LoadBalancer.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, 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/BackendInterface.hpp"
#include "etl/ETLState.hpp"
#include "etl/InitialLoadObserverInterface.hpp"
#include "etl/LoadBalancerInterface.hpp"
#include "etl/NetworkValidatedLedgersInterface.hpp"
#include "etl/Source.hpp"
#include "feed/SubscriptionManagerInterface.hpp"
#include "rpc/Errors.hpp"
#include "util/Mutex.hpp"
#include "util/Random.hpp"
#include "util/ResponseExpirationCache.hpp"
#include "util/config/ConfigDefinition.hpp"
#include "util/log/Logger.hpp"
#include "util/prometheus/Counter.hpp"
 
#include <boost/asio.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/json/object.hpp>
#include <boost/json/value.hpp>
#include <grpcpp/grpcpp.h>
#include <org/xrpl/rpc/v1/get_ledger.pb.h>
#include <org/xrpl/rpc/v1/ledger.pb.h>
#include <xrpl/proto/org/xrpl/rpc/v1/xrp_ledger.grpc.pb.h>
 
#include <chrono>
#include <concepts>
#include <cstdint>
#include <expected>
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <vector>
 
namespace etl {

struct LoadBalancerTag {
    virtual ~LoadBalancerTag() = default;
};
 
template <typename T>
concept SomeLoadBalancer = std::derived_from<T, LoadBalancerTag>;

class LoadBalancer : public LoadBalancerInterface, LoadBalancerTag {
public:
    using RawLedgerObjectType = org::xrpl::rpc::v1::RawLedgerObject;
    using GetLedgerResponseType = org::xrpl::rpc::v1::GetLedgerResponse;
    using OptionalGetLedgerResponseType = std::optional<GetLedgerResponseType>;
 
private:
    static constexpr std::uint32_t kDEFAULT_DOWNLOAD_RANGES = 16;
 
    util::Logger log_{"ETL"};
    // Forwarding cache must be destroyed after sources because sources have a callback to
    // invalidate cache
    std::optional<util::ResponseExpirationCache> forwardingCache_;
    std::optional<std::string> forwardingXUserValue_;
 
    std::unique_ptr<util::RandomGeneratorInterface> randomGenerator_;
 
    std::vector<SourcePtr> sources_;
    std::optional<ETLState> etlState_;
    std::uint32_t downloadRanges_ = kDEFAULT_DOWNLOAD_RANGES; /*< The number of markers to use when
                                                                 downloading initial ledger */
 
    struct ForwardingCounters {
        std::reference_wrapper<util::prometheus::CounterInt> successDuration;
        std::reference_wrapper<util::prometheus::CounterInt> failDuration;
        std::reference_wrapper<util::prometheus::CounterInt> retries;
        std::reference_wrapper<util::prometheus::CounterInt> cacheHit;
        std::reference_wrapper<util::prometheus::CounterInt> cacheMiss;
    } forwardingCounters_;
 
    // Using mutex instead of atomic_bool because choosing a new source to
    // forward messages should be done with a mutual exclusion otherwise there will be a race
    // condition
    util::Mutex<bool> hasForwardingSource_{false};
 
public:
    static constexpr std::string_view kADMIN_FORWARDING_X_USER_VALUE = "clio_admin";

    static constexpr std::string_view kUSER_FORWARDING_X_USER_VALUE = "clio_user";

    LoadBalancer(
        util::config::ClioConfigDefinition const& config,
        boost::asio::io_context& ioc,
        std::shared_ptr<BackendInterface> backend,
        std::shared_ptr<feed::SubscriptionManagerInterface> subscriptions,
        std::unique_ptr<util::RandomGeneratorInterface> randomGenerator,
        std::shared_ptr<NetworkValidatedLedgersInterface> validatedLedgers,
        SourceFactory sourceFactory = makeSource
    );

    static std::shared_ptr<LoadBalancerInterface>
    makeLoadBalancer(
        util::config::ClioConfigDefinition const& config,
        boost::asio::io_context& ioc,
        std::shared_ptr<BackendInterface> backend,
        std::shared_ptr<feed::SubscriptionManagerInterface> subscriptions,
        std::unique_ptr<util::RandomGeneratorInterface> randomGenerator,
        std::shared_ptr<NetworkValidatedLedgersInterface> validatedLedgers,
        SourceFactory sourceFactory = makeSource
    );

    InitialLedgerLoadResult
    loadInitialLedger(
        uint32_t sequence,
        InitialLoadObserverInterface& observer,
        std::chrono::steady_clock::duration retryAfter
    ) override;

    OptionalGetLedgerResponseType
    fetchLedger(
        uint32_t ledgerSequence,
        bool getObjects,
        bool getObjectNeighbors,
        std::chrono::steady_clock::duration retryAfter = std::chrono::seconds{2}
    ) override;

    boost::json::value
    toJson() const override;

    std::expected<boost::json::object, rpc::CombinedError>
    forwardToRippled(
        boost::json::object const& request,
        std::optional<std::string> const& clientIp,
        bool isAdmin,
        boost::asio::yield_context yield
    ) override;

    std::optional<ETLState>
    getETLState() noexcept override;

    void
    stop(boost::asio::yield_context yield) override;
 
private:
    template <typename Func>
    void
    execute(
        Func f,
        uint32_t ledgerSequence,
        std::chrono::steady_clock::duration retryAfter = std::chrono::seconds{2}
    );

    void
    chooseForwardingSource();
};
 
}  // namespace etl