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       1                 :            : // Copyright (c) 2022 The Bitcoin Core developers
       2                 :            : // Distributed under the MIT software license, see the accompanying
       3                 :            : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :            : 
       5                 :            : #ifndef BITCOIN_NODE_MINI_MINER_H
       6                 :            : #define BITCOIN_NODE_MINI_MINER_H
       7                 :            : 
       8                 :            : #include <consensus/amount.h>
       9                 :            : #include <primitives/transaction.h>
      10                 :            : #include <uint256.h>
      11                 :            : 
      12                 :            : #include <map>
      13                 :            : #include <memory>
      14                 :            : #include <optional>
      15                 :            : #include <set>
      16                 :            : #include <stdint.h>
      17                 :            : #include <vector>
      18                 :            : 
      19                 :            : class CFeeRate;
      20                 :            : class CTxMemPool;
      21                 :            : 
      22                 :            : namespace node {
      23                 :            : 
      24                 :            : // Container for tracking updates to ancestor feerate as we include ancestors in the "block"
      25                 :          0 : class MiniMinerMempoolEntry
      26                 :            : {
      27                 :            :     const CTransactionRef tx;
      28                 :            :     const int64_t vsize_individual;
      29                 :            :     int64_t vsize_with_ancestors;
      30                 :            :     const CAmount fee_individual;
      31                 :            :     CAmount fee_with_ancestors;
      32                 :            : 
      33                 :            : // This class must be constructed while holding mempool.cs. After construction, the object's
      34                 :            : // methods can be called without holding that lock.
      35                 :            : 
      36                 :            : public:
      37                 :          0 :     explicit MiniMinerMempoolEntry(CAmount fee_self,
      38                 :            :                                    CAmount fee_ancestor,
      39                 :            :                                    int64_t vsize_self,
      40                 :            :                                    int64_t vsize_ancestor,
      41                 :            :                                    const CTransactionRef& tx_in):
      42                 :          0 :         tx{tx_in},
      43                 :          0 :         vsize_individual{vsize_self},
      44                 :          0 :         vsize_with_ancestors{vsize_ancestor},
      45                 :          0 :         fee_individual{fee_self},
      46                 :          0 :         fee_with_ancestors{fee_ancestor}
      47                 :          0 :     { }
      48                 :            : 
      49                 :          0 :     CAmount GetModifiedFee() const { return fee_individual; }
      50                 :          0 :     CAmount GetModFeesWithAncestors() const { return fee_with_ancestors; }
      51                 :          0 :     int64_t GetTxSize() const { return vsize_individual; }
      52                 :          0 :     int64_t GetSizeWithAncestors() const { return vsize_with_ancestors; }
      53                 :          0 :     const CTransaction& GetTx() const LIFETIMEBOUND { return *tx; }
      54                 :          0 :     void UpdateAncestorState(int64_t vsize_change, CAmount fee_change) {
      55                 :          0 :         vsize_with_ancestors += vsize_change;
      56                 :          0 :         fee_with_ancestors += fee_change;
      57                 :          0 :     }
      58                 :            : };
      59                 :            : 
      60                 :            : // Comparator needed for std::set<MockEntryMap::iterator>
      61                 :            : struct IteratorComparator
      62                 :            : {
      63                 :            :     template<typename I>
      64                 :          0 :     bool operator()(const I& a, const I& b) const
      65                 :            :     {
      66                 :          0 :         return &(*a) < &(*b);
      67                 :            :     }
      68                 :            : };
      69                 :            : 
      70                 :            : /** A minimal version of BlockAssembler, using the same ancestor set scoring algorithm. Allows us to
      71                 :            :  * run this algorithm on a limited set of transactions (e.g. subset of mempool or transactions that
      72                 :            :  * are not yet in mempool) instead of the entire mempool, ignoring consensus rules.
      73                 :            :  * Callers may use this to:
      74                 :            :  * - Calculate the "bump fee" needed to spend an unconfirmed UTXO at a given feerate
      75                 :            :  * - "Linearize" a list of transactions to see the order in which they would be selected for
      76                 :            :  *   inclusion in a block
      77                 :            :  */
      78                 :          0 : class MiniMiner
      79                 :            : {
      80                 :            :     // When true, a caller may use CalculateBumpFees(). Becomes false if we failed to retrieve
      81                 :            :     // mempool entries (i.e. cluster size too large) or bump fees have already been calculated.
      82                 :            :     bool m_ready_to_calculate{true};
      83                 :            : 
      84                 :            :     // Set once per lifetime, fill in during initialization.
      85                 :            :     // txids of to-be-replaced transactions
      86                 :            :     std::set<uint256> m_to_be_replaced;
      87                 :            : 
      88                 :            :     // If multiple argument outpoints correspond to the same transaction, cache them together in
      89                 :            :     // a single entry indexed by txid. Then we can just work with txids since all outpoints from
      90                 :            :     // the same tx will have the same bumpfee. Excludes non-mempool transactions.
      91                 :            :     std::map<uint256, std::vector<COutPoint>> m_requested_outpoints_by_txid;
      92                 :            : 
      93                 :            :     // Txid to a number representing the order in which this transaction was included (smaller
      94                 :            :     // number = included earlier).  Transactions included in an ancestor set together have the same
      95                 :            :     // sequence number.
      96                 :            :     std::map<Txid, uint32_t> m_inclusion_order;
      97                 :            :     // What we're trying to calculate. Outpoint to the fee needed to bring the transaction to the target feerate.
      98                 :            :     std::map<COutPoint, CAmount> m_bump_fees;
      99                 :            : 
     100                 :            :     // The constructed block template
     101                 :            :     std::set<uint256> m_in_block;
     102                 :            : 
     103                 :            :     // Information on the current status of the block
     104                 :            :     CAmount m_total_fees{0};
     105                 :            :     int32_t m_total_vsize{0};
     106                 :            : 
     107                 :            :     /** Main data structure holding the entries, can be indexed by txid */
     108                 :            :     std::map<uint256, MiniMinerMempoolEntry> m_entries_by_txid;
     109                 :            :     using MockEntryMap = decltype(m_entries_by_txid);
     110                 :            : 
     111                 :            :     /** Vector of entries, can be sorted by ancestor feerate. */
     112                 :            :     std::vector<MockEntryMap::iterator> m_entries;
     113                 :            : 
     114                 :            :     /** Map of txid to its descendants. Should be inclusive. */
     115                 :            :     std::map<uint256, std::vector<MockEntryMap::iterator>> m_descendant_set_by_txid;
     116                 :            : 
     117                 :            :     /** Consider this ancestor package "mined" so remove all these entries from our data structures. */
     118                 :            :     void DeleteAncestorPackage(const std::set<MockEntryMap::iterator, IteratorComparator>& ancestors);
     119                 :            : 
     120                 :            :     /** Perform some checks. */
     121                 :            :     void SanityCheck() const;
     122                 :            : 
     123                 :            : public:
     124                 :            :     /** Returns true if CalculateBumpFees may be called, false if not. */
     125                 :          0 :     bool IsReadyToCalculate() const { return m_ready_to_calculate; }
     126                 :            : 
     127                 :            :     /** Build a block template until the target feerate is hit. If target_feerate is not given,
     128                 :            :      * builds a block template until all transactions have been selected. */
     129                 :            :     void BuildMockTemplate(std::optional<CFeeRate> target_feerate);
     130                 :            : 
     131                 :            :     /** Returns set of txids in the block template if one has been constructed. */
     132                 :          0 :     std::set<uint256> GetMockTemplateTxids() const { return m_in_block; }
     133                 :            : 
     134                 :            :     /** Constructor that takes a list of outpoints that may or may not belong to transactions in the
     135                 :            :      * mempool. Copies out information about the relevant transactions in the mempool into
     136                 :            :      * MiniMinerMempoolEntrys.
     137                 :            :     */
     138                 :            :     MiniMiner(const CTxMemPool& mempool, const std::vector<COutPoint>& outpoints);
     139                 :            : 
     140                 :            :     /** Constructor in which the MiniMinerMempoolEntry entries have been constructed manually,
     141                 :            :      * presumably because these transactions are not in the mempool (yet). It is assumed that all
     142                 :            :      * entries are unique and their values are correct, otherwise results computed by MiniMiner may
     143                 :            :      * be incorrect. Callers should check IsReadyToCalculate() after construction.
     144                 :            :      * @param[in] descendant_caches A map from each transaction to the set of txids of this
     145                 :            :      *                              transaction's descendant set, including itself. Each tx in
     146                 :            :      *                              manual_entries must have a corresponding entry in this map, and
     147                 :            :      *                              all of the txids in a descendant set must correspond to a tx in
     148                 :            :      *                              manual_entries.
     149                 :            :      */
     150                 :            :     MiniMiner(const std::vector<MiniMinerMempoolEntry>& manual_entries,
     151                 :            :               const std::map<Txid, std::set<Txid>>& descendant_caches);
     152                 :            : 
     153                 :            :     /** Construct a new block template and, for each outpoint corresponding to a transaction that
     154                 :            :      * did not make it into the block, calculate the cost of bumping those transactions (and their
     155                 :            :      * ancestors) to the minimum feerate. Returns a map from outpoint to bump fee, or an empty map
     156                 :            :      * if they cannot be calculated. */
     157                 :            :     std::map<COutPoint, CAmount> CalculateBumpFees(const CFeeRate& target_feerate);
     158                 :            : 
     159                 :            :     /** Construct a new block template and, calculate the cost of bumping all transactions that did
     160                 :            :      * not make it into the block to the target feerate. Returns the total bump fee, or std::nullopt
     161                 :            :      * if it cannot be calculated. */
     162                 :            :     std::optional<CAmount> CalculateTotalBumpFees(const CFeeRate& target_feerate);
     163                 :            : 
     164                 :            :     /** Construct a new block template with all of the transactions and calculate the order in which
     165                 :            :      * they are selected. Returns the sequence number (lower = selected earlier) with which each
     166                 :            :      * transaction was selected, indexed by txid, or an empty map if it cannot be calculated.
     167                 :            :      */
     168                 :            :     std::map<Txid, uint32_t> Linearize();
     169                 :            : };
     170                 :            : } // namespace node
     171                 :            : 
     172                 :            : #endif // BITCOIN_NODE_MINI_MINER_H