[refactor] Add txmempool helper for node/interfaces

Author: TheCharlatan

src/node/interfaces.cpp

@@ -648,8 +648,7 @@ class ChainImpl : public Chain
     {
         if (!m_node.mempool) return false;
         LOCK(m_node.mempool->cs);
-        auto it = m_node.mempool->GetIter(txid);
-        return it && (*it)->GetCountWithDescendants() > 1;
+        return m_node.mempool->GetTxCountWithDescendants(txid) > 1;
     }
     bool broadcastTransaction(const CTransactionRef& tx,
         const CAmount& max_tx_fee,

src/txmempool.cpp

@@ -993,6 +993,14 @@ bool CTxMemPool::HasNoInputsOf(const CTransaction &tx) const
     return true;
 }
 
+uint64_t CTxMemPool::GetTxCountWithDescendants(const uint256& txid) const
+{
+    AssertLockHeld(cs);
+    auto it = GetIter(txid);
+    if (!it) return 0;
+    return (*it)->GetCountWithDescendants();
+}
+
 CCoinsViewMemPool::CCoinsViewMemPool(CCoinsView* baseIn, const CTxMemPool& mempoolIn) : CCoinsViewBacked(baseIn), mempool(mempoolIn) { }
 
 bool CCoinsViewMemPool::GetCoin(const COutPoint &outpoint, Coin &coin) const {

src/txmempool.h

@@ -531,6 +531,8 @@ class CTxMemPool
      * don't actually exist in the mempool, returns an empty vector. */
     std::vector<txiter> GetIterVec(const std::vector<uint256>& txids) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
+    uint64_t GetTxCountWithDescendants(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+
     /** Remove a set of transactions from the mempool.
      *  If a transaction is in this set, then all in-mempool descendants must
      *  also be in the set, unless this transaction is being removed for being