Make UpdateTransactionsFromBlock use Epochs

Author: JeremyRubin

src/txmempool.cpp

@@ -122,8 +122,6 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashes
     // setMemPoolChildren will be updated, an assumption made in
     // UpdateForDescendants.
     for (const uint256 &hash : reverse_iterate(vHashesToUpdate)) {
-        // we cache the in-mempool children to avoid duplicate updates
-        setEntries setChildren;
         // calculate children from mapNextTx
         txiter it = mapTx.find(hash);
         if (it == mapTx.end()) {
@@ -132,17 +130,21 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashes
         auto iter = mapNextTx.lower_bound(COutPoint(hash, 0));
         // First calculate the children, and update setMemPoolChildren to
         // include them, and update their setMemPoolParents to include this tx.
-        for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
-            const uint256 &childHash = iter->second->GetHash();
-            txiter childIter = mapTx.find(childHash);
-            assert(childIter != mapTx.end());
-            // We can skip updating entries we've encountered before or that
-            // are in the block (which are already accounted for).
-            if (setChildren.insert(childIter).second && !setAlreadyIncluded.count(childHash)) {
-                UpdateChild(it, childIter, true);
-                UpdateParent(childIter, it, true);
+        // we cache the in-mempool children to avoid duplicate updates
+        {
+            const auto epoch = GetFreshEpoch();
+            for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
+                const uint256 &childHash = iter->second->GetHash();
+                txiter childIter = mapTx.find(childHash);
+                assert(childIter != mapTx.end());
+                // We can skip updating entries we've encountered before or that
+                // are in the block (which are already accounted for).
+                if (!visited(childIter) && !setAlreadyIncluded.count(childHash)) {
+                    UpdateChild(it, childIter, true);
+                    UpdateParent(childIter, it, true);
+                }
             }
-        }
+        } // release epoch guard for UpdateForDescendants
         UpdateForDescendants(it, mapMemPoolDescendantsToUpdate, setAlreadyIncluded);
     }
 }