto delay, auto&& fn)
        : timer(
              executor,
              delay,
              [state = state, fn = std::forward<decltype(fn)>(fn)](auto ec) mutable {
                  state->emplace(fn(ec));
              }
          )
    {
    }
 
    ~BasicScheduledOperation() override
    {
        if (not wasMoved())
            abort();
    }
 
    BasicScheduledOperation(BasicScheduledOperation const&) = default;
    BasicScheduledOperation&
    operator=(BasicScheduledOperation const&) = default;
    BasicScheduledOperation(BasicScheduledOperation&&) = default;
    BasicScheduledOperation&
    operator=(BasicScheduledOperation&&) = default;
 
    [[nodiscard]] auto
    get()
    {
        return state->get().get();
    }
 
    void
    wait() noexcept
    {
        state->get().wait();
    }
 
    void
    cancel() noexcept
    {
        timer.cancel();
    }
 
    void
    requestStop() noexcept
        requires(SomeStoppableOperation<OpType>)
    {
        state->get().requestStop();
    }
 
    void
    abort() noexcept
    {
        cancel();
 
        if constexpr (SomeStoppableOperation<OpType>)
            requestStop();
    }
};
 
}  // namespace impl

template <typename RetType, typename StopSourceType>
class StoppableOperation : public impl::BasicOperation<StoppableOutcome<RetType, StopSourceType>>,
                           public util::MoveTracker {
    using OutcomeType = StoppableOutcome<RetType, StopSourceType>;
 
    StopSourceType stopSource_;
 
public:
    explicit StoppableOperation(OutcomeType* outcome)
        : impl::BasicOperation<OutcomeType>(outcome), stopSource_(outcome->getStopSource())
    {
    }
 
    ~StoppableOperation() override
    {
        if (not wasMoved())
            requestStop();
    }
 
    StoppableOperation(StoppableOperation const&) = delete;
    StoppableOperation&
    operator=(StoppableOperation const&) = delete;
    StoppableOperation(StoppableOperation&&) = default;
    StoppableOperation&
    operator=(StoppableOperation&&) = default;

    void
    requestStop() noexcept
    {
        stopSource_.requestStop();
    }
};

template <typename RetType>
using Operation = impl::BasicOperation<Outcome<RetType>>;

template <typename CtxType, typename OpType>
using ScheduledOperation = impl::BasicScheduledOperation<CtxType, OpType>;

template <typename CtxType>
class RepeatingOperation : public util::MoveTracker {
    util::Repeat repeat_;
    std::function<void()> action_;
 
public:
    template <std::invocable FnType>
    RepeatingOperation(auto& executor, std::chrono::steady_clock::duration interval, FnType&& fn)
        : repeat_(executor)
        , action_([fn = std::forward<FnType>(fn), &executor] { boost::asio::post(executor, fn); })
    {
        repeat_.start(interval, action_);
    }
 
    ~RepeatingOperation() override
    {
        if (not wasMoved())
            abort();
    }
 
    RepeatingOperation(RepeatingOperation const&) = delete;
    RepeatingOperation&
    operator=(RepeatingOperation const&) = delete;
    RepeatingOperation(RepeatingOperation&&) = default;
    RepeatingOperation&
    operator=(RepeatingOperation&&) = default;

    void
    abort() noexcept
    {
        repeat_.stop();
    }

    void
    invoke()
    {
        action_();
    }
};
 
}  // namespace util::async