OfferStream.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2014 Ripple Labs Inc.
 
    Permission to use, copy, modify, and/or 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.
*/
//==============================================================================
 
#ifndef RIPPLE_APP_BOOK_OFFERSTREAM_H_INCLUDED
#define RIPPLE_APP_BOOK_OFFERSTREAM_H_INCLUDED
 
#include <xrpld/app/tx/detail/BookTip.h>
#include <xrpld/app/tx/detail/Offer.h>
#include <xrpld/ledger/View.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/chrono.h>
#include <xrpl/beast/utility/Journal.h>
 
#include <boost/container/flat_set.hpp>
 
namespace ripple {
 
template <class TIn, class TOut>
class TOfferStreamBase
{
public:
    class StepCounter
    {
    private:
        std::uint32_t const limit_;
        std::uint32_t count_;
        beast::Journal j_;
 
    public:
        StepCounter(std::uint32_t limit, beast::Journal j)
            : limit_(limit), count_(0), j_(j)
        {
        }
 
        bool
        step()
        {
            if (count_ >= limit_)
            {
                JLOG(j_.debug()) << "Exceeded " << limit_ << " step limit.";
                return false;
            }
            count_++;
            return true;
        }
        std::uint32_t
        count() const
        {
            return count_;
        }
    };
 
protected:
    beast::Journal const j_;
    ApplyView& view_;
    ApplyView& cancelView_;
    Book book_;
    bool validBook_;
    NetClock::time_point const expire_;
    BookTip tip_;
    TOffer<TIn, TOut> offer_;
    std::optional<TOut> ownerFunds_;
    StepCounter& counter_;
 
    void
    erase(ApplyView& view);
 
    virtual void
    permRmOffer(uint256 const& offerIndex) = 0;
 
    template <class TTakerPays, class TTakerGets>
    bool
    shouldRmSmallIncreasedQOffer() const;
 
public:
    TOfferStreamBase(
        ApplyView& view,
        ApplyView& cancelView,
        Book const& book,
        NetClock::time_point when,
        StepCounter& counter,
        beast::Journal journal);
 
    virtual ~TOfferStreamBase() = default;
 
    TOffer<TIn, TOut>&
    tip() const
    {
        return const_cast<TOfferStreamBase*>(this)->offer_;
    }
 
    bool
    step();
 
    TOut
    ownerFunds() const
    {
        return *ownerFunds_;
    }
};
 
class OfferStream : public TOfferStreamBase<STAmount, STAmount>
{
protected:
    void
    permRmOffer(uint256 const& offerIndex) override;
 
public:
    using TOfferStreamBase<STAmount, STAmount>::TOfferStreamBase;
};
 
template <class TIn, class TOut>
class FlowOfferStream : public TOfferStreamBase<TIn, TOut>
{
private:
    boost::container::flat_set<uint256> permToRemove_;
 
public:
    using TOfferStreamBase<TIn, TOut>::TOfferStreamBase;
 
    // The following interface allows offer crossing to permanently
    // remove self crossed offers.  The motivation is somewhat
    // unintuitive.  See the discussion in the comments for
    // BookOfferCrossingStep::limitSelfCrossQuality().
    void
    permRmOffer(uint256 const& offerIndex) override;
 
    boost::container::flat_set<uint256> const&
    permToRemove() const
    {
        return permToRemove_;
    }
};
}  // namespace ripple
 
#endif