blockassembler.h

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Copyright (c) 2021 The PIVX Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or https://www.opensource.org/licenses/mit-license.php.

#ifndef PIVX_BLOCKASSEMBLER_H
#define PIVX_BLOCKASSEMBLER_H

#include "primitives/block.h"
#include "txmempool.h"

#include <stdint.h>
#include <memory>
#include "boost/multi_index_container.hpp"
#include "boost/multi_index/ordered_index.hpp"

class CBlockIndex;
class CChainParams;
class CReserveKey;
class CStakeableOutput;
class CScript;
class CWallet;

namespace Consensus { struct Params; };

struct CBlockTemplate
{
    CBlock block;
    std::vector<CAmount> vTxFees;
    std::vector<int64_t> vTxSigOps;
};

// Container for tracking updates to ancestor feerate as we include (parent)
// transactions in a block
struct CTxMemPoolModifiedEntry {
    CTxMemPoolModifiedEntry(CTxMemPool::txiter entry)
    {
        iter = entry;
        nSizeWithAncestors = entry->GetSizeWithAncestors();
        nModFeesWithAncestors = entry->GetModFeesWithAncestors();
        nSigOpCountWithAncestors = entry->GetSigOpCountWithAncestors();
    }

    CTxMemPool::txiter iter;
    uint64_t nSizeWithAncestors;
    CAmount nModFeesWithAncestors;
    unsigned int nSigOpCountWithAncestors;
};

/** Comparator for CTxMemPool::txiter objects.
 *  It simply compares the internal memory address of the CTxMemPoolEntry object
 *  pointed to. This means it has no meaning, and is only useful for using them
 *  as key in other indexes.
 */
struct CompareCTxMemPoolIter {
    bool operator()(const CTxMemPool::txiter& a, const CTxMemPool::txiter& b) const
    {
        return &(*a) < &(*b);
    }
};

struct modifiedentry_iter {
    typedef CTxMemPool::txiter result_type;
    result_type operator() (const CTxMemPoolModifiedEntry &entry) const
    {
        return entry.iter;
    }
};

// This matches the calculation in CompareTxMemPoolEntryByAncestorFee,
// except operating on CTxMemPoolModifiedEntry.
// TODO: refactor to avoid duplication of this logic.
struct CompareModifiedEntry {
    bool operator()(const CTxMemPoolModifiedEntry &a, const CTxMemPoolModifiedEntry &b) const
    {
        double f1 = (double)a.nModFeesWithAncestors * b.nSizeWithAncestors;
        double f2 = (double)b.nModFeesWithAncestors * a.nSizeWithAncestors;
        if (f1 == f2) {
            return CTxMemPool::CompareIteratorByHash()(a.iter, b.iter);
        }
        return f1 > f2;
    }
};

// A comparator that sorts transactions based on number of ancestors.
// This is sufficient to sort an ancestor package in an order that is valid
// to appear in a block.
struct CompareTxIterByAncestorCount {
    bool operator()(const CTxMemPool::txiter &a, const CTxMemPool::txiter &b) const
    {
        if (a->GetCountWithAncestors() != b->GetCountWithAncestors())
            return a->GetCountWithAncestors() < b->GetCountWithAncestors();
        return CTxMemPool::CompareIteratorByHash()(a, b);
    }
};

typedef boost::multi_index_container<
    CTxMemPoolModifiedEntry,
    boost::multi_index::indexed_by<
        boost::multi_index::ordered_unique<
            modifiedentry_iter,
            CompareCTxMemPoolIter
        >,
        // sorted by modified ancestor fee rate
        boost::multi_index::ordered_non_unique<
            // Reuse same tag from CTxMemPool's similar index
            boost::multi_index::tag<ancestor_score>,
            boost::multi_index::identity<CTxMemPoolModifiedEntry>,
            CompareModifiedEntry
        >
    >
> indexed_modified_transaction_set;

typedef indexed_modified_transaction_set::nth_index<0>::type::iterator modtxiter;
typedef indexed_modified_transaction_set::index<ancestor_score>::type::iterator modtxscoreiter;

struct update_for_parent_inclusion
{
    update_for_parent_inclusion(CTxMemPool::txiter it) : iter(it) {}

    void operator() (CTxMemPoolModifiedEntry &e)
    {
        e.nModFeesWithAncestors -= iter->GetFee();
        e.nSizeWithAncestors -= iter->GetTxSize();
        e.nSigOpCountWithAncestors -= iter->GetSigOpCount();
    }

    CTxMemPool::txiter iter;
};


/** Generate a new block */
class BlockAssembler
{
private:
    // The constructed block template
    std::unique_ptr<CBlockTemplate> pblocktemplate;
    // A convenience pointer that always refers to the CBlock in pblocktemplate
    CBlock* pblock{nullptr};

    // Configuration parameters for the block max size
    unsigned int nBlockMaxSize{0};

    // Information on the current status of the block
    uint64_t nBlockSize{0};
    uint64_t nBlockTx{0};
    unsigned int nBlockSigOps{0};
    CAmount nFees{0};
    CTxMemPool::setEntries inBlock;

    // Chain context for the block
    int nHeight{0};
    const CChainParams& chainparams;

    // Keep track of block space used for shield txes
    unsigned int nSizeShielded{0};

    // Whether should print priority by default or not
    const bool defaultPrintPriority{false};

public:
    BlockAssembler(const CChainParams& chainparams, const bool defaultPrintPriority);
    /** Construct a new block template with coinbase to scriptPubKeyIn */
    std::unique_ptr<CBlockTemplate> CreateNewBlock(const CScript& scriptPubKeyIn,
                                   CWallet* pwallet = nullptr,
                                   bool fProofOfStake = false,
                                   std::vector<CStakeableOutput>* availableCoins = nullptr,
                                   bool fNoMempoolTx = false,
                                   bool fTestValidity = true,
                                   CBlockIndex* prevBlock = nullptr,
                                   bool stopPoSOnNewBlock = true,
                                   bool fIncludeQfc = true);

private:
    // utility functions
    /** Clear the block's state and prepare for assembling a new block */
    void resetBlock();
    /** Add a tx to the block */
    void AddToBlock(CTxMemPool::txiter iter);

    // Methods for how to add transactions to a block.
    /** Add transactions based on feerate including unconfirmed ancestors */
    void addPackageTxs();
    /** Add the tip updated incremental merkle tree to the header */
    void appendSaplingTreeRoot();

    // helper functions for addPackageTxs()
    /** Remove confirmed (inBlock) entries from given set */
    void onlyUnconfirmed(CTxMemPool::setEntries& testSet);
    /** Test if a new package would "fit" in the block */
    bool TestPackage(uint64_t packageSize, unsigned int packageSigOps);
    /** Test if a set of transactions are all final */
    bool TestPackageFinality(const CTxMemPool::setEntries& package);
    /** Return true if given transaction from mapTx has already been evaluated,
      * or if the transaction's cached data in mapTx is incorrect. */
    bool SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set &mapModifiedTx, CTxMemPool::setEntries &failedTx);
    /** Sort the package in an order that is valid to appear in a block */
    void SortForBlock(const CTxMemPool::setEntries& package, CTxMemPool::txiter entry, std::vector<CTxMemPool::txiter>& sortedEntries);
    /** Add descendants of given transactions to mapModifiedTx with ancestor
      * state updated assuming given transactions are inBlock. */
    void UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded, indexed_modified_transaction_set &mapModifiedTx);

};

/** Modify the nonce/extranonce in a block */
bool SolveBlock(std::shared_ptr<CBlock>& pblock, int nHeight);
void IncrementExtraNonce(std::shared_ptr<CBlock>& pblock, int nHeight, unsigned int& nExtraNonce);
int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev);
int32_t ComputeBlockVersion(const Consensus::Params& consensusParams, int nHeight);

// Visible for testing purposes only
bool CreateCoinbaseTx(CBlock* pblock, const CScript& scriptPubKeyIn, CBlockIndex* pindexPrev);
CMutableTransaction CreateCoinbaseTx(const CScript& scriptPubKeyIn, CBlockIndex* pindexPrev);

// Visible for testing purposes only
uint256 CalculateSaplingTreeRoot(CBlock* pblock, int nHeight, const CChainParams& chainparams);

#endif // PIVX_BLOCKASSEMBLER_H