WriterState.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2025, 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 "data/LedgerCacheInterface.hpp"
#include "etl/SystemState.hpp"
#include "util/prometheus/Bool.hpp"
#include "util/prometheus/Label.hpp"
#include "util/prometheus/Prometheus.hpp"
 
#include <functional>
#include <memory>
 
namespace etl {

class WriterStateInterface {
public:
    virtual ~WriterStateInterface() = default;

    [[nodiscard]] virtual bool
    isReadOnly() const = 0;

    [[nodiscard]] virtual bool
    isWriting() const = 0;

    virtual void
    startWriting() = 0;

    virtual void
    giveUpWriting() = 0;

    [[nodiscard]] virtual bool
    isFallback() const = 0;

    [[nodiscard]] virtual bool
    isFallbackRecovery() const = 0;

    virtual void
    setFallbackRecovery(bool newValue) = 0;

    virtual void
    setWriterDecidingFallback() = 0;

    [[nodiscard]] virtual bool
    isEtlStarted() const = 0;

    [[nodiscard]] virtual bool
    isCacheFull() const = 0;

    [[nodiscard]] virtual std::unique_ptr<WriterStateInterface>
    clone() const = 0;
};

class WriterState : public WriterStateInterface {
private:
    std::shared_ptr<SystemState>
        systemState_; 
    std::reference_wrapper<data::LedgerCacheInterface const> cache_;

    util::prometheus::Bool isFallbackRecovery_ = PrometheusService::boolMetric(
        "etl_writing_deciding_fallback_recovery",
        util::prometheus::Labels{},
        "Whether clio is in recovery from the fallback writer decision mechanism"
    );
 
public:
    WriterState(std::shared_ptr<SystemState> state, data::LedgerCacheInterface const& cache);
 
    bool
    isReadOnly() const override;

    bool
    isWriting() const override;

    void
    startWriting() override;

    void
    giveUpWriting() override;

    void
    setWriterDecidingFallback() override;

    bool
    isFallback() const override;

    bool
    isFallbackRecovery() const override;

    void
    setFallbackRecovery(bool newValue) override;

    bool
    isEtlStarted() const override;

    bool
    isCacheFull() const override;

    std::unique_ptr<WriterStateInterface>
    clone() const override;
};
 
}  // namespace etl