txmempool: Store pointers to transactions claiming SPKs

Author: luke-jr

src/kernel/mempool_entry.h

@@ -37,8 +37,8 @@ struct LockPoints {
 
 enum MemPool_SPK_State {
     MSS_UNSEEN  = 0,
-    MSS_SPENT   = 1,
-    MSS_CREATED = 2,
+    MSS_SPENT   = 1,  // .second
+    MSS_CREATED = 2,  // .first
     MSS_BOTH    = 3,
 };
 

src/txmempool.cpp

@@ -487,7 +487,14 @@ void CTxMemPool::addUnchecked(const CTxMemPoolEntry &entry, setEntries &setAnces
     newit->idx_randomized = txns_randomized.size() - 1;
 
     for (auto& vSPK : entry.mapSPK) {
-        mapUsedSPK[vSPK.first] = MemPool_SPK_State(mapUsedSPK[vSPK.first] | vSPK.second);
+        const uint160& SPKKey = vSPK.first;
+        const MemPool_SPK_State& claims = vSPK.second;
+        if (claims & MSS_CREATED) {
+            mapUsedSPK[SPKKey].first = &tx;
+        }
+        if (claims & MSS_SPENT) {
+            mapUsedSPK[SPKKey].second = &tx;
+        }
     }
 
     TRACE3(mempool, added,
@@ -518,6 +525,7 @@ void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
         std::chrono::duration_cast<std::chrono::duration<std::uint64_t>>(it->GetTime()).count()
     );
 
+    const CTransaction& tx = it->GetTx();
     for (const CTxIn& txin : it->GetTx().vin)
         mapNextTx.erase(txin.prevout);
 
@@ -535,10 +543,15 @@ void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
         txns_randomized.clear();
 
     for (auto& vSPK : it->mapSPK) {
-        if (vSPK.second == mapUsedSPK.find(vSPK.first)->second) {
-            mapUsedSPK.erase(vSPK.first);
-        } else {
-            mapUsedSPK[vSPK.first] = MemPool_SPK_State(mapUsedSPK[vSPK.first] & ~vSPK.second);
+        const uint160& SPKKey = vSPK.first;
+        if (mapUsedSPK[SPKKey].first == &tx) {
+            mapUsedSPK[SPKKey].first = NULL;
+        }
+        if (mapUsedSPK[SPKKey].second == &tx) {
+            mapUsedSPK[SPKKey].second = NULL;
+        }
+        if (!(mapUsedSPK[SPKKey].first || mapUsedSPK[SPKKey].second)) {
+            mapUsedSPK.erase(SPKKey);
         }
     }
 

src/txmempool.h

@@ -402,7 +402,7 @@ class CTxMemPool
 
     uint64_t CalculateDescendantMaximum(txiter entry) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
-    SPKStates_t mapUsedSPK;
+    std::map<uint160, std::pair<const CTransaction *, const CTransaction *>> mapUsedSPK;
 
 private:
     typedef std::map<txiter, setEntries, CompareIteratorByHash> cacheMap;

src/validation.cpp

@@ -959,9 +959,9 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
                     return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "txn-spk-reused-change");
                 }
             }
-            mssit = m_pool.mapUsedSPK.find(hashSPK);
-            if (mssit != m_pool.mapUsedSPK.end()) {
-                if (mssit->second & MSS_SPENT) {
+            const auto& SPKit = m_pool.mapUsedSPK.find(hashSPK);
+            if (SPKit != m_pool.mapUsedSPK.end()) {
+                if (SPKit->second.second /* Spent */) {
                     return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "txn-mempool-spk-reused-spend");
                 }
             }