From 2ccb7cca4ac67198ac89bd58f5b4ae41a5163ceb Mon Sep 17 00:00:00 2001
From: Jeremy Rubin <j@rubin.io>
Date: Tue, 14 Jan 2020 11:31:36 -0800
Subject: Add Epoch Guards to CTXMemPoolEntry and CTxMemPool

---
 src/txmempool.cpp | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

(limited to 'src/txmempool.cpp')

diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 441255182e..64b91d6296 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -23,7 +23,7 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFe
                                  int64_t _nTime, unsigned int _entryHeight,
                                  bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp)
     : tx(_tx), nFee(_nFee), nTxWeight(GetTransactionWeight(*tx)), nUsageSize(RecursiveDynamicUsage(tx)), nTime(_nTime), entryHeight(_entryHeight),
-    spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp)
+    spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp), m_epoch(0)
 {
     nCountWithDescendants = 1;
     nSizeWithDescendants = GetTxSize();
@@ -325,7 +325,7 @@ void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, CAmount modifyFee,
 }
 
 CTxMemPool::CTxMemPool(CBlockPolicyEstimator* estimator)
-    : nTransactionsUpdated(0), minerPolicyEstimator(estimator)
+    : nTransactionsUpdated(0), minerPolicyEstimator(estimator), m_epoch(0), m_has_epoch_guard(false)
 {
     _clear(); //lock free clear
 
@@ -1105,4 +1105,23 @@ void CTxMemPool::SetIsLoaded(bool loaded)
     m_is_loaded = loaded;
 }
 
+
+CTxMemPool::EpochGuard CTxMemPool::GetFreshEpoch() const
+{
+    return EpochGuard(*this);
+}
+CTxMemPool::EpochGuard::EpochGuard(const CTxMemPool& in) : pool(in)
+{
+    assert(!pool.m_has_epoch_guard);
+    ++pool.m_epoch;
+    pool.m_has_epoch_guard = true;
+}
+
+CTxMemPool::EpochGuard::~EpochGuard()
+{
+    // prevents stale results being used
+    ++pool.m_epoch;
+    pool.m_has_epoch_guard = false;
+}
+
 SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
-- 
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