Add ancestor tracking to mempool

This implements caching of ancestor state to each mempool entry, similar to
descendant tracking, but also including caching sigops-with-ancestors (as that
metric will be helpful to future code that implements better transaction
selection in CreatenewBlock).

src/main.cpp

@@ -1323,7 +1323,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
                     FormatMoney(nModifiedFees - nConflictingFees),
                     (int)nSize - (int)nConflictingSize);
         }
-        pool.RemoveStaged(allConflicting);
+        pool.RemoveStaged(allConflicting, false);
 
         // Store transaction in memory
         pool.addUnchecked(hash, entry, setAncestors, !IsInitialBlockDownload());

src/txmempool.cpp

@@ -38,6 +38,11 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
     assert(inChainInputValue <= nValueIn);
 
     feeDelta = 0;
+
+    nCountWithAncestors = 1;
+    nSizeWithAncestors = nTxSize;
+    nModFeesWithAncestors = nFee;
+    nSigOpCountWithAncestors = sigOpCount;
 }
 
 CTxMemPoolEntry::CTxMemPoolEntry(const CTxMemPoolEntry& other)
@@ -58,6 +63,7 @@ CTxMemPoolEntry::GetPriority(unsigned int currentHeight) const
 void CTxMemPoolEntry::UpdateFeeDelta(int64_t newFeeDelta)
 {
     nModFeesWithDescendants += newFeeDelta - feeDelta;
+    nModFeesWithAncestors += newFeeDelta - feeDelta;
     feeDelta = newFeeDelta;
 }
 
@@ -99,6 +105,8 @@ void CTxMemPool::UpdateForDescendants(txiter updateIt, cacheMap &cachedDescendan
             modifyFee += cit->GetModifiedFee();
             modifyCount++;
             cachedDescendants[updateIt].insert(cit);
+            // Update ancestor state for each descendant
+            mapTx.modify(cit, update_ancestor_state(updateIt->GetTxSize(), updateIt->GetModifiedFee(), 1, updateIt->GetSigOpCount()));
         }
     }
     mapTx.modify(updateIt, update_descendant_state(modifySize, modifyFee, modifyCount));
@@ -108,6 +116,7 @@ void CTxMemPool::UpdateForDescendants(txiter updateIt, cacheMap &cachedDescendan
 // which has been re-added to the mempool.
 // for each entry, look for descendants that are outside hashesToUpdate, and
 // add fee/size information for such descendants to the parent.
+// for each such descendant, also update the ancestor state to include the parent.
 void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashesToUpdate)
 {
     LOCK(cs);
@@ -228,6 +237,20 @@ void CTxMemPool::UpdateAncestorsOf(bool add, txiter it, setEntries &setAncestors
     }
 }
 
+void CTxMemPool::UpdateEntryForAncestors(txiter it, const setEntries &setAncestors)
+{
+    int64_t updateCount = setAncestors.size();
+    int64_t updateSize = 0;
+    CAmount updateFee = 0;
+    int updateSigOps = 0;
+    BOOST_FOREACH(txiter ancestorIt, setAncestors) {
+        updateSize += ancestorIt->GetTxSize();
+        updateFee += ancestorIt->GetModifiedFee();
+        updateSigOps += ancestorIt->GetSigOpCount();
+    }
+    mapTx.modify(it, update_ancestor_state(updateSize, updateFee, updateCount, updateSigOps));
+}
+
 void CTxMemPool::UpdateChildrenForRemoval(txiter it)
 {
     const setEntries &setMemPoolChildren = GetMemPoolChildren(it);
@@ -236,11 +259,30 @@ void CTxMemPool::UpdateChildrenForRemoval(txiter it)
     }
 }
 
-void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove)
+void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants)
 {
     // For each entry, walk back all ancestors and decrement size associated with this
     // transaction
     const uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
+    if (updateDescendants) {
+        // updateDescendants should be true whenever we're not recursively
+        // removing a tx and all its descendants, eg when a transaction is
+        // confirmed in a block.
+        // Here we only update statistics and not data in mapLinks (which
+        // we need to preserve until we're finished with all operations that
+        // need to traverse the mempool).
+        BOOST_FOREACH(txiter removeIt, entriesToRemove) {
+            setEntries setDescendants;
+            CalculateDescendants(removeIt, setDescendants);
+            setDescendants.erase(removeIt); // don't update state for self
+            int64_t modifySize = -((int64_t)removeIt->GetTxSize());
+            CAmount modifyFee = -removeIt->GetModifiedFee();
+            int modifySigOps = -removeIt->GetSigOpCount();
+            BOOST_FOREACH(txiter dit, setDescendants) {
+                mapTx.modify(dit, update_ancestor_state(modifySize, modifyFee, -1, modifySigOps));
+            }
+        }
+    }
     BOOST_FOREACH(txiter removeIt, entriesToRemove) {
         setEntries setAncestors;
         const CTxMemPoolEntry &entry = *removeIt;
@@ -264,10 +306,7 @@ void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove)
         // transactions as the set of things to update for removal.
         CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
         // Note that UpdateAncestorsOf severs the child links that point to
-        // removeIt in the entries for the parents of removeIt.  This is
+        // removeIt in the entries for the parents of removeIt.
-        // fine since we don't need to use the mempool children of any entries
-        // to walk back over our ancestors (but we do need the mempool
-        // parents!)
         UpdateAncestorsOf(false, removeIt, setAncestors);
     }
     // After updating all the ancestor sizes, we can now sever the link between each
@@ -278,7 +317,7 @@ void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove)
     }
 }
 
-void CTxMemPoolEntry::UpdateState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount)
+void CTxMemPoolEntry::UpdateDescendantState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount)
 {
     nSizeWithDescendants += modifySize;
     assert(int64_t(nSizeWithDescendants) > 0);
@@ -287,6 +326,17 @@ void CTxMemPoolEntry::UpdateState(int64_t modifySize, CAmount modifyFee, int64_t
     assert(int64_t(nCountWithDescendants) > 0);
 }
 
+void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount, int modifySigOps)
+{
+    nSizeWithAncestors += modifySize;
+    assert(int64_t(nSizeWithAncestors) > 0);
+    nModFeesWithAncestors += modifyFee;
+    nCountWithAncestors += modifyCount;
+    assert(int64_t(nCountWithAncestors) > 0);
+    nSigOpCountWithAncestors += modifySigOps;
+    assert(int(nSigOpCountWithAncestors) >= 0);
+}
+
 CTxMemPool::CTxMemPool(const CFeeRate& _minReasonableRelayFee) :
     nTransactionsUpdated(0)
 {
@@ -377,6 +427,7 @@ bool CTxMemPool::addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry,
         }
     }
     UpdateAncestorsOf(true, newit, setAncestors);
+    UpdateEntryForAncestors(newit, setAncestors);
 
     nTransactionsUpdated++;
     totalTxSize += entry.GetTxSize();
@@ -459,7 +510,7 @@ void CTxMemPool::removeRecursive(const CTransaction &origTx, std::list<CTransact
         BOOST_FOREACH(txiter it, setAllRemoves) {
             removed.push_back(it->GetTx());
         }
-        RemoveStaged(setAllRemoves);
+        RemoveStaged(setAllRemoves, false);
     }
 }
 
@@ -532,7 +583,7 @@ void CTxMemPool::removeForBlock(const std::vector<CTransaction>& vtx, unsigned i
         if (it != mapTx.end()) {
             setEntries stage;
             stage.insert(it);
-            RemoveStaged(stage);
+            RemoveStaged(stage, true);
         }
         removeConflicts(tx, conflicts);
         ClearPrioritisation(tx.GetHash());
@@ -590,6 +641,8 @@ void CTxMemPool::check(const CCoinsViewCache *pcoins) const
         innerUsage += memusage::DynamicUsage(links.parents) + memusage::DynamicUsage(links.children);
         bool fDependsWait = false;
         setEntries setParentCheck;
+        int64_t parentSizes = 0;
+        unsigned int parentSigOpCount = 0;
         BOOST_FOREACH(const CTxIn &txin, tx.vin) {
             // Check that every mempool transaction's inputs refer to available coins, or other mempool tx's.
             indexed_transaction_set::const_iterator it2 = mapTx.find(txin.prevout.hash);
@@ -597,7 +650,10 @@ void CTxMemPool::check(const CCoinsViewCache *pcoins) const
                 const CTransaction& tx2 = it2->GetTx();
                 assert(tx2.vout.size() > txin.prevout.n && !tx2.vout[txin.prevout.n].IsNull());
                 fDependsWait = true;
-                setParentCheck.insert(it2);
+                if (setParentCheck.insert(it2).second) {
+                    parentSizes += it2->GetTxSize();
+                    parentSigOpCount += it2->GetSigOpCount();
+                }
             } else {
                 const CCoins* coins = pcoins->AccessCoins(txin.prevout.hash);
                 assert(coins && coins->IsAvailable(txin.prevout.n));
@@ -610,17 +666,19 @@ void CTxMemPool::check(const CCoinsViewCache *pcoins) const
             i++;
         }
         assert(setParentCheck == GetMemPoolParents(it));
+        // Also check to make sure ancestor size/sigops are >= sum with immediate
+        // parents.
+        assert(it->GetSizeWithAncestors() >= parentSizes + it->GetTxSize());
+        assert(it->GetSigOpCountWithAncestors() >= parentSigOpCount + it->GetSigOpCount());
         // Check children against mapNextTx
         CTxMemPool::setEntries setChildrenCheck;
         std::map<COutPoint, CInPoint>::const_iterator iter = mapNextTx.lower_bound(COutPoint(it->GetTx().GetHash(), 0));
         int64_t childSizes = 0;
-        CAmount childModFee = 0;
         for (; iter != mapNextTx.end() && iter->first.hash == it->GetTx().GetHash(); ++iter) {
             txiter childit = mapTx.find(iter->second.ptx->GetHash());
             assert(childit != mapTx.end()); // mapNextTx points to in-mempool transactions
             if (setChildrenCheck.insert(childit).second) {
                 childSizes += childit->GetTxSize();
-                childModFee += childit->GetModifiedFee();
             }
         }
         assert(setChildrenCheck == GetMemPoolChildren(it));
@@ -812,9 +870,9 @@ size_t CTxMemPool::DynamicMemoryUsage() const {
     return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 12 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(mapLinks) + cachedInnerUsage;
 }
 
-void CTxMemPool::RemoveStaged(setEntries &stage) {
+void CTxMemPool::RemoveStaged(setEntries &stage, bool updateDescendants) {
     AssertLockHeld(cs);
-    UpdateForRemoveFromMempool(stage);
+    UpdateForRemoveFromMempool(stage, updateDescendants);
     BOOST_FOREACH(const txiter& it, stage) {
         removeUnchecked(it);
     }
@@ -832,7 +890,7 @@ int CTxMemPool::Expire(int64_t time) {
     BOOST_FOREACH(txiter removeit, toremove) {
         CalculateDescendants(removeit, stage);
     }
-    RemoveStaged(stage);
+    RemoveStaged(stage, false);
     return stage.size();
 }
 
@@ -941,7 +999,7 @@ void CTxMemPool::TrimToSize(size_t sizelimit, std::vector<uint256>* pvNoSpendsRe
             BOOST_FOREACH(txiter it, stage)
                 txn.push_back(it->GetTx());
         }
-        RemoveStaged(stage);
+        RemoveStaged(stage, false);
         if (pvNoSpendsRemaining) {
             BOOST_FOREACH(const CTransaction& tx, txn) {
                 BOOST_FOREACH(const CTxIn& txin, tx.vin) {

src/txmempool.h

@@ -80,6 +80,12 @@ private:
     uint64_t nSizeWithDescendants;  //! ... and size
     CAmount nModFeesWithDescendants;  //! ... and total fees (all including us)
 
+    // Analogous statistics for ancestor transactions
+    uint64_t nCountWithAncestors;
+    uint64_t nSizeWithAncestors;
+    CAmount nModFeesWithAncestors;
+    unsigned int nSigOpCountWithAncestors;
+
 public:
     CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
                     int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
@@ -103,7 +109,9 @@ public:
     size_t DynamicMemoryUsage() const { return nUsageSize; }
 
     // Adjusts the descendant state, if this entry is not dirty.
-    void UpdateState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount);
+    void UpdateDescendantState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount);
+    // Adjusts the ancestor state
+    void UpdateAncestorState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount, int modifySigOps);
     // Updates the fee delta used for mining priority score, and the
     // modified fees with descendants.
     void UpdateFeeDelta(int64_t feeDelta);
@@ -113,6 +121,11 @@ public:
     CAmount GetModFeesWithDescendants() const { return nModFeesWithDescendants; }
 
     bool GetSpendsCoinbase() const { return spendsCoinbase; }
+
+    uint64_t GetCountWithAncestors() const { return nCountWithAncestors; }
+    uint64_t GetSizeWithAncestors() const { return nSizeWithAncestors; }
+    CAmount GetModFeesWithAncestors() const { return nModFeesWithAncestors; }
+    unsigned int GetSigOpCountWithAncestors() const { return nSigOpCountWithAncestors; }
 };
 
 // Helpers for modifying CTxMemPool::mapTx, which is a boost multi_index.
@@ -123,7 +136,7 @@ struct update_descendant_state
     {}
 
     void operator() (CTxMemPoolEntry &e)
-        { e.UpdateState(modifySize, modifyFee, modifyCount); }
+        { e.UpdateDescendantState(modifySize, modifyFee, modifyCount); }
 
     private:
         int64_t modifySize;
@@ -131,6 +144,22 @@ struct update_descendant_state
         int64_t modifyCount;
 };
 
+struct update_ancestor_state
+{
+    update_ancestor_state(int64_t _modifySize, CAmount _modifyFee, int64_t _modifyCount, int _modifySigOps) :
+        modifySize(_modifySize), modifyFee(_modifyFee), modifyCount(_modifyCount), modifySigOps(_modifySigOps)
+    {}
+
+    void operator() (CTxMemPoolEntry &e)
+        { e.UpdateAncestorState(modifySize, modifyFee, modifyCount, modifySigOps); }
+
+    private:
+        int64_t modifySize;
+        CAmount modifyFee;
+        int64_t modifyCount;
+        int modifySigOps;
+};
+
 struct update_fee_delta
 {
     update_fee_delta(int64_t _feeDelta) : feeDelta(_feeDelta) { }
@@ -440,8 +469,12 @@ public:
 public:
     /** 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.*/
+     *  also be in the set, unless this transaction is being removed for being
-    void RemoveStaged(setEntries &stage);
+     *  in a block.
+     *  Set updateDescendants to true when removing a tx that was in a block, so
+     *  that any in-mempool descendants have their ancestor state updated.
+     */
+    void RemoveStaged(setEntries &stage, bool updateDescendants);
 
     /** When adding transactions from a disconnected block back to the mempool,
      *  new mempool entries may have children in the mempool (which is generally
@@ -551,8 +584,12 @@ private:
             const std::set<uint256> &setExclude);
     /** Update ancestors of hash to add/remove it as a descendant transaction. */
     void UpdateAncestorsOf(bool add, txiter hash, setEntries &setAncestors);
-    /** For each transaction being removed, update ancestors and any direct children. */
+    /** Set ancestor state for an entry */
-    void UpdateForRemoveFromMempool(const setEntries &entriesToRemove);
+    void UpdateEntryForAncestors(txiter it, const setEntries &setAncestors);
+    /** For each transaction being removed, update ancestors and any direct children.
+      * If updateDescendants is true, then also update in-mempool descendants'
+      * ancestor state. */
+    void UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants);
     /** Sever link between specified transaction and direct children. */
     void UpdateChildrenForRemoval(txiter entry);