rippled/include/xrpl/ledger/OpenView.h

#pragma once

#include <xrpl/basics/ByteUtilities.h>
#include <xrpl/basics/base_uint.h>
#include <xrpl/ledger/RawView.h>
#include <xrpl/ledger/ReadView.h>
#include <xrpl/ledger/detail/RawStateTable.h>
#include <xrpl/protocol/Fees.h>
#include <xrpl/protocol/Keylet.h>
#include <xrpl/protocol/LedgerHeader.h>
#include <xrpl/protocol/Rules.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/Serializer.h>
#include <xrpl/protocol/XRPAmount.h>

#include <boost/container/pmr/monotonic_buffer_resource.hpp>
#include <boost/container/pmr/polymorphic_allocator.hpp>

#include <cstddef>
#include <functional>
#include <map>
#include <memory>
#include <optional>
#include <utility>

namespace xrpl {

/**
 * Open ledger construction tag.
 *
 * Views constructed with this tag will have the
 * rules of open ledgers applied during transaction
 * processing.
 */
inline constexpr struct OpenLedgerT
{
    explicit constexpr OpenLedgerT() = default;
} kOpenLedger{};

/**
 * Batch view construction tag.
 *
 * Views constructed with this tag are part of a stack of views
 * used during batch transaction application.
 */
inline constexpr struct BatchViewT
{
    explicit constexpr BatchViewT() = default;
} kBatchView{};

//------------------------------------------------------------------------------

/**
 * Writable ledger view that accumulates state and tx changes.
 *
 * @note Presented as ReadView to clients.
 */
class OpenView final : public ReadView, public TxsRawView
{
private:
    // 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);

    class TxsIterImpl;

    struct TxData
    {
        std::shared_ptr<Serializer const> txn;
        std::shared_ptr<Serializer const> meta;

        // Constructor needed for emplacement in std::map
        TxData(
            std::shared_ptr<Serializer const> const& txn,
            std::shared_ptr<Serializer const> const& meta)
            : txn(txn), meta(meta)
        {
        }
    };

    // List of tx, key order
    // Use boost::pmr functionality instead of std::pmr
    // functions b/c clang does not support pmr yet (as-of 9/2020)
    using txs_map = std::map<
        key_type,
        TxData,
        std::less<>,
        boost::container::pmr::polymorphic_allocator<std::pair<key_type const, TxData>>>;

    // monotonic_resource_ must outlive `items_`. Make a pointer so it may be
    // easily moved.
    std::unique_ptr<boost::container::pmr::monotonic_buffer_resource> monotonicResource_;
    txs_map txs_;
    Rules rules_;
    LedgerHeader header_;
    ReadView const* base_;
    detail::RawStateTable items_;
    std::shared_ptr<void const> hold_;

    /**
     * In batch mode, the number of transactions already executed.
     */
    std::size_t baseTxCount_ = 0;

    bool open_ = true;

public:
    OpenView() = delete;
    OpenView&
    operator=(OpenView&&) = delete;
    OpenView&
    operator=(OpenView const&) = delete;

    OpenView(OpenView&&) = default;

    /**
     * Construct a shallow copy.
     *
     * Effects:
     *
     *     Creates a new object with a copy of
     *     the modification state table.
     *
     * The objects managed by shared pointers are
     * not duplicated but shared between instances.
     * Since the SLEs are immutable, calls on the
     * RawView interface cannot break invariants.
     */
    OpenView(OpenView const&);

    /**
     * Construct an open ledger view.
     *
     * Effects:
     *
     *     The sequence number is set to the
     *     sequence number of parent plus one.
     *
     *     The parentCloseTime is set to the
     *     closeTime of parent.
     *
     *     If `hold` is not nullptr, retains
     *     ownership of a copy of `hold` until
     *     the MetaView is destroyed.
     *
     *     Calls to rules() will return the
     *     rules provided on construction.
     *
     * The tx list starts empty and will contain
     * all newly inserted tx.
     */
    OpenView(
        OpenLedgerT,
        ReadView const* base,
        Rules rules,
        std::shared_ptr<void const> hold = nullptr);

    OpenView(OpenLedgerT, Rules const& rules, std::shared_ptr<ReadView const> const& base)
        : OpenView(kOpenLedger, &*base, rules, base)
    {
    }

    OpenView(BatchViewT, OpenView& base) : OpenView(std::addressof(base))
    {
        baseTxCount_ = base.txCount();
    }

    /**
     * Construct a new last closed ledger.
     *
     * Effects:
     *
     *     The LedgerHeader is copied from the base.
     *
     *     The rules are inherited from the base.
     *
     * The tx list starts empty and will contain
     * all newly inserted tx.
     */
    OpenView(ReadView const* base, std::shared_ptr<void const> hold = nullptr);

    /**
     * Returns true if this reflects an open ledger.
     */
    bool
    open() const override
    {
        return open_;
    }

    /**
     * Return the number of tx inserted since creation.
     *
     * This is used to set the "apply ordinal"
     * when calculating transaction metadata.
     */
    std::size_t
    txCount() const;

    /**
     * Apply changes.
     */
    void
    apply(TxsRawView& to) const;

    // ReadView

    LedgerHeader const&
    header() const override;

    Fees const&
    fees() const override;

    Rules const&
    rules() const override;

    bool
    exists(Keylet const& k) const override;

    std::optional<key_type>
    succ(key_type const& key, std::optional<key_type> const& last = std::nullopt) const override;

    SLE::const_pointer
    read(Keylet const& k) const override;

    std::unique_ptr<SlesType::iter_base>
    slesBegin() const override;

    std::unique_ptr<SlesType::iter_base>
    slesEnd() const override;

    std::unique_ptr<SlesType::iter_base>
    slesUpperBound(uint256 const& key) const override;

    std::unique_ptr<TxsType::iter_base>
    txsBegin() const override;

    std::unique_ptr<TxsType::iter_base>
    txsEnd() const override;

    bool
    txExists(key_type const& key) const override;

    tx_type
    txRead(key_type const& key) const override;

    // RawView

    void
    rawErase(SLE::ref sle) override;

    void
    rawInsert(SLE::ref sle) override;

    void
    rawReplace(SLE::ref sle) override;

    void
    rawDestroyXRP(XRPAmount const& fee) override;

    // TxsRawView

    void
    rawTxInsert(
        key_type const& key,
        std::shared_ptr<Serializer const> const& txn,
        std::shared_ptr<Serializer const> const& metaData) override;
};

}  // namespace xrpl