RawStateTable.h

#pragma once
 
#include <xrpl/ledger/RawView.h>
#include <xrpl/ledger/ReadView.h>
 
#include <boost/container/pmr/monotonic_buffer_resource.hpp>
#include <boost/container/pmr/polymorphic_allocator.hpp>
 
#include <map>
#include <utility>
 
namespace xrpl::detail {
 
// Helper class that buffers raw modifications
class RawStateTable
{
public:
    using key_type = ReadView::key_type;
    // Initial size for the monotonic_buffer_resource used for allocations
    // The size was chosen from the old `qalloc` code (which this replaces).
    // It is unclear how the size initially chosen in qalloc.
    static constexpr size_t kInitialBufferSize = kilobytes(256);
 
    RawStateTable()
        : monotonicResource_{std::make_unique<boost::container::pmr::monotonic_buffer_resource>(
              kInitialBufferSize)}
        , items_{monotonicResource_.get()} {};
 
    RawStateTable(RawStateTable const& rhs)
        : monotonicResource_{std::make_unique<boost::container::pmr::monotonic_buffer_resource>(
              kInitialBufferSize)}
        , items_{rhs.items_, monotonicResource_.get()}
        , dropsDestroyed_{rhs.dropsDestroyed_} {};
 
    RawStateTable(RawStateTable&&) = default;
 
    RawStateTable&
    operator=(RawStateTable&&) = delete;
    RawStateTable&
    operator=(RawStateTable const&) = delete;
 
    void
    apply(RawView& to) const;
 
    [[nodiscard]] bool
    exists(ReadView const& base, Keylet const& k) const;
 
    [[nodiscard]] std::optional<key_type>
    succ(ReadView const& base, key_type const& key, std::optional<key_type> const& last) const;
 
    void
    erase(SLE::ref sle);
 
    void
    insert(SLE::ref sle);
 
    void
    replace(SLE::ref sle);
 
    [[nodiscard]] SLE::const_pointer
    read(ReadView const& base, Keylet const& k) const;
 
    void
    destroyXRP(XRPAmount const& fee);
 
    [[nodiscard]] std::unique_ptr<ReadView::SlesType::iter_base>
    slesBegin(ReadView const& base) const;
 
    [[nodiscard]] std::unique_ptr<ReadView::SlesType::iter_base>
    slesEnd(ReadView const& base) const;
 
    [[nodiscard]] std::unique_ptr<ReadView::SlesType::iter_base>
    slesUpperBound(ReadView const& base, uint256 const& key) const;
 
private:
    enum class Action {
        Erase,
        Insert,
        Replace,
    };
 
    class SlesIterImpl;
 
    struct SleAction
    {
        Action action;
        SLE::pointer sle;
 
        // Constructor needed for emplacement in std::map
        SleAction(Action action, SLE::pointer sle) : action(action), sle(std::move(sle))
        {
        }
    };
 
    // Use boost::pmr functionality instead of the std::pmr
    // functions b/c clang does not support pmr yet (as-of 9/2020)
    using items_t = std::map<
        key_type,
        SleAction,
        std::less<key_type>,
        boost::container::pmr::polymorphic_allocator<std::pair<key_type const, SleAction>>>;
    // monotonic_resource_ must outlive `items_`. Make a pointer so it may be
    // easily moved.
    std::unique_ptr<boost::container::pmr::monotonic_buffer_resource> monotonicResource_;
    items_t items_;
 
    XRPAmount dropsDestroyed_{0};
};
 
}  // namespace xrpl::detail