From 778f545a23a57f369003f37ab4a3fc70fb9925fa Mon Sep 17 00:00:00 2001
From: ismaelsadeeq <ask4ismailsadiq@gmail.com>
Date: Mon, 20 May 2024 10:46:50 +0100
Subject: [PATCH] [fees]: add method that linearize transaction removed from
 mempool

Co-authored-by: willcl-ark <will@256k1.dev>
---
 src/policy/fees_util.cpp | 33 +++++++++++++++++++++++++++++++++
 src/policy/fees_util.h   |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/src/policy/fees_util.cpp b/src/policy/fees_util.cpp
index ae5daf8d2688a..9aab82d5722cd 100644
--- a/src/policy/fees_util.cpp
+++ b/src/policy/fees_util.cpp
@@ -3,6 +3,8 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 
+#include <node/mini_miner.h>
+#include <policy/feerate.h>
 #include <policy/fees_util.h>
 #include <policy/policy.h>
 #include <primitives/transaction.h>
@@ -65,3 +67,34 @@ TxAncestorsAndDescendants GetTxAncestorsAndDescendants(const std::vector<Removed
     }
     return visited_txs;
 }
+
+node::LinearizationResult LinearizeTransactions(const std::vector<RemovedMempoolTransactionInfo>& txs_removed_for_block)
+{
+    // Cache all the transactions for efficient lookup
+    std::map<Txid, TransactionInfo> tx_caches;
+    for (const auto& tx : txs_removed_for_block) {
+        tx_caches.emplace(tx.info.m_tx->GetHash(), TransactionInfo(tx.info.m_tx, tx.info.m_fee, tx.info.m_virtual_transaction_size, tx.info.txHeight));
+    }
+
+    const auto& txAncestorsAndDescendants = GetTxAncestorsAndDescendants(txs_removed_for_block);
+    std::vector<node::MiniMinerMempoolEntry> transactions;
+    std::map<Txid, std::set<Txid>> descendant_caches;
+    transactions.reserve(txAncestorsAndDescendants.size());
+
+    for (const auto& transaction : txAncestorsAndDescendants) {
+        const auto& txid = transaction.first;
+        const auto& [ancestors, descendants] = transaction.second;
+        int64_t vsize_ancestor = 0;
+        CAmount fee_with_ancestors = 0;
+        for (auto& ancestor_id : ancestors) {
+            const auto& ancestor = tx_caches.find(ancestor_id)->second;
+            vsize_ancestor += ancestor.m_virtual_transaction_size;
+            fee_with_ancestors += ancestor.m_fee;
+        }
+
+        descendant_caches.emplace(txid, descendants);
+        auto tx_info = tx_caches.find(txid)->second;
+        transactions.emplace_back(tx_info.m_tx, tx_info.m_virtual_transaction_size, vsize_ancestor, tx_info.m_fee, fee_with_ancestors);
+    }
+    return node::MiniMiner(transactions, descendant_caches).Linearize();
+}
diff --git a/src/policy/fees_util.h b/src/policy/fees_util.h
index 46bfa05b4a633..b0bc258892215 100644
--- a/src/policy/fees_util.h
+++ b/src/policy/fees_util.h
@@ -6,7 +6,9 @@
 #define BITCOIN_POLICY_FEES_UTIL_H
 
 #include <kernel/mempool_entry.h>
+#include <node/mini_miner.h>
 #include <policy/feerate.h>
+#include <primitives/transaction.h>
 
 #include <map>
 #include <set>
@@ -49,4 +51,6 @@ using TxAncestorsAndDescendants = std::map<Txid, std::tuple<std::set<Txid>, std:
  */
 TxAncestorsAndDescendants GetTxAncestorsAndDescendants(const std::vector<RemovedMempoolTransactionInfo>& transactions);
 
+node::LinearizationResult LinearizeTransactions(const std::vector<RemovedMempoolTransactionInfo>& txs_removed_for_block);
+
 #endif // BITCOIN_POLICY_FEES_UTIL_H