BasePatriciaTree.h

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#pragma once
#include "BasePatriciaTreeDelta.h"
#include "catapult/utils/HexFormatter.h"
#include "catapult/exceptions.h"
 
namespace catapult { namespace tree {
 
    template<typename TEncoder, typename TDataSource, typename THasher = std::hash<typename TEncoder::KeyType>>
    class BasePatriciaTree {
    public:
        using KeyType = typename TEncoder::KeyType;
        using ValueType = typename TEncoder::ValueType;
        using DeltaType = BasePatriciaTreeDelta<TEncoder, TDataSource, THasher>;
 
    public:
        explicit BasePatriciaTree(TDataSource& dataSource)
                : m_dataSource(dataSource)
                , m_tree(m_dataSource)
        {}
 
        BasePatriciaTree(TDataSource& dataSource, const Hash256& rootHash) : BasePatriciaTree(dataSource) {
            if (!m_tree.tryLoad(rootHash))
                CATAPULT_THROW_RUNTIME_ERROR_1("unable to load tree with root hash", rootHash);
        }
 
    public:
        Hash256 root() const {
            return m_tree.root();
        }
 
        std::pair<Hash256, bool> lookup(const KeyType& key, std::vector<TreeNode>& nodePath) const {
            return m_tree.lookup(key, nodePath);
        }
 
    public:
        std::shared_ptr<DeltaType> rebase() {
            if (m_pWeakDelta.lock())
                CATAPULT_THROW_RUNTIME_ERROR("only a single attached delta is allowed at a time");
 
            auto pDelta = std::make_shared<DeltaType>(m_dataSource, root());
            m_pWeakDelta = pDelta;
            return pDelta;
        }
 
        std::shared_ptr<DeltaType> rebaseDetached() const {
            return std::make_shared<DeltaType>(m_dataSource, root());
        }
 
    public:
        void commit() {
            auto pDelta = m_pWeakDelta.lock();
            if (!pDelta)
                CATAPULT_THROW_RUNTIME_ERROR("attempting to commit changes to a tree without any outstanding attached deltas");
 
            // copy all pending changes directly into the data source, update the root hash and reset the delta
            pDelta->setCheckpoint(); // commit should always create a checkpoint
            pDelta->copyPendingChangesTo(m_dataSource);
            pDelta->copyRootTo(m_tree); // cannot lookup in m_dataSource directly because of delayed write data sources
            pDelta->reset(pDelta->root());
        }
 
    private:
        TDataSource& m_dataSource;
        PatriciaTree<TEncoder, TDataSource> m_tree;
        std::weak_ptr<DeltaType> m_pWeakDelta;
    };
}}