Track transaction packages in CTxMemPoolEntry

Associate with each CTxMemPoolEntry all the size/fees of descendant
mempool transactions.  Sort mempool by max(feerate of entry, feerate
of descendants).  Update statistics on-the-fly as transactions enter
or leave the mempool.

Also add ancestor and descendant limiting, so that transactions can
be rejected if the number or size of unconfirmed ancestors exceeds
a target, or if adding a transaction would cause some other mempool
entry to have too many (or too large) a set of unconfirmed in-
mempool descendants.

1 files changed, 24 insertions, 3 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 27278b977a..2a24d38e52 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -921,6 +921,17 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
                 REJECT_HIGHFEE, "absurdly-high-fee",
                 strprintf("%d > %d", nFees, ::minRelayTxFee.GetFee(nSize) * 10000));
 
+        // Calculate in-mempool ancestors, up to a limit.
+        CTxMemPool::setEntries setAncestors;
+        size_t nLimitAncestors = GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
+        size_t nLimitAncestorSize = GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
+        size_t nLimitDescendants = GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
+        size_t nLimitDescendantSize = GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
+        std::string errString;
+        if (!pool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
+            return state.DoS(0, false, REJECT_NONSTANDARD, "too-long-mempool-chain", false, errString);
+        }
+
         // Check against previous transactions
         // This is done last to help prevent CPU exhaustion denial-of-service attacks.
         if (!CheckInputs(tx, state, view, true, STANDARD_SCRIPT_VERIFY_FLAGS, true))
@@ -942,7 +953,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
         }
 
         // Store transaction in memory
-        pool.addUnchecked(hash, entry, !IsInitialBlockDownload());
+        pool.addUnchecked(hash, entry, setAncestors, !IsInitialBlockDownload());
     }
 
     SyncWithWallets(tx, NULL);
@@ -2033,13 +2044,23 @@ bool static DisconnectTip(CValidationState &state) {
     if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
         return false;
     // Resurrect mempool transactions from the disconnected block.
+    std::vector<uint256> vHashUpdate;
     BOOST_FOREACH(const CTransaction &tx, block.vtx) {
         // ignore validation errors in resurrected transactions
         list<CTransaction> removed;
         CValidationState stateDummy;
-        if (tx.IsCoinBase() || !AcceptToMemoryPool(mempool, stateDummy, tx, false, NULL))
+        if (tx.IsCoinBase() || !AcceptToMemoryPool(mempool, stateDummy, tx, false, NULL)) {
             mempool.remove(tx, removed, true);
+        } else if (mempool.exists(tx.GetHash())) {
+            vHashUpdate.push_back(tx.GetHash());
+        }
     }
+    // AcceptToMemoryPool/addUnchecked all assume that new mempool entries have
+    // no in-mempool children, which is generally not true when adding
+    // previously-confirmed transactions back to the mempool.
+    // UpdateTransactionsFromBlock finds descendants of any transactions in this
+    // block that were added back and cleans up the mempool state.
+    mempool.UpdateTransactionsFromBlock(vHashUpdate);
     mempool.removeCoinbaseSpends(pcoinsTip, pindexDelete->nHeight);
     mempool.check(pcoinsTip);
     // Update chainActive and related variables.
@@ -4258,7 +4279,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             LogPrint("mempool", "AcceptToMemoryPool: peer=%d %s: accepted %s (poolsz %u)\n",
                 pfrom->id, pfrom->cleanSubVer,
                 tx.GetHash().ToString(),
-                mempool.mapTx.size());
+                mempool.size());
 
             // Recursively process any orphan transactions that depended on this one
             set<NodeId> setMisbehaving;