Create a txgraph inside CTxMemPool

src/txmempool.cpp

@@ -413,6 +413,7 @@ static CTxMemPool::Options&& Flatten(CTxMemPool::Options&& opts, bilingual_str&
 CTxMemPool::CTxMemPool(Options opts, bilingual_str& error)
     : m_opts{Flatten(std::move(opts), error)}
 {
+    m_txgraph = MakeTxGraph(64, 101'000, ACCEPTABLE_ITERS);
 }
 
 bool CTxMemPool::isSpent(const COutPoint& outpoint) const
@@ -1042,7 +1043,7 @@ void CCoinsViewMemPool::Reset()
 size_t CTxMemPool::DynamicMemoryUsage() const {
     LOCK(cs);
     // Estimate the overhead of mapTx to be 15 pointers + an allocation, as no exact formula for boost::multi_index_contained is implemented.
-    return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 15 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(txns_randomized) + cachedInnerUsage;
+    return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 15 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(txns_randomized) + m_txgraph->GetMainMemoryUsage() + cachedInnerUsage;
 }
 
 void CTxMemPool::RemoveUnbroadcastTx(const Txid& txid, const bool unchecked) {

src/txmempool.h

@@ -19,6 +19,7 @@
 #include <primitives/transaction.h>
 #include <primitives/transaction_identifier.h>
 #include <sync.h>
+#include <txgraph.h>
 #include <util/epochguard.h>
 #include <util/feefrac.h>
 #include <util/hasher.h>
@@ -49,6 +50,11 @@ struct bilingual_str;
 /** Fake height value used in Coin to signify they are only in the memory pool (since 0.8) */
 static const uint32_t MEMPOOL_HEIGHT = 0x7FFFFFFF;
 
+/** How many linearization iterations required for TxGraph clusters to have
+ * "acceptable" quality, if they cannot be optimally linearized with fewer
+ * iterations. */
+static constexpr uint64_t ACCEPTABLE_ITERS = 1'700;
+
 /**
  * Test whether the LockPoints height and time are still valid on the current chain
  */
@@ -376,6 +382,7 @@ public:
 
     uint64_t CalculateDescendantMaximum(txiter entry) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 private:
+    std::unique_ptr<TxGraph> m_txgraph GUARDED_BY(cs);
     typedef std::map<txiter, setEntries, CompareIteratorByHash> cacheMap;