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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 <txmempool.h>
       9                 :            : 
      10                 :            : #include <memory>
      11                 :            : #include <optional>
      12                 :            : #include <stdint.h>
      13                 :            : 
      14                 :            : namespace node {
      15                 :            : 
      16                 :            : // Container for tracking updates to ancestor feerate as we include ancestors in the "block"
      17                 :            : class MiniMinerMempoolEntry
      18                 :            : {
      19                 :            :     const CAmount fee_individual;
      20                 :            :     const CTransactionRef tx;
      21                 :            :     const int64_t vsize_individual;
      22                 :            :     CAmount fee_with_ancestors;
      23                 :            :     int64_t vsize_with_ancestors;
      24                 :            : 
      25                 :            : // This class must be constructed while holding mempool.cs. After construction, the object's
      26                 :            : // methods can be called without holding that lock.
      27                 :            : 
      28                 :            : public:
      29                 :          0 :     explicit MiniMinerMempoolEntry(CTxMemPool::txiter entry) :
      30                 :          0 :         fee_individual{entry->GetModifiedFee()},
      31                 :          0 :         tx{entry->GetSharedTx()},
      32   [ #  #  #  # ]:          0 :         vsize_individual(entry->GetTxSize()),
      33   [ #  #  #  # ]:          0 :         fee_with_ancestors{entry->GetModFeesWithAncestors()},
      34   [ #  #  #  # ]:          0 :         vsize_with_ancestors(entry->GetSizeWithAncestors())
      35                 :          0 :     { }
      36                 :            : 
      37                 :          0 :     CAmount GetModifiedFee() const { return fee_individual; }
      38                 :          0 :     CAmount GetModFeesWithAncestors() const { return fee_with_ancestors; }
      39                 :          0 :     int64_t GetTxSize() const { return vsize_individual; }
      40                 :          0 :     int64_t GetSizeWithAncestors() const { return vsize_with_ancestors; }
      41                 :          0 :     const CTransaction& GetTx() const LIFETIMEBOUND { return *tx; }
      42                 :          0 :     void UpdateAncestorState(int64_t vsize_change, CAmount fee_change) {
      43                 :          0 :         vsize_with_ancestors += vsize_change;
      44                 :          0 :         fee_with_ancestors += fee_change;
      45                 :          0 :     }
      46                 :            : };
      47                 :            : 
      48                 :            : // Comparator needed for std::set<MockEntryMap::iterator>
      49                 :            : struct IteratorComparator
      50                 :            : {
      51                 :            :     template<typename I>
      52                 :          0 :     bool operator()(const I& a, const I& b) const
      53                 :            :     {
      54                 :          0 :         return &(*a) < &(*b);
      55                 :            :     }
      56                 :            : };
      57                 :            : 
      58                 :            : /** A minimal version of BlockAssembler. Allows us to run the mining algorithm on a subset of
      59                 :            :  * mempool transactions, ignoring consensus rules, to calculate mining scores. */
      60                 :            : class MiniMiner
      61                 :            : {
      62                 :            :     // When true, a caller may use CalculateBumpFees(). Becomes false if we failed to retrieve
      63                 :            :     // mempool entries (i.e. cluster size too large) or bump fees have already been calculated.
      64                 :            :     bool m_ready_to_calculate{true};
      65                 :            : 
      66                 :            :     // Set once per lifetime, fill in during initialization.
      67                 :            :     // txids of to-be-replaced transactions
      68                 :            :     std::set<uint256> m_to_be_replaced;
      69                 :            : 
      70                 :            :     // If multiple argument outpoints correspond to the same transaction, cache them together in
      71                 :            :     // a single entry indexed by txid. Then we can just work with txids since all outpoints from
      72                 :            :     // the same tx will have the same bumpfee. Excludes non-mempool transactions.
      73                 :            :     std::map<uint256, std::vector<COutPoint>> m_requested_outpoints_by_txid;
      74                 :            : 
      75                 :            :     // What we're trying to calculate.
      76                 :            :     std::map<COutPoint, CAmount> m_bump_fees;
      77                 :            : 
      78                 :            :     // The constructed block template
      79                 :            :     std::set<uint256> m_in_block;
      80                 :            : 
      81                 :            :     // Information on the current status of the block
      82                 :            :     CAmount m_total_fees{0};
      83                 :            :     int32_t m_total_vsize{0};
      84                 :            : 
      85                 :            :     /** Main data structure holding the entries, can be indexed by txid */
      86                 :            :     std::map<uint256, MiniMinerMempoolEntry> m_entries_by_txid;
      87                 :            :     using MockEntryMap = decltype(m_entries_by_txid);
      88                 :            : 
      89                 :            :     /** Vector of entries, can be sorted by ancestor feerate. */
      90                 :            :     std::vector<MockEntryMap::iterator> m_entries;
      91                 :            : 
      92                 :            :     /** Map of txid to its descendants. Should be inclusive. */
      93                 :            :     std::map<uint256, std::vector<MockEntryMap::iterator>> m_descendant_set_by_txid;
      94                 :            : 
      95                 :            :     /** Consider this ancestor package "mined" so remove all these entries from our data structures. */
      96                 :            :     void DeleteAncestorPackage(const std::set<MockEntryMap::iterator, IteratorComparator>& ancestors);
      97                 :            : 
      98                 :            :     /** Perform some checks. */
      99                 :            :     void SanityCheck() const;
     100                 :            : 
     101                 :            : public:
     102                 :            :     /** Returns true if CalculateBumpFees may be called, false if not. */
     103                 :          0 :     bool IsReadyToCalculate() const { return m_ready_to_calculate; }
     104                 :            : 
     105                 :            :     /** Build a block template until the target feerate is hit. */
     106                 :            :     void BuildMockTemplate(const CFeeRate& target_feerate);
     107                 :            : 
     108                 :            :     /** Returns set of txids in the block template if one has been constructed. */
     109                 :          0 :     std::set<uint256> GetMockTemplateTxids() const { return m_in_block; }
     110                 :            : 
     111                 :            :     MiniMiner(const CTxMemPool& mempool, const std::vector<COutPoint>& outpoints);
     112                 :            : 
     113                 :            :     /** Construct a new block template and, for each outpoint corresponding to a transaction that
     114                 :            :      * did not make it into the block, calculate the cost of bumping those transactions (and their
     115                 :            :      * ancestors) to the minimum feerate. Returns a map from outpoint to bump fee, or an empty map
     116                 :            :      * if they cannot be calculated. */
     117                 :            :     std::map<COutPoint, CAmount> CalculateBumpFees(const CFeeRate& target_feerate);
     118                 :            : 
     119                 :            :     /** Construct a new block template and, calculate the cost of bumping all transactions that did
     120                 :            :      * not make it into the block to the target feerate. Returns the total bump fee, or std::nullopt
     121                 :            :      * if it cannot be calculated. */
     122                 :            :     std::optional<CAmount> CalculateTotalBumpFees(const CFeeRate& target_feerate);
     123                 :            : };
     124                 :            : } // namespace node
     125                 :            : 
     126                 :            : #endif // BITCOIN_NODE_MINI_MINER_H