refactor: make CTxMemPool::GetIter strongly typed

This allows adding a GetIter(const Wtxid&) overload in a next
commit, making it easier to visit this function from a variant.

Co-authored-by: stickies-v <stickies-v@protonmail.com>

src/rpc/mempool.cpp

@@ -523,12 +523,12 @@ static RPCHelpMan getmempooldescendants()
     if (!request.params[1].isNull())
         fVerbose = request.params[1].get_bool();
 
-    uint256 hash = ParseHashV(request.params[0], "parameter 1");
+    Txid txid{Txid::FromUint256(ParseHashV(request.params[0], "parameter 1"))};
 
     const CTxMemPool& mempool = EnsureAnyMemPool(request.context);
     LOCK(mempool.cs);
 
-    const auto it{mempool.GetIter(hash)};
+    const auto it{mempool.GetIter(txid)};
     if (!it) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not in mempool");
     }

src/test/txvalidation_tests.cpp

@@ -304,7 +304,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
 
         Package package_v3_v2{mempool_tx_v3, tx_v2_from_v3};
         BOOST_CHECK_EQUAL(*PackageTRUCChecks(tx_v2_from_v3, GetVirtualTransactionSize(*tx_v2_from_v3), package_v3_v2, empty_ancestors), expected_error_str);
-        CTxMemPool::setEntries entries_mempool_v3{pool.GetIter(mempool_tx_v3->GetHash().ToUint256()).value()};
+        CTxMemPool::setEntries entries_mempool_v3{pool.GetIter(mempool_tx_v3->GetHash()).value()};
         BOOST_CHECK_EQUAL(*PackageTRUCChecks(tx_v2_from_v3, GetVirtualTransactionSize(*tx_v2_from_v3), {tx_v2_from_v3}, entries_mempool_v3), expected_error_str);
 
         // mempool_tx_v3  mempool_tx_v2
@@ -339,7 +339,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
 
         Package package_v2_v3{mempool_tx_v2, tx_v3_from_v2};
         BOOST_CHECK_EQUAL(*PackageTRUCChecks(tx_v3_from_v2, GetVirtualTransactionSize(*tx_v3_from_v2), package_v2_v3, empty_ancestors), expected_error_str);
-        CTxMemPool::setEntries entries_mempool_v2{pool.GetIter(mempool_tx_v2->GetHash().ToUint256()).value()};
+        CTxMemPool::setEntries entries_mempool_v2{pool.GetIter(mempool_tx_v2->GetHash()).value()};
         BOOST_CHECK_EQUAL(*PackageTRUCChecks(tx_v3_from_v2, GetVirtualTransactionSize(*tx_v3_from_v2), {tx_v3_from_v2}, entries_mempool_v2), expected_error_str);
 
         // mempool_tx_v3  mempool_tx_v2
@@ -536,7 +536,7 @@ BOOST_FIXTURE_TEST_CASE(version3_tests, RegTestingSetup)
         // Configuration where parent already has 2 other children in mempool (no sibling eviction allowed). This may happen as the result of a reorg.
         AddToMempool(pool, entry.FromTx(tx_v3_child2));
         auto tx_v3_child3 = make_tx({COutPoint{mempool_tx_v3->GetHash(), 24}}, /*version=*/3);
-        auto entry_mempool_parent = pool.GetIter(mempool_tx_v3->GetHash().ToUint256()).value();
+        auto entry_mempool_parent = pool.GetIter(mempool_tx_v3->GetHash()).value();
         BOOST_CHECK_EQUAL(entry_mempool_parent->GetCountWithDescendants(), 3);
         auto ancestors_2siblings{pool.CalculateMemPoolAncestors(entry.FromTx(tx_v3_child3), m_limits)};
 

src/txmempool.cpp

@@ -154,7 +154,7 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256>& vHashes
     for (const auto& txid : descendants_to_remove) {
         // This txid may have been removed already in a prior call to removeRecursive.
         // Therefore we ensure it is not yet removed already.
-        if (const std::optional<txiter> txiter = GetIter(txid)) {
+        if (const std::optional<txiter> txiter = GetIter(Txid::FromUint256(txid))) {
             removeRecursive((*txiter)->GetTx(), MemPoolRemovalReason::SIZELIMIT);
         }
     }
@@ -984,9 +984,9 @@ const CTransaction* CTxMemPool::GetConflictTx(const COutPoint& prevout) const
     return it == mapNextTx.end() ? nullptr : it->second;
 }
 
-std::optional<CTxMemPool::txiter> CTxMemPool::GetIter(const uint256& txid) const
+std::optional<CTxMemPool::txiter> CTxMemPool::GetIter(const Txid& txid) const
 {
-    auto it = mapTx.find(txid);
+    auto it = mapTx.find(txid.ToUint256());
     if (it != mapTx.end()) return it;
     return std::nullopt;
 }
@@ -1007,7 +1007,7 @@ std::vector<CTxMemPool::txiter> CTxMemPool::GetIterVec(const std::vector<uint256
     std::vector<txiter> ret;
     ret.reserve(txids.size());
     for (const auto& txid : txids) {
-        const auto it{GetIter(txid)};
+        const auto it{GetIter(Txid::FromUint256(txid))};
         if (!it) return {};
         ret.push_back(*it);
     }

src/txmempool.h

@@ -498,7 +498,7 @@ public:
     const CTransaction* GetConflictTx(const COutPoint& prevout) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Returns an iterator to the given hash, if found */
-    std::optional<txiter> GetIter(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    std::optional<txiter> GetIter(const Txid& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Translate a set of hashes into a set of pool iterators to avoid repeated lookups.
      * Does not require that all of the hashes correspond to actual transactions in the mempool,