Add GetTransactionAncestry to CTxMemPool for general purpose chain limit checking

Author: kallewoof

src/txmempool.cpp

@@ -1066,6 +1066,16 @@ uint64_t CTxMemPool::CalculateDescendantMaximum(txiter entry) const {
     return top->GetCountWithDescendants();
 }
 
+void CTxMemPool::GetTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants) const {
+    LOCK(cs);
+    auto it = mapTx.find(txid);
+    ancestors = descendants = 0;
+    if (it != mapTx.end()) {
+        ancestors = it->GetCountWithAncestors();
+        descendants = CalculateDescendantMaximum(it);
+    }
+}
+
 bool CTxMemPool::TransactionWithinChainLimit(const uint256& txid, size_t ancestor_limit, size_t descendant_limit) const {
     LOCK(cs);
     auto it = mapTx.find(txid);

src/txmempool.h

@@ -620,6 +620,12 @@ class CTxMemPool
     /** Expire all transaction (and their dependencies) in the mempool older than time. Return the number of removed transactions. */
     int Expire(int64_t time);
 
+    /**
+     * Calculate the ancestor and descendant count for the given transaction.
+     * The counts include the transaction itself.
+     */
+    void GetTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants) const;
+
     /** Returns false if the transaction is in the mempool and not within the chain limit specified. */
     bool TransactionWithinChainLimit(const uint256& txid, size_t ancestor_limit, size_t descendant_limit) const;